Geron Corporation Halts Stem Cell Trial

Geron Corporation is leaving the field that it helped pioneer. It was a calculated business move to sink so much money into embryonic stem cell-derived stem cells. This illustrates the long, expensive path it takes to make stem cell-based products. Late Monday, the company said it would halt its study of a stem cell-based treatment for spinal cord injury, which is the first embryonic stem cell trial approved in the U.S. Now Geron is putting its stem cell division up for sale.

See the rest of the story here.

Stem Cells Repair Lung Damage After Flu Infection

Everyone has struggled with influenza at some point in their lives. This seasonal infection can knock us for a loop and decrease our lung capacity for an inconvenient period of time. How does our body cope with it? In the first place our immune response destroys the influenza virus and the cells infected with it. Secondly, the lung regenerates damaged cells to reclaim the lost lung capacity. Researchers have recently identified and characterized the adult stem cells that can regenerate lung tissue. These findings come from studies of isolated human stem cells, and from parallel studies of mice infected with a particularly nasty strain of H1N1 influenza virus. These findings could potentially be the impetus for new regenerative therapies for acute and chronic airway diseases.

The main authors of this work Frank McKeon of the Genome Institute of Singapore and the Harvard Medical School in Boston, and Wa Xian of the Institute of Medical Biology in Singapore and the Brigham and Women’s Hospital in Boston published this research in the October 28th issue of the prestigious journal Cell.

The H1N1 strain of the influenza virus is as close as you can get to the virus that was responsible for the 1918 influenza pandemic. H1N1 can cause massive lung damage with lots of inflammation and loss of lung tissue. Such infections produce acute respiratory distress syndrome, marked by extensive lung damage and low levels of oxygen in the blood. What hasn’t been clear is what happens to the lungs of those who manage to survive, since two months after the infection, the lungs look normal again in those who survived the infection.

In this paper, studies in influenza-infected mice showed that lungs are capable of true regeneration. Stem cells found along the surfaces of the airways (in the bronchiolar epithelium) proliferate rapidly in mice after viral infection and migrate to sites of damage. Once the stem cells reach the sites of lung damage, they assemble into stem cell “pods” and activate genes that identify them as lung alveoli, which are the small, hollow structures that function as the sites of gas exchange in the lung.

McKeon and Xian were able to clone these same stem cells from human lung tissue. Even if grown in a laboratory culture dish, these lung-specific stem cells show that they can form alveolar-like structures. This is in spite of the fact that these stem cells from the bronchiolar epithelium have a gene expression profile that is very similar to stem cells found in the upper respiratory airways.

This work suggests that airway stem cells are an important and underappreciated ingredient in regenerative medicine. However, in the case of severe, fast-moving infections, the damage to the lungs would overwhelm the regenerative capacity of the lungs. McKeon noted: “The problem in the case of a pandemic is that people die quickly. It is hard to imagine how a cell-based treatment will play in [sic] those time constraints.”

While McKeon is certainly correct, such stem cell-based therapies or secreted factors identified by this study could play an important role in therapies that attempt to enhance the speed of lung regeneration. Such regenerative therapies could aid in those with hard-to-treat condition like pulmonary fibrosis, in which lung tissue becomes scarred. “Pulmonary fibrosis is a bad disease,” McKeon said. “The question is: could you get rid of the fibrosis and replace it with real lung tissue?”

A second study published in the same issue of Cell identifies those molecular pathways in the lung that may also lead to new strategies for encouraging lung regeneration. In that case, researchers led by Shahin Rafii at Weill Cornell Medical College examined mice with one lung removed, a treatment that causes the remaining lung to produce more alveoli.

Pluristem Therapeutics had positive 12-month results from Phase I clinical trials for its PLX stem cells for the treatment of critical limb ischemia

Critical Limb Ischemia or CLI is the culmination of a condition s degenerative disorder called peripheral artery disease (PAD). PAD results from the obstruction of blood vessels, and the most common cases of PAD occur in the blood vessels in the legs. The symptoms are leg pain, difficulty in walking, progressive tissue damage and death, which leads to a need to amputate the limb in order to prevent the onset of gangrene. The best way to treat PAD create new blood vessels that can deliver blood to the tissues of the leg, which will keep the leg tissue alive and prevent cell death and limb degeneration.

