核因子相关因子2参与间充质干细胞调节大鼠梗死心肌氧化应激作用

Nuclear factor erythroid 2-related factor 2 contributes to oxidative stress regulated by mesenchymal stem cells in rat with myocardial infarction

目的探讨间充质干细胞(MSC)移植对梗死心肌组织氧化应激反应的调节作用及其作用机制。方法清洁级雄性Spragye-Dawley(SD)大鼠60只,建立心肌梗死大鼠模型,按随机数字表随机分入对照组、MSC移植组和MSC移植+血红素氧化酶1(HO-1)抑制剂组,每组20只。以密度梯度离心并贴壁培养获得骨髓源MSC,于心肌梗死模型建立后经心肌局部多点注射MSC悬液。在细胞移植后不同时间点测定心肌梗死和梗死交界区组织的超氧化物歧化酶(SOD)、还原型谷胱甘肽(GSH)和丙二醛(MDA)水平,采用Western印迹法检测核因子相关因子(Nrf)2和HO-1蛋白表达。结果 3组间心肌梗死前的心肌组织中SOD、GSH和MDA水平的差异均无统计学意义(P值均>0.05)。3组在细胞移植后24h、72h、7d的心肌组织中SOD和GSH水平均显著低于同组心肌梗死前(P值均<0.05),以72h时最低,以后逐渐回升,至细胞移植14d时与心肌梗死前的差异无统计学意义(P值均>0.05);同时,MDA水平均显著高于同组心肌梗死前(P值均<0.05),以72h时最高,以后逐渐下降,至细胞移植14d时与心肌梗死前的差异无统计学意义(P值均>0.05)。MSC移植组在细胞移植24、72h的心肌组织中SOD和GSH水平均显著高于对照组和MSC移植+HO-1抑制剂组同时间点(P值均<0.05),而MDA水平显著降低(P值均<0.05);MSC移植+HO-1抑制剂组与对照组间的差异无统计学意义(P值均>0.05)。对照组中,细胞移植后24和72h时心肌梗死组织Nrf2和HO-1的表达水平均较心肌梗死前有升高趋势,但差异无统计学意义(P值均>0.05);而MSC移植组细胞移植后24和72h时Nrf2和HO-1蛋白表达水平均显著高于同组心肌梗死前和对照组同时间点(P值均<0.05),且细胞移植后7d时的HO-1水平仍显著高于对照组同时间点(P<0.05)。结论心肌梗死后移植MSC可能通过促进局部Nrf2及其下游抗氧化酶靶基因HO-1蛋白表达而调节梗死心肌的氧化应激反应,进而减轻氧化应激诱导的心肌损伤。

Objective To explore the effect and mechanism of mesenchymal stem cell （MSC~ transplantation on oxidative stress in rat models with myocardial infarction. Methods Myocardial infarction was induced in 60 healthy male Spragye-Dawley rats. According to random digits table, the rats were divided into three groups： control group, MSC group and MSC ＋ erythroid 2-related factor 2 （Nrf2） group （n = 20~. Bone marrow derived MSCs were obtained with density gradient centrifugation and adherent culture, and injected into infracted myocardium. Superoxide dismutase （SOD）, glutathione （GSH） and malonaldehyde （MDA） in plasma, in#acted myocardium and junctional zone were measured after MSC transplantation. The expression of Nrf2 and heme oxygenase-1 （HO-1） was detected with Western blotting analysis. Results There were no significant differences in the baseline levels of SOD, GSH or MDA between groups （all P〈0.05）. Compared with baseline values, the levels of SOD and GSH were significantly decreased in myocardium of all rats at 24 h, 72 h and 7 d after MSC transplantation, while MDA was increased significantly （all P〈0.05）. The levels of SOD, GSH and MDA reached the peak 72 h after MSC transplantation and returned to the baseline 14 d after MSC transplantation. Compared with those in the control group and MSC＋ Nrf2 group, the levels of SOD and GSH were significantly increased and MDA was decreased in MSC group at 24 h and 72 h after cell transplantation （all P〈O. 05）. But there were no significant differences in the levels of SOD, GSH or MDA between control group and MSC ＋ Nrf2 group （all P〉 0.05）. In control group, the expression of Nrf2 and He-1 in myocardium at 24 h and 72 h after MSC transplantation was increased, but no difference was found as compared with that before myocardial infarction （all P〉0.05）. In MSC group, the expression of Nrf2 and He-1 at 24 h and 72 h after MSC transplantation was significantly higher than that before myocardial infarction （all P〈0. 05）. The expression of Nrf2 and He-1 in MSC group at 24 h and 72 h after MSC transplantation was significantly higher than that in control group （all P〈0. 05） ; so was He-1 at 7 d after MSC transplantation between the two groups （P〈0.05）. Conclusion MSC may regulate oxidative stress after myocardial infarction through promoting Nrf2 and its downstream target gene such as He-1, further alleviating myocardial injury induced by oxidative stress.