Developmental Regression: Making Placental Cells from Embryonic Stem Cells


A research group from Copenhagen, Denmark has discovered a way to make placental cells from embryonic stem cells. In order to do this, the embryonic stem cells must be developmentally regressed so that they can become wither placenta-making cells rather than inner cell mass cells.

This study is significant for two reasons. First of all, it was thought to be impossible to make placental cells from embryonic stem cells because embryonic stem cells (ESCs) are derived from the inner cell mass cells of 4-5-day old human blastocysts. These early embryos begin as single-celled embryos that divide to form 12-16-cell embryos that undergo compaction. At this time, the cells on the outside become trophoblast cells, which will form the trophectoderm and form the placenta and the cells on the inside will form the inner cell mass, which will form the embryo proper and a few extraembryonic structures. Since ESCs are derived from inner cell mass cells that have been isolated and successfully cultured, they have already committed to a cell fate that is not placental. Therefore, to differentiate ESCs into placental cells would require that ESCs developmentally regress, which is very difficult to do in culture.

Secondly, if this could be achieved, several placental abnormalities could be more easily investigated, For example, pre-eclampsia is a very serious prenatal condition that is potentially fatal to the mother, and is linked to abnormalities of the placenta. Studying a condition such as pre-eclampsia in a culture system would definitely be a boon to gynecological research.

Because human ESCs can express genes that are characteristic of trophoblast cells if they are treated with a growth factor called Bone Morphogen Protein 4 (BMP4), it seems possible to make placental cells from them (see Xu R.H., Chen X., Li D.S., Li R., Addicks G.C., Glennon C., Zwaka T.P., Thomson J.A. BMP4 initiates human embryonic stem cell differentiation to trophoblast. Nat. Biotechnol. 2002;20:1261–1264, and Xu RH. Methods Mol Med. 2006;121:189-202). However, a study by Andreia S. Bernardo and others from the laboratory of Roger Pedersen at the Cambridge Stem Cell Institute strongly suggested that BMP4 treatment, even in the absence of FGF signaling (another growth factor that has to be absent for BMP4 to induce trophoblast-like gene expression from ESCs) the particular genes induced by BMP4 are not exclusive to trophoblast cells and more closely resemble mesodermal gene profiles (see AS Bernardo, et al., Cell Stem Cell. 2011 Aug 5;9(2):144-55).

Into the fray of this debate comes a paper by stem cells scientists at the Danish Stem Cell Center at the University of Copenhagen that shows that it is possible to rewind the developmental state of ESCs.

In this paper, Josh Brickman and his team discovered that if they maintained mouse ESCs under specific conditions, they could cause the cells to regress into very early pre-blastocyst embryonic cells that can form trophoblast cells or ICM cells.

“It was a very exciting moment when we tested the theory, said Brinkman. “We found that not only can we make adult cells but also placenta, in fact we got precursors of placenta, yolk sac as well as embryo from just one cell.”

“This new discovery is crucial for the basic understanding of the nature of embryonic stem cells and could provide a way to model the development of the organism as a whole, rather than just the embryonic portion,” said Sophie Morgani, graduate student and first author of this paper. “In this way we may gain greater insight into conditions where extraembryonic development is impaired, as in the case of miscarriages.”

To de-differentiate the ESCs, Brinkman and his colleagues grew them in a solution called “2i.”  This 2i culture medium contained inhibitors of MEK and GSK3.  MEK is a protein kinase that is a central participant in the “MAP kinase signaling pathway, which is a signaling pathway that is central to cell growth and survival.  This particular signaling pathway is the target of the anthrax toxin, which illustrates its importance,  GSK3 stands for “glycogen synthase kinase 3,” which is a signaling protein in the Wnt pathway.

When the mouse ESCs were grown in 2i medium they expressed genes normally found only in pre-blastocyst embryos (Hex, for example).  Therefore, the 2i medium directs mouse ESCs to de-differentiate.  When ESCs grown in 2i were implanted into mouse embryos, they divided and differentiated into cells that were found in placental and embryonic fates.  This strongly argues that the ESCs grown in 2i became pre-blastocyst embryonic cells.  When the ESCs grown in 2i were also grown with LIF, which stands for “leukemia inhibitory factor” (LIF is a protein required for the maintenance of mouse ESCs in culture), the 2i cells were maintained in culture and grew while maintaining their pre-blastocyst status.  These cells differentiated into placental cells, embryonic or fetal cells.  Essentially, the 2i-cultured cells when from being pluripotent to being “totipotent,” or able to form ALL cell types in the embryo, fetus, or the adult.

ESC de-differentiation in totipotence

“In our study we have been able to see the full picture unifying LIF’s functions: what LIF really does, is to support the very early embryo state, where the cells can make both embryonic cells and placenta. This fits with LIFs’ role in supporting implantation,” said Brinkman.

This study definitively shows that ESCs are NOT embryos.  ESCs can regress in their development but embryos develop forward, becoming more committed as they develop and more restricted in the cell fates they can form.  This should effectively put the nail in the coffin of Lee Silver’s argument against Robert P. George that embryonic stem cells are embryos.  They are definitely and unequivocally, since embryos do NOT develop in reverse, but ESCs can and do.

Robert P. George argues that early human embryos, like the kind used to make ESCs are very young  members of the human race and deserve, at the minimum, the right not to be harmed.  Silver counters that George’s argument is inconsistent because George would not extend the same right to an ESC cell line, which is the same as an embryo.  His reasoning is that mouse ESCs can be transplanted into other mouse embryos that have four copies of each chromosome.  The messed up mouse embryo will make the placenta and the ESCs will make the inner cell mass and the mouse will develop and even come to term.  This is called tetraploid rescue, and Silver thinks that this procedure is a minor manipulation, but that it shows that ESCs are functionally the same as embryos.

I find Silver’s argument wanting on just about all fronts.  This is not a minor manipulation.  The tetraploid embryo is bound for certain death, but the implanted ESCs use the developmental context of the tetraploid embryo to find their place in it and make the inner cell mass.  The ESCs do not do it all on their own, but instead work with the tetraploid embryo in a complex developmental give-and-take to make an embryo with the placenta from one animal and the embryo proper from another.

Thus Silver’s first argument does not demonstrate what he says it does.  All it demonstrates is that ESCs can contribute to an embryo, which is something we already knew and expected.  This new data completes blows Silver’s assertion out of the water, since ESCs can take developmental steps backward and embryos by their very nature and programming, do not.  Thus these two entities are distinct entities and are not identical.  The early embryo is a very young human person, full stop.  We should stop dismembering them in laboratories just to stem our scientific curiosity.

New Liver Stem Cell Might Aid in Liver Regeneration


For patients with end-stage liver disease, a liver transplant is the only viable option to stave off death. Liver failure is the 12th leading cause of death in the United States, and finding a way to regenerate failing livers is one of the Holy Grails of liver research. New research suggests that one it will be feasible to use a patient’s own cells to regenerate their liver.

Researchers at the Icahn School of Medicine at Mount Sinai have discovered that a particular human embryonic stem cell line can be differentiated into a previously unknown liver progenitor cell that can differentiate into mature liver cells.

“The discovery of the novel progenitor represents a fundamental advance in this field and potentially to the liver regeneration field using cell therapy,” said Valerie Gouon-Evans, the senior author of this study and assistant professor of medicine at the Icahn School of Medicine. “Until now, liver transplantation has been the most successful treatment for people with liver failure, but we have a drastic shortage of organs. This discovery may help circumvent that problem.”

Gouon-Evans collaborated with the laboratory of Matthew J. Evans and showed that the liver cells that were made from the differentiating liver progenitor cells could be infected with hepatitis C virus. Since this is a property that is exclusive to liver cells, this result shows that these are bona fide liver cells that are formed from the progenitor cells.

One critical step in this study was the identification of a new cell surface protein called KDR, which is the vascular endothelial growth factor 2. KDR was thought to be restricted to blood vessels, blood vessels progenitor cells (EPCs), and blood cells.  However, the Evans / Gouon-Evans study showed that activation of KDR in liver progenitor cells caused them to differentiate into mature liver cells (hepatocytes).  KDR is one of the two receptors for VEGF or vascular endothelial growth factor.  Mutations of this gene are implicated in infantile capillary hemangiomas.

KDR Protein Crystal Structure
KDR Protein Crystal Structure

The next step in this work is to determine if liver cells formed from these embryonic stem cells could potentially facilitate the repair of injured livers in animal models of liver disease.

Neural Stem Cells Improve Spinal Injuries in Rats


Disclaimer:  I am reporting on this experiment because of its significance for people with spinal cord-injuries even though I remain appalled at the manner in which the stem cells were acquired.

An international research team has reported that a single set of injections of human neural stem cells had provided significant neuronal regeneration and improvement of function in rats impaired by acute spinal cord injury.

Dr. Martin Marsala, who is professor of anesthesiology at the University of California, San Diego, with colleagues from academic institutions in Slovakia, the Czech Republic, and the Netherlands, used neural stem cells derived from an aborted human fetus to treat spinal cord-injured rats.

Sprague-Dawley rats received spinal cord injuries at the level of the third lumbar vertebra by means of compression. Such injuries render the rats incapable of using their hind legs. They cannot climb a ladder, walk a catwalk or perform other tasks that require the effective use of their hind legs.

The stem cells that were transplanted into the spinal cords of these rats were NSI-566RSC cells, which were provided by the biotechnology company Neuralstem. These cells were initially isolated from the spinal cord of an eight-week old human fetus whose life was terminated through elective abortion. These cells have been grown in culture and split many times. They are a neural stem cell culture that has the capacity to form neurons and glia.

The rats were broken into six groups, and four of these groups received spinal cord injuries. One of these spinal cord-injured groups received injections of were injured NSI-566RSC cells (12 injections total, about 20,000 cells per microliter of fluid injected), another received injections of only fluid, and the third group received no injections. The final spinal cord-injured group of rats received injections of NSI-566RSC cells that had been genetically engineered to express a green glowing protein. Another group of rats were operated on, but no spinal cord injury was given to these animals, and the final group of rats were never operated on.

All rats that received injections of cells were administered powerful drugs to prevent their immune systems from rejecting the administered human cells before the injections (methylprednisolone acetate for those who are interested at 10 mg / kg), and after the stem cell injections (tacrolimus at 1.5 mg / kg).

The results were significant and exciting. In the words of Marsala, “The primary benefits were improvement in the positioning and control of paws during walking tests and suppression of muscle spasticity.” Spasticity refers to an exaggerated muscle tone or uncontrolled spasms of muscles. Spasticity is a serious and common complication of traumatic injury. It can cause severe cramping and uncontrolled contractions of muscles, which increases the patient’s pain and decreases their control.

First, it is clear from several control experiments that the injection procedure did not affect the spinal cord function of these animals, since the sham injected rats had perfectly normal use of their hind limbs and normal sensory function of their limbs. Thus the injection procedure is innocuous. Also, the use of the drugs to suppress the immune response were also equally unimportant when it came to the spinal cord health of the rats.

