Repair of transversal spinal cord injury in rats by porous silk fibroin scaffolds seeded with bone mesenchymal stem cells

Abstract

Objective To investigate the therapeutic effects of porous silk fibroin scaffolds (PSFSs) seeded with bone mesenchymal stem cells (BMSCs) on the repair of transversal spinal cord injury (SCI) in rats.Methods Ninety-six SD rats were randomly divided into control group,PSFSs group,BMSCs group and PSFSs plus BMSCs group (24 each).The function repair was evaluated by Basso-Beattie-Bresnahan (BBB) score system at lst,2nd and 4th week.Immunohistochemistry and Western blotting were applied to detect the expression of growth associated protein 43 (GAP-43) and myelin basic protein (MBP) in the injured spinal cord.The intensity of GAP-43 expression was measured by immuno-fluorescence staining.Results At 4th week after injury,the implanted groups exhibited a more significant improvement in hindlimb locomotor function than in control group in BBB scores (P ＜0.05).The BBB sores in control group,PSFSs group,BMSCs group and PSFSs plus BMSCs group were 5.23 ± 1.13,7.17 ±1.11,7.35 ± 1.59 and 9.43 ± 2.16 respectively.Immunohistochemistry showed that the integral absorbance (IA) values of GAP-43 and MBP in implanted groups were significantly higher than those in control group (P ＜ 0.05).In control group,PSFSs group,BMSCs group and PSFSs plus BMSCs group,the IA values of GAP-43 were 13.94 ±3.63,26.07 ±5.31,22.14 ±4.56 and 33.03 ±7.58,and those of MBP were 13.80 ± 3.41,21.16 ± 3.36,32.96 ± 7.74 and 44.06 ± 7.99,respectively.The immuno-fluorescence staining indicated that there were more GAP-43 positive growth cones at the lesion site in PSFSs plus BMSCs group.Western blotting results showed that there was significant difference in the expression of GAP-43 and MBP proteins between control group and implanted groups (P ＜ 0.05).In control group,PSFSs group,BMSCs group and PSFSs plus BMSCs group,the gray value ratio of GAP-432 was 0.16 ± 0.04,0.41 ±0.05,0.33 ±0.06 and 0.72 ±0.16,and that of MBP was 0.96 ±0.11,1.85 ±0.08,2.14 ±0.16 and 2.43 ± 0.31,respectively.Conclusion Transplantation of PSFSs seeded with BMSCs can promote the axonal regeneration,myelination and functional recovery after SCI in rats. Key words: Spinal cord injury;  Bone mesenchymal stem cells;  Silk fibroin;  Transplantation