Sex-Selection Abortion is taken up by the US Congress.

A recent poll shows that 77% of Americans are opposed to sex-selection abortion. This is the real war against women. Sex-selection occurs, for the most part, because couples do not want a little girl. This odious practice is being targeted by the Prenatal Nondescrimination Act. While this act might pass the House, it will probably die in the Democrat-dominated Senate.

The President is indicating that he is against this legislation. He is too far into the pockets of Planned Parenthood to support this legislation.

This act should be passed.  Abortion because the baby is female is horrific.  As David Bass puts it:  “pro-choice ideology claims to place the highest value on women and womanhood. Yet they are forced to accept, as both moral and legal, the aborting of an unborn baby strictly because she is female. To do anything less would violate their core beliefs about the un-personhood of the fetus and the absolute autonomy of the parents (specifically, the mother) in deciding whether to terminate the unborn life.”

Pro-choice advocates want abortion at any cost and for any reason, but sex-selection abortion is what we get when we allow abortion for any reason.  Murdering women because they are women is the ultimate misogyny, and defending it is complicity with such misogyny.  This simple fact of the matter is that pro-choice advocates are not pro-choice, they are pro-abortion.  See the following articles by David Bass at the American Spectator see here, and here.

Update – June 1, 2012 Wall Street Journal reported that the Prenatal Nondiscrimination Act failed to pass the House.

The First Limbal Stem Cell Transplant with Cultured Limbal Stem Cells from a Cadaver

A genetic condition called “aniridia” results from mutations in the PAX6 gene. Approximately 1/50,000-1/1000,000 babies have aniridia. Aniridia results in the complete absence of an iris, and aniridia patients are unable to adjust to light differences.

Because mutations in the PAX6 gene are dominant, aniridia patients half a 50% chance of passing the aniridia condition to their children.

Fortunately for aniridia patients, limbal stem cells can now be cultured in the laboratory and used in clinical settings (see Di Iorio E, et al., Ocul Surf. 2010;8(3):146-53). A Scottish woman with aniridia has just received on of the first limbal stem cell transplants from a cadaver. These cadaver limbal stem cells were cultured and then transplanted onto the surface of her eye.

This woman, Sylvia Paton, who is 50 years old and from the Scottish town of Corstorphine (a west suburb of Edinburgh), is the first person in the United Kingdom to experience this ground-breaking treatment in February of 2012. Her procedure will hopefully reduce her vision problems and ready her for another procedure whereby her lens will be replaced.

For this procedure, limbal stem cells from a dead donor were cultured in the laboratory. The cells were attached to a membrane and then transplanted onto the surface of the left eye. The operation took a total of three hours.

Before her operation, Mrs. Paton could previously only see dark and light through her eye, but this treatment should repair her cornea, and prepare her for another surgery one year later to remove her cataract.

Dr Ashish Agrawal, the National Health Service consultant ophthalmologist who performed the operation, said: “It is now 12 weeks since the transplant and I am delighted to report that Sylvia is recovering well. Her cornea is clear and I hope that it will continue to maintain clarity. However, this is the first and the major step in the complex visual rehabilitation process and she will require further surgical treatment to restore vision.”

We wish Mrs. Paton well and hope that her vision continues to improve.

Dental Stem Cells for Therapeutic Purposes

Brazilian and American scientists have made induced pluripotent stem cells (iPSCs) from stem cells found in teeth. These adult stem cells are immature enough so that forming iPSCs from that is relatively easy.

Human immature dental pulp stem cells (IDPSCs) are found in dental pulp. Dental pulp is the soft living tissue inside a tooth, and it houses various stem cell populations. These stem cells express a whole cluster of genes normally found in very young and immature cells. Therefore, IDPSCs are “primal” cells that are very young and undifferentiated.

According to Dr. Patricia C.B. Bealtrao-Braga of the National Institute of Science and Technology in Stem and Cell Therapy in Ribeirao Preto, Brazil, human IDPSCs are easily isolated from adult or baby teeth during routine dental visits. IDPSCs are not viewed as foreign by the immune system and can be used in the absence of any drugs that suppress the immune system. They have very valuable cell therapy applications, including the reconstruction of large cranial defects.

Another research project in the Republic of Korea, at the college of Veterinary Medicine, Gyeongsang National University, Republic of Korea have examined a stem cell population from third molars called human dental papilla stem cells (DpaSCs). DpaSCs can form dentin and dental pulp, but they also have biological features that are similar to those of bone marrow-derived mesenchymal stem cells (MSCs).

MSCs have been very heavily studied. While these stem cells have remarkable therapeutic capabilities, they have the disadvantage of only being able to grow in culture or a short period of time. After growing in culture for about a week, MSCs tend to go to sleep and not grow anymore.

DPaSCs, however, have a remarkable capacity to grow in culture. Data from work done in the laboratory of Gyu-Jin Ryo has shown they can grow for a longer period of time than MSCs in culture without going to sleep. Therefore, they not only can form a greater number of progeny, but they can also, potentially, form larger tissues and structures.

Based on their increased culture capabilities, DPaSCs can provide a source of stem cells for tooth regeneration and repair and, possibly, a source of cells for a wide variety of regenerative medical applications.

Drug Developers Increase Their Use of Stem Cells

Industries have increased their use of stem cells in research and development and product testing and the industrial use of stem cells will almost certainly increase in the future.

Despite the image of stem cells in the popular imagination as the stalwarts of regenerative medicine, stem cells have revolutionized drug development and testing. James Thomson, director of regenerative biology at the Morgridge Institute for Research in Madison, Wisconsin, and one of the founders of Cellular Dynamics International, also in Madison, said, “I think there are tremendous parallels to the early days of recombinant DNA in this field. I don’t think people appreciated what a broad-ranging tool recombinant DNA was in the middle ’70s.” Thomson also thinks that people also seriously underestimate the tremendous number of hurdles that must be overcome in order to use such technologies in clinical treatments. Stem cells, according to Thomson, are in a similar situation. While the therapeutic use of these cells might eventually come to fruition, “people underappreciate how broadly enabling a research tool it is.”

About two years ago, drug companies began to investigate the use of stem cells in testing and evaluating new drugs. Today, the pharmaceutical industries all over the world are increasingly using stem cell lines to test drug toxicity and identify and evaluate potential new therapies. For example, Thomson’s company, Cellular Dynamics, sells human heart cells called cardiomyocytes, which are made from induced pluripotent stem (iPS) cells. Thomson says that “essentially all the major pharma companies” have purchased these cells for use in their laboratories. The company also produces brain cells and cells that line blood vessels, and is about to release a line of human liver cells.

Cellular Dynamics is not the only company that makes stem cell lines for drug testing. Three years ago, a stem-cell biologist named Stephen Minger left his job in at a United Kingdom university to be the head of General Electric Healthcare’s push into stem cells. This medical-technology company, which is headquartered in Chalfont St. Giles, UK, has been selling human heart cells made from embryonic stem (ES) cells for well over a year, and is due to start selling ES cell-derived liver cells soon.

Minger’s team at GE Healthcare assessed their ES-derived heart muscle cells in a blind trial against a set of unnamed drug compounds to determine if they could determine which compounds were toxic. Once the tests were completed, Minger said that they found that the cells had been affected by those compounds that are known to be toxic. However, the stem cells also identified a problem that had only been discovered after the drugs had reached the market (after they had been approved by the US Food and Drug Administration). According to Minger, “These are compounds which went all the way through animal testing, then went through phase I, II, III and then were licensed in many cases by the FDA.”