Two months after the stem cell injections, the rats were subjected to the “catwalk test,” in which the animals walked a narrow path and their paw position was assessed. As you can see in the figure below, the stem cell-injected rats have a paw position that is far more similar to the normal rats than to the spinal cord injured rats.

Improvement in hind paw positioning and muscle spasticity in SCI animals grafted with HSSC. A: CatWalk gait analysis of hind paw positioning at two months after treatment. In comparison to SCI control animals, a significant improvement was seen in HSSC-grafted animals. B1-B3: An example of paw step images taken from the CatWalk software in naïve (B1), SCI-control (B2) and SCI-HSSC-treated animals (B3). Note a large paw footprint overlap between the front and hind paws in naïve animals (B1) but a substantial dissociation in footprint overlap in SCI controls (B2). An improvement in paw placement in SCI-HSSC-treated animals can be seen (B3). C: Statistical analysis showed significant suppression of spasticity response (expressed as a muscle resistance ratio: values at two months versus seven days post injury in ‘HIGH spasticity’ HSSC-treated animals if compared to ‘HIGH spasticity’ controls). D: To identify the presence of muscle spasticity in fully awake animals, the hind-paw ankle is rotated 40° at a velocity of 80°/second. Spasticity is identified by exacerbated EMG activity measured in the gastrocnemius muscle and corresponding increase in muscle resistance. In control SCI animals with developed spasticity (that is, ‘high spasticity’/HIGH group), no change in spasticity response if compared to seven days post-vehicle injection was seen at two months (compare D1 to D3). In contrast to SCI control animals, a decrease in spasticity response was seen in SCI-HSSC-treated animals at two months after cell injections (compare D4 to D6). To identify mechanical resistance, animals are anesthetized with isoflurane at the end of the recording session and the contribution of mechanical resistance (which is, isoflurane non-sensitive) is calculated. (D2, D5: data expressed as mean ± SEM; one-way ANOVAs). ANOVA, analysis of variance; EMG, electromyography; HSSC, human fetal spinal cord-derived neural stem cells; SCI, spinal cord injury; SEM, standard error of the mean.
Improvement in hind paw positioning and muscle spasticity in SCI animals grafted with HSSC. A: CatWalk gait analysis of hind paw positioning at two months after treatment. In comparison to SCI control animals, a significant improvement was seen in HSSC-grafted animals. B1-B3: An example of paw step images taken from the CatWalk software in naïve (B1), SCI-control (B2) and SCI-HSSC-treated animals (B3). Note a large paw footprint overlap between the front and hind paws in naïve animals (B1) but a substantial dissociation in footprint overlap in SCI controls (B2). An improvement in paw placement in SCI-HSSC-treated animals can be seen (B3). C: Statistical analysis showed significant suppression of spasticity response (expressed as a muscle resistance ratio: values at two months versus seven days post injury in ‘HIGH spasticity’ HSSC-treated animals if compared to ‘HIGH spasticity’ controls). D: To identify the presence of muscle spasticity in fully awake animals, the hind-paw ankle is rotated 40° at a velocity of 80°/second. Spasticity is identified by exacerbated EMG activity measured in the gastrocnemius muscle and corresponding increase in muscle resistance. In control SCI animals with developed spasticity (that is, ‘high spasticity’/HIGH group), no change in spasticity response if compared to seven days post-vehicle injection was seen at two months (compare D1 to D3). In contrast to SCI control animals, a decrease in spasticity response was seen in SCI-HSSC-treated animals at two months after cell injections (compare D4 to D6). To identify mechanical resistance, animals are anesthetized with isoflurane at the end of the recording session and the contribution of mechanical resistance (which is, isoflurane non-sensitive) is calculated. (D2, D5: data expressed as mean ± SEM; one-way ANOVAs). ANOVA, analysis of variance; EMG, electromyography; HSSC, human fetal spinal cord-derived neural stem cells; SCI, spinal cord injury; SEM, standard error of the mean.

Secondly, when muscle spasticity was measured, the stem cell-injected rats showed definite decreases in muscle spasticity. The spinal cord-injured rats that received no stem cell injections showed no such changes.

Sensory assessments also showed improvements in the stem cell-treated rats, but the improvements were not stellar. Nevertheless, the stem cell-treated rats progressively improved in their sensory sensitivity whereas the non-treated spinal cord-injured rats consistently showed no such improvement.

Amelioration of hypoesthesia in SCI-HSSC-grafted animals. Baseline and biweekly assessments of perceptive thresholds for (A) mechanical and (B) thermal stimuli, applied below the level of injury, showed a trend towards progressive recovery in SCI-HSSC-grafted animals. C: When expressed as percentages of the maximal possible effect for mechanical and thermal perceptive thresholds improvements, SCI-HSSC-treated animals showed significant improvements in sensory function for both mechanical and thermal components. (A-C: data expressed as mean ± SEM; A-B: repeated measures ANOVAs; C: Student t-tests). ANOVA, analysis of variance; HSSC, human fetal spinal cord-derived neural stem cells; SCI, spinal cord injury; SEM, standard error of the mean.
Amelioration of hypoesthesia in SCI-HSSC-grafted animals. Baseline and biweekly assessments of perceptive thresholds for (A) mechanical and (B) thermal stimuli, applied below the level of injury, showed a trend towards progressive recovery in SCI-HSSC-grafted animals. C: When expressed as percentages of the maximal possible effect for mechanical and thermal perceptive thresholds improvements, SCI-HSSC-treated animals showed significant improvements in sensory function for both mechanical and thermal components. (A-C: data expressed as mean ± SEM; A-B: repeated measures ANOVAs; C: Student t-tests). ANOVA, analysis of variance; HSSC, human fetal spinal cord-derived neural stem cells; SCI, spinal cord injury; SEM, standard error of the mean.

What were the implanted cells doing? To answer this question, Marsala and his co-workers examined tissue sections of spinal cords from the rats implanted with the glowing green stem cells. According to Marsala, the implanted neural stem cells are stimulating host neuron regeneration and partially replacing the function of lost neurons.

Marsala explained: “Grafted spinal stem cells are a rich source of different growth factors which can have a neuroprotective effect and can promote sprouting of nerve fibers of host neurons. We have demonstrated that grafted neurons can develop contacts with the host neurons and, to some extent, restore the connectivity between centers, above and below the injury, which are involved in motor and sensory processing.”

The implanted neural stem cells definitely showed extensive integration with the spinal nerves of the host rats. Again Marsala, “In all cell-grafted animals, there was a robust engraftment and neuronal maturation of grafted human neurons was noted.” Marsala continued: “Importantly cysts or cavities were not present in any cell-treated animal. The injury-caused cavity was completely filled by grafted cells.”

Effective cavity-filling effect by transplanted cells in SCI HSSC-injected animals. At the end of the two-month post-treatment survival, animals were perfusion fixed with 4% PFA, the spinal column dissected and MRI-imaged in situ before spinal cord dissection for further histological processing. A, B: Three-dimensional MRI images of spinal cord segments in animals with previous traumatic injury and treated with spinal HSSC (A) or media (B) injections. Note the near complete injected-cells cavity-filling effect in HSSC-treated animals. A1, A2, B1, B2: To validate the presence of grafted cells or cavitation at the epicenter of injury, the same region was histologically processed, semi-thin plastic sections prepared and compared to the corresponding MRI image (compare A1 to A2 and B1 to B2). C: Two-dimensional MRI image taken from a naïve-non-injured animal. D: Quantification of the cavity and scar volume from serial MRI images showed significantly decreased cavity and scar volumes in SCI-HSSC-injected animals if compared to media-injected SCI controls. (D: data expressed as mean ± SEM; Student t-tests), (Scale Bars: A, B: 5 mm; A1, A2, B1, B2, C: 3 mm). HSSC, human fetal spinal cord-derived neural stem cells; MRI, magnetic resonance imaging; PFA, paraformaldehyde; SCI, spinal cord injury; SEM, standard error of the mean.
Effective cavity-filling effect by transplanted cells in SCI HSSC-injected animals. At the end of the two-month post-treatment survival, animals were perfusion fixed with 4% PFA, the spinal column dissected and MRI-imaged in situ before spinal cord dissection for further histological processing. A, B: Three-dimensional MRI images of spinal cord segments in animals with previous traumatic injury and treated with spinal HSSC (A) or media (B) injections. Note the near complete injected-cells cavity-filling effect in HSSC-treated animals. A1, A2, B1, B2: To validate the presence of grafted cells or cavitation at the epicenter of injury, the same region was histologically processed, semi-thin plastic sections prepared and compared to the corresponding MRI image (compare A1 to A2 and B1 to B2). C: Two-dimensional MRI image taken from a naïve-non-injured animal. D: Quantification of the cavity and scar volume from serial MRI images showed significantly decreased cavity and scar volumes in SCI-HSSC-injected animals if compared to media-injected SCI controls. (D: data expressed as mean ± SEM; Student t-tests), (Scale Bars: A, B: 5 mm; A1, A2, B1, B2, C: 3 mm). HSSC, human fetal spinal cord-derived neural stem cells; MRI, magnetic resonance imaging; PFA, paraformaldehyde; SCI, spinal cord injury; SEM, standard error of the mean.

Marsala’s goal is to used a neuronal stem cell line derived from a patient-specific induced pluripotent stem cell line in a clinical trial. For now, the UC San Diego Institutional Review Board or IRB is reviewing a small phase 1 clinical trial to test the safety and efficacy of this neural stem cell line in patients with spinal cord injuries who have no feeling or motor function below the level of the spinal cord injury.

Mouse Model of Huntington’s Disease Shows Replacement of Lost Neurons by Endogenous Stem Cell Populations


Huntington’s disease (HD) is a debilitating and invariably fatal disease that results from mutations in the IT15 gene. IT151 stands for “interesting transcript 15,” but it is more commonly referred to as the “huntingtin” gene. Mutations in the front of the gene (exon 1 for those who are interested) expand a run of CAG codons, and these mutations are probably the result of DNA polymerase slippage. Because CAG codons encode the amino acid glutamine, the mutant proteins contain long polyglutamine repeats and these repeats tend to clump inside neurons.

These protein aggregates form in neurons of the “striatum.” The striatum is a region of the brain that is also called the striate nucleus of the striate body. The striatum receives its name from the fact that it is organized in striped layers of gray and white matter. The striate nucleus is part of the cerebrum or forebrain.

Striatum

Mutant Huntington (Htt) protein has a toxic that causes cell death by means of unknown mechanisms. Clinically, the most obvious symptoms of HD involve involuntary movements of the arms, legs, and face. But the severe cognitive and personality changes are the most devastating to HD patients and most troubling for their caregivers.

Researchers are using animal models of HD to study the disease pathogenesis, to elucidate areas of the brain involved in structural and functional decline, and to evaluate potential therapeutic interventions. These animal models include injecting toxins into the brain to kill off those populations of neurons that typically die in HD patients, and transgenic models in which animals are bred with either extra mutant copies of the Htt gene or a pair of copies of the mutant Htt gene that have replaced the original, normal copies. All of these model systems have limitations, but they are all useful in some way for assessing the pathology of HD.

