Multiple Sclerosis

Coding Dimension ID: 
311
Coding Dimension path name: 
Neurological Disorders / Multiple Sclerosis

Targeting Stem Cells to Enhance Remyelination in the Treatment of Multiple Sclerosis

Funding Type: 
Early Translational III
Grant Number: 
TR3-05617
ICOC Funds Committed: 
$4 327 175
Disease Focus: 
Multiple Sclerosis
Neurological Disorders
Stem Cell Use: 
Adult Stem Cell
Cell Line Generation: 
Adult Stem Cell
oldStatus: 
Active
Public Abstract: 
Multiple sclerosis (MS) is an autoimmune disease in which the myelin sheath that insulates neurons is destroyed, resulting in loss of proper neuronal function. Existing treatments for MS are based on strategies that suppress the immune response. While these drugs do provide benefit by reducing relapses and delaying progression (but have significant side effects), the disease invariably progresses. We are pursuing an alternative therapy aimed at regeneration of the myelin sheath through drugs that act on an endogenous stem cell population in the central nervous system termed oligodendrocyte precursor cells (OPCs). Remission in MS is largely dependent upon OPCs migrating to sites of injury and subsequently differentiating into oligodendrocytes – the cells that synthesize myelin and are capable of neuronal repair. Previous studies indicate that in progressive MS, OPCs are abundantly present at sites of damage but fail to differentiate to oligodendrocytes. As such, drug-like molecules capable of inducing OPC differentiation should have significant potential, used alone or in combination with existing immunomodulatory agents, for the treatment of MS. The objective of this project is to identify a development candidate (DC) for the treatment of multiple sclerosis (MS) that functions by directly stimulating the differentiation of the adult stem cells required for remyelination.
Statement of Benefit to California: 
Multiple Sclerosis (MS) is a painful, neurodegenerative disease that leads to an impairment of physical and cognitive abilities. Patients with MS are often forced to stop working because their condition becomes so limiting. MS can interfere with a patient's ability to even perform simple routine daily activities, resulting in a decreased quality of life. Existing treatments for MS delay disease progression and minimize symptoms, however, the disease invariably progresses to a state of chronic demyelination. The goal of this project is to identify novel promyelinating drugs, based on differentiation of an endogenous stem cell population. Such drugs would be used in combination with existing immunosuppressive drugs to prevent disease progression and restore proper neuronal activity. More effective MS treatment strategies represent a major unmet medical need that could impact the roughly 50,000 Californians suffering from this disease. Clearly the development of a promyelinating therapeutic would have a significant impact on the well-being of Californians and reduce the negative economic impact on the state resulting from this degenerative disease.
Progress Report: 
  • Multiple sclerosis (MS) is an autoimmune disease characterized by the destruction of the myelin sheath that insulates neurons, resulting in loss of proper neuronal function. Existing treatments for MS are based exclusively on strategies that suppress the immune response. We are pursuing an alternative stem cell-based therapeutic approach aimed at enhancing regeneration of the myelin sheath. Specifically, we are focused on the identification of drug-like molecules capable of inducing oligodendrocyte precursor cell (OPC) differentiation. To date, we have identified a series approved drugs that effectively induce OPC differentiation under tissue culture conditions. Additionally, we have demonstrated that several of these drug candidates reduce MS-like symptoms in relevant rodent models of the disease. We are currently conducting detailed pharmacology experiments to determine which of the identified molecules will serve as the best candidate for future clinical development.