To this end, an Israeli stem cell therapy company called “Pluristem” has completed a Phase I clinical trial for its PLX-1 stem cell line as treatment for critical limb ischemia.  This phase 1 trial continued for 12 months and was conducted under protocols approved by the United States Food & Drug Administration (FDA), and the German Paul-Ehrlich-Institute.  In order for such a clinical trial to be considered significant, the treatment must enhance the percentage of patients who survive without suffering amputation of the affected limb.  This endpoint is called the amputation free survival or AFS rate.

Based on the AFS rate after 12 months of treatment, the clinicians involved in the study concluded that PLX-PAD cells seem to provide effective treatment for CLI.  Edwin Horwitz, president of the International Society for Cellular Therapy and chairman of Pluristem’s Scientific Advisory Board, stated: “AFS is the single most important endpoint in CLI clinical trials… Even though these Phase I trials were not controlled studies, the data collected in these trials on AFS indicate significant potential for PLX-PAD cells in treating CLI patients.” Because Phase I studies are designed to test the safety of the treatment, they cannot be used to determine the efficacy of the treatment.  The PLX-1 cells are definitely safe for human patients, since the study met all endpoints and did not have to be stopped because of unforeseen side effects.  Therefore, Pluristem will almost certainly be allowed to conduct Phase II studies with PLX-1 cells, which are designed to determine the efficacy of treatments.

PLX-1 cells are derived from human placenta.  Human placenta contains a wealth of stem cells, and one of the stem cell populations in human placenta is a mesenchymal stem cell that can form blood vessels and stimulate the regenerative effects of other stem cells.  These particular mesenchymal stem cells derived from placenta can potentially enhance the capabilities of umbilical blood-making stem cells when such cells are used to reconstitute the bone marrow of human patients (see Prather, Toren, Meiron, Expert Opin Biol Ther.2008;8(8):1241-50).  Furthermore, these same PLX-1 cells restore blood flow in laboratory animals that suffer from CLI (Prather, et al., Cytotherapy. 2009;11(4):427-34).

Since the only present cure for CLI is amputation of the affected limb, regenerative treatments like PLX-1 are a welcome site for those who suffer from Peripheral Artery Disease.

Using Induced Pluripotent Stem Cells to Model Mental Diseases in a Dish

The brains of patients who suffer from neurological disorders like autism or schizophrenia work differently than those who do not have such conditions. The precise functional differences in the neurons of those who suffer from such conditions are not completely understood, but stem cell technology has provided a way to study this very question. Scientists have literally been able to “turn back the clock” on the neurons of schizophrenic patients and see some of the abnormalities they display during development.

Researchers isolated skin cells from schizophrenia patients and converted the skin cells into induced pluripotent skins cells (iPSCs) by utilizing using genetic engineering technologies. They then treated these iPSCs with various growth factors to reprogram them into neurons, which are the cells in the central and peripheral nervous systems that generate nerve impulses and are responsible for thinking, reasoning, emotion, and other basic and higher brain functions. Once they made the cultured neurons, they subjected them to various physiological tests and measured the ability of neurons made from the iPSCs derived from patients with schizophrenia, and compared them to neurons made by the same protocol from patients who do not suffer from schizophrenia. The results were telling.

Neurons made from iPSCs derived from skin cells from schizophrenia patients looked normal, but the connections they made with other neurons were abnormal. Neurons connect with each other through special connections called “synapses.” Synapses consist of the end of the neuron, which is called the “axon terminus,” and the cell that receives the neural impulse from the signaling neuron. Neurons can give their input to the front part of another neuron, or they can give their input to other parts of a neuron. Synapses consist of a host of special proteins that dock the neurons together and facilitate the reception of signals from one neuron to another. Defects in synapses lead to abnormalities in nerve impulse conduction, and the neurons from schizophrenic patients showed structural abnormalities in the synapses that they made with other neurons and also produced fewer synapses with other neurons in general.