This long introduction leads us to new data from the laboratory of Steve Goldman, the co-director of the University of Rochester Medical Center’s Center for Translational Medicine. Goldman and his colleagues triggered the production of new neurons in mice that had a rodent form of HD. These new neurons successfully integrated into the brain’s existing neural networks and dramatically extended the survival of the mice.

“This study demonstrates the feasibility of a completely new concept to treat Huntington’s disease, by recruiting the brain’s endogenous neural stem cells to regenerate cell lost the disease,” said Goldman.

One of the types of neurons most commonly affected in HD patients is the medium spinal neuron, which is critical to motor control. Goldman banked on findings from previous studies in his laboratory on canaries. Songbirds such as canaries have the ability to lay down new neurons in the adult brain when mating season comes. The male birds, in response to a flush of male sex hormones,, grow a gaggle of new neurons in the vocal control centers of the brain, and this provides the bird the means to sing specific songs in order to attract mates. This event is known as adult neurogenesis, and Goldman and Fernando Nottebohm of the Rockefeller University discovered this phenomenon in the early 1980s.

“Our work with canaries essentially provided us with the information we needed to understand how to add new neurons to adult brain tissue,” said Goldman. Once we mastered how this happened in birds, we set about how to replicate the process in the adult mammalian brain.”

Humans possess the ability to make new neurons, but Goldman’s lab demonstrated in the 1990s that a font of neuronal precursor cells exist in the lining of the ventricles (these are structures at the very center of the brain and spinal cord that are filled with cerebrospinal fluid). In early development, these cells are actively producing neurons.

Shortly after birth, the neural stem cells stop generating neurons and produce support cells called glia. Some parts of the human brain continue to produce neurons into adulthood, the most prominent example is the hippocampus, where memories are formed and stored. However, the striatum, new neuron production is switched off in adulthood.

Goldman sought to switch neuron production back on in the striatum. He tested a cadre of growth factors that would switch the neural stem cells of the striatum (a region that is ravaged by HD) from producing new glia to producing new neurons. Goldman, however, had some help from his recent work in canaries. Namely that once mating season was upon the birds, targeted expression of brain-derived neurotrophic factor (BDNF) flared up in the vocal centers of the brain, where many new neurons were being produced.

Goldman used genetically engineered viruses to express BDNF and another protein called “Noggin” in the striatum. Goldman and others found that a single intraventricular injection of the adenoviruses expressing BDNF and Noggin triggered the sustained recruitment of new neurons in both normal of R6/2 (HD) mice. These treated mice also showed that the newly formed neurons were recruited to form new medium spiny neurons; the ones destroyed in HD. These new neurons also matured and achieved circuit integration.

Medium Spinal Neuron
Medium Spinal Neuron

Also the treated mice showed delayed deterioration of motor function and substantially increased survival.

When the same experiments were conducted in squirrel monkeys, there was a similar addition of new striatal neurons.

Thus, induced neuronal addition may therefore represent a promising avenue for decreasing the ravages of HD and increasing cognitive ability.

ATHENA Trial Tests Fat-Derived Stem Cells as a Treatment for Heart Failure


The FDA-approved ATHENA trial is the brainchild of stem cell researchers at the Texas Heart Institute at St. Luke’s Episcopal Hospital. The ATHENA trial is the first trial in the United States to examine the efficacy of adipose-derived regenerative cells or ADRCs as a treatment for a severe form of heart failure.

To harvest ADRCs, Texas Heart Institute researchers used a technique that was developed by Cytori Therapeutics, which is a biotechnology company that specializes in cell-based regenerative therapies. Previous clinical trials in Europe strongly suggest that such ADR-based therapies are quite safe and feasible. To date, physicians are the Texas Heart Institute have treated six patients as a part of the ATHENA trial.

athena_process_illustration_500x369.jpg

James Willerson, the president and medical director of the Texas Heart Institute, is the principal investigator in the ATHENA trial. Willerson said, “We have found that body fat tissue is a valuable source of regenerative stem cells that are relatively easy to access. We have high hopes for the therapeutic promise of this research and believe that it will lead quickly to larger trials.”

The subjects for the ATHENA trial are patients who suffer from chronic heart failure due to coronary heart disease. Coronary heart disease results from blockage of the coronary vessels and feed the heart muscle and limits the oxygen supply to the heart muscle, and consequently, the pumping activity of the heart muscle. Data from the American Heart Association reveals that there are about 5.1 million Americans who currently live with heart failure, and in many cases, the only viable treatment is a left ventricular assist device (LVAD) or a heart transplant. Unfortunately, there are only about 2,200 heart transplants a year due to a severe shortage of organs.

Coronary artery disease

Patients who are enrolled in the ATHENA trials are randomized and some will receive a placebo treatment and others will receive the experimental treatment. All patients will undergo liposuction in order to remove adipose or fat tissue. Processing of the fat tissue isolates the ADRCs, and the experimental patients will have these cells injected directly into their heart muscle, but the placebo patients will receive injections of culture medium or saline that contains no cells. ATHENA will measure several data endpoints that include objective measures of heart function, exercise capacity, and questionnaires that assess the symptoms and health-related quality-of-life.

The US trial will enroll a total of 45 patients at several centers around the country and these centers include the Texas Heart Institute, Minneapolis Heart Institute, Scripps Green Hospital in San Diego, CA, the University of Florida at Gainesville, and Cardiology P.C. in Birmingham. Patients are being enrolled.

Healthline has recently compiled the statistics on heart disease in an impressive and colorful manner at this link.

Adult Stem Cells to Cure Diabetes?


Type 1 diabetics must inject themselves with insulin on a daily basis in order to survive. Without these shots, they would die.

Insulin injection

In most cases, type 1 diabetics have diabetes because their immune systems have attacked their insulin-producing cells and have destroyed them. However, a recent study at the University of Missouri has revealed that the immune system-dependent damage to the pancreas in type 1 diabetics goes beyond direct damage to the insulin-producing cells in the pancreas, The immune response also destroys blood vessels that feed tissues within the pancreas. This finding could provide the impetus for a cure that includes a combination of drugs and stem cells.

Habib Zaghouani and his research team at the University of Missouri School of Medicine discovered that “type 1 diabetes destroys not only insulin-producing cells but also blood vessels that support them,” explained Zaghouani. “When we realized how important the blood vessels were to insulin production, we developed a cure that combines a drug we created with adult stem cells from bone marrow. The drug stop the immune system attack, and the stem cells generate new blood vessels that help insulin-producing cells to multiply and thrive.”

Type 1 diabetes or juvenile diabetes, can lead to numerous complications, including cardiovascular disease, kidney damage, nerve damage, osteoporosis and blindness. The immune response that leads to type 1 diabetes attacks the pancreas, and in particular, the cell clusters known as the islet of Langerhans or pancreatic islets. Pancreatic islets contain several hormone-secreting cells types, but the one cell type in particular attacked by the immune system in type 1 diabetics are the insulin-secreting beta cells.

Pancreatic islets
Pancreatic islets

Destruction of the beta cells greatly decreases the body’s capability to make insulin, and without sufficient quantities of insulin, the body’s capability to take up, utilize and store sugar decelerates drastically, leading to mobilization of fats stores, the production of acid, wasting of several organs, excessive water loss, constant hunger, thirst, urination, acidosis (acidification of the blood), and eventually coma and death if left untreated.

The immune system not only destroys the beta cells, it also causes collateral damage to small blood vessels (capillaries) that carry blood to and from the pancreatic islets. This blood vessel damage led Zaghouani to examine ways to head this off at the pass and heal the resultant damage.

In previous studies, Zaghouani and others developed a drug against type 1 diabetes called Ig-GAD2. Treatment with this drug stops the immune system from attacking beta cells, but, unfortunately too few beta cells survived the onslaught from the immune system to reverse the disease. In his newest study, Zaghouani and his colleagues treated non-obese diabetic (NOD) with Ig-GAD2 and then injected bone marrow-based stem cells into the pancreas in the hope that these stem cells would differentiate into insulin-secreting beta cells.

“The combination of Ig-GAD2 and bone marrow [stem] cells did result in production of new beta cells, but not in the way we expected,” explained Zaghouani. “We thought the bone marrow [stem] cells would evolve directly into beta cells. Instead, the bone marrow cells led to growth of new blood vessels, and it was the new blood vessels that facilitated reproduction of the new beta cells. In other words, we discovered that to cure type 1 diabetes, we need to repair the blood vessels that allow the subject’s beta cells to grow and distribute insulin throughout the body.”

Zaghouani would lie to acquire a patent for his promising treatment and hopes to translate his preclinical research discovery from mice to larger animals and then to humans. In the meantime, his research continues to be funded by the National Institutes of Health and the University of Missouri.

Stem Cells to Make Red Blood Cells and Platelets in Culture


A collaborative study between Boston University School of Public Health and researchers at Boston Medical Center has used induced pluripotent stem cells to make unlimited numbers of human red blood cells and platelets in culture.

This finding could potentially reduce the need for blood donations to treat patients who require blood transfusions. Such research could also help researchers examine fresh and new therapeutic targets in order to treat blood diseases such a sickle-cell anemia.

The lead scientist on this project was George Murphy, assistant professor of medicine at Boston University School of Medicine and co-director of the Center for Regenerative Medicine at Boston University. Murphy’s main collaborator was David Sherr, professor of environmental health at Boston University School of Medicine and the Boston University School of Public Health.

Induced pluripotent stem cells or iPSCs are made from adult cells by applying genetic engineering technology to the adult cells that introduces genes into them. The introduction of four specific genes de-differentiates the adult cells into pluripotent stem cells that can, potentially, differentiate into any adult cell type. This makes iPSCs powerful tools for research and potential therapeutic agents for regenerative medicine.

In this study, Murphy and others used iPSCs from the CreM iPS Cell Bank and exposed them to a battery of different growth factors in order to push them to differentiate into different adult cell types. They were looking for the precise cocktail to differentiate iPSCs into red blood cells, since they wanted to further study red blood cell development in detail.

One group of compounds given to the set of iPSCs were molecules that activate “aryl hydrocarbon” receptors. Aryl hydrocarbon receptors (AHRs) play important roles in the expansion of hematopoietic stem cells, which make blood cells, since antagonism of AHRs promotes expansion of hematopoietic stem cells (see AE Boitano et al.,Science 10 September 2010: Vol. 329 no. 5997 pp. 1345-1348). In this case, however, Murphy and his colleagues observed a dramatic increase in the production of functional red blood cells and platelets in a short period of time. THis suggests that the ARH is important for normal blood cell development.

Aryl Hydrocarbon Receptor
Aryl Hydrocarbon Receptor

“This finding has enabled us to overcome a major hurdle in terms of being able to produce enough of these cells to have a potential therapeutic impact both in the lab and, down the line, in patients,” said Murphy. “Additionally, our work suggests that AHR has a very important biological function in how blood cells form in the body.”

“Patient-specific red blood cells and platelets derived from iPSC cells, which would solve problems related to immunogenicity and contamination, could potentially be used therapeutically and decrease the anticipated shortage and the need for blood donation,” added Murphy.

iPS-derived cells have tremendous potential as model systems in which scientists can test and develop new treatments for disease, given that such diseases can be constructed in the laboratory. These iPSC-derived red blood cells could be used by malaria researchers, and IPSC-derived platelets could be used to explore cardiovascular disease and treatments for blood clotting disorders.

