They were four women that were dying of leukemia. All four were given bone marrow transplants from men before their death in an unsuccessful attempt to treat their cancers. Dr. Eva Mezey of the National Institute of Neurological Disorders and Stroke had an idea that might give their deaths some meaning. She knew that marrow stem cells had been shown two years ago to migrate to the brain and create new neurons in mice. Examining the preserved brains of the four terminal patients, Mezey determined the same thing had apparently happened to them as a result of the unsuccessful medical treatments before their death. In the brains of all four, Mezey’s group identified neurons that had Y chromosomes, found only in men. A few of the patients’ brain cells apparently came from stem cells in the donated bone marrow, the researchers say in this week’s Feb. 3 issue of the Proceedings of the National Academy of Sciences. In the most promising of Mezey’s study group, about 7 of 10,000 neurons had a Y chromosome – and this was without any attempt to artificially stimulate the process at all. “The important message is that there are indeed cells in the blood that can enter the human brain and become neurons there,” Dr. Mezey said. The implications for things like Alzheimer treatments and spinal cord repair – or perhaps even futuristic brain augmentation – are obvious.