Autologous adult rodent neural progenitor cell transplantation represents a feasible strategy to promote structural repair in the chronically injured spinal cord

Abstract

Adult neural progenitor cells (NPCs) represent an attractive source for cell-based regenerative strategies in CNS disease. In animal models of spinal cord injury, syngenic adult NPCs, which were isolated from pooled post-mortem CNS tissue and co-transplanted together with fibroblasts, have been shown to promote substantial structural repair. The autologous transplantation of adult NPCs represents a major advantage compared with other sources of neural stem/progenitor cells. However, the feasibility of autologous NPC generation from a single biopsy in a relevant preclinical CNS disease model has yet to be demonstrated. To investigate this matter, adult Wistar rats underwent a cervical spinal cord lesion, which was followed by a minimal subventricular zone aspiration biopsy 2 days later. NPCs were isolated and propagated separately for each animal for the following 8 weeks. Thereafter, they were co-transplanted with simultaneously harvested skin fibroblasts in an autologous fashion into the cervical spinal cord lesion site. A total of 4 weeks later, graft survival, tissue replacement and axonal regeneration were assessed histologically. Animals receiving either allogenic NPCs combined with fibroblasts or autologous pure fibroblast grafts served as control groups. Within 8 weeks after the biopsy more than 3 million NPCs could be generated from a single aspiration biopsy, which displayed a differentiation pattern indistinguishable from syngenic NPC grafts. NPCs within autologous co-grafts readily survived, replaced cystic lesion defects completely and differentiated exclusively into glial phenotypes, thus paralleling previous findings with syngenic NPCs. The delayed transplantation 8 weeks after the spinal cord lesion elicited substantial axonal regeneration. These findings demonstrate that the therapeutic strategy to induce structural repair by transplanting adult autologous NPCs, after the successful propagation from a small brain biopsy into an acute CNS disease model, such as spinal cord injury, is feasible at the preclinical level.