Combined Transplantation Of Olfactory Bulb Sheath Cells And VitroGel^TM 3D-RGD Hydrogel To Treat Complete Spinal Cord Transection Injury In Rats

Objective:To investigate whether combined transplantation of OECs and Vitrogel^TM 3D-RGD hydrogel can promote SCI recovery in rats,the combined transplantation of OECs and Vitrogel^TM 3D-RGD hydrogel was used to treat rats with complete transection spinal cord injury（SCI）model.Methods:Live/Dead cells were stained at 1d,3d and 7d,respectively,to detect the cell viability,when the OECs were co-cultured with Vitrogel^TM 3D-RGD hydrogel in vitro.Through activity identification,the cells with the best co-culture time were selected for animal experiment.The internal structure of Vitrogel^TM 3D-RGD hydrogel was observed under scanning electron microscope.Adult male SD rats were divided into sham operation group,spinal cord injury model group,OECs transplantation group and Vitrogel^TM 3D-RGD transplantation group,with 12 rats in each group.They were observed before treatment,1d,3d,7d and 14d after surgery,respectively,and sacrificed on 28 days.The Basso,Beattie,and Bresnahan（BBB）scores,HE staining,immunohistochemistry and transmission electron microscopy were used to evaluate the recovery of spinal cord injury in rats.Results:（1）The cell activity of OECs/VitroGel^TM 3D-RGD hydrogel co-culture was well,and the cells were in the best condition at the 3rd day,but the cells were obviously connected to each other to form axons at the 7th day.（2）The OECs/Vitrogel^TM 3D-RGD hydrogel has good biocompatibility,and many empty structures can be seen under transmission electron microscope.（3）The BBB scores of all the animals before surgery reached 21 points,and the BBB scores of the hind limbs of the OECS/Vitrogel^TM 3D transplantation group were statistically significant compared with those of the other groups.（4）On day 28,HE staining results showed that tissue edema disappeared and vacuolar degeneration was reduced in the OECs/Vitrogel^TM 3D-RGD transplantation group.The nerve cells were evenly distributed and normal in the gray matter,and the nerve fibers were neatly arranged in the white matter.（5）Immunohistochemical results showed that the expressions of 5-HT and NF were significantly increased in the OECs/Vitrogel^TM 3D-RGD transplantation group.（6）In the OECs/VitroGel^TM 3D-RGD transplantation group,the ultrastructure of the nerve tissue at the center of SCI was complete and only a small amount of glial scar was formed under transmission electron microscopy.Conclusion:1、In vitro co-culture of rat olfactory bulb sheath cells with VitroGel^TM 3D hydrogel showed that the gel had good biocompatibility and could promote cell junction and axon regeneration between OECs.2、Vitrogel^TM 3D/OECS combined transplantation therapy can significantly promote neuronal regeneration and nerve fiber formation,reduce glial scar and promote SCI repair compared with other groups.