Limitations of intravenous human bone marrow CD133+ cell grafts in stroke rats.

We examined the effects of timing and routes of transplantation on survival and functional benefits of human bone-marrow-derived CD133+ cells in experimentally stroke Sprague-Dawley rats. At day 7 post-stroke, both immediate and delayed intracerebral transplantation resulted in similar graft survival (7%) that was localized within the original transplant site and reduction of motor (27%) and neurological (40%) deficits. In contrast, graft survival (0.01-0.04%) was only detected in delayed intravenous transplantation, characterized by cell migration throughout the ipsilateral stroke hemisphere. Behavioral improvement, however, was limited to neurological response and only apparent in immediate intravenous transplantation. Reduction of cerebral infarct (25%) was only noted in intracerebral transplantation. Intravenous transplantation requires optimization for improved therapeutic outcome of CD133+ cell grafts in stroke.