How stem cell implants heal traumatic brain injury

In numerous studies, stem cell implantation has substantially improved brain function after brain trauma, but researchers did not understand why this worked. In new experiments with both laboratory rats and an apparatus that enabled researchers to simulate the impact of trauma on human neurons, scientists have identified key molecular mechanisms by which implanted human neural stem cells -- cells that are in the process of developing into neurons -- aid recovery from traumatic injury. The researchers investigated the role of a substance called glial derived neurotrophic factor (GDNF), which is secreted from stem cells and seemed to help injured rat brains recover from injury. Initial results matched those seen in rat experiments, with GDNF protecting axons and dendrites from additional damage after trauma and significantly reducing the levels of other compounds which hindered recovery.