Angiogenic potency of bone marrow stromal cells improved by ex vivo hypoxia prestimulation

To study the angiogenic potency of hypoxia-prestimulated bone marrow stromal cells (BMSCs) when transplanted into acute myocardial infarction models of rats. BMSCs were cultured under hypoxia condition for 24 h. Their expression of VEGF was investigated. The rat acute myocardial infarction models were made by coronary artery ligation and divided into 3 groups at random. In normoxia group, twice-passaged BMSCs were labeled with Bromodeoxyuridine (BrdU) and then implanted into the infarction regions and ischemic border of the recipients in 4 weeks. The rats in hypoxia group were implanted with hypoxia-prestimulated BMSCs. In control group, the model rats received only DMEM medium injection. Six-weeks after AMI, the infarction regions were examined to identify the angiogenesis and the expression of the VEGF. Our results showed that viable cells labeled with BrdU could be identified in the host hearts. The infarction regions in normoxia and hypoxia groups had a greater capillary density and increased VEGF expression than the regions in control group. The capillary density and VEGF expression in hypoxia group were higher than in normoxia group. It is concluded that the enhanced expression of VEGF in BMSCs could be induced by ex vivo hypoxia stimulation. BMSCs implantation promoted the angiogenesis in myocardial infarction tissue via supplying exogenic VEGF. Angiogenic potency of bone marrow stromal cells was improved by ex vivo hypoxia prestimulation though the enhanced VEGF expression.