Because my mother died from myelodysplasia, this finding has some personal interest to me. Mom had a difficult blood type to match, since she had the Bombay blood type (H). Finding blood for her was a major tour de force, and as she received blood that was less and less well matched to her body, she suffered the ravages of poorly matched blood. A treatment of red blood cells made from IPSCs derived from her own cells might have extended her life and even improved her quality of life in her later years.

I look forward to this research eventually culminating in clinical trials.

Tests to Improve Stem Cell Safety


Stem cell scientists from the Commonwealth Scientific and Industrial Research Organisation or CSIRO (the Australian version of the NIH) have developed a test to identify unsafe pluripotent stem cells that can potentially cause tumors. This test is one of the first tests specifically designed for human induced pluripotent stem cells or iPSCs.

The development of this test marks a significant breakthrough in improving the quality of iPSCs and identifying unwanted stem cells that can form tumors. The test also directly assesses the stability of iPSCs when they are grown in the lab.

Andrew Laslett and his team have spent the last five years working on this research project and perfecting their test.

Laslett explained: “The test we have developed allows us to easily identify unsafe iPSC cells. Ensuring the safety of these cell lines is paramount and we hope this test will become a routine screen as part of developing safe and effective iPS-based cell therapies.”

Laslett’s research focused on comparing different types of iPS cells with human embryonic stem cells. Induced pluripotent stem cells are, at this time, the most commonly used type of pluripotent stem cell in research.

Laslett’s method has established that iPSCs made in certain ways are inherently less stable and riskier than those made by alternative means. For example, the classical way of making iPSCs, with genetically engineered retroviruses that insert their genes into the chromosomes of the cells they infect, can cause insertional mutations and are inherently more likely to cause tumors. In comparison, iPSCs made with viruses that do not integrate into the host cell’s DNA (that is, with genetically engineered adenoviruses), or made with plasmid DNA, mRNA or modified proteins, do not form tumors.

Laslett hopes the study and the new test method will help to raise the awareness and the importance of stem cell safety. He also predicts that tests like his will promote a kind of quality control over the production of iPSC lines.

“It is widely accepted that iPS cells made using viruses should not be used for human treatment, but they can also be used in research to understand diseases and identify new drugs. Having the assurance of safe and stable cells in all situations should be a priority,” said Laslett.

This test utilizes laser technology that activates fluorescent dyes attached to antibodies that are bound to specific cell surface proteins.  If the cell has the cell surface protein bound by the antibody, the cell and its surface proteins fluoresce, and it is sent into the positive test tube.  If it does not fluoresce, it is sent to the negative test tube.  This technique is called fluorescence activated cell sorting or FACS.  In order to identify proteins found the surfaces of iPSCs, Laslett’s team used dye-conjugated antibodies that bound to surface proteins TG30 (CD9) and GCTM-2.  The presence of these specific cell-surface proteins provides a means to separate cells into safe and unsafe cell lines.  Very early-stage differentiated stem cells that expressed TG30 (CD9) and GCTM-2 on their cell surfaces tend to dedifferentiate into pluripotent cells after differentiation and cause tumors, whereas those very early-stage differentiation stem cell lines that do not express TG30 (CD9) and GCTM-2 on their cell surfaces do not cause tumors.  After separation of the stem cell lines by FACS, the iPSC lines were further monitored as they grew in culture.  Unsafe iPS cell lines that form tumors usual clump together to make recognizable clusters of cells.  However, the safe iPS cell lines do no such thing. This test can also be applied to somatic cell nuclear transfer human embryonic stem cells.

Professor Martin Pera, the Program Leader of Stem Cells, Australia said, “Although cell transplantation therapies based on iPS cells are being fast tracked for testing in humans, there is still much debate in the scientific community over the potential hazards of this new technology.”

Improving Cartilage Production By Stem Cells


To repair cartilage, surgeons typically take a piece of cartilage from another part of the injured joint and patch the damaged area, this procedure depends on damaging otherwise healthy cartilage. Also, such autotransplantation procedures are little protection against age-dependent cartilage degeneration.

There must be a better way. Bioengineers want to discover more innovative ways to grow cartilage from patient’s own stem cells. A new study from the University of Pennsylvania might make such a wish come true.

This research, comes from the laboratories of Associate professors Jason Burdick and Robert Mauck.

“The broad picture is trying to develop new therapies to replace cartilage tissue, starting with focal defects – things like sports injuries – and then hopefully moving toward surface replacement for cartilage degradation that comes with aging. Here, we’re trying to figure the right environment for adult stem cells to produce the best cartilage,” said Burdick.

Why use stem cells to make cartilage? Mauck explained, “As we age, the health and vitality of cartilage cells declines so the efficacy of any repair with adult chondrocytes is actually quite low. Stem cells, which retain this vital capacity, are therefore ideal.”

Burdick and his colleagues have long studied mesenchymal stem cells (MSCs), a type of adult stem cell found in bone marrow and many other tissues as well that can differentiate into bone, cartilage and fat. Burdick’s laboratory has been investigating the microenvironmental signals that direct MSCs to differentiate into chondrocytes (cartilage-making cells).

chondrocytes
chondrocytes

A recent paper from Burdick’s group investigated the right conditions for inducing fat cell or bone cell differentiation of MSCs while encapsulated in hydrogels, which are polymer networks that simulate some of the environmental conditions as which stem cells naturally grow (see Guvendiren M, Burdick JA. Curr Opin Biotechnol. 2013 Mar 29. pii: S0958-1669(13)00066-9. doi: 10.1016/j.copbio.2013.03.009). The first step in growing new cartilage is initiating cartilage production or chondrogenesis. To do this, you must convince the MSCs to differentiate into chondrocytes, the cells that make cartilage. Chondrocytes secrete the spongy matrix of collagen and acidic sugars that cushion joints. One challenge in promoting MSC differentiation into chondrocytes is that chondrocyte density in adult tissue is rather low. However, cartilage production requires that the chondrocytes be in rather close proximity.

Burdick explained: “In typical hydrogels used in cartilage tissue engineering, we’re spacing cells apart so they’re losing that initial signal and interaction. That’s when we started thinking about cadherins, which are molecules that these cells used to interact with each other, particularly at the point they first become chondrocytes.”

Desmosomes can be visualized as rivets through the plasma membrane of adjacent cells. Intermediate filaments composed of keratin or desmin are attached to membrane-associated attachment proteins that form a dense plaque on the cytoplasmic face of the membrane. Cadherin molecules form the actual anchor by attaching to the cytoplasmic plaque, extending through the membrane and binding strongly to cadherins coming through the membrane of the adjacent cell.
Desmosomes can be visualized as rivets through the plasma membrane of adjacent cells. Intermediate filaments composed of keratin or desmin are attached to membrane-associated attachment proteins that form a dense plaque on the cytoplasmic face of the membrane. Cadherin molecules form the actual anchor by attaching to the cytoplasmic plaque, extending through the membrane and binding strongly to cadherins coming through the membrane of the adjacent cell.

In order to simulate this microenvironment, Burdick and his collaborators and colleagues used a peptide sequence that mimics these cadherin interactions and bound them to the hydrogels that were then used to encapsulate the MSCs.

According to Mauck, “While the direct link between cadherins and chondrogenesis is not completely understood, what’s known is that if you enhance these interactions early during tissue formation, you can make more cartilage, and, if you block them, you get very poor cartilage formation. What this gel does is trick the cells into think it’s got friends nearby.”

See L Bian, et al., PNAS 2013; DOI:10.1073/pnas.1214100110.

Studying Tough-to-Examine Disease by Using Brain Cells Made from Stem Cells


Diseases that are hard to study, such as Alzheimer’s, schizophrenia, and autism can be examined more safely and effectively thanks to an innovative new method for making mature brain cells from reprogrammed skin cells. Gong Chen, the Verne M. William Chair in Life Sciences and professor of biology at Penn State University and the leader of the research team that designed this method said this: “The most exciting part of this research is that it offers the promise of direct disease modeling, allowing for the creation, in a Petri dish, of mature human neurons that behave a lot like neurons that grow naturally in the human brain.”

Chen’s method could lead to customized treatment for individual patients that are based on their own genetic and cellular profile. Chen explained it this way: “Obviously we do not want to remove someone’s brain to experiment on, so recreating the patient’s brain cells in a Petri dish is the next best thing for research purposes and drug screening.”

In previous work, scientists at the University of Wisconsin in James Thomson’s laboratory and in Shinya Yamanaka’s laboratory at Kyoto University in Kyoto, Japan discovered a way to reprogram adult cells into pluripotent stem cells. Such stem cells are called induced pluripotent stem cells or iPSCs. To make iPSCs, scientists infect adult cells with genetically engineered viruses that introduce four specific genes (OCT4, SOX2, KLF4 and cMYC for those who are interested). These genes encode transcription factors, which are proteins that bind to DNA or to the machinery that directly regulates gene expression.  These transcription factors turn on those genes (e.g., OCT4, NANOG, REX1, DNMT3β and SALL4, and OCT4) that induce pluripotency, which means the ability to form any adult cell type.  Once in the pluripotent state, iPSCs can be cultured and grown life embryonic stem cells and can differentiate into adult cell types and tissues.

As Chen explained, “A pluripotent stem cell is a kind of blank slate.”  Chen continued, “During development, such stem cells differentiate into many diverse specialized cell types, such as a muscle cell, a brain cell, or a blood cell.  So, after generating iPSCs from skin cells, researchers then can culture them to become brain cells, or neurons, which can be studies safely in a Petri dish.”

Chen’s team invented a protocol to differentiate iPSCs into mature human neurons much more effectively than previous protocols.  This generates cells that behave neurons in our own brains and can be used to model the individualized disease of a single patient.

In the brain, neurons rarely work alone, but instead are usually in close proximity to star-shaped cells called astrocytes.  Astrocytes are very abundant cells and they assist neuron function and mediate neuronal survival.  “Because neurons are adjacent to astrocytes in the brain, we predicted that this direct physical contact might be an integral part of neuronal growth and health,” said Chen.  To test this hypothesis, Chen and his colleagues began by culturing iPSCs-derived neural stem cells, which are stem cells that have the potential to become neurons.  These cells were cultured on top of a one-cell-thick layer of astrocytes sop that the two cell types were physically touching each other.

Astrocytes
Astrocytes

“We found that these neural stem cells cultured on astrocytes differentiated into mature neurons much more effectively,” Chen said.  This contrasts Chen’s method with other neural stem cells that were cultured alone in a Petri dish.  As Chen put it, the astrocytes seems to be “cheering the stem cells on, telling them what to do, and helping them to fulfill their destiny to become neurons.”

While this sounds a little cheesy, it is undeniable that the astrocyte layer increases the efficiency of neuronal differentiation of iPSCs.  Personalized medicine is moving beyond the gene level, to the level of cellular organization and tissue physiology, and iPSCs are showing the way.

