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Stem Cell Transplantation for the Treatment of MS (ACTRIMS 2016)
A presentation at Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2016, held February 18-20 in New Orleans highlighted therapeutic strategies for stem cell-based approaches to protect and restore neurological function in patients with progressive MS.
Andrew Goodman, MD, University of Rochester, NY, USA described the current status of stem cell-based therapies for MS. Stem cells are cells capable of self-renewal and in vivo functional reconstitution of tissue, and are pluripotent.
There are three potential therapeutic targets for stem cells in MS, Dr. Goodman explained. These are: reduce inflammation, protect from demyelination and axonal transection, and as cell replacement or to augment intrinsic repair mechanisms. However, there are many issues related to the use of stem cell therapy in MS. Some of the challenges include:
the need to combine anti-inflammatory, neuroprotective, and repair strategies
the route of administration needs to address multifocal lesions
at this time, the appropriate time window for treatment has as yet not been identified
regeneration strategies require terminal differentiation and functional integration
the effects of paradoxical immune activation need to be overcome
stem cells from MS patients may be deficient in some manner, and the MS immune system or CNS may provide an inhospitable environment for stem cells.
Immunoablation and Reconstitution. There have been a handful of studies looking at stem cell therapy in MS for immunoablation and reconstitution with hematopoietic stem cell transplantation that suggest a high level of efficacy in relapsing-remitting MS. These studies also suggest that younger patients with recent disease onset, that are still ambulatory may be better candidates for stem cell therapy. To date, these studies have only included a small number of patients and were without a control group. However, there is some risk of early toxicity, MS relapse or adverse effects associated with immunoablation. There is also some risk of late toxicity and development of secondary autoimmune disorders. The biggest question with this approach is “where would it stack up in terms of risk versus benefit relative to the highly active treatments that we already have,” stated Dr. Goodman.
Mesenchymal Stem Cells. Mesenchymal stem cells (MSCs) can be isolated from many kinds of adult tissue and preclinical work suggests that these cells could have immunomodulatory or neurotrophic activities. There have been several small studies that suggest MSCs are safe and well-tolerated, with mixed efficacy in MS patients. There are still several remaining questions for this approach that need to be investigated. For example, what should be the source of MScs (bone marrow, adipose, or other source), issues related to cell culture, route of administration, and dosing schedule.
Oligodendrocyte Precursor Cells. Oligodendrocyte precursor cells (OPCs) are multipotent cells derived from a variety of sources (embryonic, fetal, or adult) explained Dr. Goodman. OPCs can be manipulated through culture conditions to promote proliferation or differentiation into neurons, astrocytes, or oligodendrocytes. There are both practical and ethical issues with OPCs including a limited proliferation capacity, they require direct injection, and require immunosuppression. Dr. Goodman described a proposed OPC trial. This trial will be a first-in-human safety study of OPCs in patients with secondary progressive MS, currently going through FDA and IRB approval.
Dr. Goodman concluded that there are several types of cell-based therapeutic strategies under investigation each carrying different risks, benefits, and goals. Some of the strategies show promise, but there are many methodological and safety questions that need to be worked out.
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