Multiple Sclerosis therapy: Human Pluripotent Stem Cell-Derived Neural Progenitor Cells

Funding Type: 
Early Translational III
Grant Number: 
TR3-05603
ICOC Funds Committed: 
$4 799 814
Disease Focus: 
Multiple Sclerosis
Neurological Disorders
Stem Cell Use: 
Embryonic Stem Cell
iPS Cell
oldStatus: 
Active
Public Abstract: 
Multiple Sclerosis (MS) is a disease of the central nervous system (CNS) caused by inflammation and loss of cells that produce myelin, which normally insulates and protects nerve cells. MS is a leading cause of neurological disability among young adults in North America. Current treatments for MS include drugs such as interferons and corticosteroids that modulate the ability of immune system cells to invade the CNS. These therapies often have unsatisfactory outcomes, with continued progression of neurologic disability over time. This is most likely due to irreversible tissue injury resulting from permanent loss of myelin and nerve destruction. The limited ability of the body to repair damaged nerve tissue highlights a critically important and unmet need for MS patients. The long-term goal of our research is to develop a stem cell-based therapy that will not only halt ongoing loss of myelin but also lead to remyelination and repair of damaged nerve tissue. Our preliminary data in animal models of human MS are very promising and suggest that this goal is possible. Research efforts will concentrate on refining techniques for production and rigorous quality control of clinically-compatible transplantable cells generated from high-quality human pluripotent stem cell lines, and to verify the therapeutic activity of these cells. We will emphasize safety and development of the most therapeutically beneficial cell type for eventual use in patients with MS.
Statement of Benefit to California: 
One in seven Americans lives in California, and these people make up the single largest health care market in the United States. The diseases and injuries that affect Californians affect the rest of the US and the world. Many of these diseases involve degeneration of healthy cells and tissues, including neuronal tissue in diseases such as Multiple Sclerosis (MS). The best estimates indicate that there are 400,000 people diagnosed with MS in the USA and 2.2 million worldwide. In California, there are approximately 160,000 people with MS – roughly half of MS patients in the US live in California. MS is a life-long, chronic disease diagnosed primarily in young adults who have a virtually normal life expectancy but suffer from progressive loss of motor and cognitive function. Consequently, the economic, social and medical costs associated with the disease are significant. Estimates place the annual cost of MS in the United States in the billions of dollars. The development of a stem cell therapy for treatment of MS patients will not only alleviate ongoing suffering but also allow people afflicted with this disease to return to work and contribute to the economic stabilization of California. Moreover, a stem cell-based therapy that will provide sustained recovery will reduce recurrence and the ever-growing cost burden to the California medical community.
Progress Report: 
  • The team has been highly productive during the first year of work on this award. A major goal of the project is to evaluate the efficacy of neural progenitor cell transplantation to promote remyelination following virus induced central nervous system damage. With intracranial infection by the virus mouse hepatitis virus (MHV), mice develop paralysis due to immune mediated destruction of cells that generate myelin. Using protocols developed in the Loring laboratory, neural precursor cells (NPC) were derived from the human embryonic stem cell line H9. Mice developing paralysis due to intracranial infection with MHV were subject to intraspinal transplantation of these NPC, resulting in significant clinical recovery beginning at 2-3 weeks following transplant. This clinical effect of NPC transplantation remained out to six months, suggesting that these NPC are effective for long-term repair following demyelination. Despite this striking recovery, these human ES cell derived NPC were rapidly rejected. Several protocols for the generation of NPC for transplantation have been characterized, with the greatest clinical impact observed for NPC cultures bearing a high level of expression of TGF beta I and TGF beta II. These findings support the hypothesis that transplanted NPC reprogram the immune system within the central nervous system (CNS), leading to the activation of endogenous NPC and other repair mechanisms. Thus, it may not be necessary to induce complete immune suppression in order to promote remyelination and CNS repair following NPC transplantation for demyelinating diseases such as multiple sclerosis.