If that was not enough, Gage and his co-workers went the next step. They treated these cultured neurons with drugs that are normally used to treat schizophrenia. These drugs reversed the abnormalities found in the cultured neurons. This completely contradicts some of the current thinking regarding the treatment of schizophrenia, which asserts that by regulating the amount of particular neurotransmitters like dopamine and serotonin, psychiatrists can ameliorate the symptoms of schizophrenia. Now it appears that the drugs actually induce structural changes in the neurons and the synaptic junctions they make with other neurons and this is the reason these drugs mitigate schizophrenia symptoms.

Lead researcher, Fred (Rusty) Gage, professor of genetics at the Salk Institute for Biological Studies and a member of the executive committee of the Kavli Institute for Brain and Mind (KIBM) at the University of California, San Diego, said: “This allows us to identify subtle changes in the functioning of neuronal circuits that we never had access to before.” Gage continued: “As we accumulate models for these diseases – bipolar disease, schizophrenia, depression, autism – we are going to be able to explore if there are really differences between them that exist on a cellular or gene expression level.” — Fred Gage

Gage also noted that the need to induce structural changes in the neurons in order to assuage the symptoms of schizophrenia might explain why schizophrenia drugs take time before they actually help the patient. In fact, this might explain why other psychoactive drugs take so long to work as well. For example, if depression was simply a matter of modulating the concentration of a particular neurotransmitter, then an anti-depressant should have immediate effects. However, such drugs like antidepressants often take weeks to work. Could it be that such medications work at the structural level and not only at the neurotransmitter level?

When asked what technological advances are needed to explore this further, Gage responded: “One limitation is we haven’t differentiated the cells into specific cell types—neuronal subtypes. Right now we’re just laying these neurons down and allowing them to form connections as they might. Looking ahead, it’s going to be important for us to differentiate the cells. For example, to differentiate and model the cortical neurons, which are responsible for thinking tasks, or the hippocampal neurons, which are responsible for memory tasks. I can one day see us using microfluidic chambers to achieve this. They will allow us to compartmentalize microscopically specific subtypes of neurons in certain locations, and then regulate how they connect to each other. That way you can simulate in a more accurate manner how these subtypes connect with each other in the brain. The future of this is really exciting because the dish is going to get much more complicated.”

Regenexx Corporation uses stem cells to help young woman with lower back pain

Regenexx Corporation in Broomfield, CO specializes in using a patient’s own stem cells to treat joint problems. They have treated arthritic knees, shoulders, and backs with their on-site bone marrow stem cell processing procedure. By transplanting the expanded stem cells from a patient into the joint, patients can experience relief of symptoms and structural improvement of the affected joint.

Regenexx has just announced that a 36-year old woman who suffered from significant back pain for two and a half years was treated by the Regenexx procedure. She had tried physical therapy, IDET (a procedure where a catheter is inserted in the low back disc to burn away painful nerves), epidural steroid injections, facet injections, and trigger point injections, but her pain did not abate. Her MRI showed reactive bone swelling in the vertebrae with compression of the left S1 nerve root. Regenexx physicians had her own specially cultured stem cells were injected into the L5-S1 lower back disc using the Regenexx-C technique.

Her response was telling.  When asked how she felt now as opposed to before the procedure, she said that she felt “Good,” and had experienced “noticeable improvement.” She now only has mild pain, and her range of motion has increased. She can do more since the procedure, and she wrote: ”Much more active and back to a normal life!”

She had failed about every existing conservative low back injection therapy and surgery, but she responded well to the injection of her own specially cultured stem cells into the L5-S1 disc. Regenexx scientists cautiously noted that not every patient achieve these same results, but they were able to help this young lady return to a more active lifestyle.

Umbilical Cord Blood Stem Cells and Spinal Cord injury

In a previous post we discussed statements stem cell scientist Alan Trounson about the use of bone marrow-derived mesenchymal stem cells as a treatment for spinal cord injuries.  In this post, we will examine other statements he makes about umbilical cord stem cells as treatments for spinal cord injury.

