Grafts of hydrogel-embedded electrically stimulated subventricular stem cells into the stroke cavity improves functional recovery of mice

The major aim of stroke therapy is to stimulate brain repair and improve behavioral recovery after cerebral ischemia. One option is to stimulate endogenous neurogenesis in the subventricular zone and direct the newly formed neurons to the damaged area. However, only a small percentage of these neurons survive, and many do not reach the damaged area, possibly because the corpus callosum impedes the migration of subventricular zone-derived stem cells into the lesioned cortex. A second major obstacle to stem cell therapy is the strong inflammatory reaction induced by cerebral ischemia, whereby the associated phagocytic activity of brain macrophages removes both therapeutic cells and/ or cell-based drug carriers. To address these issues, neurogenesis was electrically stimulated in the subventricular zone, followed by isolation of proliferating cells, including newly formed neurons, which were subsequently mixed with a nutritional hydrogel. This mixture was then transferred to the stroke cavity of day 14 post-stroke mice. We found that the performance of the treated animals improved in behavioral tests, including novel object, open field, hole board, grooming, and "time-to-feel" adhesive tape tests. Furthermore, immunostaining revealed that the stem cell marker nestin, the neuroepithelial marker Mash1, and the immature neuronal marker doublecortin-positive cells survived in the transplanted area for 2 weeks, possibly due to reduced phagocytic activity and supportive angiogenesis. These results clearly indicate that the transplantation of committed subventricular zone stem cells combined with a protective nutritional gel directly into the infarct cavity after the peak of stroke-induced neuroinflammation represents a feasible approach to improve neurorestoration after cerebral ischemia.