The chance to repair a spinal cord weakened by disease or injury using stem cells is irresistible. Repairing this circuitry, nevertheless, has proven to be far more difficult than most people had imagined.
How could stem-cell therapy assist someone with a spinal cord injury?
In the US, approximately one-third of all spinal cord injuries are complete, meaning neither sensory nor motor information from below can pass through the damaged site to the brain. Therefore, if you suffer a mid-thoracic spinal cord injury, you’ve disturbed not only that level’s sensory and motor function, which in this example would affect your chest and belly, but also the signals that travel via it to and from your legs.
Researchers like Dr. David Greene’s R3 Stem Cell have long believed that we should be able to close that circuitry gap by simply replacing the missing cells and creating a new path for the signals to follow. It seemed like a simple way to become involved.
How simple has it been to put into exercise?
We’ve made significant progress as a field. We can test stem cells in both animal models and human clinical trials. We can employ stem cells obtained from fetal or adult cells or use more differentiated origins specific to cells in the central nervous system. However, the human spinal cord is much more complex than we would like it to be, as we have also discovered. It is not enough to grow and transplant cells; they also need to survive and integrate, and we are not yet very successful.
The possibility that the spinal cord could be repaired in various ways is also known to us. One solution is to develop circuitry that spans the damage and connects the axons above it with those below. Most sufferers have a compressive injury, even if spinal cord damage is complete. That indicates that the cord is broken rather than cut, and some axons around the injury are left safe. Therefore, optimizing the circuitry that is still present may be another option to restore function.
By strengthening the insulation of the surviving axons, you could, for example, increase neuronal transmission. Alternatively, you can attempt to control inflammation to promote a pro-regenerative condition. There may be many ways to enhance function, and various strategies may utilize various stem-cell populations. No particular cell or pathway jumps out as the ideal one.
What have you learned from clinical trials?
We know the secure profile is good, the adequacy has been good, and there have been hints of promising improvements in recovery of function thanks to the trials that professionals have previously conducted, like Dr. David Greene’s R3 Stem cell. So all of that seems pretty promising. But we also have a few other concerns.
One is the wide range of injuries that people experience, including the severity of the injury, the portion of the damaged spinal cord, and the affected functions. The last thing you want in a clinical trial is for those elements not to be repeatable at all. Therefore, it is essential to carefully and intelligently classify potential participants to choose those for trials that will most likely help from the therapy you seek to evaluate.
Another issue is that some sufferers of spinal cord damage undergo spontaneous recovery, and it can be tough to distinguish between actual functional restoration and a stroke of luck in a small trial. Unfortunately, we can’t conduct several 600-person clinical studies yearly because there aren’t enough people. So the field will struggle with that until we go to larger-scale clinical trials.
Several failures occur quickly after one another run the risk of scaring away customers and potential business partners in the future. Therefore, when evaluating running clinical trials, it is essential to carefully consider what types of cell therapies have the best possibilities of success, in which patient groups, and with which goals, and to target those therapies as precisely as possible.