Human stem cell derived oligodendrocytes for treatment of stroke and MS

Funding Type: 
Comprehensive Grant
Grant Number: 
RC1-00135
ICOC Funds Committed: 
$2 566 701
Disease Focus: 
Multiple Sclerosis
Neurological Disorders
Stroke
Immune Disease
Stem Cell Use: 
Adult Stem Cell
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • Over the last year we have succeeded in generating nearly pure cultures of human ES cell derived oligodendrocyte precursors from two different human ES cell lines. We are now also testing whether manipulation of transcription factors or morphogenic signaling pathways regulates the ability of these cells to differentiate into oligodendrocytes that produce myelin. We are testing these cells in a rodent stroke model to determine if they survive in the region of the stroke. If they survive, we will test whether they help to treat the strokes. We are also testing cells in transplantation into a developmental ischemia model and a model for genetic failure to produce myelin.
  • Our proposal centers on developing novel effective methods to generate oligodendrocytes from human ES cells. We focus on identifying signaling pathways (using studies in rodent neural stem cells) that can be adapted to human ES cells and used to regulate the efficiency of oligodendrocyte specification and differentiation from human ES cells. We then hope to use these human ES cell derived oligodendrocytes to determine whether transplantation of these cells is feasible in well characterized animal models associated with damage to oligodendrocytes. Over the last year we have made major progress toward these goals.
  • First, we have completed and submitted for publication two studies identifying the roles of Wnts and Sox10 in regulating the development of oligodendrocytes both during brain development and during stem cell differentiation in vitro. One of these papers is in the final stages of consideration after revision and the other is submitted awaiting reviews.
  • Second, we have developed a novel method for culturing human ES cell derived oligodendrocyte precursors. This is based on modifications of published methods but leads to greatly enhanced purity of final oligodendrocytes in our cultures (about 80% oligodendrocytes and 20% astrocytes). We have used this culture approach to address the role of sonic hedgehog in the differentiation of oligodendrocytes from human oligodendrocyte progenitors and have identified sonic hedgehog as a major regulator of oligodendrocyte differentiation and myelin production. This is quite distinct from rodent neural cells where sonic hedgehog doesn't appear to have this function. This will provide a novel therapeutic target to affect oligodendrocyte maturation and regeneration in disease models and will be of great utility for studying the function of mature human oligodendrocytes. This work is in preparation for submission.
  • Third, we have made some significant progress in our transplantation studies. We completed studies transplanting human ES derived oligodendrocyte progenitors into a rodent model of focal stroke and found that at 1 week post stroke and 2 weeks post stroke the survival of oligodendrocytes from these transplants is very minimal. Thus, we have discontinued this work because of this feasibility issue. We have moved on to examine studies of transplantation into newborn rodents with hypoxic injury and with dysmyelination becahse of the shiverer mutation. The progress here is good. The hypoxia model we are using is a chronic (up to 1 week) exposure to low oxygen tension of P2 mice, which is known to cause oligodendrocyte injury. We are initially characterizing the injury to oligodendrocytes at various durations of hypoxic exposure so that we can identify the best time point to transplant our cells into the brains. We are using immunodeficient mice to decrease the chances of rejection of the transplanted cells. In addition, we are generating a mouse colony with the shiverer allele combined with an immunodeficiency allele in order to be able to transplant cells in this model. In the meantime, we are determining the survival of transplanted cells into newborn mice to identify technical factors that will need to be overcome to allow efficient transplantation and to determine if our human cells participate in differentiation in these mice. Preliminarily we have found good survival of oligodendrocyte lineage cells after transplantation into P2 mice and the expression of myelin antigens after an appropriate period of development in vivo. This is very encouraging.
  • In the last year we have continued our efforts to transplant oligodendrocyte progenitors obtained by differentiation of human ES cells. Our progress in this area has been mixed because of substantial technical hurdles in consistent production of the oligodendrocyte progenitors from frozen stocks of cells. This will necessitate a no-cost extension for a small portion of the work to allow completion of the analysis of already transplanted animals.
  • We have made substantial progress as well in showing that these cells are capable of myelinating axons effectively in vitro. In addition, we've found that the human ES derived oligodendrocytes are capable of myelinating artificial nanofibers in vitro as well. This may serve as a useful platform in the future for drug discovery or other high throughput studies.
  • We have also identified an important novel molecular regulator of oligodendrocyte number and development and this work will continue into the future.
  • In this NCE period we were completing studies with animals that had received neonatal ischemic injury and were implanted with human ES cell derived cells of the oligodendrocyte lineage. These experiments showed that the cells survive and have oligodendrocyte lineage markers for three weeks post injection. Longer survival experiments are still ongoing.

