Hypoxic preconditioning increases the protective effect of bone marrow mesenchymal stem cells on spinal cord ischemia/reperfusion injury

Transplantation of bone marrow mesenchymal stem cells (BMSCs) protect against spinal cord ischemia/reperfusion injury (SCIRI). However, a large number of transplanted BMSCs often undergo apoptosis, which severely affects the treatment outcome. Previous studies have demonstrated that hypoxic preconditioning effectively increases the survival rate of BMSCs following transplantation, and increases their protective effect on injured tissues. However, there have been few reports regarding roles of hypoxic preconditioning in SCIRI. The present study isolated rat BMSCs and separately transplanted hypoxia- and non-hypoxia-preconditioned BMSCs into the spinal cord tissues of rats with SCIRI. The role of hypoxic preconditioning in the promotion of the protective effect of BMSCs on SCIRI was investigated using neurological function scores, Evans blue staining, hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling. In addition, reverse transcription-quantitative polymerase chain reaction and western blotting were used to detect the expression levels of hypoxia-inducible factor 1α (HIF-1α), and to investigate its possible underlying mechanism of action. The results indicated that hypoxic preconditioning effectively increased the protective effects of BMSCs on neurological function, blood spinal cord barrier and tissue damage following SCIRI, and inhibited apoptosis. Furthermore, hypoxic preconditioned BMSCs upregulated the expression of HIF-1α in spinal cord tissues. Therefore, hypoxic preconditioning effectively increased the protective effect of BMSCs on SCIRI and may be associated with upregulation of the expression of HIF-1α. Hypoxic preconditioning may serve as an effective means of increasing the protective effect of BMSCs on SCIRI.