血管内皮生长因子对脂肪干细胞成骨分化基因转录水平的调节

Regulation of VEGF on transcription of osteoblastic differentiation gene in adipose stem cells

目的探讨内源性血管内皮生长因子(VEGF)体外诱导脂肪干细胞(ADSCs)分化成骨的转录活化机制。方法脂肪干细胞来自大白鼠腹股沟处脂肪,脂肪内干细胞的分离根据JMGimblel所描述的方法获取,培养鉴定后以BMP-2修饰组作为阳性对照组,提取细胞总RNA,采用RT-PCR法及琼脂糖凝胶电泳方法分析在不同诱导条件下Cbfa1和Osterix表达的差异。结果 BMP-2重组蛋白组的Cbfa1基因转录水平明显高于VEGF诱导组(P<0.01),两者联合应用未见Cbfa1基因转录增强;在以VEGF为诱导因子的ADSCs组,Osterix的mRNA水平明显低于BMP-2组(P<0.01),与Cbfa1基因转录模式不同,VEGF联合BMP-2共同诱导ADSCs成骨分化组,Osterix基因的mRNA水平有增高的趋势。结论通过Cbfa1和Osterix在ADSC成骨分化的不同时间的表达差异,本研究认为在ADSCs诱导成骨分化过程中,Cbfa1启动和激活Osterix转录,仍是主要的信号传导途径。VEGF具有一定的诱导ADSCs成骨分化能力,但其作用主要是非依赖性Cbfal通路调控的Osterix表达。

Objective To investigate the mechanism of endogenous VEGF on inducing adipose stem cells （ADSCs） to differentiate into bone cells in vitro. Methods The adipose stem cells （ADSCs） were harvested from rat inguinal fat. After ADSCs were cultured and identified, the ADSCs modified by BMP-2 were used as a positive control group. The total RNA of ADSCs in different groups was extracted, then RT-PCR and agarose gel electrophoresis were applied to analysis differences of Cbfal and Osterix expression in different groups. Results Cbfal transcription level was significantly higher in recombinant protein BMP-2 modified group than that in VEGF induced group （ P 〈 0. 01 ）. No enhanced Cbfal gene transcription showed in BMP and VEGF combined group; mRNA level of Osterix trascription was significantly lower in VEGF induced group than that in BMP-2 modified group （P 〈 0. O1 ）. However, different from Cbfal transcription mode, there was an increasing trend of Osterix expression in the BMP-2 and VEGF combination induced ADSCs osteogenic differentiation group. Conclusions According to the difference in Cbfal and Osterix expression at different times of ADSCs osteogenic differentiation, we found that during the ADSCs osteogenic differentiation process, the activation of Cbfal and Osterix transcription is also another major signal transduction pathway. VEGF has a certain ability to induce ADSCs into osteogenic differentiation. However, maybe its main effect is to promote ADSCs osteogenic differentiation ability,rather than to start the process of osteogenic differentiation.