Human Embryonic Stem Cells and Remyelination in a Viral Model of Demyelination

Funding Type: 
SEED Grant
Grant Number: 
RS1-00409
ICOC Funds Committed: 
$425 594
Disease Focus: 
Multiple Sclerosis
Neurological Disorders
Immune Disease
Stem Cell Use: 
Embryonic Stem Cell
oldStatus: 
Closed
Public Abstract: 
Statement of Benefit to California: 
Progress Report: 
  • Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that results in demyelination and axonal loss, culminating in extensive disability through defects in neurologic function. The demyelination that defines MS pathology is progressive over time; however, studies indicate that myelin repair can occur during the course of disease in patients with MS and in animal models designed to mimic the immunopathogenesis of MS. While it is generally thought that endogenous oligodendrocyte precursor cells (OPCs) are largely responsible for spontaneous remyelination, it is unclear why these cells are only able to transiently induce myelin repair in the presence of ongoing disease. Along these lines, two therapies for demyelinating diseases look promising; implanting OPCs into sites of neuroinflammation that are directly capable of inducing remyelination of the damaged axons and/or modifying the local environment to stimulate and support remyelination by endogenous OPCs. Indeed, we have shown that human embryonic stem cell (hESC)-derived oligodendrocytes surgically implanted into the spinal cords of mice with virally induced demyelination promoted focal remyelination and axonal sparing. We are currently investigating how the implanted OPCs positionally migrate to areas of on-going demyelination and the role these cells play in repairing the damaged CNS. The purpose of this research is to identify the underlying mechanism(s) responsible for hESC-induced remyelination.
  • Oligodendrocyte progenitor cells (OPCs) are important in mediating remyelination in response to demyelinating lesions. As such, OPCs represent an attractive cell population for use in cell replacement therapies to promote remyelination for treatment of human demyelinating diseases. High-purity OPCs have been generated from hESC and have been shown to initiate remyelination associated with improved motor skills in animal models of demyelination. We have previously determined that engraftment of hESC-derived OPCs into mice with established demyelination does not significantly improve clinical recovery nor reduce the severity of demyelination. Importantly, remyelination is limited following OPC transplantation. These findings highlight that the microenvironment is critical with regards to the remyelination potential of engrafted cells. In addition, we have determined that human OPCs are capable of migrating in response to proinflammatory molecules often associated with human neuroinflammatory diseases such as multiple sclerosis. This is an important observation in that it will likely be necessary for engrafted OPCs to be able to positionally navigate within tissue in order to move from the site of surgical transplantation to areas of damage to initiate repair and tissue remodeling. Finally, we have also made a novel discovery of a unique signaling pathway that protects OPCs from damage/death in response to treatment with proinflammatory cytokines. We believe this is an important and translationally relevant observation as OPCs are critical in contributing to remyelination and remyelination failure is an important clinical feature for many human demyelinating diseases inclusing spinal cord injury and MS. We have identified a putative protective ligand/receptor interaction affords protection from cytokine-induced apoptosis. These findings may reveal novel avenues for therapeutic intervention to prevent damage/death of OPCs and enhance remyelination.

