School of Stomatology, Tongji University, Shanghai, China.
Cell Prolif. 2011 Jun;44(3):234-43. doi: 10.1111/j.1365-2184.2011.00747.x.
Hypoxia-inducible factor 1α (HIF-1α) is a pivotal regulator of hypoxic and ischaemic vascular responses that drives transcriptional activation of hundreds of genes involved in vascular reactivity, angiogenesis and arteriogenesis. Previous reports based on gene knockout technology have demonstrated that HIF-1α can promote osteogenesis. However, this protein is easily degraded in a normoxic state, which makes in vitro studies of HIF-1α-induced mesenchymal stem cell (MSC) osteogenesis difficult. For better understanding of HIF-1α promoting osteogenesis, the role of HIF-1α-induced MSC osteogenesis in the normoxic state has been investigated here.
HIF-1α was made to overexpress using a lentiviral vector, and its effects on bone marrow-derived mesenchymal stem cell (BMSC) osteogenesis were investigated. Real-time quantitative and western blotting (to assess expression levels of angiogenic and osteogenic related genes regulated by Lenti-HIF-1α), alkaline phosphatase (ALP) and alizarin red-S staining analyses, were performed.
In HIF-1α gene-transfected BMSCs, expression levels of angiogenic, cartilaginous and osteogenic genes were all increased significantly compared to Lenti LacZ-transfected cells, at both mRNA and protein levels. ALP activity and alizarin red-S staining were significantly enhanced in HIF-1α transduced cells compared to control cells, on day 21.
These results indicate that Lenti-HIF-1α can induce BMSC overexpression levels of angiogenic and osteogenic genes in vitro in the normoxic state. Further study will be focused on whether HIF-1α can also improve bone repair in vivo.
缺氧诱导因子 1α（HIF-1α）是调节缺氧和缺血性血管反应的关键调节因子，可驱动涉及血管反应性、血管生成和动脉生成的数百个基因的转录激活。基于基因敲除技术的先前报告表明，HIF-1α 可促进成骨作用。然而，这种蛋白质在常氧状态下很容易降解，这使得体外研究 HIF-1α 诱导间充质干细胞（MSC）成骨作用变得困难。为了更好地理解 HIF-1α 促进成骨作用，本研究探讨了 HIF-1α 诱导的 MSC 成骨作用在常氧状态下的作用。
使用慢病毒载体使 HIF-1α 过表达，并研究其对骨髓来源的间充质干细胞（BMSC）成骨作用的影响。进行实时定量和 Western 印迹（评估受 Lenti-HIF-1α 调节的血管生成和成骨相关基因的表达水平）、碱性磷酸酶（ALP）和茜素红 S 染色分析。
在 HIF-1α 基因转染的 BMSCs 中，与 Lenti LacZ 转染的细胞相比，在 mRNA 和蛋白质水平上，血管生成、软骨和成骨基因的表达水平均显著增加。与对照细胞相比，HIF-1α 转导细胞的 ALP 活性和茜素红 S 染色在第 21 天显著增强。
这些结果表明，Lenti-HIF-1α 可在常氧状态下体外诱导 BMSC 过表达血管生成和成骨基因。进一步的研究将集中在 HIF-1α 是否也能改善体内骨修复。
