The Study Of Transplantation Of Induced Differentiated Bone Marrow Mesenchymal Stem Cells On The Neurological Function Recovery After Spinal Cord Injury In Rats

Objective:To investigate the effects and the suitable engraftment time of transplantation of oriented-induced bone marrow mesenchymal stem cells (BMSCs) on the nerve function recovery after spinal cord injury (SCI) in rats. Methods:1) BMSCs were cultured and purified by adherence method. The BMSCs at 3th passage were resuspended and induced in the DMEM/F12 medium without serum containing EGF, bFGF, B27. Immunocytochemistry was used to identify expression of nestin (maker for NSCs). And then we added serum, and immunocytochemistry was used to identify expression of NF200 (maker for neuron), GFAP (maker for astrocytes). The oriented-induced BMSCs were labeled with Brdu 3 days before they were transplanted.2) The rat models of SCI were established by using Allen's method, and 45 rat models of SCI were allocated randomly into three groups (each group n=15). The oriented-induced BMSCs were slowly injected into the injured site of the SCI rats in group A (transplantation at 1 week postinjury) and group B (transplantation at 2 weeks postinjury). The SCI rats in group C as the control group and were injected into the equal normal saline. The BBB scores after transplantation were recorded so as to estimate the nerve function recovery of rats in every group. The distribution and differentiation of transplanted cells were observed by using immunofluorescence staining with antibodies against Brdu combined with Nestion and Brdu combined with NF200. NF200 immunofluorescence staining was used to show the axonal regeneration. We measured the cavity area by staining with hematoxylin-eosin (HE). Results:1) The cultivation of BMSCs in vitro shows that they increased lastingly and has a fast multiplication speed in vitro. The BMSCs at 3th passage could differentiate into cellular spheres with positive nestin in the medium containing EGF, bFGF, B27. Following differentiation of cellular spheres in the medium with serum, some of them formed neuron showed positive NF200, some formed astrocytes showed positive GFAP.2) After the surgery, the moter function of the rats in three groups recovered gradually over time at 1-6 weeks after SCI. BBB scores in group A and group B were significantly higher than group C (P<0.05). The immunofluorescence showed that a large number of Brdu and Nestin double-positive cells and some Brdu and NF200 double-positive cells filled the injured site and linked the two sides of the injured area in group A and group B, and the lesion area of the spinal cord were less than those in the group C (P<0.05). More importantly, further reduction in lesion area and improvement in function were observed in group A. Conclusion:The oriented-induced BMSCs have the biological function of neural stem cells and have the ability to differentiate into neuron, astrocytes. the transplantation of oriented-induced BMSCs could effectively promote the nerve function recovery after SCI, and the effect of transplantation at 1 week postinjury was better than transplantation at 2 weeks postinjury.