Developmental Regulation of Human Embryonic Stem Cells by microRNAs

Funding Type: 
SEED Grant
Grant Number: 
RS1-00409
ICOC Funds Committed: 
$0
Disease Focus: 
Multiple Sclerosis
Neurological Disorders
Immune Disease
Stem Cell Use: 
Embryonic Stem Cell
Public Abstract: 
Stem cells are remarkable cells which have two unique properties: self-renewal (self replication) and pluripotency (the ability to regenate a wide range of tissue-specific cells). These properties and the associated potential to use these cells to cure a wide range of degenerative diseases such as Alzheimer’s Disease, Parkinson’s Disease, and heart disease, have made stem cells a subject of intense scientific and medical interest. The recent discovery of cancer stem cells implies that stem cell research will also have important implications for cancer therapy, since cancer stem cells must be targeted by cancer drugs to prevent relapse of tumors. The mechanisms by which stem cells self-renew and differentiate are poorly understood. Several genes have been isolated and are thought to be essential to mammalian stem cell renewal and differentiation. Recent evidence has identified a new and potentially important molecular mechanism for regulating these genes in ESCs. These molecules are small bits of RNA, of approximately 22 nucleotides (nt) in length, and often termed microRNAs (miRNAs). miRNAs appear to play an important part in regulating gene activity. These small RNAs “turn off” genes by directly binding to them and preventing the production of proteins based on the gene’s genetic code. Several recent studies indicate that the types of miRNAs present in stem cells (miRNA “expression profiles”) are different from other cells and tissues. We propose to identify candidate miRNAs that are playing key roles in hESCs and to characterize the effects of their actions on self-renewal and differentiation. Our preliminary data also indicates that miRNA “expression profiles” differ depending on whether a stem cell is differentiating, self-renewing, or quiescent. This project will employ a wide range of techniques in molecular biology, including microarrays, bioinformatics, and bioluminescent reporter gene assays, to determine which specific miRNAs show differential expression between stem cell states and we will identify the genes they target. Having identified candidate miRNAs that play an important role in determining stem cell fate, we will manipulate their expression levels using biotechnology techniques known as RNA oligos and plasmid or viral expression vectors. We will then determine if these manipulations change the cell’s decision-making process in regard to differentiation or self-renewal. This will be done using molecular biology and biochemical assays on undifferentiated and differentiated cells. Ultimately we will investigate the underlying regulatory mechanisms in hESCs that control miRNA expression. We anticipate that our results will contribute to understanding the transitions between stem cells and differentiated cells, as well as normal and cancer cells. This type of information can be invaluable in designing new therapeutic approaches for stem cell replacement or cancer treatment.
Statement of Benefit to California: 
Human embryonic stem cells (hESCs) hold the potential to revolutionize human medicine by making cell replacement therapies, drug delivery, or in vivo modifications of cell populations a reality. In degenerative conditions we may be able to replace dead cells with functional new ones derived from hESCs. This approach could be used to treat Parkinson’s Disease, Alzheimer’s Disease, heart disease, diabetes, or paralytic spinal cord injuries. There is also potential for new cancer treatments, as cancer stem cells share many properties of hESCs. This type of medical technology would benefit the citizens of California in several general ways. It could offer hope to Californians suffering from these diseases. It could help relieve the pain and suffering for affected individuals and their families and loved ones. Finally, the economic impact of hESC-based therapies is likely to be significant. Chronic diseases will no longer incapacitate patients and they can return to productive work lives. State government and private expenditures on health care will actually decrease. Companies will organize to commercialize these hESC-based therapies and this will stimulate the California economy by providing new jobs and tax revenue. Most medical economists believe that significant revenues from patents, royalties, and licenses will flow from scientific discoveries pioneered in California based stem