Apoptosis of neural cells in response to hBDNF-modified rMSCs transplantation after spinal cord injury in rats

Abstract

Objective To discuss the survivorship of rat mesenchymal stem cells (rMSCs) and the expression of human brain-derived neurotrophic factor (hBNDF) protein after transplantation of the hBDNF-modified rMSCs (hBDNF-rMSCs) to the adult rats with spinal cord injury (SCI) and discuss the effect of hBDNF-rMSCs on the apoptosis of rat neural cells. Methods A total of 240 adult male Sprague-Dawley rats were randomly divided into sham operation group,SCI group,hBDNF-rMSCs transplantation group and empty vector-rMSCs transplantation group,with60 rats in each group.The SCI model was established by using the modified Allen technique.At day 7 after modeling,an equal volume of hBDNFrMSCs suspension,empty vector-rMSCs suspension and phosphate buffered saline (PBS) were injected through the L4,5 subarachnoid space into the hBDNF-rMSCs group,empty vector-rMSCs group and SCI group,respectively.Then,the injured spinal cord tissues were obtained from each group at days 1,2,3,7 and 14 after transplantation to observe the viability and distribution of rMSCs with enhanced green fluorescent protein gene by fluorescent microscope,measure the expression of hBDNF protein by Western blot and detect the apoptosis of neural cells by TdT-mediated dUTP nick end labeling (TUNEL). Results Both hBDNF-rMSCs and empty vector-rMSCs groups showed green fluorescence expression of rMSCs.The hBDNF protein expression was observed in hBDNF-rMSCs group and changed with time,ie,the expression was detected at day 2 after transplantation,reached the highest level at day 7 and then decreased gradually.Among the hBDNF-rMSCs,empty vector-rMSCs and SCI groups,the number of TUNEL positive cells was the least in hBDNF-rMSCs group,followed by the empty vector-rMSCs group and the number was relatively more in SCI group at days 2,3,7 and 14 after transplantation,with significant differences among groups (P ＜ 0.05). Conclusions Transplantation of the hBDNF-modified rMSCs through subarachnoid approach are able to survive and assemble at the injured spinal cord area and express hBDNF protein.The hBDNF-modified rMSCs can inhibit the apoptosis of neural cells after SCI. Key words: Spinal cord injuries; Brain-derived neurotrophic factor; Mesenchymal stem cells; Gene therapy; Apoptosis