[Brain ischemia--regenerative therapy using human neural stem cells].

The mortality of stroke is still the those of single organs. Even if patients survive the brain attack they often suffer from not only motor functional disability but also psychiatric problems such as post-stroke depression and decrease in spontaneity. The stoke is the number one cause of the bed-ridden state "Netakiri". Presently only anti-thrombotic and anti-oxidative stress therapies are available and the ischemic core destroyed immediately after the stroke could never be rescued. We have started to study the basic aspect of transplantation therapy of cerebral infarction using neural stem cells. Using a focal ischemic model of the gerbil by repeated occlusion of the unilateral carotid artery, we grafted human neural stem cells which were cultured and proliferated for a long period. Grafted animals showed significant and marked improvement in all three functions including motor, sensory and cognitive functions associated with a significant reduction of infarction volume. Synaptic contacts between neurons from grafted human neural stem cells and host neurons were confirmed by immuno-electron microscopy. This is a very encouraging report although it is necessary to elucidate the precise mechanism of the functional recovery or the effect of neural stem cell transplantation.