cell research centers. This project will also enhance California’s competitive position in biomedical research and push the State to the forefront of research not only in America, but also the world. It will be a reflection of the enormous ongoing investment in science on the part of the state and private institutions, fueled in recent decades by the high-tech and biotechnology industries. All of the research will be done in California. The project focuses on the role of microRNA (miRNA) molecules in controlling the fate of hESCs. miRNAs are recently discovered molecules that play an important part in gene regulation. The expression profiles of miRNAs in stem cells are different from other tissues, and miRNAs may play an essential role in stem cell self-renewal and differentiation. Many potential target genes for miRNAs are essential players in stem cell renewal and differentiation. Some of the most exciting and innovative work on miRNAs has taken place in California and this project will help confirm the State’s leading role in miRNA research and California’s role as a place where miRNA researchers’ specific application to stem cell biology is being studied.
Progress Report: 
  • Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that results in demyelination and axonal loss, culminating in extensive disability through defects in neurologic function. The demyelination that defines MS pathology is progressive over time; however, studies indicate that myelin repair can occur during the course of disease in patients with MS and in animal models designed to mimic the immunopathogenesis of MS. While it is generally thought that endogenous oligodendrocyte precursor cells (OPCs) are largely responsible for spontaneous remyelination, it is unclear why these cells are only able to transiently induce myelin repair in the presence of ongoing disease. Along these lines, two therapies for demyelinating diseases look promising; implanting OPCs into sites of neuroinflammation that are directly capable of inducing remyelination of the damaged axons and/or modifying the local environment to stimulate and support remyelination by endogenous OPCs. Indeed, we have shown that human embryonic stem cell (hESC)-derived oligodendrocytes surgically implanted into the spinal cords of mice with virally induced demyelination promoted focal remyelination and axonal sparing. We are currently investigating how the implanted OPCs positionally migrate to areas of on-going demyelination and the role these cells play in repairing the damaged CNS. The purpose of this research is to identify the underlying mechanism(s) responsible for hESC-induced remyelination.
  • Oligodendrocyte progenitor cells (OPCs) are important in mediating remyelination in response to demyelinating lesions. As such, OPCs represent an attractive cell population for use in cell replacement therapies to promote remyelination for treatment of human demyelinating diseases. High-purity OPCs have been generated from hESC and have been shown to initiate remyelination associated with improved motor skills in animal models of demyelination. We have previously determined that engraftment of hESC-derived OPCs into mice with established demyelination does not significantly improve clinical recovery nor reduce the severity of demyelination. Importantly, remyelination is limited following OPC transplantation. These findings highlight that the microenvironment is critical with regards to the remyelination potential of engrafted cells. In addition, we have determined that human OPCs are capable of migrating in response to proinflammatory molecules often associated with human neuroinflammatory diseases such as multiple sclerosis. This is an important observation in that it will likely be necessary for engrafted OPCs to be able to positionally navigate within tissue in order to move from the site of surgical transplantation to areas of damage to initiate repair and tissue remodeling. Finally, we have also made a novel discovery of a unique signaling pathway that protects OPCs from damage/death in response to treatment with proinflammatory cytokines. We believe this is an important and translationally relevant observation as OPCs are critical in contributing to remyelination and remyelination failure is an important clinical feature for many human demyelinating diseases inclusing spinal cord injury and MS. We have identified a putative protective ligand/receptor interaction affords protection from cytokine-induced apoptosis. These findings may reveal novel avenues for therapeutic intervention to prevent damage/death of OPCs and enhance remyelination.