Trounson also writes earlier in the same article: “Studies involving umbilical cord blood for neurological indications have been promoted as a result of preclinical data on the apparent formation of neurons in vitro but there is little evidence of their transdifferentiation to functional neurons or glial cells in vivo.”

This statement, like the one about bone marrow-derived mesenchymal stem cells, is misleading.  First of all, umbilical cord blood contains a wide variety of cell types and stem cells.  There is a blood-making stem cell in cord blood, and there are also mesenchymal stem cells, unrestricted somatic cells, and neural stem cells.  Furthermore, there is no evidence that embryonic stem cells form neurons in the spinal cord of human patients either.  Therefore, Trounson is setting a standard for umbilical stem cells that even embryonic stem cells cannot yet meet.  The real question is does administration of umbilical cord stem cells help patients with neurological conditions.

Can umbilical cord stem cells form neurons in culture?  The answer is a clear yes.  Buzanska and colleagues established the existence of a neural stem cell population in umbilical cord blood.  They expanded a population of neural stem/progenitor cells selected from the non-blood-making fraction of umbilical cord blood.  From this fraction, they established a human umbilical cord blood neural stem-like cell (HUCB-NSC) line.  They treated the cells with serum and a chemical called dBcAMP to make them form neurons.  Upon treatments, the HUCB-NSC cells expressed many functional proteins for a variety of different types of neurons, and also showed the types electrophysiological characteristics of neurons.   This definitively showed that cord blood-derived progenitors could be effectively differentiated into functional neuron-like cells in vitro  (Buzanska et al., Neurodegener Dis. 2006;3(1-2):19-26).

Buzanska’s data is significant because most of the time when umbilical cord blood stem cells are used in experiments, a mixed population is used that consists of a few neural-progenitor cells and many other type of progenitor cells.  Therefore, the failure of umbilical cord stem cells to form neuron in vivo is not an indication of the failure of the specific neural progenitor population to form neurons.  Rather it is an indication that the small population of neural progenitor cells was unable to form enough detectable neurons for the experiment in question.

Secondly, Trounson states that there is little evidence of the differentiation of cells to neurons or glia in vivo.  However, an experiment by Lim and his colleagues have shown that this is not the case.  Lim and coworkers administered human umbilical cord mesenchymal stem cells (MSCs) into the spinal cord by means of lumbar puncture and intravenously into the tail vein of rats that had suffered a stroke.  The cells were transplanted 3 days after the stroke, and the rats were tested one week, two weeks, three weeks, and four weeks after the stroke.  Rat brains were also examined one week after the administration of the umbilical cord stem cells.  That rats that had received hUCB-MSCs by means of lumbar puncture had significantly more cells in the damaged areas of the brain than those rats that had received cells intravenously.  Also, many of the cells administered by means of lumbar puncture expressed genes specific to neurons and astrocytes.  Animals that received hUCB-MSCs also showed significantly improved motor function and reduced ischemic damage when compared with untreated control animals.  This is good evidence that umbilical stem cells can form neurons in vivo, which is in direct contradiction to Trounson’s assertion (Lim JY, et al., Stem Cell Res Ther. 2011 Sep 22;2(5):38).

Additionally, administration of umbilical cord cells can help patients with neurological diseases even though they may not differentiate into neurons in the spinal cords of patients.  For instance, several stroke patients have shown improvement after administration of umbilical cord stem cells (Harris DT, Stem Cell Rev. 2008 Dec;4(4):269-74).  Therefore, umbilical cord stem cells have therapeutic potential for neurological conditions, that is, as yet, untapped, and deprecating them does patients no good at all.

Remember that Trounson is receiving lots of taxpayer money for his California Stem Cell Institute.  This institute is pushing embryo-destructive research on the public by using taxpayer dollars.  Therefore, it is necessary for him to make somatic stem cells look as paltry as possible and push embryonic stem cells into as positive light as possible,  However, the huge amount of money simply cannot be justified and neither can the wanton destruction of human life.  Trounson has overstated the vase of embryonic stem cells and understated the case for adult and umbilical stem cells.  It is simple politics and not science.

