Abstract
Background. This study investigated behavioral recovery in rats following implanting increasing doses of CTX0E03 cells into the putamen ipsilateral to the stroke damage. Postmortem histological analysis investigated possible mechanisms of behavioral recovery. Methods. At 4 weeks after middle cerebral artery occlusion (MCAO), rats were treated with 4500, 45 000, or 450 000 CTX0E03 cells or vehicle implanted into the putamen with testing on a battery of tasks preocclusion and postocclusion. Histological examination of brains included assessment of lesion volumes, implant cell survival and differentiation, changes to host brain matrix, angiogenesis, and neurogenesis using immunohistochemical methods. Results. Statistically significant dose-related recovery in sensorimotor function deficits (bilateral asymmetry test [BAT; P < .0002] in the mid- and high-dose groups and rotameter test after amphetamine exposure [P < .05] in the high-dose group) was found in the CTX0E03 cell implanted groups compared to the vehicle group. In-life functional improvements correlated with cell dose, though did not correlate with survival of CTX0E03 cells measured at postmortem. Surviving CTX0E03 cells differentiated into oligodendroglial and endothelial phenotypes. MCAO-induced reduction of neurogenesis in the subventricular zone (SVZ) was partially restored to that observed in sham operated controls. No adverse CTX0E03 cell-related effects were observed during in-life observations or on tissue histology. Conclusions. This study found that the implantation of CTX0E03 human neural stem cells in rats after MCAO stroke promoted significant behavioral recovery depending on cell dose. The authors propose a paracrine trophic mechanism, which is triggered early after CTX0E03 cell implantation, and which in turn targets restoration of neurogenesis in the SVZ of MCAO rats.