Transplantation of neural stem cells: cellular & gene therapy for hypoxic-ischemic brain injury.

We have tracked the response of host and transplanted neural progenitors or stem cells to hypoxic-ischemic (HI) brain injury, and explored the therapeutic potential of neural stem cells (NSCs) injected into mice brains subjected to focal HI injury. Such cells may integrace appropriately into the degenerating central nervous system (CNS), and showed robust engraftment and foreign gene expression within the region of HI inury. They appeared to have migrated preferentially to the site of ischemia, experienced limited proliferation, and differentiated into neural cells lost to injury, trying to repopulate the damaged brain area. The transplantation of exogenous NSCs may, in fact, augment a natural self-repair process in which the damaged CNS "attempts" to mobilize its own pool of stem cells. Providing additional NSCs and trophic factors may optimize this response. Therefore, NSCs may provide a novel approach to reconstituting brains damaged by HI brain injury. Preliminary data in animal models of stroke lends support to these hypotheses.