I have to admit that my first response to these reports out of Britain that stem cells had been successfully used to repair a complete spinal cord transection was skepticism incredulity even. Theyre reporting that a man with a completely severed spinal cord at level T10-T11 is able to walk again! The Guardian gushes! The Daily Mail gets in the act (always a bad sign)! When I read that the patient had an 8mm gap in his spinal cord that had been filling up with scar tissue for the last two years, I was even more doubtful: under the best of conditions, it was unlikely that youd get substantial connectivity across that distance.
So I read the paper. Im less skeptical now, for a couple of reasons. They actually did this experiment on 3 people, and all showed degrees of improvement, although the newspapers are all focusing on just the one who had the greatest change. The gradual changes are all documented thoroughly and believably. And, sad to say, the improvements in the mans motor and sensory ability are more limited and more realistic than most of the accounts would have you think.
The story is actually in accord with what weve seen in stem cell repair of spinal cord injury in rats and mice.
Overall, they found that stem cell treatment results in an average improvement of about 25% over the post-injury performance in both sensory and motor outcomes, though the results can vary widely between animals. For sensory outcomes the degree of improvement tended to increase with the number of cells introduced scientists are often reassured by this sort of dose response, as it suggests a real underlying biologically plausible effect. So the good news is that stem cell therapy does indeed seem to confer a statistically significant improvement over the residual ability of the animals both to move and feel things beyond the spinal injury site.
Significant but far from complete improvement is exactly what wed expect, and that improvement is a very, very good thing. It is an accomplishment to translate animal studies into getting measurable clinical improvements in people.
The basic procedure is straightforward. There is a population of neural cells in humans that do actively and continuously regenerate: the cells of the olfactory bulb. So what they did is remove one of the patients own olfactory bulbs, dissociate it into a soup of isolated cells, and inject them into locations above and below the injury. They also bridged the gap with strips of nerve tissue harvested from the patients leg. The idea is that the proliferating cells and the nerves would provide a nerve growth-friendly environment and build substrate bridges that would stimulate the damaged cells and provide a path for regrowth.
Big bonus: this was an autologous transplant (from the patients own tissues), so there was no worry about immune system rejection. There were legitimate worries about inflammation, doing further damage to the spinal cord, and provoking greater degeneration, and part of the purpose of this work was to assess the safety of the procedure. There were no complications.
Also, Im sure you were worried about this, but the lost olfactory cells also regenerated and the patients completely recovered their sense of smell.
Now heres the clinical assessment. Three patients were operated on; T1 is the one who has made all the news with the most remarkable improvement. There were also three control patients who showed no improvement over the same period.
Neurological function improved in all three transplant recipients (T1, T2, T3) during the first year postsurgery. This included a decrease of muscle spasticity (T1, T2) as well as improvement of sensory (T1, T2, T3) and motor function (T1, T2, T3) below the level of spinal cord injury.
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Stem cell treatment of spinal cord injuries [Pharyngula]
