目的  探讨低氧预处理对老年人骨髓间充质干细胞（hBMSCs）促血管新生能力的影响，为改善老年患者自体干细胞移植治疗缺血性心肌损伤疗效提供支持。   方法  老年hBMSCs经过低氧预处理后，倒置相差显微镜下摄片观察细胞形态，流式细胞术检测细胞表面标志物，并进行成骨、成脂诱导分化检测其分化潜能。随后收集青年hBMSCs常氧培养基（norCM），老年hBMSCs常氧和低氧培养基（hypoCM），分别为norCM-young、norCM-old和hypoCM-old 3组条件培养基，未加干细胞的等体积培养基为阴性对照（control）组。各组条件培养基分别处理人脐静脉内皮细胞（HUVECs），用CCK-8法检测细胞存活率，用管状结构形成实验检测体外血管新生能力。BCA法检测各组条件培养基总蛋白含量，Western blotting技术检测细胞中及条件培养基中低氧诱导因子1α(HIF-1α)含量。   结果  低氧预处理对老年hBMSCs形态、表面标志物及分化潜能影响不显著（P>0.05，n≥3）。HypoCM-old组与norCM-old组相比，低氧-复氧培养条件下HUVECs的存活率显著提高（P<0.05，n=5）， HUVECs细胞管状结构形成能力也显著提高（P<0.01，n=5）。HypoCM-old组总蛋白量显著高于norCM-old组（P<0.05，n=3），hypoCM-old组 hBMSCs中HIF-1α表达量显著高于norCM-old 组（P<0.05，n=3），同时hypoCM-old组培养基中HIF-1α的含量显著高于norCM-old组（P<0.01，n=3）。   结论  低氧预处理的老年hBMSCs通过旁分泌促进体外HUVECs存活和管状结构的形成，而其促进作用与HIF-1α的活化相关。 

Objective  To investigate the effect of hypoxic pretreatment on the angiogenesis of aged human bone marrow mesenchymal stem cells (hBMSCs),  so to provide experimental support for more effective autologous stem cell transplantation therapy in aged patients with ischemic myocardial injury.    Methods  The aged hBMSCs were cultured in a hypoxic incubator, and then the cell morphology  was observed under inverted phase-contrast microscope, the surface markers were detected by flow cytometry, and the differentiation potential was detected by osteogenic and adipogenic differentiation. Subsequently, the conditioned medium(CM) of young hBMSCs under normoxic culture (norCM), the conditioned media of aged hBMSCs under normoxic and hypoxic culture(hypoCM) were collected respectively. They were named as norCM-young, norCM-old and hypoCM-old. The equal volume of medium, which was not treated with stem cells, was set as control group. Human umbilical vein endothelial cells (HUVECs) were treated with 4 conditioned media, the cell survival rate was detected by CCK-8 assay, and the tube formation experiment was used to detect the angiogenesis ability in vitro. The BCA method  was used to detect the total protein concentration of the conditioned medium of each group, and the Western blotting was used to detect  the expression of hypoxia inducible factor-1α (HIF-1α) in the cells and the conditioned media.    Results  There was not significant effect of hypoxic pretreatment on the morphology, surface markers and differentiation ability of aged hBMSCs (P>0.05. n≥3). Compared with the norCM-old group, hypoCM-old group significantly improved the survival of HUVECs under hypoxia-reoxygenation condition (P<0.05, n=5), and the tube formation ability of it (P<0.01, n=5). The total protein concentration of hypoCM-old group was significantly higher than that of norCM-old group (P<0.05, n=3). The expression of HIF-1α in hBMSCs of hypo-old group was significantly higher than that of nor-old group (P<0.05,n=3), while the content of HIF-1α in conditioned medium of hypoCM-old group was significantly higher than that in norCM-old group (P<0.01,n=3).    Conclusion  The aged hBMSCs pretreated with hypoxia can promote the survival and tube formation of HUVECs through paracrine in vitro, which is HIF-1α-related.