SAN DIEGO – A team of San Diego scientists has moved embryonic stem cell research a step closer to helping repair the brains of stroke victims and people with diseases such as Parkinson's and Alzheimer's. The team, led by the Burnham Institute's Stuart Lipton, figured out how to coax the embryonic stem cells of mice to become nerve cells that, when transplanted into a mouse brain damaged by stroke, link themselves to the existing network of neurons. The mice showed therapeutic improvement, and none of them developed tumors, which has been a problem associated with the implantation of stem cells,...