Effect of hypoxia-preconditioned BMSCs on expression of HO-1 during spinal ischemia-reperfusion in rats

Abstract

Objective To evaluate the effect of hypoxia-preconditioned bone marrow mesenchymal stem cells (BMSCs) on the expression of HO-1 during spinal ischemia-reperfusion (I/R) in rats. Methods Thirty healthy adult Sprague-Dawley rats, weighing 200-250 g, were randomly divided into 5 groups with 6 animals in each group using a random number table: sham operation group (group S), I/R group, PBS group, BMSC transplantation group (BMSC group) and hypoxic preconditioning group (group HP). In group HP, BMSCs were exposed to 3%O2-5%CO2-92%N2 for 24 h for hypoxia preconditioning.In PBS, BMSC and HP groups, PBS, BMSCs and BMSCs for hypoxic preconditioning were injected intrathecally, respectively, and 60 min later spinal I/R was induced by clamping the aorta in the rats anesthetized with chloral hydrate.At 6, 12, 24 and 48 h and 7 days of reperfusion, the neurological function was evaluated and scored.At day 7 of reperfusion, the rats were sacrificed, and spinal cord tissues were obtained for determination of HO-1 expression (by Western blot) and HO-1 mRNA expression (using real-time PCR). Results Compared with group S, the neurological function score was significantly decreased at each time point of reperfusion, and the expression of HO-1 mRNA and protein in spinal cord tissues was up-regulated in the other groups.Compared with group I/R, the neurological function score was significantly increased at each time point of reperfusion, and the expression of HO-1 mRNA and protein in spinal cord tissues was up-regulated in BMSC and HP groups, and no significant change was found in group PBS in the parameters mentioned above.Compared with group BMSC, the neurological function score was significantly increased at each time point of reperfusion, and the expression of HO-1 mRNA and protein in spinal cord tissues was up-regulated in group HP. Conclusion The mechanism by which hypoxic preconditioning enhances protection of spinal cord by BMSC transplantation may be related to up-regulation of HO-1 expression in rats. Key words: Cell hypoxia; Ischemic preconditioning; Mesenchymal stem cell transplantation; Reperfusion injury; Spinal cord; Heme oxygenase-1