Stem cell lines can do more than identify drugs with dangerous side effects’ they can save the industry millions of dollars in wasted development costs. However, they might also be tools for drug development. Cellular Dynamics and GE Healthcare even market their cells from this very purpose. Adam Rosenthal, senior director for strategic and corporate development at iPierian, a biopharmaceutical company based in San Francisco, California, said, “Many of the animal models out there are poor, demonstrating great efficacy in the mouse, but not repeating in man during late-stage clinical trials. Therefore having an in vitro model years before, which can actually recapitulate human disease, would be a huge advantage.

iPierian has a different strategy than other stem cell companies, since it has its own proprietary in-house stem cell lines that it uses. It does not sell those cell lines, but uses them to develop treatments for neurodegenerative diseases; e.g., Alzheimer’s. This same company has recently announced that they are going to move forward with their development of monoclonal antibodies that target the tau proteins thought to be important in the onset of Alzhiemer’s disease. iPierian made this decision based on information that came from stem-cell work.

Lee Rubin, co-founder of iPierian and director of translational medicine at the Harvard Stem Cell Institute in Cambridge, Massachusetts, says that there is debate within industry if stem cells serve as appropriate model systems to study certain diseases. This is particularly the case with particularly non-genetic or late-onset disorders or conditions that result from pathological interactions between different tissues. Rubin has used stem cells in his research to model a disease called spinal muscular atrophy, which is actually a group of early onset genetic disorders. Rubin makes it clear that the only way to definitively demonstrate that stem cells are a superior model system from drug discovery is to show that the drugs developed from stem cell-based models works in people. Rubin put it this way, “That’s a long-term project. That’s the ultimate test.”

Thomson notes that stem cells will almost certainly find even wider uses than drug-development work. “What human ES cells and iPS cells now do is give you access to the basic building blocks of the human body, just for basic study. We will understand the human body at a much greater detail because of these cells.” How stem cells will be used are not clear, but Thomson added, “But I do think it will profoundly change human medicine.”

The Notch Signaling Pathway

Because stem cell differentiation is controlled by signal transduction pathways, some of my readers have suggested that I discuss particular signal transduction pathways. In the previous post, the Notch signaling pathway was mentioned, and this provides a good reason to introduce my readers to it.

To think of signal transduction, one should consider the popular board game, Mouse Trap. When your game icon lands on the mouse trap spot on the game board, you turn a crank, and this crank rotates a vertical gear that is connected to a gear. Once that gear turns, it pushes lever that is braced with a rubber band until it snaps back and hits a swinging boot. The boot kicks over a bucket, which sends a marble down a rickety staircase. At the bottom of the staircase, the marble enters a chute and eventually taps a vertical pole. At the top of this pole is an open hand (palm-up) that supports another marble. The movement of the pole, caused by the tapping of its base by the first marble knocks the second marble free and it falls through a hole in its platform into a bathtub, and then through a hole in the tub onto one end of a seesaw. The propulsion of the seesaw launches a plastic diver on the other end into a round tub that is on the same base as the barbed pole that supports the mouse cage. The tub’s movement shakes the cage free from the top of the pole and the cage falls to trap the mouse.

This machine that traps the mouse is very similar to signal transduction in cells. The signal to catch the mouse (turning the crank), is far removed from the cage that eventually catches the mouse. Also, the act of catching the mouse (the dropping of the mouse cage), requires the prior execution of many other causally linked steps.

Notch signaling begins with a cell surface protein called Notch. Notch has a large region of the protein outside the cell and a small part of it that intersects the cell membrane, and another region that extends into the cell interior. All three of these domains of the Notch protein play an essential role in the function of Notch.

To turn the crank of this mouse trap, Notch must bind to its receptor. The Notch receptor can be a member of the DSL (Delta, Serrate and Lag-2) gene family.  The receptor is found on the surface of another cell. The binding of Notch to its receptor is the action that “turns the crank” on this mouse trap. Notch binding changes the structure of Notch, and it is clipped into two unequal halves by an enzyme that clips proteins at specific sites (the gamma-secretase). The Notch protein is now broken into a portion that remains anchored in the cell membrane, and another regions that remains inside the cell. This portion of the Notch protein is called “Intracellular Notch” or ICN (Wang MM.Int J Biochem Cell Biol.2011 Nov;43(11):1550-62 & D’Souza B, Miyamoto A, Weinmaster G. Oncogene. 2008 Sep 1;27(38):5148-67).

With the cleavage of Notch, the boot has knocked over the bucket and the marble has moved down the rickety staircase to the chute. ICN is able to enter the cell nucleus. There are proteins in the cytoplasm that can bind to ICN and prevent it from doing so, but we will not discuss them at this time (see van Tetering G, Vooijs M. Curr Mol Med. 2011 Jun;11(4):255-69).

Once in the nucleus, ICN teams up with another protein to activate the express of particular genes. Therefore, what began at the cell surface with the binding of the Notch protein by its receptor had culminated in the changes in gene expression in the nucleus. The other proteins that work together with ICN are members of the “CSL” gene family. CSL stands for “CBF1/RBP-Jκ/Suppressor of Hairless/LAG-1.” When ICN combines with CSL the two proteins are converted from inactive proteins into a complex that actives the synthesis of messenger RNAs for specific genes. This rattles the pole that brings the cage down on the mouse’s head (see Kovall RA. Oncogene. 2008 Sep 1;27(38):5099-109).

What are the target genes of Notch signaling? Great question, but the answer is frustrating, since it depends on the cell type. In developing pancreas, once of the target genes of Notch signaling is PTF1a, but in other cell types and tissues, other genes are activated.

In embryonic stem cells and other stem cells as well, the Notch signaling pathway plays a vital role in the differentiation of these cells into various cell types. Notch signaling is also an important component of the pathology of organ failure in many organs and is also a central pathway involved in the onset and maintenance of several different types of cancers.  Understanding its function and how to regulate it is crucial.

Stem Cell Research Provides New Insights into Insulin Production

Insulin is a protein hormone made by the beta cells of the pancreatic islets. It signals to the liver, skeletal muscles, and fat tissue to take up glucose and store it as glycogen (a polymer of glucose), or to convert it into fat. Insulin also induces the uptake of amino acids by muscles and the liver to form protein. This makes insulin one of the most important anabolic (building) hormones in the body.

Without sufficient quantities of insulin, blood sugar levels soar, since cells do not have the signal to take up sugar. Large quantities of sugar are quite damaging to cells and tissues, and the accumulating damage causes blindness, kidney failure, heart failure, circulatory and peripheral nerve troubles and other ailments.

This pathological condition is known as diabetes mellitus, and treatment of it requires routine injections of insulin. In order to actually treat insulin, we must somehow replace the deleted or damaged beta cells. Stem care cell treatment can potentially do this, but the details are still being worked out.

Danish stem cell scientists have provided some insights into ways to convert stem cells into pancreatic beta cells. By examining pancreatic development in mice, Palle Serup and his research group discovered a new gene called “Mind Bomb-1” that plays a role in pancreatic beta cell formation.

Accord to Dr., Serup, “To get stem cells to develop into insulin-producing beta cells, it is necessary tp know what signaling mechanisms normally control the creation of beta cells during fetal development. This is what our new research results can contribute. When we know the signaling paths, we can copy then in test tubes and thus in time convert stem cells to beta cells.” Dr. Serup is a member of the Danish Stem Cell Center or DanStem at the University of Copenhagen.

In a collaboration with researchers at DanStem, the Danish Hagedorn Research Institute, and other international partners in Japan, Germany, South Korea and the United States, these new findings were published in the April edition of the Proceedings of the National Academy of Sciences.