The role of HER2 signaling in differentiation and maintenance of human embryonic stem cells

Funding Type: 
SEED Grant
Grant Number: 
RS1-00409
ICOC Funds Committed: 
$0
Disease Focus: 
Multiple Sclerosis
Neurological Disorders
Immune Disease
Stem Cell Use: 
Embryonic Stem Cell
Public Abstract: 
The ability to propagate high quality human embryonic stem cells (hESCs) that are capable of giving rise to multiple cell types is essential in using hESCs to treat human diseases. Understanding the signaling pathways that control the maintenance of pluripotency and differentiation of hESCs is necessary for endowing such ability. The goal of this project is to determine whether HER2, a receptor tyrosine kinase, is essential in maintaining hESCs. HER2 is a multiple functional protein. De-regulation of HER2 expression or signaling is implicated in several human diseases. For example, over-expression of HER2 is found in 20-30% of breast cancer patients. Herceptin, a humanlized blocking monoclonal antibody, has been approved by the Food and Drug Agency to treat breast cancer patients. HER2 is required as an essential partner for the response of cells to multiple growth factors, including neuregulin (NRG). Mutation of the NRG1 gene is associated with Schizophrenia in several populations. Studies in mice suggest that HER2 may play a role in the etiology of Hirschsprung disease and in preventing dilated cardiomyopathy and muscular dystrophy. Interestingly, some breast cancer patients treated with Herceptin develop cardiac dysfunction, revealing multiple functions of HER2 and the complication of designing an ideal therapy. NRG1 has been shown to play a role in the formation of the conduction system (pacemaker) of the heart in mice. Improper processing of NRG1 may play a role in Alzheimer's Disease and neuropathy. We found that NRG1 plays a role in the recovery rate of rat neural stem cells. HER2 is highly expressed in undifferentiated hESCs. These data demonstrate that HER2 has pleitropic effects on multiple cell types and organs and suggest that HER2 is capable of integrating diverse signaling pathways that are essential in the control of maintenance and/or differentiation of hESCs where HER2 is highly expressed. Understanding whether and how HER2 regulates the maintenance and/or differentiation of hESCs may provide insight into harnessing the strategy to grow and use hESCs to treat human disease.
Statement of Benefit to California: 
The ability to propagate high quality human embryonic stem cells (hESCs) that are capable of giving rise to multiple cell types is essential in using hESCs to treat human diseases. Understanding the signaling pathways that control the maintenance of pluripotency and differentiation of hESCs is necessary for endowing such ability. HER2 is a receptor tyrosine kinase and has been shown to play essential roles or is implicated in breast cancer, dilated cardiomyopathy, muscular dystrophy, heart pace maker, peripheral neuropathy, Schizophrenia and Alzheimer's Disease. For example, over-expression of HER2 is found in 20-30% of breast cancer patients. Herceptin, a humanlized blocking monoclonal antibody, has been approved by the Food and Drug Agency to treat breast cancer patients. Several lines of evidence suggest that HER2 is a multiple functional protein and may play essential roles in the maintenance and/or differentiation of hESCs. Understanding whether and how HER2 regulates the maintenance and differentiation of hESCs may provide insight into harnessing the strategy to grow and use high quality hESCs to treat human disease.
Progress Report: 
  • Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) that results in demyelination and axonal loss, culminating in extensive disability through defects in neurologic function. The demyelination that defines MS pathology is progressive over time; however, studies indicate that myelin repair can occur during the course of disease in patients with MS and in animal models designed to mimic the immunopathogenesis of MS. While it is generally thought that endogenous oligodendrocyte precursor cells (OPCs) are largely responsible for spontaneous remyelination, it is unclear why these cells are only able to transiently induce myelin repair in the presence of ongoing disease. Along these lines, two therapies for demyelinating diseases look promising; implanting OPCs into sites of neuroinflammation that are directly capable of inducing remyelination of the damaged axons and/or modifying the local environment to stimulate and support remyelination by endogenous OPCs. Indeed, we have shown that human embryonic stem cell (hESC)-derived oligodendrocytes surgically implanted into the spinal cords of mice with virally induced demyelination promoted focal remyelination and axonal sparing. We are currently investigating how the implanted OPCs positionally migrate to areas of on-going demyelination and the role these cells play in repairing the damaged CNS. The purpose of this research is to identify the underlying mechanism(s) responsible for hESC-induced remyelination.
  • Oligodendrocyte progenitor cells (OPCs) are important in mediating remyelination in response to demyelinating lesions. As such, OPCs represent an attractive cell population for use in cell replacement therapies to promote remyelination for treatment of human demyelinating diseases. High-purity OPCs have been generated from hESC and have been shown to initiate remyelination associated with improved motor skills in animal models of demyelination. We have previously determined that engraftment of hESC-derived OPCs into mice with established demyelination does not significantly improve clinical recovery nor reduce the severity of demyelination. Importantly, remyelination is limited following OPC transplantation. These findings highlight that the microenvironment is critical with regards to the remyelination potential of engrafted cells. In addition, we have determined that human OPCs are capable of migrating in response to proinflammatory molecules often associated with human neuroinflammatory diseases such as multiple sclerosis. This is an important observation in that it will likely be necessary for engrafted OPCs to be able to positionally navigate within tissue in order to move from the site of surgical transplantation to areas of damage to initiate repair and tissue remodeling. Finally, we have also made a novel discovery of a unique signaling pathway that protects OPCs from damage/death in response to treatment with proinflammatory cytokines. We believe this is an important and translationally relevant observation as OPCs are critical in contributing to remyelination and remyelination failure is an important clinical feature for many human demyelinating diseases inclusing spinal cord injury and MS. We have identified a putative protective ligand/receptor interaction affords protection from cytokine-induced apoptosis. These findings may reveal novel avenues for therapeutic intervention to prevent damage/death of OPCs and enhance remyelination.
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