Effect of the implant composite of poly lactide-co-glycolide and bone mesenchymal stem cells modified by basic fibroblast growth factor on injured spinal cord in rats

Abstract

Objective To investigate the effect of the implant composite of poly lactide-co-glycolide (PLGA) and bone mesenchymal stem cells (BMSCs) modified by basic fibroblast growth factor (bFGF) on injured spinal cord in rats.Methods Two hundred and forty rats were made models of spinal cord injury by hemisection of T7. They were randomly divided into 4 groups. Group A were treated with implantation of bFGF-modified BMSCs plus PLGA, group B with implantation of bFGF-modified BMSCs, group C with implantation of BMSCs without genetic modification, and group D served as control. On day 3, week 2, week 3,week 8 and week 12 after operation, 12 rats were randomly sacrificed in each group for harvest of the injured spinal cord sections, after evaluation by the Basso, Beattie & bresnahan (BBB) locomotor rating scale and measurements of somatosensory evoked potentials (SEP) . The sections from 6 rats were used for reverse transcription polymerase chain reaction (RT-PCR) analysis to detect the mRNA expression level of bFGF gene, and those from the other 6 were used for the immunohistochemical examination of neurofilament-200(NF-200), gorwth-associated protein-43(GAP-43), glial fibrillary acidic proetin (GFAP) expressions and histomorphological observation of HE staining.ResultsThe BBB scores in 4 groups were all lower than 2 points on week 2, without any significant difference among the 4 groups ( P ＞ 0. 05 ) . After week 3, the scores increased faster in each group. Group A had a significantly higher score than the other 3 groups ( P ＜0.05). SEP eoult be monitored in all rats before operation. During operation, the latent period was prolonged by more than 10％ and the SEP amplitude declined by more than 50％. However, SEP could not be monitored in each group within 3 weeks after operation and could be monitored in part of the rats after 8weeks in each group. The results of RT-PCR, HE staining and immunohistochemical examination in group A showed significant improvements in regeneration of nerve fibers compared with the other groups( P ＜0. 05).Conclusions For rats with spinal cord injury, implantation of BMSCs alone can promote nerve regeneration to some extent, implantation of bFGF-BMSCs can improve therapeutic effect, and the implanted bFGF-BMSCs + PLGA composite can further improve the therapeutic effect. Key words: Spinal cord injury; Bone marrow cells; Tissue engineering; Gene therapy