Previous work has established that during the early hours of the development of the pancreas, a signaling pathway that utilizes the “Notch” protein prevents pancreatic cells from differentiating into endocrine (hormone-making) cells and promotes the continued growth and proliferation of a kind of generic, all-purpose pancreas precursor cell. These all-purpose pancreatic precursor cells are called multipotent progenitor cells or MPCs, and they express two genes: Nkx6-1, and Ptf1.

A bit later, Nkx6 and Ptf1a start to antagonize each other such that cells that express Nkx6 cannot express and Ptf1 and Ptf1-expressing cells cannot express Nkx6. This antagonism between these two genes segregates the developing pancreas into two domains. The bit that is furthest away from the ductal system expresses Ptf1a+ and form “acinar progenitors.” The acinar cells are the clusters that make all the digestive enzymes released by the pancreas the bicarbonate ions. The portion of the developing pancreas that is closet to the ductal system expresses Nkx6-1, and makes the pancreatic duct and β-cell progenitors (see Russ HA, Efrat S. Pediatr Endocrinol Rev. 2011 Dec;9(2):590-7).

This sounds simple, but there are still several gaps that have yet to be filled in. For example, the signals that regulate patterning of the incipient pancreas and cause the segregation of the cells from one end to the other. Also, what dictates the formation of β-cell progenitors as opposed to ductal cells is also presently unknown.

In this present article, Serup and his colleagues discovered that deleting Mind Bomb-1 activity from the developing pancreas preventing the segregation of MPCs into Nkx6-expressing and Ptf1a-expressing cells. Instead the Nkx6-1-expressing cells were replaced by Ptf1-expressing cells. This prevented the formation of beta cells.

Interestingly, Serup and his team found that once the Notch protein acts early during pancreatic development, it actually acts again to help establish the segregated pancreas with Nkx6-1-expressing cells at one end and Ptf1a-expressing cells at the other. This shows that Notch is not only necessary early on, but also later for beta cell formation.

According the Serup, “Our research contributes knowledge about the next step in development and the signaling involved in the communication between cells – an area that has not been extensively described. This new knowledge about the ability of the so-called “Notch” signaling first to inhibit and then to stimulate the creation of hormone-producing cells is crucially important to being able to control stem cells better when working with them in test tubes.”

Genes and Growth Factors that Control Neural Stem Cells

Neuron-producing stem cells in the brain are controlled by a host of mechanisms, and two of these have been more precisely enumerated thanks to work by Steven Levison and Teresa Wood at the University of Medicine and Dentistry of New Jersey and Anna Lasorella at Columbia University Medical Center.

The first study by Levison and Wood examined proteins that are soluble in the cerebrospinal fluid. Neural stem cells are in constant contact with the cerebrospinal fluid, and therefore, any signaling molecules that are secreted into the cerebrospinal fluid (CSF), can potentially influence the activity of neural stem cells.

Insulin-like growth factors are typically made in response to growth hormone. Because these insulin-like growth factors mediate the response of growth hormone, they are called somatomedins. Insulin-like growth factors (IGFs) also play roles in the development of the brain. There are two main IGFs, IGF-1 and IGF-2. IGF-I and its receptor (IGF-IR) are widely expressed in the central nervous system, and IGF-2 is expressed in a more restricted pattern. IGF-binding proteins are similarly expressed during varying phases of brain development. IGF-I regulates both neuronal and glial cell proliferation and differentiation, apparently by an initial increase in neural progenitor proliferation. Loss of function mutations in the genes that encode either IGF-I or IGF-IR result in brain retardation, and overexpression leads to brain overgrowth. A few cases of IGF-I or IGF-IR mutations have been described in humans, and both of them result in some form of mental retardation and even microcephaly (small head). Later in development, circulating IGF-I levels are elevated and brain levels-specific are reduced, but circulating IGF-I can cross the blood-brain barrier and influence brain biology. It seems to prevent programmed cell death of neurons (see D’Ercole AJ, Ye P 2008 Minireview: expanding the mind: insulin-like growth factor I and brain development. Endocrinology 149:5958–5962).

This study by Levison and Wood established that IGF-1 & 2 are essential for neural stem cell renewal and cell proliferation. IGF-1 maintains neural stem cell numbers by promoting cell division. However, IGF-2 drives the expression of those proteins necessary to main the undifferentiated state of the neural stem cells.

Since the concentration of both these proteins declines with age, it might explain the cognitive decline associated with aging.

The second study identified a molecular pathway that controls the retention and release of the brain-specific stem cells. Antonio Iavarone and Anna Lasorella at Columbia University Medical Center were able to establish that neural stem cells reside in small areas called “niches.” This molecular pathway also works to maintain the neural stem cell population.

According to Iavarone, “From this research, we knew that when stem cells detach from their niche, they lose their identity as stem cells and begin to differentiate into specific cell types.”

Stem cell niches in the brain are located right next to the “ventricles.” Ventricles are fluid-filled spaces within the central nervous system. These fluid-filled spaces are loaded with cerebrospinal fluid. the number of neural stem cells within these neural stem cell niches is carefully regulated so that enough cells are present for cell division, but enough are released into the brain to replenish dead or heavily-needed neurons. However, as explained by Anna Lasorella, associate professor of pathology and pediatrics, “the pathways that regulate the interaction of stem cells with their niche were obscured.”

In previous work, Iavarone and Lasorella showed that molecules called ID or inhibitor of differentiation proteins, regulate stem cell properties (Iavarone A, Lasorella A. Trends Mol Med. 2006 Dec;12(12):588-94). This present study determined how Id proteins regulate stem cell identity.

In this study, mice with loss-of-function mutations in the gene that encodes the Id protein. They also made strains in which the amount of the Id protein was not eliminated, but decreased. In the mice with no ID protein, the mice died within 24 hours of birth. The brains of these mice showed very low levels of neural stem cell proliferation and the entire neural stem cell population was greatly reduced.

When Iavarone and Lasorella and their co-workers examined what genes were reduced in the absence of Id proteins, they discovered some of these genes encoded proteins involved in cell adhesion. Therefore the Id proteins brings on-line a whole host of proteins that cause the neural stem cells to stick to their stem cell niche., This adhesion allows the neural stem cells to divide and increase in numbers. However, the Id protein is not completely segregated to the sister cell and this cell does not express the cell adhesion genes and detaches from the stem cell niche. The detachment from the stem cell niche induces differentiation in the neural stem cell, and the specific cell type it forms depends upon microenvironmental cues.

Therapeutic application of these finds will require a good deal more research.  Dr. Iavarone said. “Multiple studies show that NSCs respond to insults such as ischemic stroke or neurodegenerative diseases. If we can understand how to manipulate the pathways that determine stem cell fate, in the future we may be able to control NSC properties for therapeutic purposes.”

“Another aspect,” added Dr. Lasorella, “is to determine whether Id proteins also maintain stem cell properties in cancer stem cells in the brain. In fact, normal stem cells and cancer stem cells share properties and functions. Since cancer stem cells are difficult to treat, identifying these pathways may lead to more effective therapies for malignant brain tumors.”

Stephen G. Emerson, MD, PhD, director of the Herbert Irving Comprehensive Cancer Center at NewYork-Presbyterian Hospital & Columbia University Medical Center, added that, “Understanding the pathway that allows stem cells to develop into mature cells could eventually lead to more effective, less toxic cancer treatments. This beautiful study opens up a wholly unanticipated way to think about treating brain tumors.”

Gallbaldder Contains Stem Cell Source for Liver Regeneration

The research group of Guido Carpino at the University of Rome has announced at the 2012 International Liver Congress the existence of a stem cell population in the gallbladder. This is significant because the gall bladder is an organ that is often discarded during organ donations and surgical procedures, but this organ contains a multipotential stem cell population.