The HPV Vaccines Work


I have blogged before on the Human Papillomavirus (HPV) vaccines, in particular Gardasil. After reviewing the data, I came to the conclusion that this vaccine is essentially safe and does what Merck advertises what it does. The epidemiological data is pretty hard to argue with, and the safety of the vaccine also seems pretty well established. Some readers did not like my conclusions, but that what the data leads me to conclude.

I am not for mandating the vaccine. HPV is acquired by having sex, and young girls can decide for themselves if they are going to have sex and if they should get vaccinated. Health care professionals should definitely encourage sexually active men and women to be vaccinated.

Now a new study provides further evidence that HPV vaccines are effective. A new paper in the Journal of Infectious Diseases by Lauri E. Markowitz, Susan Hariri, Carol Lin, Eileen F. Dunne, Martin Steinau, Geraldine McQuillan, and Elizabeth R. Unger reports that the prevalence of four strains of HPV that can cause cervical cancer, has decreased more than 50% among females aged 14-19 since the introduction of the vaccine in 2006. This is strongly suggests that the vaccine is effective and should result in a reduction in cervical cancer deaths in the long run.

In this study, Markowitz and others analyzed HPV prevalence data from two periods of time: the vaccine era (2007–2010) and the prevaccine era (2003–2006). These data came from National Health and Nutrition Examination Surveys. The prevalence of HPV was determined by detecting HPV in vaginal swab samples from females aged 14–59 years; there were 4150 provided samples in 2003–2006, and 4253 provided samples in 2007–2010.

The results of these surveys showed that among females aged 14–19 years, the prevalence of those HPV strains against which the vaccine was made (HPV-6, -11, -16, or -18) decreased from 11.5% in 2003–2006 to 5.1% in 2007–2010. This is a decline of 56%, and statistically speaking, the confidence intervals for these findings were very high, indicating that these data are quite trustworthy.

Markowitz and her group concluded, “Within 4 years of vaccine introduction, the vaccine-type HPV prevalence decreased among females aged 14–19 years despite low vaccine uptake. The estimated vaccine effectiveness was high.”

Is HPV a problem? Clearly it is. Consider the following data: Approximately 79 million Americans, most in their late teens and early 20s, are infected with HPV, and every year about 14 million people become newly infected.

“This report shows that HPV vaccine works well, and the report should be a wake-up call to our nation to protect the next generation by increasing HPV vaccination rates,” said CDC Director Tom Frieden, M.D., M.P.H. “Unfortunately only one-third of girls aged 13-17 have been fully vaccinated with HPV vaccine. Countries such as Rwanda have vaccinated more than 80 percent of their teen girls. Our low vaccination rates represent 50,000 preventable tragedies – 50,000 girls alive today will develop cervical cancer over their lifetime that would have been prevented if we reach 80 percent vaccination rates. For every year we delay in doing so, another 4,400 girls will develop cervical cancer in their lifetimes.”

According to CDC, each year in the United States, about 19,000 cancers caused by HPV occur in women, and cervical cancer is the most common. About 8,000 cancers caused by HPV occur each year in men in the United States, and oropharyngeal (throat) cancers are the most common.

Clearly HPV is a health problem, and the fact that there is a vaccine available that works is a good thing.

Some news reports quote experts who are troubled that “only” 49% of females aged 13-17 have received a dose of the vaccine, and “only” 32% have received all three doses recommended by the manufacturer. However, the same survey found that only 50% of females aged 14-19 have had sex. Therefore, it is probable that these data suggest that the vaccine is reaching exactly the people who need it and not those who do not.

The words of the Family Research Council seem rather prescient in this regard: “Not every female “needs” the HPV vaccine — those who practice sexual abstinence until marriage and fidelity within marriage have a negligible risk of infection. Those women (and men) who abstain are, at the same time, protecting themselves from other strains of HPV not covered by the vaccine, other STDs, unintended pregnancy, and a range of emotional and relationship problems.”

The HPV vaccine works. If you need it, get it. If you don’t, then don’t. That’s my take.

Beta Blockers and Cardiac Progenitor Cells


The heart receives nerve input from several nerves. Some of these inputs come from the branches of the autonomic nervous system. If that sounds cryptic, just think of the word “automatic.” In other words, the things your body does without you consciously thinking about it are largely directed by the autonomic nervous system: digestion, breathing, the beating of your heart, and so on are all things that our body does without us consciously thinking about it.

The autonomic nervous system consists of two branches, the sympathetic and the parasympathetic branches of the autonomic nervous system. With respect to the heart, the sympathetic nerve inputs to the heart accelerate the heart beat and the force of the heart’s contractions. The parasympathetic inputs to the heart slow the heartbeat, but do not have any direct effect on the force of the heart’s contractions.

autonomic innervation of the heart

The sympathetic nerves that connect to the heart release the neurotransmitters epinephrine and norepinephrine. These neurotransmitters bind to receptors on the surface of heart muscle cells in order to elicit their stimulatory responses. The receptors that bind epinephrine and norepinephrine are called “adrenergic” receptors because they bind epinephrine, which used to be called “adrenaline.” When pharmacists talk about “adrenergic” stimulation, they mean receptors that bind to epinephrine and norepinephrine (for the sake of brevity, I am going to abbreviate these two molecules as Epi/NE).

Activation of Beta2 resize bronchial tubes

Now if all this seems confusing, I am sorry, but it is going to get worse. You see there are different flavors of adrenergic receptors. There are alpha and beta adrenergic receptors. Both alpha and beta adrenergic receptors bind Ep/NE, but the specific responses they elicit can differ, depending on the cell and the machinery it has to respond to the bound receptor. A quick example might help make this clear. If you get an asthma attack, you can breathe in a product called Primatene Mist, which is simply aerosolized epinephrine. Epi, in your lungs, causes the smooth muscles that surround your breathing passages to relax and your breathing passages dilate. This allows you to breath much more easily. However, that same molecule, Epi, will cause your heart to beat faster and harder. The same molecule – Epi – elicits two completely distinct responses from two tissues. This is due to the fact that the heart has one type of adrenergic receptor on the surfaces of its cells (so-called beta1 adrenergic receptors), and the bronchial smooth muscle has a distinct beta adrenergic receptor the on the surfaces of its cells (so-called beta2 adrenergic receptors).

I realize that this is a very long introduction, but it is necessary in order to talk about the paper that I found. In this paper, scientists in Mark Sussman’s laboratory at the San Diego Heart Research Institute have examined cardiac progenitor cells (CPCs) from male mice and their response to beta adrenergic stimulation. You see, once we are born, adrenergic stimulation causes the heart to grow and mature. However, once the heart muscle cells mature, this stimulation no longer causes the heart to enlarge in the same way that heart normally does shortly after birth, although the heart is still capable of remodeling in response to constant aerobic exercise. However, after a heart attack, the secretion of Epi/Ne tends to drive deterioration of the heart. Therefore, a common drug strategy to treat heart attack patients is to prescribe a class of drugs called “beta blockers,” which protect the heart from the deleterious effects of adrenergic stimulation after a heart attack. However, the effects of adrenergic stimulation on CPCs is unknown, and Sussman’s laboratory used cultured CPCs to determine the effects of adrenergic stimulation on CPCs.

CPCs are a stem cell population that resides in the heart. A respectable corpus of literature has shown that CPCs can differentiate into various heart-specific cell types and replace dying heart muscle. Our hearts do not recover properly after a heart attack because the CPCs healing capacities are overwhelmed after a heart attack (See Leri A, Kajstura J, and Anversa P, Circulation Research 109 (2011) 941-61 for an excellent summary of the physiological tasks performed by CPCs).

In the Sussman paper, cultured CPCs from mice and humans were cultured in the laboratory.  It was quickly discovered that CPCs do NOT express beta1 adrenergic receptors on their surfaces, but beta2 adrenergic receptors.  You might smirk and this and say “so what?”  However this is significant for the following reason:  Early in their lives, heart muscle cells expression beta2 adrenergic receptors, but they later switch to exclusive expression of beta1 adrenergic receptors.  They express beta2 adrenergic receptors during that time when they can rapidly divide and respond to the needs of the heart.  CPCs express beta 2 adrenergic receptors only when they are in their undifferentiated state.  Once they differentiate, they switch to beta1 adrenergic receptors.

Secondly, Sussman and his crew discovered that stimulation of the beta2 adrenergic receptors on the surfaces of CPCs caused them to divide.  Sussman and others used a molecule called fenoterol, which binds very tightly to beta2 adrenergic receptors and activates them.

Third, once the CPCs were differentiated into heart muscle cells, they no longer expressed beta2 adrenergic receptors, but expressed beta 1 adrenergic receptors.  Did this change the response of the cells to adrenergic stimulation?  YES.  Instead of dividing in response to adrenergic stimulation, the cells were much more sensitive to dying.  To make sure that this result was not a fluke, Sussman and others engineered CPCs to express beta1 adrenergic receptors, and, sure enough, those cells were also sensitized to cell death upon expression of beta1 adrenergic receptor.

This is all fine and dandy for a culture dish, but can this make a difference in a living animal?  Sussman used a specific mouse strain called TOT.  These mice have a special pathology in that their hearts enlarge and start to not work very well once they are exposed to large quantities of Epi/NE.  Can beta blockers prevent this enlargement of the heart in TOT mice?  It definitely can.  However, Sussman wanted to know what happened to the CPCs.  Therefore, they broke the mice into three groups.  Two groups received metoprolol and the third did not.  Then four weeks later, one TOT mouse group that had received metoprolol and another that had not received transplantations of marked CPCs into their hearts (the CPCs glowed).  Then they examined the CPCs two weeks after the implantation.  The CPCs in non-metoprolol-treated TOT mice took a beating.  However, in the metoprolol-treated mice, the CPCs were three times more prevalent and showed overall lower levels of programmed cell death.  There was less DNA synthesis in the hearts of metoprolol-treated animals, indicating that there was less of a need for replacement of dead cells.

These results indicate that beta blockers do more than protect the heart from excessive Epi/NE after a heart attack.  They also protect the CPCs in the heart, and that could be an even more significant contribution to the life of the heart after a heart attack.  It is might be possible to direct or even augment the activity of CPCs in the heart after a heart attack to accelerate cardiac healing.  That would be a tremendous step in cardiac healing.

BMP-2 Treatment Limits Infarct Size in After a Heart Attack in Mice


Bone Morphogen Protein 2 (BMP2) is a powerful signaling molecule that is made during development, healing, and other significant physiological events. During the development of the heart, BMP2 modulates the activation of cardiac genes. In culture, BMP2 can protect heart muscle cells from dying during serum starvation. Can BMP2 affect hearts that have just experienced a heart attack?

Scientists from the laboratories of Karl Werdan and Thomas Braun at the Max Planck Institute or Heart and Lung Research in Bad Nauheim, Germany have addressed this question in a publication in the journal Shock.

