低氧诱导因子过表达对人外周血内皮祖细胞分化影响的体外研究

为了研究低氧诱导因子（hypoxia inducible factor-1alpha,HIF-1α）在体外对人外周血内皮祖细胞（endothelial progenitor cells,EPC）向血管内皮细胞（endothelial cells,EC）分化的影响,用密度梯度离心法分离人外周血EPC,电穿孔技术转染HIF-1α质粒至EPC,计算转染效率,RT-PCR方法测定HIF-1α、HIF-1β及HIF-1α下游靶基因血管内皮生长因子（vascular endothelial growth factor,VEGF）mRNA在质粒转染前后含量变化,免疫细胞化学方法检测在常氧下HIF-1α蛋白在HIF-1α质粒转染前后不同时点蛋白表达情况,细胞膜表面抗原决定簇流式细胞术测定FITC-CD31^＋EPCs/EC在未转染组、pEGFP空质粒或HIF-1α质粒转染组转染3-10天后的组间差异,光镜下观察转染前后细胞形态及分化程度.结果表明：EPC获得后经电穿孔转染,质粒转染效率约20%;RT-PCR示HIF-1α mRNA在常氧中有表达,并在HIF-1α过表达组合量增加（P＜0.05）;其下游靶基因VEGF在HIF-1α过表达组表达上调（P＜0.05）;HIF-1β表达在各组中无明显差异（P＞0.05）.免疫组织化学显示常氧下HIF-1α蛋白无表达,转染HIF-1α质粒12小时后HIF-1α蛋白表达阳性,转染24小时后蛋白表达阴性.流式细胞仪检测显示电穿孔转染HIF-1α质粒使CD31＋细胞的百分比增加（P＜0.05）.细胞形态学观察显示：未转染及pEGFP空质粒转染组细胞在培养6天后呈集落样散在分布,培养14天后贴壁细胞部分呈梭样;穿孔转染的HIF-1α质粒组细胞于培养6天后集落周边分化出梭样贴壁细胞,培养14天后呈梭样,或铺路石样牢固贴壁.结论：HIF-1α质粒能有效地用于基因干扰治疗,有助于EPC向EC分化,为体内研究奠定了基础,也为进一步体内诱导血管新生、治疗缺血性心脏病提供了更广阔的治疗选择.

Overexpression of Hypoxia Inducible Factor-1alpha (HIF-1α) Promotes the Differentiation of Endothelial Progenitor Cell Ex Vivo

To investigate the influence of HIF-1alpha overexpression on the differentiation of endothelial progenitor cells (EPCs) ex vivo, EPCs were isolated from human peripheral blood by density gradient centrifugation, overexpressed HIF-1alpha was transfected to EPCs by electroporation; HIF1alpha, HIF1beta, vascular endothelial growth factor (VEGF) mRNA level were measured with RT-PCR; HIF-1alpha protein was detected with immunohistochemistry in a time course. CD31(+) cells were measured with flow cytometry. Cell morphology was observed after transfection. The results showed that the transfection efficiency of HIF-1alpha to EPCs was about 20%. HIF-1alpha and its controlled target gene VEGF were markedly induced by HIF-1alpha vector (P < 0.05). HIF1beta had its same level as it before interference (P > 0.05). HIF-1alpha protein was induced by HIF-1alpha transfection after 12 hours but was undetectable at 24 hours. After 7 - 14 days cultured in 21% oxygen pressure, fluorescence-trace experiments revealed that CD31 + EPCs/EC could be generated more efficiently from overexpressed HIF-1alpha than that from pEGFP transfected group (P > 0.05). EPC morphology was observed by light microscopy. HIF-1alpha-transfected cells under normoxia sprouted more rapidly from the EPC colonies than the untransfected cells or cells transfected with an GFP vector, which essentially maintained the original colony formation. HIF-1alpha transfected cells took on an array-like arrangement rather than random dispersal, suggesting that they were in an advanced state of differentiation. It is concluded that the utility of overexpression of HIF-1alpha can induce target genes which have influence on cell differentiation. HIF-1alpha transfection was found to give a prospected way to do the insight research on ischemic treatment in vivo.