Biliary tree stem/progenitor cells (BTSCs) have been previously identified in human extra hepatic bile ducts. BTSCs can form liver, gall-bladder and pancreas-specific cell types in culture and when injected into a laboratory animal (See Vincenzo Cardinale, et al., Hepatology 2011;54(6):2159-72).

In the present study, Carpino and his co-workers discovered that in the gallbladders of normal and sick mice, a stem cell population was available that could be easily isolated and were able to repopulate the liver and improve liver function (see Vincenzo Cardinale, et al., Nature Reviews Gastroenterology and Hepatology 2012; 9: 231-240).

Stem Cell Differentiation Requires Proper Compaction of DNA

Human cells have a compartment that houses the chromosomes known as the nucleus. The nucleus in human cells contains so much DNA that if the DNA was laid out end to end, it would stretch out for about one meter. Think of that – almost every cell in your body has one meter’s length of DNA in it. In order to properly package all that DNA into the nucleus of the cell, it must be assembled into a structure called “chromatin.”

Chromatin involves winding the DNA around small spools, and the spools are coiled into a fiber and then the fiber is looped into rosettes. The spools are composed of proteins called “histones.” Histone proteins are extremely conserved from one organism to another. In fact, histone proteins from cow peas and extremely similar to histones from cows. This tells scientists that the function of histones is exactly the same from one organism to another. The tiny spools are composed of four “core histones” known as H2A, H2B, H3 and H4. Each tiny spool has two copies of each core histone protein. The DNA is then wound around each of these histone complexes 1.8 times. The core histone complex with its DNA wound about it is either called a “core particle,” or a “nucleosome.”

To form chromatin, the nucleosomes are bound together by another histone proteins called H1. H1 winds the nucleosomes together into a chromatin fiber that is about 30 nanometers in diameter. These chromatin fibers are looped into a 300 nanometer coiled chromatin fiber, and these coiled chromatin fibers are then wound into 700 nanometer condensed chromatin. A chromosome that has been observed during the height of cell division (a phase called metaphase for those who are interested) has a diameter of 1400 nanometers, and since there are two chromatids present during cell division that compose each chromosome, these measurements agree completely with other work.

All of this might seem rather dry and uninteresting, except that researchers at the Georgia Institute of Technology and Emory University have demonstrated that chromatin compaction is essential for embryonic stem cell differentiation. Embryonic stem cells (ESCs) express several different types of H1 subtypes, and ESCs that fail to express these H1 subtypes show reduced chromatin compaction and impaired differentiation. The diminished differentiation capacity of these genes seems to derived from the inability of these cells to properly silence particular genes.

Yuhong Fan, assistant professor in the Georgia Tech School of Biology said, “While researchers have observed that embryonic stem cells exhibit a relaxed, open chromatin structure and differentiated cells exhibit a compact chromatin structure, our study is the first to show that this compaction is not a mere consequence of the differentiation process but is instead a necessity for differentiation to proceed normally,”

In this study, which was led by Fan and Todd McDevitt, who is an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, a ESC strain was used that lack three H1 subtypes; H1c, H1d, and H1e. These three H1 subtypes show increased expression levels during ESC differentiation, and the ESC strains triply deficient for these three H1 subtypes were unable to differentiate, even under standard culture conditions that normally induce differentiation. They also failed to differentiate in embryoid bodies, and could not form neural cells.

Anthony Carter, who oversees grants at National Institutes of Health’s National Institute of General Medical Sciences that deal with the effects of chromatin structure on gene expression, made these comments about this work: “This study has uncovered a new, regulatory function for histone H1, a protein known mostly for its role as a structural component of chromosomes. By showing that H1 plays a part in controlling genes that direct embryonic stem cell differentiation, the study expands our understanding of H1’s function and offers valuable new insights into the cellular processes that induce stem cells to change into specific cell types.”

When the triply-deficient ESCs were subjected to differentiation protocols, they remained tightly packed together, much like the early embryo. The cells also expressed genes that are found in the inner cell mass of the early embryo, such as Oct4. In order for the cells of the early embryo to properly differentiate, genes like Oct4 must undergo programmed down-regulation.

Accord to Fan, ““H1 depletion impaired the suppression of the Oct4 and Nanog pluripotency genes, suggesting a novel mechanistic link by which H1 and chromatin compaction may mediate pluripotent stem cell differentiation by contributing to the epigenetic silencing of pluripotency genes. While a significant reduction in H1 levels does not interfere with embryonic stem cell self-renewal, it appears to impair differentiation.”

In order to make embryoid bodies, this study utilized a rotary suspension technique that was developed by McDevitt and his co-workers. Normally, scientists use the so-called “hanging drop” method in which cells are placed in a drop of medium with few growth factors (20% serum usually), and suspended upside down on a microscope slide in a sealed chamber that prevents desiccation. under these conditions, the ESCs will form roundish little balls of cells that differentiate on the inside. These are known as embryoid bodies, and McDevitt’s technique forms three-dimensional embryoid bodies at very high-efficiency.

Embryoid bodies contain cell types of all three primary embryonic germ layers (endoderm, mesoderm and ectoderm). However, when the triply-deficient ESC line was subjected the McDevit’s embryoid body-making protocol, that lacked differentiated cell types and largely resisted differentiation.

As noted by McDevitt, “H1 triple-knockout embryoid bodies displayed a reduced level of activation of many developmental genes and markers in rotary culture, suggesting that differentiation to all three germ layers was affected.”

Fan and MCDevitt’s groups tried to add back H1 subtypes to the triply-deficient ESC strain. According to Fan, “When we added one of the deleted H1 subtypes to the embryoid bodies, Oct4 was suppressed normally and embryoid body differentiation continued. The epigenetic regulation of Oct4 expression by H1 was also evident in mouse embryos.”

This work also examined the ability of the triply-deficient ESC strain to differentiate into neural cells. However, the H1 triple-knockout ESCs could form neither neuronal nor glial cells, and unable to contribute to the formation of a neural network. Only 10% of the H1 triple-knockout embryoid bodies formed neurites and they produced on average eight neurites each in comparison to normal embryoid bodies, which produced, on average, 18 neurites.

In he future, Fan and McDevitt would like to investigate if controlling H1 histone levels can be used to influence the reprogramming of adult cells to form induced pluripotent stem cells, which have the capacity to differentiate into tissues in a way similar to embryonic stem cells.

Half of all Americans are Pro-Life

The Gallup Pole’s new numbers have shown that at least half of all Americans, which includes, Republicans, Democrats, and Independents, are pro-life. This does not mean that 50% of all Americans think that abortion should be illegal, but that enough of them think that abortion is immoral enough to call themselves as pro-life.  This suggests that the pro-life movement has gone from fringe to mainstream.  It may not be too long before enough Americans view abortion as immoral so that it becomes a restricted practice, and is permissible only under particular circumstances.

See Wesley J Smith’s article about it here.

Embryonic Stem Cells – Not all Genes are On

Early thinking about embryonic development and differentiation tended to view development as a matter of going from a cell with all kinds of genes on to progeny cells that have a host of these genes turned off and only a small subset of the original cache of genes turned on. If those genes were muscle-specific genes, then the cell became a muscle cell, and if they were nervous system-specific genes, then the cell became a neuron or glial cell.

Several different experiments questioned this conventional wisdom, and in particular, microarray experiments that allowed researchers to examine the gene expression pattern of the entire genome at a time showed that this was not the case. Instead of a host of genes being on in embryonic cells, a particular subset of genes were on, and as the embryo grew and aged, some cells shut one set of genes and turned on others, while a different group of cells turn off yet another set of genes and turned on a completely distinct set of genes.