In this paper, Henning Ebelt and his colleagues Gave intravenous BMP2 to mice after a heart attack. CD-1 mice were subjected to LAD-ligation to induce a heart attack (LAD stands for left anterior descending coronary artery, which is tied shut to deprive the heart muscle of oxygen). 1 hour after the heart attack, mice were given 80 microgram / gram of body weight of intravenous recombinant BMP2. The hearts of some animals were removed 5-7 days after the heart attack, but others were examined 21 days after the heart attack to determine the physiological performance of the hearts. Control animals were given intravenous phosphate buffered saline.

Coronary arteries

The extirpated hearts were analyzed for cell death, and the size of their heart scars. Also, protein expression analyses showed the different proteins expressed in the heart muscle cells as a result of BMP2 treatment. Also, the effects of BMP2 on cultured heart muscle cells was ascertained.

The results showed that BMP2 could protect cultured heart muscle cells from dying in culture if they when they were exposed to hydrogen peroxide. Hydrogen peroxide mimics stressful conditions and under normal circumstances, cultured heart muscle cells pack up and die in the presence of hydrogen peroxide (200 micromolar for those who are interested). However, if cultured with 80 ng / mL BMP2, the survival of cultured heart muscle cells greatly increased.

When it came to the hearts of mice that were administered iv BMP2, the BMP2-administered mice survived better and had a smaller infarct size (almost 50% of the heart in the controls and less than 40% in the BMP2-administered hearts). When the degree of cell death was measured in the mouse hearts, those hearts from mice that were administered BMP2 showed less cell death (as determined by the TUNEL assay). BMP2 also increased the beat frequency and contractile performance of isolated heart muscle cells.

FInally, the physiological parameters of the BMP2-treated animals were slightly better than in the control animals. The improvements were consistent, but not overwhelming.

Interestingly, when the proteins made by the hearts of BMP2- and PBS-administered animals were analyzed, there were some definite surprises. BMP2 normally signals to cells by binding a two-part receptor that sticks phosphates on itself, and in doing so, recruits “SMAD” proteins to it that end up getting attached to them. The SMAD proteins with phosphates on them stick together and go to the nucleus where they activate gene expression.

BMP signaling

However, the heart muscle cells of the BMP2-administered mice did not contain heavily phosphorylated SMAD2, even though they did show phosphorylated SMAD1, 5, & 8.  I realize that this may sound like Greek to you, but it means this:  Different members of the BMP superfamily signal to cells by utilizing different combinations of phosphorylated SMADs.  The related signaling molecule, TGF-beta (transforming growth factor-beta), increases scar formation in the heart after a heart attack.  TGF-beta signals through SMAD2.  BMP2 does not signal through SMAD2, and therefore, elicits a distinct biological response than TGF-beta.

These results show that BMP2 administration after a heart attack decreases cell death and decreases the size of the heart scar.  There might be a clinical use for BMP2 administration after a heart attack.

See Henning Ebelt, et al., Shock 2013 Apr;39(4):353-60.

An Easy Way to Make Retinal Pigment Epithelium from Pluripotent Stem Cells


Age-related macular degeneration is the leading cause of irreversible vision loss and blindness among the aged in industrialized countries. One of the earliest events associated with age-related macular degeneration (AMD) is damage to the retinal pigmented epithelium (RPE), which lies just behind the photoreceptor cells in the retinal. The RPE serves several roles in visual function, including absorption of stray light, formation of blood retina barrier, transport of nutrients, secretion of growth factors, isomerization of retinol, and daily clearance of shed outer photoreceptor outer segments. RPE cell death and dysfunction is associated with both wet (neovascular) and dry (atrophic) forms of AMD.

How then do we make RPE cells from stem cells in order to treat AMD? In previous experiments, scientists have used RPEs made from human embryonic stem cells to treat two patients with inherited eye diseases. The results from these experiments were underwhelming to say the least. Also, the derivation of RPEs from embryonic stem cells was tedious and laborious. Is there a better way?

Make that a yes. A paper in Stem Cells Translational Medicine from Donald Zack’s laboratory at Johns Hopkins University School of Medicine describes a simple and highly scalable process for deriving RPEs from human pluripotent stem cells.

To begin with, the cells were plated at relatively high densities (20,000 cells / cm square centimeter) in a medium called TeSR1. This medium can support the growth of human pluripotent stem cells and can also keep them undifferentiated without the use of animal feeder cell lines. SInce there are no feeder cells to make, the cultivation of these cells is much simpler than before and the variability from culture to culture decreases.

After five days of growth, the cells grew to a monolayer (the cells had grown and spread throughout the culture dish) and were transferred to a 5% carbon dioxide and 20% oxygen incubator. Three days later, they were transferred to Delbecco’s Modified Eagle Medium with F12 supplement or DMEM/F12. This culture medium supports stem cell differentiation. The cells grew and differentiated, for about 25 days, but RPEs were easily visible because they make loads of dark pigment. Once the dark colonies appeared, the cells were allowed to grow another 25 days. The cells were transferred into Delbecco’s Medium with enzymes to pull the cells apart from each other for four hours, then, after pipetting them vigorously, the cells were centrifuged, and suspended in a cell detachment solution called Accumax.

The separated cells were filtered and plated on specially coated plates, and cultured in “RPE medium.” This is a mixture of several different culture media that favors the survival and growth of RPEs. Because RPE colonies were easily seen with their dark pigments, they were specifically picked and passaged. The result was extremely clean RPE cultures from pluripotent stem cells.

Differentiation of hPSCs into RPE. (A): Schematic view of the differentiation process. (B): Kinetics of marker expression of differentiating hESCs and hiPSCs as measured by quantitative real-time polymerase chain reaction. d1 denotes the time at which the cells were transferred to DM. Error bars represent standard deviation of biological replicates. (C): Morphology of hPSCs after 50 days in DM, with arrowheads indicating representative pigmented colonies. Scale bar = 5 mm. (D, E): Flow cytometric analysis of the expression of RPE65 by differentiating hPSCs after 50 days in DM. The profile of cells stained with the anti-RPE65 antibody is shown in red, and the isotype control is displayed in black. Only a minority of cells were RPE65-positive, which is in accordance with the limited number of pigmented colonies obtained in (C). Abbreviations: d, day of the experiment; DM, differentiation medium; hESC, human embryonic stem cell; hiPSC, human induced pluripotent stem cell; hPSC, human pluripotent stem cell; P1, first passage; P2, second passage; RPE, retinal pigment epithelium; w, week.
Differentiation of hPSCs into RPE. (A): Schematic view of the differentiation process. (B): Kinetics of marker expression of differentiating hESCs and hiPSCs as measured by quantitative real-time polymerase chain reaction. d1 denotes the time at which the cells were transferred to DM. Error bars represent standard deviation of biological replicates. (C): Morphology of hPSCs after 50 days in DM, with arrowheads indicating representative pigmented colonies. Scale bar = 5 mm. (D, E): Flow cytometric analysis of the expression of RPE65 by differentiating hPSCs after 50 days in DM. The profile of cells stained with the anti-RPE65 antibody is shown in red, and the isotype control is displayed in black. Only a minority of cells were RPE65-positive, which is in accordance with the limited number of pigmented colonies obtained in (C). Abbreviations: d, day of the experiment; DM, differentiation medium; hESC, human embryonic stem cell; hiPSC, human induced pluripotent stem cell; hPSC, human pluripotent stem cell; P1, first passage; P2, second passage; RPE, retinal pigment epithelium; w, week.

The cells were subjected to a battery of tests: flow cytometry, Western blotting, Immunostaining and so on. These cells passed with flying colors and they are clearly RPE cells that express RPE-specific genes, have RPE-specific proteins on their cell surfaces, and even snuggle up to photoreceptors and recycle their terminal segments.  The final functional test came from a transplantation experiment in which human RPEs made from human pluripotent stem cells were transplanted behind the retinas of mice with impaired immune systems.  The cells, as you can see in the figures below, integrated beautifully, and were also highly functional, as indicated by the rhodopsin-positive vesicles in the implanted RPE cells.   No tumors were seen in any of the laboratory animals implanted with the stem cell-derived RPEs.

Transplantation of human pluripotent stem cell (hPSC)-RPE cells into the subretinal space of albinos NOD-scid mice. (A): Fundus photograph of an injected eye, 1 week post-transplantation. Note the numerous pigmented clusters formed by the transplanted hPSC-RPE cells. (B): Confocal micrograph showing the presence of rhodopsin-positive material (yellow arrows) within the cell membrane of carboxyfluorescein diacetate succinimidyl ester-labeled hPSC-RPE cells, 1 week after subretinal injection. Scale bars = 10 μm. Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole; ONL, outer nuclear layer; OS, outer segment; RPE, retinal pigment epithelium.
Transplantation of human pluripotent stem cell (hPSC)-RPE cells into the subretinal space of albinos NOD-scid mice. (A): Fundus photograph of an injected eye, 1 week post-transplantation. Note the numerous pigmented clusters formed by the transplanted hPSC-RPE cells. (B): Confocal micrograph showing the presence of rhodopsin-positive material (yellow arrows) within the cell membrane of carboxyfluorescein diacetate succinimidyl ester-labeled hPSC-RPE cells, 1 week after subretinal injection. Scale bars = 10 μm. Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole; ONL, outer nuclear layer; OS, outer segment; RPE, retinal pigment epithelium.

This new procedure is able to make RPEs from pluripotent stem cells in a simple and highly scalable way.  If human induced pluripotent stem cells could be used with this protocol, and there seems little reason that should not be highly possible, then such cells could be easily used for human clinical trials.

Regeneration of Tooth Roots With Borrowed Stem Cells in Pigs


Because a recent post about tooth-making stem cells in alligators generated so much interest, I found another recent paper that reports the regeneration of the tooth root structure in pigs. This is a proof-of-concept paper that demonstrated the feasibility of such a procedure.

The journal is Stem Cells and Development and the research team is from the Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction in Beijing, China. The corresponding author is Songlin Wang from the Molecular Laboratory for Gene Therapy and Tooth Regeneration.

Tooth loss represents a growing problem in an aging population. Dental implants provide one solution, but without a good jaw bone into which these implants can be attached, implants have little chance of staying put. Regenerating a tooth root that can support a natural or artificial crown is the most important part of the tooth in maintaining tooth function.

In previous work, Wang and his collaborator Songtao Shi from UCLA have shown that stem cells from root apical papilla and periodontal ligament stem cells from exfoliated teeth can coat bioengineered surfaces and form tooth structures that can support artificial crowns in miniature pigs (see Sonoyama et al., PLoS One 1:e79-e92). However, aged patients sometimes have bone marrow stem cells that do not grow well in culture and respond poorly to bioengineering protocols. Therefore, Wang and his crew sought to demonstrate that mesenchymal stem cells from donor animals (allogeneic stem cells) could provide the same kind of benefit.

