The combined therapy of chondroitinase and Schwann cells transplantation after spinal cord injury in rats

Objective To investigate the effect of the combination of chondroitinase and Schwann cells (SCs) transplantation after spinal cord injury (SCI) in adult rats. Methods Eighty adult Wistar rats were divided into four groups; the control group (A), the Schwann cells transplantation group ( B), the chondroitinase ABC(ChABC) group (C) and the SCs transplantation plus chondroitinase ABC group (D). The thoracic T10 spinal cord injury model was made by Impactor model II manual (10g×4 cm). After SCI, the rats in group B received SCs transplantation in injured sites, those in group C received ChABC treatment, and those in group D received the combined treatment. The rats in group A only received blank saline and medium. The locomotor functions were evaluated according to the BBB score scale (total 21), and the neuroelectrophysiological changes (SEP&MEP) were examined by electromyographic machine. Twelve weeks after SCI, biotinylated dextran amine (BDA) was injected into the cerebral cortex to trace the corticospinal tracts. Two weeks after the tracing, the animals were killed and the spinal cord frozen sections were made. The tissue sections were processed with Cy3 fluorescence stain, HE stain and anti NF-200 immuohistological stain. Results From 4 weeks after SCI, the rats in groups B, C and D had obviously higher BBB scores than in control group (P<0.05) , and BBB scores in group D was the highest. The scores in groups A, B, C and D were 9. 11 ±1.41, 11.22 ±1.59, 11.77 ±1.76 and 14. 22 ± 1. 92 respectively 12 weeks later. In electromyographic examination (SEP&MEP) , the rats in groups B, C and D gained better recovery than group A (P <0. 05), and group D was the best. At the week 12, the MEP wave recovery rate was 28. 8% , 44. 9% , 49. 0% and 56. 8% in groups A, B, C and D respectively. In BDA tracing slides, some axons could cross the injured sites in group D. There was significant difference in anti-NF-200 stain area among four groups (P<0.05). The absorbance ( A) ratio between groups B, D, D and group A was 1.44, 1. 55 and 2. 78, respectively. Conclusion Combined therapy with ChABC and SCs transplantation can promote axonal regeneration and function recovery after SCI. Key words: Spinal cord injury;  Regeneration;  Schwann cells;  Chondroitinase;  Cell transplantation