With embryonic stem (ES) cells, the gene expression pattern depended on the culture system. Therefore, it was always difficult to interpret the results of such experiments.

This problem has now been largely solved, since Austin Smith at the Welcome Trust Stem Cell Institute in Cambridge (UK) has developed a culture system to standardize these conditions for embryonic stem cells. By employing this new methods, Hendrik Marks at the Nijmegen Centre for Molecular Sciences of the Radboud University Nijmegen, the Netherlands, showed that the ground state genes expression of embryonic stem cells is surprising.

There are only a few genes that are activated in embryonic stem cells. However, other genes that are not activated are not actively repressed. Instead that are ready to go and are in a kind of “on hold” status. The protooncogene (a gene that drives cells to divide and grow) c-myc, was thought to be essential for embryonic stem cell growth and division is hardly detectable.

This provides added clues as to how to keep ES cells as ES cells or how to drive them to differentiate into one cell type or another.

According to Marks, formerly researchers thought that “ES cells would subsequently differentiate by turning genes off that are not relevant for a specific specialization, to finally reach the correct combination of active genes for a particular specialization. We now see the opposite: genes are selectively turned on.”

The proteins that bind to DNA and direct gene expression, however, the so-called “epigenome,” are already prepared for action. Thus ES cells are poised to become one thing or another, and the environmental cues that they receive coaxe them into one differentiation pathway or another.

This finding also calls into question the work of Ronald Bailey who thinks that ES cell research is not immoral for the following reason: “So what about the claims that incipient therapies based on human embryonic stem cell research are immoral? That brings us to the question of whether the embryos from which stem cells are derived are persons. The answer: Only if every cell in your body is also a person.” Bailey continues: “Each skin cell, each neuron, each liver cell is potentially a person. All that’s lacking is the will and the application of the appropriate technology. Cloning technology like that which famously produced the Scottish sheep Dolly in 1997 could be applied to each of your cells to potentially produce babies.”

To support his claim, he quotes the Australian bioethicist Julian Savulescu from the 1999 Journal of Medical Ethics: “What happens when a skin cell turns into a totipotent stem cell [a cell capable of developing into a complete organism] is that a few of its genetic switches are turned on and others turned off. To say it doesn’t have the potential to be a human being until its nucleus is placed in the egg cytoplasm [i.e., cloning] is like saying my car does not have the potential to get me from Melbourne to Sydney unless the key is turned in the ignition.”

Savulescu is simply wrong. Many experiments have called this account of development into question, and now Marks’ experiments have placed the nail in the coffin. Furthermore, his analogy that Ta body cell does not have the “potential to be a human being until its nucleus is placed in the egg cytoplasm [i.e., cloning] is like saying my car does not have the potential to get me from Melbourne to Sydney unless the key is turned in the ignition,” is also flawed. The cell of our body are not undergoing development. Development is a process we know a great deal about, and our cells are not undergoing development. Embryos are undergoing development and they are unique human persons. Embryos give rise to our bodies. We are human persons and we began to assume our adult form when the embryo initiated development (i.e., at the termination of fertilization). Development also involves the hierarchical activation and inactivation of various genes. This is not a process that occurs in adult human bodies. Embryos are the beginning of a human person and they are human persons. Savulescu’s analogy would be more accurate if we say that the engine without the car would be unable to get him to Sydney, Australia: It needs a frame, tires and so on. They also all need to be properly connected and integrated with each other to work. His analogy is simply inaccurate and bogus.

Likewise, what Bailey calls “the application of the appropriate technology,” during a cloning experiment is the wholesale creation of a new human being. To say that this new human being is one of your cells is to woefully misunderstand the biological nature has happened during cloning. An egg from a female has its nucleus removed and is fused with a cell from another part of your body. After appropriate manipulation, the egg starts to divide and undergo embryonic development. Even this cell has the same genetic information as the cell from your body, it will not development into an exact duplicate of yourself. There are too many random events that occur during development that cause the individual to become a unique person who may have some similarities with their genetic parent, but will not resemble them completely. Cloning is not a minor manipulation – it is the creation of a new life, and this is a process that our cells are not going through; they are not developing. Therefore, they are not “potential persons.”

Secondly, the embryo is not a potential person, it is a very young human person.  It is a potential adult person, but it is a person nonetheless.

Michael J Fox Changes Tune on Embryonic Stem Cells

Actor Michael J. Fox, whose acting career has included such greats as the “Back to the Future.” series, and the television series “Spin City,” and others has been diagnosed with early onset Parkinson’s disease (PD). He has also been a stalwart proponent of embryonic stem cell research. Apparently, he believes that embryonic stem cell research will provide a potential treatment for his PD and many other PD patients as well. The Michael J Fox Foundation has been a supporter of PD research, which includes embryonic stem cell research into PD treatments.

Michael J. Fox was the subject of some controversy a few years ago when he appeared in some political ads for Missouri 2006, Michael J. Fox endorsed Claire McCaskill, Democratic candidate for the senate from the state of Missouri, who is also an ardent supporter of embryonic stem cell research. In those ads, Fox told viewers in the ad that Ms. McCaskill supported stem cell research that could provide a cure for his Parkinson’s disease. There were also accusations that Fox had gone off his PD-controlling medications during the period of time the ad was shot in order to increase his symptoms and elicit sympathy. The radio talk show host Rush Limbaugh suggested that Fox could have been acting, but many people emailed Limbaugh saying that Fox typically went off his medication before testifying before Congress.

Nevertheless, Fox no longer believes that embryonic stem cell research is the sina qua non of PD treatment. In an article at the New Scientist web site, Fox stated that the problems with stem cell-based treatments made him less sanguine about the possibilities of a stem cell-based treatment for PD.  This does NOT mean that Fox is no longer a supporter of embryonic stem cell research.  It simply means that one of the most vociferous advocates of embryonic stem cell research is unwilling to place all his hope in it as a viable cure for PD.  This is truly a remarkable development.

PD has been experimentally treated with cells from aborted fetuses.  These experiments are nothing short of gruesome, and they did not provide any evidence of lasting viable cures.  Furthermore, when the brains of individuals who had received the transplants were examine postmortem, the implanted cells showed the same pathologies as the surrounding tissue.  Therefore the implants were a rousing flop.  Some successes have been seen with transplantation of animal tissue, but these experiments were few and far between, and have risks of infecting patients with animal viruses.

With respect to stem cell treatments or PD, a highly-publicized Nature paper implanted dopamine-making neurons that were made from embryonic stem cells into the brains of PD mice.  While many of the symptoms improved, the implanted cells generated lots of tumors (see Roy N et al., Functional engraftment of human ES cell–derived dopaminergic neurons enriched by coculture with telomerase-immortalized midbrain astrocytes, Nature Medicine 12, 1259-68; November
2006).  Wesley J Smith has noted that Fox called these tumors “tissue residue.”  This is either ignorance or dishonesty.  100% of the rats in these experiments that received that implants developed tumors.  This is not tissue residue, they are tumors.

On the other hand, adult and umbilical cord stem cells have shown some remarkable successes, as have experiments with specific proteins called “neurotrophic factors,” which stimulate endogenous brain cells wot divide and make new connections with other cells.  For example, PD rats that were treated with umbilical cord stem cells showed significant recovery in motion and behavior (Weiss ML, et al., Stem Cells 24, 781-792, March 2006).  Additionally, researchers from Kyoto University treated PD mice by transplanting nerve cells developed from their own bone marrow stromal cells (Mari Dezawa et al., Journal of Clinical Investigation 113:1701-1710, 2004).

