Stem Cell Mix Helps Paralyzed Rats Walk
Rodents regained mobility after receiving a combination of drugs and stem cells that rewired their nervous systems

SOURCE: “Recovery from Paralysis in Adult Rats Using Embryonic Stem Cells”
D. M. Deshpande et al.
Annals of Neurology 60(1): 32-44

Results: Scientists from Johns Hopkins University found that a complex combination of treatments, including stem cells and growth factors, can heal damaged neural circuits, allowing partially paralyzed rats to walk. According to the findings, 11 out of 15 rats with spinal-cord injuries regained some motor function after receiving the full battery of treatments.

Why it matters: Previous studies on paralyzed rats demonstrated the possibility of boosting the function of the nervous system and improving motor skills. But this is the first study to show that newly grown nerve fibers can emerge from the spinal cord, extend all the way to ­muscles in the rats’ haunches and limbs, and form functional connections with them. These findings represent a significant step forward in regenerative medicine, providing new treatment possibilities for some types of spinal-cord injury and for diseases in which motor neurons are damaged, such as amyotrophic lateral sclerosis (ALS).

Methods: The researchers transplanted motor neurons, derived from embryonic stem cells, into the spinal cord. Then they added a mix of growth factors to help the new cells survive and grow, as well as two chemicals known to block the signals that normally keep nerve fibers from growing out of the spinal cord.

In order to get the newly sprouted fibers to span the wide gap between the spinal cord and the muscles, the researchers injected neural stem cells into the target muscles. These cells produced a nerve growth stimulator that drew growing motor neurons to the muscle and allowed them to make functional neuromuscular connections.

Next steps: The team is now planning tests in pigs. Studies in larger animals are necessary to make sure that the new neurons can grow to great enough lengths that the treatment will work in humans. If those experiments are successful, the scientists say, human clinical trials could begin within five years.