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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| Contributed by: AAAS DoSER and the Institute for
Civil Society
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