Porous Silk Fibroin Scaffolds Combined With Chondroitinase ABC In The Therapy Of Rats With Spinal Cord Injury

Objective: To investigate the effects of porous silk fibroin scaffolds（PSFSs）combined with chondroitinase ABC（ChABC）to enhance nerve regeneration andfunctional recovery in a standardized transaction defect created in the rat spinal cord.Methods: After the cylindrical nerve scaffold with the pores called PSFSs made ofsilkworm was fabricated via freeze drying, of which the surface and the cross-sectionshape were observed by the scanning electron microscopy(SEM).Ninety-six SD rats weremade the models of T9spinal cord transection injury and divided into4groups,24rats ineach group. In group A, injured site was not treated; in groups B, C and D, PSFSs, ChABCand PSFSs+ChABC were implanted into injured site, respectively. At1st、2nd、4th weekafter injury, the BBB score system was used to evaluate the motion function,the spinal cordsamples were harvested for HE staining, and immunohistochemistry analysis to detect thechange of neurofilament-200(NF-200), glial fibrillary acidic protein (GFAP), and growthassociated protein-43(GAP-43) of the injured spinal cord. The immuno-fluorescencestaining for GAP-43was also carried out to evaluate the regeneration of nerve fiber.Meanwhile, the western blotting analysis was used for the quantitative detection ofNF-200，GFAP and GAP-43.Results: SEM showed that PSFSs is a porous, spongelike scaffold with uniformlydistributed pores and channels. At2nd week after injury, the BBB score of groups B,C,Dwas significantly higher than that of group A (P <0.05), and the BBB score of group Dwas significantly higher than those of groups B,C at4th week after injury (P <0.05). HEstaining showed that the formation of the cavity and the necrosis of neurons in group Dwere more moderately than those in group A，B，C at4th week after injury.immunohistochemistry staining showed that the integral absorbance (IA) values of NF-200and GAP-43in groups B,C,D were significantly higher than those in group A (P <0.05), and the IA values of NF-200and GAP-43were significantly higher in group D than ingroups B,C at4th week after injury (P <0.05), but the positive area of GFAP wassignificantly smaller in group D than groups A,B,C (P <0.05), the positive area of GFAPin groups B,C was significantly smaller than group A at2nd,4th week after injury(P <0.05). However, there were no significant differences between group B and C about thosevalues. The immuno-fluorescence staining indicated that the expression of GAP-43wasmore intense in group D than groups A、B and C at4th week after injury. Western blotresults showed that there were significant differences in the expression of those proteinsbetween control group and treatment groups, the expression of GFAP in the control groupwas more obvious than all the treatment groups (P <0.05), while the expression ofGAP-43, NF-200was more obvious in all the treatment groups(P <0.05).Conclusions: Transplantation of PSFSs combined with chondroitinase ABC canenhance the nerve regeneration and promote the recovery of locomotor function in spinalcord injury (SCI) using a transection rat model.