小鼠胎肝间充质干细胞在缺血脑组织中迁移机制的研究

THE STUDY OF THE MIGRATION MECHANISM OF MURINE FLMSCS IN ISCHEMIC INJURED BRAIN

目的:探讨小鼠胎肝间充质干细胞(flMSC_S)在缺血脑组织中迁移的机制。方法:分离和培养小鼠flMSC_S,制备小鼠脑缺血再灌注模型,RT-PCR方法检测小鼠flMSC_S表达的趋化因子受体及其唯一配体基质细胞来源因子1α(SDF-1α)在缺血损伤脑组织中的mRNA表达;Westem blot检测SDF-1α蛋白在缺血损伤脑组织中的表达;免疫组织化学检测SDF-1α在缺血损伤脑组织中的表达和分布;Boyden chamber法进行SDF-1α诱导flMSC_S迁移的体外实验。结果:flMSC_S经RT-PCR检测表达趋化因子受体CR1,CR3,CXCR1,CXCR2,CXCR3,CXCR4。脑缺血损伤侧脑组织SDF-1αmRNA表达显著增高,与正常脑组织SDF-1αmRNA比,具有显著差异(P<0.01)。Western blot检测显示缺血侧脑组织SDF-1α蛋白表达量在12、24、48 h分别为0.35±0.05,0.88±0.04,0.74±0.07,与正常脑组织SDF-1α蛋白(0.22±0.04)比,差异有显著性(P<0.01)。免疫组织化学检测显示,缺血损伤后24 h,缺血侧脑皮质,海马等缺血边缘区SDF-1α表达显著增高,缺血对侧及正常脑组织未见明显SDF-1α表达。体外迁移实验显示SDF-1α体外可以趋化flMSC_S发生迁移,CXCR4阻断抗体可以阻断SDF-1α诱导flMSC_S发生的迁移。结论:SDF-1α可以诱导flMSC_S发生迁移,趋化因子受体CXCR4及其配体SDF-1α的相互作用是flMSC_S在缺血损伤脑组织中迁移的机制之一。

Aim： To investigate the migration mechanism of murine flMSCs in ischemic injured brain. Methods： flMSCs were isolated and cultured in vitro. BALB/c mice were adopted to build model of cerebral isehemia. Chemokine receptor mRNA in flMSCs and SDF-1α （the only ligand for CXCR4） nRNA in injured brains were determined by RT-PCR. Expression and distribution of SDF-1α protein was detected by Westem blot and irnmunohistochemistry. Migration of flMSCs induced by SDF-1α in vitro was detected by Boyden chamber assay. Results： Murine flMSCs expressed a restricted set of chemoklne receptors including CR1, CR3, CXCR1, CXCR2, CXCR3, CXCR4. Expression of SDF-1α mRNA was significantly increased in ischemic injured brain compared with those in normal brain（ P 〈 0.01 ）. Protein level of SDF-1α in ischemie injured brain（ 12 h： 0.35±0.05,24 h： 0.35 ±0.05,48 h： 0.88 ± 0.04） was statistically up-regulated compared with those in normal braim（0.74 ± 0.07, P 〈 0.01 ） . Expression of SDF-1α was significantly increased in peri-ischemia area such as cerebral cortex and hippocampus 24 h after ischemie injury. Expression of SDF-1α Wash＇ t detected in contralateral hemisphere and normal brain. Migration of flMSCs could be induced by SDF-1α and blocked by CXCR4 antibody in vitro. Conclusion： Interaction between CXCR4 and SDF-1α is one of the mechanisms in directing murine flMSCs migration in ischemic injured brain.