腺病毒介导的EGFP基因在大鼠骨髓间质干细胞中的高效表达

Adenoviral-mediated high efficiency expression of enhanced green fluorescence protein gene in ex vivo expanded rat mesenchymal stem cells

目的 :研究复制缺陷型腺病毒感染骨髓间质干细胞介导外源基因表达的可行性及感染效率。方法 :在体外低密度扩增大鼠骨髓间质干细胞 (rMSC) ,用细菌同源重组法构建巨细胞病毒 (CMV)驱动的增强型绿色荧光蛋白 (EGFP)报告基因腺病毒载体 (pAd -EGFP) ,用 2 93包装细胞制备腺病毒 ,用EGFP重组腺病毒感染rMSC ,观察重组腺病毒携带基因在MSC中的感染和表达情况 ,用细胞计数法和流式细胞仪分析感染效率。用血清撤离加入 β -巯基乙醇诱导Ad -EGFP感染的rMSC向神经样细胞定向分化。结果 :Ad -EGFP可高效感染rMSC ,感染率为 (3 6±2 ) % ,而脂质体法转染质粒pTrack -GFP在rMSC转染效率非常低且不易成功 ;Ad -EGFP感染后的不同扩增代数的rMSC在受到 β -巯基乙醇的诱导分化后在荧光显微镜下呈典型的突触形式。免疫组化鉴定发现这些诱导细胞表达神经元特异烯醇化酶 (NSE) ,表明腺病毒介导外源基因转染后rMSC仍具有分化为神经样细胞的潜能。结论 :腺病毒载体具有较高的介导外源基因表达于rMSC的效率 。

AIM: To investigate the feasibility and infection efficiency of MSCs with replication-deficient adenovirus containing delivered gene, and whether enhanced green fluorescence protein (EGFP) gene track the change during rMSCs differentiating neuron-like cells. METHODS: Rat marrow mesenchymal stem cells (rMSCs) were expanded in low density in vitro . Under the control of CMV promoter, pAd-EGFP-Vector was constructed by homologous recombination in E.coil BJ 5183, and the recombinant virus was produced in HEK 293 packaging cell line. rMSCs infected with Ad-EGFP were observed and analyzed with fluorescence microscope. Infection efficiency was assessed by microscopical scoring and flow cytometrics. After withdrawing serum and exposure to β-mercaptoethanol medium, rMSCs infected with Ad-EGFP was induced to differentiate into neuron-like cells. As a control, the plasmid of pTrack-EGFP also was transfected into rMSCs to evaluate transfection efficiency.RESULTS: The results showed that Adenovirus vector (AdVec) delivered EGFP gene with high efficiency to marrow mesenchymal stem cells. Gene expression analysis showed that 36%±2 % of rMSCs infected with recombinant adenovirus expressed the transgene of EGFP at high levels. However, the transfection of plasmid pTrack-EGFP using routine method of lipofectamin mixed with plasmid DNA (pTrack-EGFP) was not easily successful and the transfection efficiency was much lower. rMSCs infected with Ad-EGFP in different passage could differentiate into typical morphology alike neural cells after withdrawing serum and exposure to β-mercaptoethanol medium. Immuno-staining with neuron-specific enolase (NSE), a neuronal marker, was strong positive, which suggested that rMSCs infected with Ad-EGFP had the potential to differentiate into neurons or neuron-like cells. CONCLUSION: The AdVec system can deliver target gene into MSCs and EGFP gene carried by AdVec can track the change during rMSCs differentiating into neuron-like cells.