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2022, Vol. 26 ›› Issue (1): 20-26Bone marrow mesenchymal stem cells-derived exosomes combined with chondroitinase ABC for treating spinal cord injury in ratsXie Xingqi, Hu Wei, Tu Guanjun
Abstract: BACKGROUND: How to improve the local microenvironment, inhibit the formation of the glial scar, and promote repair and regeneration of damaged neurons and axons, are the difficulties of treating spinal cord injury. The research demonstrated that chondroitinase ABC can enhance the regeneration and plasticity of axons by degrading chondroitin sulfate proteoglycans. Meanwhile, bone marrow mesenchymal stem cells-derived exosome has a protective effect on spinal cord injury recovery by inhibiting apoptosis, regulating immune response, and regulating regeneration of damaged neurons. OBJECTIVE: To investigate the repair effect of bone marrow mesenchymal stem cells-derived exosome combined with chondroitinase ABC on spinal cord injury in rats and to explore its mechanism. METHODS: Using the exosomes-extracted kit to isolate bone marrow mesenchymal stem cells-derived exosome, its morphology was observed under a transmission electron microscope. The expression levels of CD63 and Alix were identified through western blot assay. Totally 50 SD rats were randomly divided into five groups: sham group, model group, chondroitinase ABC group, exosome group, and combination group, with 10 rats in each group. Rat models of spinal cord injury were established by referencing the modified Allen’s method. In the chondroitinase ABC group and combination group, a micro syringe was applied to directly inject chondroitinase ABC into the injured area. At 2 hours after surgery, the models of the exosome group and the combination group were injected with bone marrow mesenchymal stem cells-derived exosomes through the tail vein, once every 2 days, for a total of 3 injections. The hind limb motor function was scored at 1, 3, 7, 14, and 28 days after surgery. At 14 days, six rats were taken from each group to make paraffin slices after perfusion. The pathological changes were observed at the injury region by hematoxylin-eosin staining. The expression of glial fibrillary acidic protein was detected by immunofluorescence and the expression of growth-associated protein-43 was identified by immunohistochemistry. RESULTS AND CONCLUSION: (1) The exosomes presented a circular or elliptical shape or “saucer-like” and its size was uneven. The positive expression of its marker proteins CD63 and Alix could be observed. (2) Compared with the model, chondroitinase ABC, and exosome groups, BBB score was higher; damaged area was smaller; expression of glial fibrillary acidic protein was lower; the expression of growth-associated protein-43 was up-regulated in the combination group (all P < 0.05). (3) The results demonstrate that bone marrow mesenchymal stem cells-derived exosome combined with chondroitinase ABC can inhibit the expression of glial fibrillary acidic protein in the injured area, up-regulate the expression of growth-associated protein-43, and reduce the formation of the glial scar, which improve local microenvironment and promote the repair and regeneration of neurons and axons after spinal cord injury in rats. Key words:stem cells, bone marrow mesenchymal stem cells, exosomes, chondroitinase ABC, spinal cord injury, repair and regeneration, tissue engineering, glial fibrillary acidic protein, growth-associated protein-43 |