Originally posted by George78
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Geron, Stem Cell Inc., ChinaSCINet are now carrying out clinical trials transplanting cells into the spinal cord of people. In the case of Geron, they are transplanting oligodendroglial progenitor cells derived from human embryonic stem cells. Stem Cell Inc. is transplanting neural stem cells that include astrocytes into the spinal cord of people. ChinaSCINet is transplanting HLA-matched umbilical cord blood cells into the spinal cord. I know of at least half a dozen clinics around the world that have transplanted autologous bone marrow mesenchymal stem and stromal cells intravenously, intra-arterially, or intrathecally to the spinal cord.
Although some of the these transplants have been associated with transient (2-3 weeks) increase of neuropathic pain, most of these have not caused significant amounts of long lasting neuropathic pain or allodynia. In some of the cases, the transient onset of neuropathic pain seems to precede the recovery of sensory function in the patients. I would think that human clinical experience suggests that many types of cells can be transplanted into the spinal cord without the kinds of complications that Dr. Davies is talking about. It is important that limited animal experience not be used to stop clinical trials from going forward. If, for example, a cell transplant were to cause the kind of complications that Dr. Davies is talking about, one should be cautious about going forward with further clinical studies.
It is not true that 20 years of experience with stem cell transplants has been completely negative. In the case of olfactory ensheathing glial cells, a uniform experience of over half a dozen groups suggest that the cells restore sensory function to several dermatomes below the injury site. Motor recovery is limited. We shall soon see if the current ciinical trials show signficant functional benefits. It is not a good idea to block progress in clinical trials based on limited animal data.
The sparse motor recovery can be for many reasons besides the one that Dr. Davies is talking about. For example, most of the groups used non-HLA matched fetal allografts that are probably rejected within a few weeks after transplantation, leading short-term and limited recovery. Another reason for lack of recovery is that few of the groups have coupled their cell transplantation with intensive motor training. Evidence is accumulating that motor recovery requires training. Finally, there is an open question whether any single cell transplant would really do the job of allowing axons to grow across the injury site and extend all the way up and down the spinal cord. The transplants may have to be coupled with therapies such as chondroitinase, lithium, nogo antibodies, cethrin, etc. to yield signicant long distance regeneration for chronic spinal cord injury.
Wise.
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