Reprogramming human oocytes to a pluripotent stage – using triploid embryos

In the October 6, 2011 edition of the journal Nature, Scott Noggle from the New York Stem Cell Laboratory, and his collaborators from the University of San Diego and Columbia University have made a remarkable observation of cloned human embryos. When human embryos are cloned, an egg has its nucleus removed and replaced with a nucleus from a body cell. After stimulation, the egg divides and begins to recapitulate the stages of early embryonic development. This technique is often called “somatic cell nuclear transfer” or SCNT. Typically, cloned human embryos fail to develop for very long. They tend to die before they develop to the blastocyst stage, and they have massive abnormalities in gene expression. Noggle and colleagues found that if the egg nucleus is not removed, and the nucleus from the body cell is added to it, the cloned embryo develops to the blastocyst stage much more easily. Apparently, in human eggs, the removal of the nucleus conveys tremendous abnormalities upon the newly formed embryo, and prevent it from regularly developing to the blastocyst stage.  Noggle and his coworkers provide reasons for the development failure of cloned human embryos.

In this paper, Noggle and others made cloned human embryos through SCNT, but all of them stop dividing at the 6-10 cell stage.  They tried a few other experiments to determine if they could activate the egg to divide without causing developmental arrest.  First they fertilized 21 eggs with frozen sperm and 16 of these 21 eggs formed embryos that developed all the way to the spherical blastocyst stage after six days.  Because 76% of the eggs formed viable embryos, whatever problem afflicts the cloned embryos, it is not due to the quality of the eggs.  Next, the artificially activated unfertilized eggs with a molecule that let Calcium ions into the egg (called calcium ionophore).  7/52 (13.5%) of these artificially activated eggs divided and formed spherical blastocyst embryos.  Such embryos are called “parthenotes: because they were made without the benefit of fertilization and only have one copy of each chromosome (a condition that is called “haploid”).  This again confirms that the problem is not with the eggs.  To determine if developmental arrest was due to the removal of the egg’s nucleus, they removed nuclei from the eggs, and transferred egg nuclei from other eggs, and then artificially activated those eggs.  Once again, 1/7 (14.3%) of these eggs divided and formed spherical blastocysts.  In another control experiment, a nucleus from a body cell was fused with the egg, and the egg was then artificially activated, after which the body-cell nucleus was removed.  4/7  (57%) embryos developed to blastocysts after 6 days.  These control experiments suggest that the experimental manipulation the eggs are experiencing is not the cause of their developmental arrest.  Instead it is the absence of the egg nucleus that causes the developmental arrest of cloned human embryos.

To overcome the developmental arrest, they fused unmanipulated eggs with body cells and artificially activated them.  These, according to the authors, generated cells with three copies of each chromosome ( a triploid).  The problem is that they report using “MII stage oocytes.”  This is a fancy way of saying that the eggs are arrested in the last stage of meiosis.  This creates a problem:  the egg completes meiosis after fertilization and becomes a haploid cell.  The other nucleus is extruded in the form or a second polar body, which is a tiny bled of cell material attached to the egg.  Without completing meiosis, the egg has two copies of each chromosome and therefore the embryo should have four copies of each chromosome (tetraploid).  Nevertheless, they authors claim that they have generated triploid embryos, and their data support their conclusion.  They should explain more completely how they generated these cells, since the procedure they have detailed does not make complete biological sense.

Of these triploid embryos, 13/63 (20.6%) formed spherical blastocyst-stage embryos and these were used to make embryonic stem cells cultures.  From these 13 blastocysts, two embryonic stem cells lines were made.  These two lines (soPS1 and soPS2) were examined for their ability to form tumors in mice with sick immune systems.  Now only did they form the right kinds of tumors, but they expressed all the types of genes embryonic stem cell lines express.  Thus, triploid embryos can form blastocysts, and embryonic stem cell lines can be made from them.

Their gene expression studies showed that the cloned embryos failed to initiate the program of gene expression that is common observed in 4-8 cell stage human embryos.  This gene expression program, which is called “zygotic gene expression” is essential for further development, and the cloned embryos fail to properly initiate zygotic expression.