When it comes to neurotrophic factors,  University of Kentucky scientists treated ten Parkinson’s patients with a protein called glial cell line derived neurotrophic factor to stimulate the patients’ own brain stem cells and showed significant improvement in symptoms (Slevin JT, et al., Journal of Neurosurgery 102, 216-222, February 2005).  Also British researchers injected a protein known as a “neurotrophic factor” into the brains of 5 Parkinson’s patients and found that it stimulated the patients’ own adult neural stem cells. This treatment provided an average 61% improvement in motor function (Gill SS et al., Nature Medicine 9, 589-595; May 2003).  Later autopsies of these treated patients demonstrated that the neurotrophic factors stimulated sprouting of new neurons in the brain (Love S. et al., Nature Medicine 11, 703-704, July 2005).

Likewise, all present clinical trials for PD are all adult stem cell- or induced pluripotent stem cell-based.

Another treatment for PD that is not stem cell-based is Deep Brain Stimulation (DBS).  DBS uses a surgically implanted medical device called a brain pacemaker that sends electrical impulses to specific parts of the brain.  DBS in select brain regions has provided remarkable therapeutic benefits for otherwise treatment-resistant movement disorders like PD (see Kringelbach ML, et al., Nature Reviews Neuroscience. 2007;8:623–35).

Therefore Fox was certainly right to change his perspective on embryonic stem cells. If only he would see that destroying the youngest and most vulnerable members of humanity is too high a price to pay for the cures of others.  There are better and more humane and ethically-sound ways to treat PD, and those ways are being pursued.

Regenerated Hair from Adult Stem Cells

Japanese researchers led by Takashi Tsuji from the Research Institute for Science and Technology at Tokyo University of Science have made bioengineered hair follicle germ cells from adult epithelial stem cells and dermal papillae cells. These hair follicle germ cells form functional hair follicles and grow hair. This is a proof-of-concept experiment for bioengineered organ replacement that may then proceed to human clinical trials.

These bioengineered follicle germs were made with epithelial and mesenchymal stem cells from skin found on the backs of mouse embryos (stage E18 for those who are interested). Once these cells were dissociated, they were combined with stem cells from adult hair follicles (the bulge region).

In a previous paper, Tsuji’s lab showed that a bioengineered hair follicle germ that was reconstituted from embryonic follicle germ-derived epithelial and mesenchymal cells could generate a bioengineered hair follicle and shaft if they used their new technique (Nakao, K. et al. The development of a bioengineered organ germ method. Nat. Methods 4, 227–230 (2007)). However, the Nature Methods paper did not transplant these bioengineered hair follicles into the skin of laboratory mice to determine if they could produce fully functional hair regeneration that includes hair shaft elongation, hair cycles, connections with surrounding tissues, and the regeneration of stem cells and their niches.

In this recent publication, Tsuji’s co-workers in his lab rigorously established that these bioengineered hair follicles could do everything a naturally produced hair follicle could do. In order to direct the growth of the hair toward the surface of the skin, Tsuji and others used a tiny plastic container with a fine nylon thread in the middle to direct the growth of the hair shaft. Previous experience had shown that implanting the bioengineered hair follicles into the skin caused them to form “epithelial cysts,” or fluid-filled vesicles that did not form hairs. The reason for this abnormal behavior is that the implanted follicles are connected with the surface of the skin, and therefore, lack polarity. The small, plastic containers provides a surface upon which the cells can grow toward the skin surface, and the nylon thread directs the extension of the hair shaft toward the skin surface.

These hair follicles expressed all the right genes and also cycled the way normal hair follicles cycle (growth of the hair, cessation of growth, dumping the hair shaft, and then regrowth of the hair shaft). This study definitely demonstrates the ability of adult tissue-derived follicular stem cells to serve as bioengineered organ replacements therapies.

Targeting Breast Cancers with Neural Stem Cells

Singapore scientists, in particular researchers at the Institute of Bioengineering and Nanotechnology (IBN) showed that engineered neural stem cells can target and kill breast cancers.

In this study, workers in the laboratory of Shu Wang used mouse induced pluripotent stem cells (iPSCs) and differentiated them into neural stem cells (NSCs). They then engineered the NSCs to express a viral gene called thymidine kinase. Thymidine kinase comes from Herpes viruses, and this is particular gene that is not found in human cells. Therefore it is a target for anti-herpes virus drugs. By using an insect virus called “baculovirus,” Wang and his colleagues introduced thymidine kinase into NSCs. The use of baculovirus makes the NSCs safer for clinical use, since, being an insect virus, it does not grow in human cells, but can introduce genes into them.

By placing the herpes thymidine kinase gene into NSCs, it makes from susceptible to antiherpes drugs. For example, ganciclovir (Cytovene), is phosphorylated by thymidine kinase, and this molecule is quite toxic to cells. Contact between the engineered NSCs and cancer cells, would cause transfer of the toxic molecule to the cancer cells, which would kill cancer cells too. However, this begs the question: Can NSCs home to the tumor and target it?

In order to test the ability of NSCs to target and treat breast cancers, Wu’s group injected NSCs loaded with the suicide gene mice afflicted with breast tumors. Then they treated the mice with ganciclovir. Dual-colored whole body imaging was used to track the distribution and migration of the engineered NSCs.

Imaging showed that the NSCs homed in on the breast tumors in the mice, and accumulated in various organs that were infiltrated by the cancer cells. The survival of the tumor-bearing mice was prolonged from 34 days to 39 days. These data demonstrate that iPS-derived NSCs are able to effectively seek out and inhibit tumor growth and proliferation.

According to Dr Shu Wang, “We have demonstrated that tumor-targeting neural stem cells may be derived from human iPS cells, and that these cells may be used in combination with a therapeutic gene to cripple tumor growth. This is a significant finding for stem cell-based cancer therapy, and we will continue to improve and optimize our neural stem cell system by preventing any unwanted activation of the therapeutic gene in non-tumor regions and minimizing possible side effects.”

Professor Jackie. Y. Ying, IBN Executive Director, said, “IBN’s expertise in generating human stem cells from iPS cells and our novel use of insect virus carriers for gene delivery have paved the way for the development of innovative stem cell-based therapies. With their two-pronged attack on tumors using genetically engineered neural stem cells, our researchers have discovered a promising alternative to conventional cancer treatment.

Palliative Sedation is Not the Same as Euthanasia

Palliative sedation is a medical technique for terminally ill patients who cannot receive adequate pain relief while they are awake. Palliative sedation uses sedative medications to make the patient unaware and unconscious while the disease takes its course. This relieves extreme suffering by placing the patient in a kind of sleep. The sedative medication is gradually increased until the patient is comfortable and able to relax. Palliative sedation is not intended to cause death or shorten life (Erin Brender, MD; Alison Burke, MA; Richard M. Glass, MD. JAMA. 2005;294(14):1850.)

This has not stopped euthanasia advocates from asserting that palliative sedation is euthanasia. The inimitable Wesley Smith has a blog post on this and he refers to an article in the Journal of Pain & Palliative Care Pharmacotherapy that takes this deliberate conflation of these two very different things to the woodshed.  It’s a great read.  Check it out here.

Curing AIDS With Engineereed Stem Cells

Scientists from the UC Davis Health Science HIV team have demonstrated in a proof of principle study the safety and efficacy of transplanting HIV-resistant stem cells into mice.  If this protocol can be replicated in humans, it could signal a way to completely block HIV infection in human patients.

The human immunodeficiency virus (HIV) is a retrovirus.  The retroviruses contain an RNA genome, but once they infect the host cell, the RNA genome serves as a template for the synthesis of a DNA copy of the RNA genome.  The enzyme that performs this task is reverse transcriptase.  The DNA copy of the genome is inserted into the genome of the host cell.  This means that when the host cell divides, the viral DNA is passed to all of its progeny.

