摘要目的 建立能稳定分泌人内皮抑素(hES)的基因工程细胞系,观察内皮抑素(ES)蛋白和hES的表达.方法 以hES重组质粒pcDNA3.0(pcDNA3-Endo)为模板,通过聚合酶链反应(PCR)扩增获得hES基因片段,且在基因前加信号肽序列,将其定向插入真核表达载体绿色荧光蛋白(pEGFP-N1)质粒中,获得重组质粒pEGFP-N1-Es;利用阳离子脂质体介导将其转染到人胚胎肾细胞(HeK-293)细胞中,G418筛选后得到阳性克隆hES/293,采用蛋白免疫印迹(Western blot)法检测转染细胞上清中ES蛋白的表达;用海澡酸钠壳聚糖(ACA)微囊包裹hES/293细胞,分别收集培养3、7、21、35 d的ACA微囊化hES/293细胞的培养上清液,Western blot法检测包裹后培养液上清中hES的表达.结果 重组质粒pEGFP-N1-ES经限制性核对内切酶HindⅢ和限制性核酸内切酶BamH Ⅰ双酶切得到4700碱基对(bp)和600 bp 2条带;PCR扩增出600 bp条带;测序结果与NCBI上序列比对软件(BLAST)比对,同源性达到100%.pEGFP-N1-ES转染HeK-293细胞,经G418筛选后获得阳性克隆,选取筛选的10株单克隆细胞培养上清液进行Western blot分析,在相对分子质量为20×103处出现蛋白条带.在ACA微囊内hES/293细胞随着培养时间的延长,细胞团逐渐长大,充满整个囊内空间.培养3、7、21、35 d时,在相对分子质量为20×103处出现蛋白条带.结论 重组pEGFP-N1-ES真核表达载体构建正确,转染HeK-293细胞后可有效的表达hES蛋白,并能分泌到细胞外;微囊化hES/293细胞产生的ES蛋白可以自由扩散出微囊膜外,并呈持续性表达.

abstractsObjective To microencapsulate a genetically engineered cell line which stably secrete human endostatin (hES). Methods Endostatin gene fragment was amplified from plasmid pcDNA3-Endo by polymerase chain reaction, and inserted into mammalian eukaryotic expression vector pEGFP-N1, resulting into recombinant plasmid pEGFP-N1-ES. Hek-293 cells were transfected with pEGFP-N1-ES via cationic liposome and selected by G418, and were measured by Western blot for endostatin protein expression. The hES/293 cells were further entrapped by alginate-chitosan-alginate (ACA) microcapsules, and the expression of endostatin in the supernatant of cultured hES/293 cell microcapsules was examined by western blot at different time points. Results Recombinant plasmid pEGFP-N1-endostatin was digested by HindⅢ and BamHI, and resulted into 2 DNA fragments of 7 kb and 600 bp. The sequence of the 600 bp fragment was identical to human endostatin. Western blot of the supernatant of cultured hES/293 cells or hES/293 cell microcapsules detected a positive band with the relative molecular mass of 20 × 103. Conclusion The hES protein was expressed in HeK-293 transfected with pEGFP-N1-endostatin, and secreted to the culture medium, and can freely diffused outside the micro-capsule.