Adult stem cells have been used in a rat model of ALS (amyotrophic lateral sclerosis; "Lou Gehrig's disease") to strengthen muscles and their connecting nerves. Researchers injected bone marrow adult stem cells carrying a gene for GDNF (glial cell line-derived neurotrophic factor), a nurturing protein for nerves. Previous work by the group had shown that transplanting neural stem cells that released GDNF into the spinal cord could protect motor neurons that degenerate in the ALS rat, but that the nerves still did not effectively connect with the muscles that waste away due to ALS. In the current study published in Molecular Therapy, the researchers were pleasantly surprised to find that when they injected the adult stem cells into muscle, however, the cells pumped out GDNF that helped the connecting nerves survive and maintain connection, and that this delayed progression of the disease and extended the lifespan of the ALS animals. The bone marrow adult stem cells had a slight effect on their own, possibly by releasing their own protective factors, but the effect was greater when they delivered the nurturing growth protein. While any human application is still in the future, the new study provides hope for treatment in a disease that currently has no effective therapy. An advantage of this approach is that muscle is easy to access and adult stem cells could be used from the patients themselves.