HIV infection causes acquired immunodeficiency syndrome (AIDS).  AIDS is characterized by a progressive shutdown of the immune system, which leads to life-threatening infections and cancers.  HIV infection occurs through the transfer of bodily fluids, such as semen, blood, vaginal fluid, saliva, or breast milk.  Sexual transmission, transmission from breast milk, contaminated needles, or from an infected mother to her baby at birth are the four main modes of transmission.  HIV screening of blood products has largely eliminated HIV transmission from blood products.

Since the discovery of AIDS in 1981, more than 25 million people have died from it, and even though antiretroviral treatments have decreased AIDS deaths and new infections, there were still probably at least 2.5 million new cases of AIDS in 2009.

HIV destroys the immune response by infecting helper T cells (CD4+ cells).  HIV can also infect dendritic cell and macrophages.  The mass die off of T helper cells prevents them from mediating cell-mediated immunity, and this makes the patient more susceptible to opportunistic infections.  People with untreated HIV infections usually develop AIDS and die from opportunistic infections or tumors.  Without antiretroviral treatment, someone with AIDS usually dies within a year.

In order to make HIV-resistant blood cell-making stem cells, Joseph Anderson and his co-workers engineered stem cells with three different genes.  First, they introduced into the stem cells, a human/macaque TRIM5 isoform.  In order to understand the significance of this gene, we must understand HIV more deeply.  When a retrovirus enters a host cell, it must “uncoat,” which simply means that the protein coating that surrounds the virus’ genome must be removed so that the reverse transcriptase can convert the RNA genome into a DNA copy.  Macaques are very widespread Old Word nonhuman primates that are immune the infection by HIV.  The reason for the immunity of these animals to HIV infection is that they possess in their cells a form of the TRIM5 protein that binds to bits of the HIV coat proteins and interferes with the uncoating process.  This prevents successful reverse transcription and transport of the viral DNA to the nucleus.  Therefore, the expression of the macaque version of TRIM5 is these blood-making stem cells rendered them resistant to HIV infection.

Secondly, the blood-making stem cells were given a gene that expresses a short hairpin RNA (shRNA).  These shRNAs can bind to the mRNAs are particular genes that prevent their expression.  In this case, the shRNA that was introduced into the blood-making stem cells prevented the production of the CCR5 gene product.  CCR5 is one of the cell surface proteins that HIV uses to gain entry into host cells.  Therefore, these blood-making stem cells will make blood cells that lacked the target for HIV infection.

Third, cells were engineered with a “TAR decoy.”  TAR is a site in the HIV genome that is bound by the HIV-encoded proteins Tat.  Tat binding to TAR activates expression of HIV genes.  However, by introducing TAR sites into the cells, Tat proteins inordinately bind to these non-functional TAR sites and not to the viral TAR site.  This will inactivate any HIV particles that happen to infect these cells.  With all these factors introduced into them, these blood-making stem cells and their progeny are completely resistant to HIV infection.

Introduction of these engineered stem cells into mice allowed these mice to resist infection even after experimental infection with HIV.  In the words of the lead author of this paper, Joseph Anderson, “After we challenged transplanted mice with live HIV, we demonstrated that the cells with HIV-resistant genes were protected from infection and survived in the face of a viral challenge, maintaining normal human CD4 levels.”  Remember the CD4 cells are the class of T cells that are specifically targeted by HIV, although the virus can infect other cell types too.

Anderson continued: “We actually saw an expansion of resistant cells after the viral challenge, because other cells which were not resistant were being killed off, and only the resistant cells remained, which took over the immune system and maintained normal CD4 levels.”  Anderson’s optimism, however, does not end there:  “We envision this as a potential functional cure for patients infected with HIV giving them the ability to maintain a normal immune system through genetic resistance.”  Anderson is an assistant professor of internal medicine and a stem cell researcher at the UC Davis Institute for Regenerative Cures.

This study confirms the safety and efficacy of this protocol, and validates the potential of this treatment for human HIV patients.  A grant application has been submitted by Anderson and his team for human clinical trials, and they are also pursuing regulatory approval for clinical trials.

Richard Pollard, the chief of infectious diseases at UC Davis (and a co-author on the study), said: “This research represents an important step in our fight against HIV/AIDS.  Clinical trials could give us the critical information we need to determine whether our approach truly represents a functional cure for a terrible disease that has affected millions and millions of people.”

Reducing Heart Attack Scars in the Heart – Skip the Stem Cells

Two research groups have independently discovered that the heart scar that forms after a heart attack can be regenerated without stem cell treatments. Li Qian in the laboratory of Deepak Srivastava at the Gladstone Institute, and Victor Dzau’s team at Duke University have shown that the use of various molecules can trigger the conversion of scar tissue into heart muscle.

Dzau’s lab worked in mice and delivered microRNAs into fibroblasts, which are the cells that form the scar tissue in the heart. When these engineered fibroblasts took up the microRNAs, they became heart muscle cells.

MicroRNAs (miRNAs) are found inside cells are usually about 22 nucleotides long. These very small RNA molecules play important regulatory roles in animals and plants by targeting messenger RNAs (mRNAs) for cleavage or translational repression. Thus, miRNAs act as master regulatory molecules for gene expression (See Bartel DP. Cell. 2004;116(2):281-97).

“This is a significant finding with many therapeutic implications,” said Victor J. Dzau, MD, a senior author on the study who is James B. Duke professor of medicine and chancellor of health affairs at Duke University. “If you can do this in the heart, you can do it in the brain, the kidneys, and other tissues. This is a whole new way of regenerating tissue.”

After their experiments in tissue culture, Dzau’s lab showed that this conversion can also occur inside a living animal. Maria Mirotsou, PhD, assistant professor of cardiology at Duke and a senior author of the study commented, “This is one of the exciting things about our study. We were able to achieve this tissue conversion in the heart with these microRNAs, which may be more practical for direct delivery into cells and allow for possible development of therapies without using genetic methods or transplantation of stem cells.”

Since stem cells have proven difficult to manage inside the body, this mode of therapy has distinct advantages over stem cell-based treatments. Notably, the microRNA process eliminates technical problems such as genetic alterations, and also avoids the ethical dilemmas posed by the use of some stem cells.

“It’s an exciting stage for reprogramming science,” said Tilanthi M. Jayawardena, PhD, first author of the study. “It’s a very young field, and we’re all learning what it means to switch a cell’s fate. We believe we’ve uncovered a way for it to be done, and that it has a lot of potential.”

The next step is to test this approach in larger experimental animals. Dzau said therapies could be developed within a decade if additional studies advance in larger animals and humans.

“We have proven the concept,” Dzau said. “This is the very early stage, and we have only shown that is it doable in an animal model. Although that’s a very big step, we’re not there yet for humans.”

Gladstone researchers took a very different approach.  They delivered a cocktail of three genes that are known to direct cells to form heart muscle during embryonic development.  These three genes, Gata4, Mef2c and Tbx5, which are collectively called GMT, were placed into cells at the site of a heart attack.  Srivastava’s group engineered viruses to infect the heart tissue, and after inducing a heart attack, the engineered viruses were injected into the heart, at the site of the heart attack.

The heart contains several resident cell types that are not involved in contraction.  One of these resident populations is the fibroblast, which seems to be able to differentiate into heart muscle cells if properly coaxed.  The GMT-bearing viruses infected the resident fibroblasts and the infected cells differentiated into heart muscle cells that beat, formed connections with existing heart muscle cells, and contracted in synchrony.  The hearts that had suffered heart attacks came roaring back, functionally speaking, and were as good as new.