The News and Views commentary on this article by George Q. Daley suggests that triploid embryonic stem cell lines might be a potential patient-specific cell line for use in regenerative medicine.  I find this unlikely for several reasons.  Triploid embryos constitute 2-3% of all human conceptions (See D E McFadden and W P Robinson, “Phenotype of Triploid Embryos,” J Med Genet 43 (2006): 609-12), and is one of the major causes of spontaneous abortion (MR Creasy, JA Crolla, and ED Alberman, Hum Genet 1976; 31: 177–196; Kajii T, Niikawa N, Cytogenet Cell
1977; 18: 109–125; Brajenovic-Milic B, et al., Fetal Diagn Ther 1998; 13: 187–191).  Triploid result from either “digyny” (extra haploid set from mother) or “diandry” (extra haploid set from father).  Diandry tends to result in fetuses whose developmental growth is either mostly normal is or shows slow growth on one side of the fetus, but the placenta is abnormally large and filled with fluid-filled cysts.  This condition is given the formidable name of “partial hydatidiform mole,” (PHM) and it is potentially deleterious for the mother, since the huge placenta can become cancerous.  The digyny fetuses showed marked asymmetric growth in the uterus, and poor development of the adrenal hypoplasia.  The placenta is also small and underdeveloped.  The poorly developed placenta can, in some cases, or can cause preeclampsia in the mother, which is a life-threatening condition for a pregnant mother in which her blood pressure becomes dangerously high (see See Clasien van der Houwen, Tineke Schukken, and Mariëlle van Pampus, Journal of Medical Case Reports 2009, 3:7311).  Additionally, triploid fetuses may have a many other congenital anomalies that include fusion (syndactyly) of the third and fourth fingers and fusion f the toes, abnormal genitals, and cardiac, urinary tract, and brain anomalies.  These abnormalities  appear in both digynic and diandric triploids.  Given the poor developmental potential of triploid fetuses, it seems quite dangerous to use triploid embryonic stem cells for regenerative medicine, since they might cause more problems than healing.

My other problem with tis paper is that they paid women of reproductive age for their eggs.  In the first place this violates the guidelines of the National Academy of Science, which state: “Women who undergo hormonal induction to generate oocytes specifically for research purposes (such as for NT) should be reimbursed only for direct expenses incurred as a result of the procedure, as determined by an IRB. Direct expenses may include costs associated with travel, housing, child care, medical care, health insurance, and actual lost wages. No payments beyond reimbursements, cash or in-kind, should be provided for donating oocytes for research purposes. Similarly, no payments beyond reimbursements should be made for donations of sperm for research purposes or of somatic cells for use in NT.” (Final Report of the National Academies’ Human Embryonic Stem Cell Research Advisory Committee and 2010 Amendments to the National Academies’ Guidelines for Human Embryonic Stem Cell Research , Appendix C, Page 27 3.4(b) Payment and Reimbursement. See  Yet Jan Helge Solbakk, faculty member at the Centre for Medical Ethics at the University of Oslo say that the authors “deserve praise rather than criticism, because their approach helps to draw attention to a possible way out of th regulatory quagmire resulting from reduction of oocyte providers to ‘donors’ or ‘gift givers’ deserving mere;y compensation for their gifts.” so, let’s praise the authors even though they broke the rules.  Folks, those rules are in place for a reason.  Luring young women to donate their eggs with money will tend to attract those who need the money; that is poor college students, or poor women.  These procedures have real risks, and women will close their eyes to the risks, because the egg donation will help them make payments.  This is exploitation of women, and Jennifer Lahl made a movie about it called “Eggsploitation” that documents what happens to when women are paid for their eggs.  Who speaks for them?  This is a very disturbing trend in this paper, and Nature should have had the backbone to reject it our of hand for that alone.  Having said, that, the paper does make some very original observations, but it is doubtful that these cell lines will plays a significant in regenerative medicine.  Also, the developmental arrest problem in cloned embryos is real, and this underscores why cloned mouse embryos are not that good a model system for cloned human embryos.