Survival and differentiation of transplanted neural stem cells derived from human induced pluripotent stem cells in a rat stroke model.

BACKGROUND Although administration of various stem cells has shown promise in stroke models, neural stem cells (NSCs) derived from human induced pluripotent stem cells (iPSCs) have advantages over other cell types. We studied whether these cells could survive, differentiate, and improve stroke recovery in an ischemic stroke model. METHODS Human iPSCs were induced in vitro to an early NSC stage. One week after focal cerebral ischemia, 20 rats received cells or vehicle by intracerebral injection. Graft cell fate, infarct volume, and behavioral deficits were assessed. RESULTS Graft cells were found in 8 of the transplanted rats (80%), with estimated mean graft cell numbers nearly double the amount transplanted 1 month later. Graft cells also expressed markers of NSCs in 5 rats (63%), neurons in all 8 rats (100%), rare astrocytes in 4 rats (50%), and signs of proliferation in 4 rats (50%), but no tumor formation was observed. Stroke volume and behavioral recovery were similar between the groups. CONCLUSIONS To our knowledge, this is the first report of transplantation of NSCs derived from human iPSCs in a stroke model. Human iPSC-derived NSCs survived in the postischemic rat brain and appeared to differentiate, primarily into neurons. This cell transplantation approach for stroke appears to be feasible, but further optimization is needed.