Anti-inflammatory Mechanism of Bone Marrow Mesenchymal Stem Cell Transplantation in Rat Model of Spinal Cord Injury.

To explore the effect of bone marrow mesenchymal stem cell (BMSC) transplantation on the levels of toll-like receptor 4 (TLR4), interleukin-1β (IL-1β), and tumor necrosis factor (TNF-α) in spinal cord tissue of rat model of spinal cord injury (SCI). BMSCs from 4-week-old male SD rats were isolated, cultured, and characterized after three generations using specific surface markers CD34 and CD44. Fifty four SD male rats were divided into sham group, model group, and cell transplantation group (18 rats each group). SCI model was generated using an improved Allen's method. Rats in cell transplantation group were treated with BMSCs in caudal vein. Rats were sacrificed at 24 h, 72 h, and 7 d post-injury, and spinal cord tissues were taken out for detection of IL-1β and TNF-α tissue content by enzyme-linked immunosorbent assay. IL-1β and TNF-α mRNA expression was evaluated by qPCR and TLR4 protein expression was analyzed by Western blotting. IL-1β and TNF-α protein levels, as well as IL-1β, TNF-α mRNA, and TLR4 expression were significantly increased in rats with established SCI, and reached its peak in spinal cord tissues at 72 h after the initial injury (p < 0.01 comparing to sham group). BMSC transplantation resulted in significant decrease in IL-1β and TNF-α tissue content, as well as IL-1β, TNF-α mRNA, and TLR4 expression as compared with model group (p < 0.01). BMSCs may alleviate the damaging effect of spinal cord inflammation by weakening TLR4-mediated signaling pathways and reducing tissue content of IL-1β and TNF-α.