The two stem cell populations used in this paper was dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs). The DPSCs were cultured from exfoliated minipig teeth and grown in culture for two or three passages. The culture medium used, as far as I can tell, was the same one used the Gronthos in his PNAS paper that reported the isolation and characterization of DPSCs. That medium was a modified Eagle’s medium supplemented with 20% Fetal Calf Serum and 100 μM L-ascorbic acid 2-phosphate, 2 mM L-glutamine, 100 units/ml penicillin, and 100 μg/ml streptomycin. Gronthos then grew his cells at 37°C in 5% CO2 (see S. Gronthos, et al PNAS 97(25): 13625–13630). After 2-3 passages, the DPSCs were seeded on a hydroxyapatite tricalcium phosphate scaffold and grown in a bioreactor for 5-7 days

PDLSCs were grown in culture with approximately the same cocktail as the DPSCs and then plated on 60 mm dishes with vinylene carbonate (Vc). Vc induces the PDLSCs to grow s sheets that could be used to wrap the hydroxyapatite tricalcium phosphate structures that had been seeded with DPSCs.

These wrapped structures were implanted into the gums of minipigs and then used to secure dental implants.

Tooth Root Regeneration

After 6 months, the implants were assessed as was the integrity and strength of the surrounding tissue.

Gross, radiographic, and histological analysis of the bio-root 6 months after transplantation. (A, C) Gross view of the general shape of HA/TCP and the bio-root 6 months after transplantation (ellipse). (B, D) X-rays revealed that HA/TCP formed tissues without an obvious dental structure (ellipses), but the HA/TCP/DPSC/PDLSC sheet implant formed a hard root structure (ellipses). (E, F) No obvious boundary was observed between newly regenerated tissue and bone in the microcomputed tomography scan image of the HA/TCP group. (G, H) A hard root structure (arrows) was present and a clear PDL space found between the implant and surrounding bony tissue (triangle arrows). (I–K) HE staining showed some bone formation and HA/TCP remaining in the HA/TCP group (I), and PDL-like tissues were generated parallel to the dentin-like matrix structure in the autologous group (J) and allogeneic group (K). (L) Semiquantitative analysis showed that mineralized tissue regeneration capacity of autologous or allogeneic groups was significantly higher compared with the HA/TCP group. Percentage of mineralized tissues at 6 months after crown restoration was significantly higher than that before crown restoration in both autologous and allogeneic groups. No significant difference of regenerated mineralized tissue percentages was found between autologous and allogeneic groups. Scale bar: (I–K) 200 μm. B, bone; HA/TCP, hydroxyapatite/tricalcium phosphate; PDL, periodontal ligament; MT, mineralized tissue. *P<0.01 compared with autologous or allogeneic groups; #P<0.01 compared with autologous or allogeneic groups after crown restoration.
Gross, radiographic, and histological analysis of the bio-root 6 months after transplantation. (A, C) Gross view of the general shape of HA/TCP and the bio-root 6 months after transplantation (ellipse). (B, D) X-rays revealed that HA/TCP formed tissues without an obvious dental structure (ellipses), but the HA/TCP/DPSC/PDLSC sheet implant formed a hard root structure (ellipses). (E, F) No obvious boundary was observed between newly regenerated tissue and bone in the microcomputed tomography scan image of the HA/TCP group. (G, H) A hard root structure (arrows) was present and a clear PDL space found between the implant and surrounding bony tissue (triangle arrows). (I–K) HE staining showed some bone formation and HA/TCP remaining in the HA/TCP group (I), and PDL-like tissues were generated parallel to the dentin-like matrix structure in the autologous group (J) and allogeneic group (K). (L) Semiquantitative analysis showed that mineralized tissue regeneration capacity of autologous or allogeneic groups was significantly higher compared with the HA/TCP group. Percentage of mineralized tissues at 6 months after crown restoration was significantly higher than that before crown restoration in both autologous and allogeneic groups. No significant difference of regenerated mineralized tissue percentages was found between autologous and allogeneic groups. Scale bar: (I–K) 200 μm. B, bone; HA/TCP, hydroxyapatite/tricalcium phosphate; PDL, periodontal ligament; MT, mineralized tissue. *P

As you can see in panel E and F, control implants that had no cells and only hydroxyapatite calcium triphosphate showed no tooth-like structures, but in G and F, the structures with cells showed a consistent tooth structure with a periodontal ligament (see broad arrow).  In panels J and K, there is obvious bone formation with periodontal ligament in the autologous and allogeneic stem cell transplants.

Cross sections of the implants also showed that not only did these structures look like real tooth root structures, but they contained structures proteins indicative of real tooth root structures.  Dentin sialophosphoprotein (mercifully abbreviated to DSPP) is present in the cell-seeded implants, but in on the hydroxyapatite calcium triphosphate-only implants.

Clinical assessment of implants failed to detect any gingivitis or periodontal disease associated with the implants.

This experiment shows that stem cell-seeded scaffolds can regenerate tooth root structures.  Since this worked in minipigs and not simply rodents, these results strongly suggest that such a strategy could work in humans.  Clinical trials anyone?

Human Neural Stem Cell Line Heals Spinal Cord-Injured Rats


Spinal cord injuries represent one of the most intractable problems for regenerative medicine. When the spinal cord is injured, a tissue that is normally isolated from the bloodstream, now comes into contact with a variety of inflammatory factors and cells that increase the destruction of the original lesion. The spinal responds with a glial scar that plugs the lesion and prevents further exposure of the spinal cord to damaging inflammation, but the scar is also filled with molecules that repel neuronal axon growth cones. This spells curtains for neuronal regeneration, and finding a cell type that can negotiate around the glial scar and find the original muscle is a genuine tour de force.

Given this to be the case, there have been many experiments in rodents to examine the efficacy of various stem cell populations to as treatments for spinal cord injuries. A recent paper in Stem Cell Research and Therapy (van Gorp et al., 2013, 4:57) has examined human fetal spinal cord-derived neural stem cells (HSSCs) and their ability to restore motor function in rats with spinal cord injuries to the lower back. Because this group examined movement and spinal cord tissue samples, this paper contributes something significant to our knowledge of HSSC-mediate healing of spinal cord injuries.

The HSSC line used in this paper is neural stem cell line NSI566RSC, which was extracted from the spinal cord of an 8-week old “fetus.” I have placed fetus in quotes because at eight weeks, the fetus is actually a very old embryo, since the end of the eighth week is end of embryonic development. I realize that these types of age calculations have room for error, and therefore, the baby might very well have been at the early fetal stage. However, the baby’s mother terminated her pregnancy (yes it was an abortion and no I am not cool with that) and donated the dead baby’s tissue to UC San Diego for research purposes.

Sprague-Daley rats were subjected to spinal cord injuries at the level of the third lumbar vertebra. Three days later, half of the rats were given saline injections into their spinal cord and the other half were given HSSC injections into their spinal cords. The animals were evaluated for two months after the treatments on a daily basis. After two months, the rats were sacrificed (put down) and the spinal cord tissue was extensively analyzed.

Of the 35 animals employed in this study, 3 were excluded because of paw injuries or drug toxicity. Eight weeks after the cells were implanted, the rats were tested with a CatWalk apparatus to determine their gait. The rats injected with HSSCs showed a much more normal gait than those injected with saline. To give you some idea of the improvement, the rats that were not injured had a RCHPP or rostro-caudal hind paw positioning score of 0+/- 1.7mm, and the saline injected animals had an average RCHPP of -18 +/- 3.1 mm, and those injected with HSSCs had an RCHPP of -9.0 +/- 1.9 mm.

Despite these improvements, there were no significant differences in ladder climbing, stride length, overall coordination, or single-frame motion.

Next, Marsala and colleagues showed that the muscle spasms associated with spinal cord injury were slightly decreased by the implantation of HSSCs and not by injection of saline. To measure spasticity, the ankle or front paw is rotated and the electromyograph of the muscle is measured. The electromyograph or EMG measures the electrical activity of the muscle showed modest improvements in the HSSC-injected animals

Sensory sensitivity was improved in the HSSC-injected animals, and this improvement was progressive. When the rats were prodded below the level of the injury, where they should have no feeling, the HSSC-injected rats showed better response to the stimulation. This was the case with mechanical stimulation and thermal stimulation.

Post-mortem analysis also showed something interesting. When the fluid-filled cavity of the damaged spine was examined, the HSSC-injected animals had a significantly small cavity. Because the injected cells had been labeled with green fluorescent protein, they glowed under UV light and any neuronal cells derived from the injected HSSCs glowed green too. The lesioned areas in the HSSC-injected mice were repopulated with cells. Motorneurons, interneurons and glial cells were detected.

What to make of this study? The repopulation of the spinal cord and the growth of spinal nerve elements within the fluid-filled cavity is remarkable, but the lack of better motor function is disappointing. The recovery of sensory ability is significant, especially, since it is pretty clearly not due to spinal hypersensitivity.

There are two possibilities for the low motor recovery. First, there is a possibility that the these experiments were not conducted for as long a time period as they needed to be. Since the sensory ability improvement was progressive, maybe the motor recovery was too, perhaps? Secondly, maybe the grow and connection of motor neurons had trouble with the glial scar. Why the sensory nerves did not have such a problem and the motor neurons would is inexplicable at this time. However, another possibility is that the muscular targets of motor neurons are not as obvious in adult animals as they are in a developing animal. Finding ways to “paint” the muscles might be a way to increase motor neuron innervation in the future.

Thus, this cell line, NSI-566 RSC is certainly a potential treatment for spinal cord patients. A phase I trial is in the works.

Supreme Court Strikes Down Patenting of Human Genes


Can we patent human genes? After years of debate, the Supreme Court of the United States (SCOTUS) has ruled unanimously that the answer is “No.” The majority of Americans are simply unaware that approximately 25% of their genes have been patented by companies and research institutions over the last few decades by the U.S. Patent and Trademark Office. However, the SCOTUS’ decision has determined that your genes are not patentable.

There is a fine article about this in the June 13th edition of the Wall Street Journal.

The SCOTUS decision is a victory for scientists, physicians and patients who argued that such patents interfere with the practice of medicine, patient care and scientific research. In handing down its decision, SCOTUS has made one of the most significant rulings in this age of molecular medicine, since it ultimately decides who may own the fundamental building blocks of life.

In writing for the court, Justice Clarence Thomas, said the genes Myriad Genetics, Inc isolated are products of nature, which aren’t eligible for patents. Thomas penned, “Myriad did not create anything,” Justice Thomas wrote in an 18-page opinion. “To be sure, it found an important and useful gene, but separating that gene from its surrounding genetic material is not an act of invention.”

Justice Thomas and the court essentially followed the legal framework established by Solicitor General Donald Verrilli when he rejected the views of both the U.S. Patent and Trademark Office and the specialized tribunal that hears patent appeals, the U.S. Court of Appeals for the Federal Circuit.

Justice Thomas credited Myriad for a “medical breakthrough,” since they had identified, isolated, and characterized the BRCA1 and BRCA2 genes. These genes can predict if a woman has a 50% – 80% likelihood of breast cancer, in comparison to the average American woman’s 12% to 13% risk. However, Thomas opined that “”groundbreaking, innovative, or even brilliant discovery does not by itself satisfy” federal law’s requirements for a patent. To demonstrate his reasoning, Thomas made reference to a 1948 case, in which the court decided that a product that combined several different species of bacteria that were useful for improving soil-nitrogen levels was unpatentable because the bacteria themselves were naturally occurring.

