Even comparatively unsophisticated stem cell therapies, such as transplants, show potential: "Using a commonly utilized animal model for stroke, researchers administered a dose of 200,000-400,000 human stem cells into the brain of animals that had experienced significant loss of mobility and other functions. ... Treated animals experienced at least 25 percent greater improvement in motor and neurological performance than controls. ... A single dose of the cells produce robust behavioral recovery at an early period post-transplantation and the recovery was durable, lasting up to two months, which was the entire length of this study. Furthermore, animals continued to show improvement over time. ... The mechanism that we are putting forward is these donor cells are secreting nourishing trophic factors that are helping the host brain cells survive and stimulating stem cells from the host to multiply."

Link: http://www.mcg.edu/news/2006NewsRel/borlongan-hess20060407.html