The co-transplantation of human bone marrow stromal cells and embryo olfactory ensheathing cells as a new approach to treat spinal cord injury in a rat model

Background Both bone marrow stromal cells (BMSC) and olfactory ensheathing cells (OEC) have been demonstrated experimentally as promising for therapy of spinal cord injury (SCI). However, clinical use may be constrained by the margin neuronal differentiation capacity of BMSC as well as the limited number of isolatable OEC. This study therefore tested the efficacy of co-grafting human BMSC and OEC in treating thoracic SCI. Methods Rat SCI models were created with cushion forces. OEC were labeled with Hoechst 33342 and BMSC with BrdU or GFP. BMSC, OEC and BMSC plus OEC were injected into the injured sites of rat spinal cords. Histologic, electrophysiologic and functional approaches were applied to assess the effects of transplantation of these cell types. Results Behavioral evaluation showed an improvement in animals with all cell-based treatments. The co-graft led to significantly higher gait scaling. The latency of transcranial magnetic motor-evoked potential (tcMMEP) responses was also better restored in the co-graft group. Larger numbers and sizes of axon bundles through the transitional zone between the normal and injured regions were observed in the co-graft animals in comparison with all other animals. Transplanted bone marrow stromal cells were identified as neurofilament-positive in the co-grafted animals although the number of glial fibrillary acidic protein-positive cells remained the same in all groups. Discussion Taken together, our results suggest that the combined use of BMSC and OEC may provide an improved approach for the treatment of SCI.