Justice Thomas also wrote that “separating (a) gene from its surrounding genetic material is not an act of invention.” Thomas also rejected an argument put forward by the company seeking the patent, Myriad, that patenting BRCA1 and BRCA2 would promote innovation. Instead, Thomas and his colleagues thought that patenting these genes and other would stifle innovation and frustrate progress.

In a nutshell: even if a discovery is brilliant or groundbreaking, that doesn’t necessarily mean it’s patentable, according to SCOTUS.

Now what do I think? I think that this is probably good news for patients. Even though you are not aware of it, gene patenting has affected you. Once a company legally “owns” a human gene, they control who can conduct research on that gene and who can run tests on that gene. If you have a genetic disease and you need a genetic test to confirm that you have it, medical labs are limited on what genes they can offer tests for because of gene patents. This limits the range of services medical labs can offer to patients. Medical laboratories that offer particular genetic tests are only allowed to do so because they pay royalties to the companies that own the genes, and this jacks up the cost of those tests. Consequently, many labs do not offer genetic tests in order to spare themselves the cost, time, paperwork, lawyers’ fees, and hassles.

Gene patents also stifle research. You see once a company owns a patent on a gene, they sit on the patient and do not conduct any research on those genes. Gene patents also prevent other scientists from researching the gene as well. This ties the hands of medical geneticists who want to define the exact mechanisms by which particular mutations cause or contribute to specific genetic diseases. Since many diseases have a genetic component, gene patents get in the way of further research. Dr. Iris Schrijver, president of the Association for Molecular Pathology, which opposes gene patents, made this observation:

Because variation in gene sequences plays an important role in the development and progression of many diseases, through gene patents, patent holders can essentially gain ownership of the understanding of some diseases and of certain areas of patient care itself.

Fortunately, SCOTUS has put the kibosh on such occurrences. Now, we hope that there will be a new era of genetic research where our genes are not claimed by one company or another, and researchers are free to work on whatever gene they choose.

As a postscript, Justice Thomas did leave the door open for companies to patent synthetically made versions of genes.  This would allow companies the ability to patent creations of their own for further use and research and development.  As noted in the Wall Street Journal piece:

Still, a footnote gave Myriad little reason to cheer. Justice Thomas added that the court took no position on whether cDNA met the other requirements for a patent, such as being “nonobvious.” He referred to a brief filed by the Obama administration, which observed that “given the prevailing level of knowledge in biotechnological fields, future patent applications directed to cDNAs and other synthesized DNA molecules may be rejected as obvious.”

Alligator Stem Cells and Tooth Replacement


Mammals usually have one set of baby teeth (also known as milk teeth) and after those are lost, we have one set of adult teeth and these are not replaced if they are lost. This condition is called “monophyodont.” Reptiles and sharks, however constantly replace their teeth. This condition is called “polyphyodont.” Alligators and crocodiles are among one group of reptiles that replace their teeth throughout their lives, and because the development of these creatures has been studied to some extent, it is known that the ability of these creatures to replace their teeth on a regular basis results from a resident stem cell population. Studying that stem cell population more closely might provide clues for tooth replacement in humans.

American Alligator
American Alligator

A research team led by scientists at the Keck School of Medicine professor of pathology Cheng-Ming Chuong at the University of Southern California. Dr. Chuong and his collaborators from around the world have identified unique cellular and molecular mechanisms behind tooth renewals in American alligators.

Chuong explained, “Humans naturally have only two sets of teeth – baby teeth and adult teeth. Ultimately, we want to identify stem cells that can be used as a resource to stimulate tooth renewal in adult humans who have lost teeth. But, to do that, we must first understand how they renew in other animals and why they stop in people.”

Even though humans cannot replace their adult teeth, a tissue called the dental lamina remains, which is known to be crucial for tooth development.

Why are alligators potentially a good model system for tooth replacement in mammals? First author of this study, Ping Wu, explained it this way, “Alligator teeth are implanted in sockets of the dental bone, like human teeth. They have 80 teeth, each of which can be replaced up to 50 times over their lifetime, making them the ideal model for comparison to human teeth.”

Through the use of microscopic imaging techniques, Chuong and others found that each alligator tooth is a complex unit of three components: a functional tooth, a replacement tooth, and the dental lamina, all other which are at different developmental stages.

The tooth units are built to enable a smooth transition from dislodgement of the functional, mature tooth to replacement with a new tooth. Further imaging studies strongly suggested that the dental lamina contains a stem cell population from which new replacement teeth develop.

“Stem cells divide more slowly than other cells, said co-author Randall B. Widelitz, who serves as an associate professor of pathology at USC. Widelitz continued, “The cells in the alligator’s dental lamina behaved like we would expect stem cells to behave. In the future, we hope to isolate those cells from the dental lamina to see whether we can use them to regenerate teeth in the lab.”

The researchers also intend to learn what molecular networks are involved in repetitive renewal and hope to apply the principles to regenerative medicine in the future.

The authors also noted that novel cellular mechanisms are used during the development of the tooth unit. Also, unique molecular signaling speeds growth of replacement teeth when functional teeth are lost.

See P. Wu PNAS 2013; DOI: 10.1073/pnas.12132110.

RNA Molecule Protects Stem Cells During Inflammation


During inflammation and infection, bone marrow stem cells that make blood cells (so-called hematopoietic stem cells or HSCs) and progenitor cells are stimulated to proliferate and differentiate into mature immune cells. This especially the case for cells of the so-called “myeloid lineage.

Hematopoietic Stem Cells (HSCs) are able to differentiate into cells of two primary lineages, lymphoid and myeloid. Cells of the myeloid lineage develop during the process of myelopoiesis and include Granulocytes, Monocytes, Megakaryocytes, and Dendritic Cells. Circulating Erythrocytes and Platelets also develop from myeloid progenitor cells.

Hematopoiesis from Multipotent Stem Cell

Repeated infections and inflammation can deplete these cell populations, which leads to serious blood conditions and increased incidence of cancer.

A research team from the California Institute of Technology, led by Nobel Prize winner, David Baltimore, has discovered a small RNA molecule called microRNA-146a (miR-146a) that acts as a safety valve to protect HSCs during chronic inflammation. These findings also suggest that deficiencies for miR-146a might contribute to blood cancers and bone marrow failure.

Baltimore and his colleagues bred mice that lacked miR146a. MicroRNAs are very short RNA molecules (around 22 base pairs long) that regulate the activities of other genes. They control the expression of genes at the transcriptional and post-transcriptional level. In the case of miR146a(-) mice, whenever these mice were subjected to chronic inflammation, the total number and quality of their HSCs declined steadily. In contrast, miR-146a(+) mice were better able to maintain their levels of HSCs despite long-term inflammation.

The lead author of this work, Jimmy Zhao, said, “This mouse with genetic deletion of miR146a is a wonderful model with which to understand chronic inflammation-driven tumor formation and hematopoietic stem cell biology during chronic inflammation.”

Zhao also noted the surprising result that the deletion of one microRNA could cause such a profound and dramatic pathology. This underscores the critical and indispensable function of miR-146a in protecting the quality and longevity of HSCs. This work also establishes the connection between chronic inflammation and bone marrow failure and diseases of the blood.

Even more exciting is the prospect of synthesizing anti-inflammatory drugs that could treat blood disorders. In fact, it is possible that artificially synthesized miR146a might be an effective treatment if small RNAs can be effectively delivered to specific cells.

Zhao also noted the close resemblance that this mouse model has to the blood disorder human myelodysplastic syndrome or MDS. MDS is a form of pre-leukemia that causes severe anemia and a dependence on blood transfusions. MDS usually leads to acute myeloid leukemia. Further study of Zhao and Baltimore’s miR146a(-) mouse might lead to a better understanding of MDS and potential new treatments for MDS.

David Baltimore, senior author of this paper, said, “This study speaks of the importance of keeping chronic inflammation in check and provides a good rationale for broad use of safer and more effective anti-inflammatory molecules. If we can understand what cell types and proteins are critically important in chronic-inflammation-driven tumor formation and stem cell exhaustion, we can potentially design better and safer drugs to intervene.”

See Jimmy L Zhao, Dinesh S Rao, Ryan M O’Connell, Yvette Garcia-Flores, David Baltimore. MicroRNA-146a acts as a guardian of the quality and longevity of hematopoietic stem cells in mice.  DOI: http://dx.doi.org/10.7554/eLife.00537Published May 21, 2013.  Cite as eLife 2013;2:e00537.

Postscript: This paper is especially meaningful to me because my mother died of MDS. The fact that a better model system for MDS has been established is an essential first step in finding a treatment for this killer disease.

Using Over-The-Counter Abortion Pills to Trick Your Pregnant Girlfriend


Another WordPress blogger who runs a site entitled “saynsumthn” has provided the following harrowing story:

Another recent example which received national attention was the arrest and indictment of a Florida man who tricked his pregnant girlfriend into taking abortion pills to abort her pregnancy. Authorities say that 28-year-old John Andrew Welden did not want to be a father, so when his girlfriend, Remee Jo Lee, got pregnant, Welden faked a prescription for an abortion pill, switched a label so the medication appeared to be a common antibiotic, and gave her the drug. The drug did its job. The unborn baby died. Now Welden, is facing the possibility of life behind bars without parole, charged with murder under a rarely used federal statute known as the “Protection of Unborn Children Act.”

Now folks, even though Plan B does not seem to have a lot of side effects, its over-the-counter status means that it is as easy to get as chewing gum. Look for this sort of thing to happen a lot more often with the legalization and over-the-counter status of Plan B. Rapists, child molesters, incestuous family members can simply slip their victims Plan B to cover up their crime.

Giving Plan B over-the-counter status is a bad idea and this demonstrates it. Welden should have been charged with drug tampering and administering medicine without a license, but since Plan B is over the counter, he cannot be charged with such a crime even though he ought to be. What happens when these monsters start giving Plan B to pregnant women after the time of its efficacy? What birth defects await us?

Oh wait, plan B is not supposed to cause an increase in birth defects because it’s the same hormones that are in many daily birth control pills. But what about the dosage? The Princeton University Student Health Center’s own fact sheet states:

When dedicated ECPs are not available, certain ordinary birth control pills can be used in specified combinations as emergency contraception. In either case, the regimen is one dose followed by a second dose 12 hours later, where each dose consists of 1, 2, 4, 5, or 6 pills, depending on brand. Currently, 19 brands of combined oral contraceptives are approved in the United States for use as emergency contraception.

Now wait a minute people – emergency contraceptive pills or ECPs can be replaced by 1-6 regular birth control pills taken at 12 hour intervals. But these do not cause birth defects? Has this been studied? Not really.

What about Ella or ulipristal acetate, which is an antiprogestin that antagonizes the activity of progesterone on the uterus? The relative of this drug is mifepristone, which is a component of the “French abortion concoction” RU-486. This will cause birth defects if it fails to elicit abortion. How is it that Ulipristal doesn’t?

Additionally, why is it that Plan B is classified as a pregnancy Category X drug, meaning that it could lead to serious problems when taken during pregnancy, such as miscarriages or birth defects?

I do not believe the talking points concerning Plan B. Making it over the counter was a political decision pure and simple.