Dr. Qian, first author on this article, who is also a California Institute for Regenerative Medicine postdoctoral scholar and a Roddenberry Fellow. said, “These findings could have a significant impact on heart-failure patients—whose damaged hearts make it difficult for them to engage in normal activities like walking up a flight of stairs.  This research may result in a much-needed alternative to heart transplants—for which donors are extremely limited. And because we are reprogramming cells directly in the heart, we eliminate the need to surgically implant cells that were created in a petri dish.”

Dr. Srivastava noted, “Our next goal is to replicate these experiments and test their safety in larger mammals, such as pigs, before considering clinical trials in humans.  We hope that our research will lay the foundation for initiating cardiac repair soon after a heart attack—perhaps even when the patient arrives in the emergency room.”  Dr. Srivastava, is also a professor at the University of California, San Francisco (UCSF), with which Gladstone is affiliated.


Stem Cells Inc. Reports Positive Safety Data in Their Spinal Cord Injury Trial With Human Neural Stem Cells

StemCells, Inc., a biotechnology company based in Newark, California, has reported the results of their initial safety review of their human purified neural stem cell line implantations. This report represents the first planned interim safety review of the Company’s Phase I/II spinal cord injury clinical trial. This clinical trial involved a surgical implantation of the stem cells, and suppression of the immune system with anti-rejection drugs. The results of the safety trial show that both parts of the procedures seem to be well tolerated.

This trial was designed to determine the safety and potential, efficacy of the StemCells, Inc. proprietary HuCNS-SC® cells in spinal cord injury patients. HuCNS-SC cells are a purified human neural stem cell line that can form all the cells of the central nervous system (Taupin P. Curr Opin Mol Ther. 2006;8(2):156-63). When these cells are implanted into the retinas for rats that are suffering from retinal degeneration, they form a variety of retinal-specific cell types and seem to aid in retinal regeneration (McGill TJ., et al., Eur J Neurosci. 2012;35(3):468-77).

This clinical trial represents the first time that human neural stem cells have been implanted into the spinal cords of human patients as a potential therapeutic agent for spinal cord injury. The interim data come from the first cohort of patients. All of these first cohort patients suffered a complete spinal cord injury, and show no neurological function below the level of the injury.

All patients in the trial were transplanted with 20 million neural stem cells at the site of injury in the thoracic spinal cord. Observation of the patients revealed that there were no detectable abnormal responses to the cells, and all the patients were neurologically stable through the first four months following transplantation of the cells. Changes in sensitivity to touch were observed in two of the patients. These data merit the continuance of the trial, and further enrollments. Patients with partial spinal cord injuries, who might experience a broader range of improvements are also being sought for enrollment.

Armin Curt, M.D., principal investigator for the clinical trial, said, “We are very encouraged by the interim safety outcomes for the first cohort.”  Dr. Curt is Professor and Chairman of the Spinal Cord Injury Center at the University of Zurich, and Medical Director of the Paraplegic Center at Balgrist University Hospital. Dr. Curt continued, “The patients in the trial are being closely monitored and undergo frequent clinical examinations, radiological assessments by MRI and sophisticated electrophysiology testing of spinal cord function. The comprehensive battery of tests provides important safety data and is very reassuring as we progress to the next stage of the trial.”

Muscle Cells Made from Induced Pluripotent Stem Cells Successfully Treat Mice With Muscular Dystrophy

Work by researchers at the Lillehei Heart Institute at the University of Minnesota have demonstrated the ability of induced pluripotent stem cells (iPSCs) to make muscle-forming cells, and that these cells can be used to treat muscular dystrophy.

Muscular dystrophy refers to a group of inherited diseases that causes muscle fibers to be structurally weak and highly susceptible to damage. The progressive muscle damage causes the muscles to become gradually weaker and weaker until the patient will eventually require a wheelchair.

There are several different types of muscular dystrophy. Most of the varieties of muscular dystrophy causes symptoms appear during childhood, but others cause symptoms to arise during adulthood. The most common form of muscular dystrophy is Duchenne muscular dystrophy (DMD). The symptoms begin early in life (once the child learns to walk), and include frequent falls, difficulty getting up from a lying or sitting position, trouble running and jumping, waddling gait, large calf muscles, and learning disabilities. A less severe and slower progressing form of muscular dystrophy is Becker muscular dystrophy (BMD). Symptoms usually being in the teenage years, but might also not occur until the mid-20s or later. Other types of muscular dystrophy include myotonic (inability to relax muscles at will, most often begins in early adulthood, muscles of the face are usually the first to be affected), Limb-girdle (hip and shoulder muscles are first affected), congenital (apparent at birth or becomes evident before age 2 and varies in severity), fascioscapulohumeral (shoulder blades stick out like wings when the person raises his or her arms, onset occurs in teens or young adults), and oculopharyngeal (drooping of the eyelids and weakness of the muscles of the eye, face and throat, symptoms first appear in a person’s 40s or 50s).

In order to treat muscular dystrophy (MD), many researchers have tried to use gene therapy to place normal versions of the muscular dystrophy gene (which encodes a protein called Dystrophin) into the muscles of MD patients (Romero NB, et al., Hum Gene Ther. 2004;15(11):1065-76 & Mendell JR, et al., Ann Neurol. 2009;66(3):290-7. These types of experiments have met with limited success, since the immune system of muscular dystrophy patients tends to attack the muscles that express dystrophin (Mendell JR, et al., New England Journal of Medicine 2010 7;363(15):1429-37).

In light of the failure of gene therapy trials, researchers have tried stem cell treatments in MD mice. Scientists in the laboratory of Rita Perlingeiro have used muscle precursor cells made from mouse embryonic stem cells to treat MD mice (Radbod Darabi, et al., Exp Neurol. 2009; 220(1): 212–216). Given this early success, Perlingeiro and her co-workers have used mouse iPSCs to make muscle-forming cells that have been used to treat muscular dystrophy in MD mice. In this experiment, suppression of the immune system was not necessary, since the muscle cells were made from cells that came from the patients.

Perlingeiro said of the experiment, “One of the biggest barriers to the development of cell-based therapies for neuromuscular disorders like muscular dystrophy has been obtaining sufficient muscle progenitor cells to produce a therapeutically effective response. Up until now, deriving engraftable skeletal muscle stem cells from human pluripotent stem cells hasn’t been possible. Our results demonstrate that it is indeed possible and sets the stage for the development of a clinically meaningful treatment approach.”

Once transplanted, the muscle-forming cells (myogenic progenitor cells to be exact) moved into the damaged muscles and integrated into them. They formed skeletal muscle and provided extensive and long-term muscle regeneration that resulted in improved muscle function. To make the iPSC cell lines, Perlingeiro and her laboratory workers genetically modified to human iPSC lines with a gene called PAX7. PAX7 encodes a transcription factor that is essential for muscle formation and muscle regeneration. PAX7, with PAX3, designates cells as myogenic progenitor cells. Therefore, inserting the PAX7 gene into iPSCs would drive them to become myogenic progenitor cells.

Once Perlingeiro’s lab perfected the protocol for making myogenic progenitor cells from iPSCs, they found that they could make buckets and buckets of them. The iPSC-derived muscle forming cells were much more efficient at integrating into the muscles and regenerating them than other cell types. Muscle-forming stem cells from human muscle biopsies, for example, failed to persist in the muscle.

Perlingeiro concluded, “Seeing long-term maintenance of these cells without major side effects is exciting. Our research proves that these differentiated stem cells have real staying power in the fight against muscular dystrophy.”