大鼠肝卵圆细胞体外分离培养和向肝细胞的诱导分化

背景:肝卵圆细胞具有强大的自我更新复制及在一定的条件下克隆增殖并分化为成熟肝细胞的能力,既可在体外用丁构建生物人工肝的生物材料部分,也可以进行体内移植,还可为组织工程提供种子细胞,在治疗肝病方面具有广阔的前景.目的:建立成年Wistar大鼠肝卵圆细胞增殖模型,行体外分离和培养肝卵圆细胞,探索体外诱导其分化为肝细胞的可行性.设计:观察性实验.单位:南方医科大学南方医院消化病研究所.材料:实验于2003-12/2006-02在南方医院消化病研究所实验室完成.36只三四个月龄,体质量约150～200 g的健康雄性Wistar大鼠,南方医科大学实验动物中心提供.方法;将雄性Wistar大鼠行乙硫氨酸灌喂和2/3肝切除.采用两步法灌注和Percoll密度梯度离心法分离纯化肝卵圆细胞,行体外培养并添加肝细胞生长因子、肿瘤抑制因子M和成纤维细胞生长因子4诱导其分化.主要观察指标:肝卵圆细胞和诱导分化细胞的鉴定.结果:①体外分离每只模型大鼠肝脏中可获得约1.34×108L-1肝卵圆细胞,细胞为圆形、椭圆形或多角形,约为正常肝细胞1/6～1/3,核质比例大,2周后可呈克隆样增殖生长.②激光扫描共聚焦显微镜显示,肝卵圆细胞胞浆和胞膜表达干细胞标志Thy-1及C-kit.③免疫细胞化学检测其原始细胞标志甲胎蛋白呈阳性表达.肝卵圆细胞能稳定传代,肝卵圆细胞在肝细胞生长因子、肿瘤抑制因子M和成纤维细胞生长因子4刺激下细胞形态逐渐发生改变,细胞伸展且体积渐增大,贴壁能力减弱,诱导14d后分化细胞Alb明显阳性表达,且随着诱导时间的延长,其阳性率逐渐升高.④细胞化学方法显示诱导分化细胞胞浆G-6-P染色呈棕黑色沉淀,PAS染色呈红色颗粒.结论:乙硫氨酸灌喂联合2/3肝切除可复制成年Wistar大鼠的肝卵圆细胞增殖模型.胶原酶灌注结合Percoll密度梯度离心分离纯化可获得满意的肝卵圆细胞.大鼠肝卵圆细胞能在体外传代培养,在一定条件刺激下可诱导分化为肝细胞.

Isolation, culture and differentiation of rat hepatic oval cells into hepatocytes in vitro

BACKGROUND: Hepatic oval cells (HOCs) possess the potential of self-renewal, replication, and clone, proliferation and differentiation into mature hepatocytes under a certain condition. HOCs can be used as biomaterial for constructing biological artificial liver in vitro, employed for in vivo transplantation, as well as for tissue engineering as seed cells. HOCs can be widely used for improving clinical treatment of liver diseases. OBJECTIVE: To establish adult Wistar rat models of HOC proliferation, to perform/n vitro isolation and culture of HOCs, and to study the possibility of induction and differentiation of HOCs into hepatucytes. DESIGN: Observational study. SETTING: Institute of Gastroenterology, Nanfang Hospital, Southern Medical University. MATERIALS: Experiments were performed at the Laboratory of Institute of Gastroenterology of Nanfang Hospital from December 2003 to February 2006. Thirty-six healthy male Wistar rats aged 3-4 months (150-200 g) were provided by Experimental Animal Center of Southern Medical University. METHODS: Male Wistar rats were orally fed with ethionine received two-thirds partial hepatectomy (2/3 PH). HOCs were harvested and purified by two-steps perfusion and Percoll density gradient centrifugation, and then cultured in vitro and induced with hepatocyte growth factor (HGF), oncostatin M (OSM) and fibroblast growth factor-4 (FGF4). MAIN OUTCOME MEASURES: Identification and differentiation of HOCs. RESULTS: The concentration of HOCs was about 1.34×108 L-1 in each rat model after in vitro isolation. These cells were round, oval or polygon, about 1/6 1/3 the size of normal hepatocytes. The nucleus-cytoplasm ratio was relatively large. After 2 weeks, clone-like proliferation of HOCs could be observed. Laser scanning confocal microscopy indicated positive expression of stem cells markers Thy-1 and C-kit in cytoplasm and membrane of HOCs. Immunocytochemistry demonstrated positive stem cells marker alpha fetoprotein (AFP) in cytoplasm of HOCs. HOCs can stably passage and its shape gradually changed after inducing with HGF, OSM and FGF4. HOC volume became larger and HOCs lost their ability of sticking to the wall of culture flask. Apparent positive stain of cytoplasm albumin (Alb) was detected 14 days after induction, and the positive ratio increased along with the extension of inducing duration. Results of cytochemistry indicated a brown or black deposit after glucose-6-phosphotase (G-6-P) staining and red particles after periodic acid-Schiff (PAS) staining. CONCLUSION: Adult Wistar rat models of HOC proliferation are replicated by ethionine feeding combined with 2/3 PH. HOCs can be obtained through collagenase perfusion and Percoll density gradient centrifugation. Rat HOCs can be passaged and cultured in vitro. Under a certain condition, HOCs can be induced and differentiated into hepatocytes.