骨髓间质干细胞绿色荧光蛋白基因的转染和克隆化研究

目的 建立能稳定表达绿色荧光蛋白(GFP)并连续传代培养的骨髓间质干细胞(MSCs)株。方法 采用电穿孔法将带有GFP的质粒(pGFP-N1)在不同条件下转染MSCs,经过G418筛选,有限稀释法筛选阳性克隆,荧光显微镜及流式细胞仪检测GFP的表达情况。结果 电穿孔以电容量1050μF、电压260V时效果最好,转染GFP的MSCs能在含有G418的培养基中生长,未转染的骨髓间质干细胞不断死亡。转染24h后即能观察到少量荧光细胞,一个月后大部分荧光细胞呈集落样生长,荧光表达较强,转染率为50％-60％。体外克隆后,能稳定表达至10代,10代后荧光强度明显减弱。结论 GFP基因能在MSCs中进行有效的复制、转录和翻译,并可持续、稳定、高效表达;转染GFP的MSCs能作为研究MSCs的诱导分化及生物细胞工程治疗的载体细胞。     

Epigallocatechin-3-gallate, a green-tea polyphenol, suppresses Rho signaling in TWNT-4 human hepatic stellate cells

Epigallocatechin-3-gallate (EGCG), a major constituent of the polyphenoids in green tea, has been reported to possess a wide range of biologic activities, including antifibrogenesis. Activated hepatic stellate cells (HSCs) are central to hepatic fibrosis, and Rho (a small GTPase)-signaling pathways have been implicated in the activation and proliferation of HSCs. In this study, we investigated the effect of EGCG on Rho-signaling pathways in activated human HSC-derived TWNT-4 cells. EGCG inhibited stress-fiber formation, an indicator of Rho activation, and changed the distribution of alpha-smooth-muscle actin. These inhibitory effects of EGCG were restored by overexpression of constitutively active Rho. A pull-down assay revealed that activated Rho (GTP-bound state) was strongly inhibited by ECGC and accompanied by suppressed phosphorylation of focal adhesion kinase, which is a regulator of Rho-signaling pathways. 5-Bromo-2'-deoxy-uridine incorporation demonstrated that ECGC (100 micromol/L suppressed cell growth by 80%, and terminal deoxynucleotidyl transferase viotin-deoxyruidine triphosphate nick end-labeling revealed that EGCG (100 micromol/L) caused apoptosis in half of the total cells. EGCG also strongly inhibited lysophoaphatidic acid (an activator of Rho) and induced phosphorylation of mitogen-activated protein kinases (Erk1/2, c-jun kinase, and p38). These findings demonstrate that EGCG regulates the structure and growth of HSCs by way of Rho-signaling pathways and suggest that EGCG has therapeutic potential in the setting of liver fibrosis.