An article from Science Blog describes progress made in producing brain stem cells from adult bone marrow stem cells. In theory, these cells could be implanted in the brain to regenerate damage caused by neurodegenerative diseases like Parkinson's or Alzheimer's. Taking stem cells from a patient, making them turn into a certain type of precursor cell, and then returning the cells into a damaged area of the body is a technique currently showing promise for heart disease. We're a long way from human trials in this case, however. Researchers must first test this process in animal subjects - to establish whether or not it works, and find the best way to introduce stem cells into the brain.