Nervous System Diseases

Many nervous system diseases result from loss of nerve cells. Mature nerve cells cannot divide to replace those that are lost. Thus, without a “new” source of functioning nerve tissue, no therapeutic possibilities exist. In Parkinson’s disease, nerve cells that make the chemical dopamine die. In Alzheimer’s disease, cells that are responsible for the production of certain neurotransmitters die. In amyotrophic lateral sclerosis, the motor nerve cells that activate muscles die. In spinal cord injury, brain trauma, and even stroke, many different types of cells are lost or die. In multiple sclerosis, glia, the cells that protect nerve fibers are lost. Perhaps the only hope for treating such individuals comes from the potential to create new nerve tissue restoring function from pluripotent stem cells.

Remarkably, human clinical experiments have demonstrated the potential effectiveness of this approach to treatment. Parkinson’s patients have been treated by surgical implantation of fetal cells into their brain with some benefit. Although not completely effective, perhaps owing to lack of sufficient numbers of dopamine secreting cells, similar experiments using appropriately differentiated stem cells should overcome those obstacles. More complex experiments have already been successfully conducted in rodent models of Parkinson’s. Similar approaches could be developed to replace the dead or dysfunctional cells in cortical and hippocampal brain regions that are affected in patients with Alzheimer’s.

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