第3~12周人胚肝甲胎蛋白及细胞角蛋白19和c-Met的时空表达

背景：现阶段对于肝干细胞在胚胎肝发育过程中的形态学特征、时空分布、分化过程的报道很少。目的：以甲胎蛋白、细胞角蛋白19、c-Met作为标志物，观察其在不同发育阶段肝干细胞中的时空分布。设计、时间及地点：细胞学体外观察，于2005-06/2006-12在潍坊医学院中心实验室完成。材料：40例胚胎标本取自3个月内的流产胎儿，由潍坊医学院附属医院提供。方法：收集流产胚胎，30 min内制作切片，显微镜下根据胚层形成情况、体节数目及器官发育状况确定胎龄。选择胎龄第3~12周的标本切片，每隔10张抽出1张切片，行免疫组织化学染色。主要观察指标：第3~12周胚胎肝干细胞甲胎蛋白、c-Met、细胞角蛋白19的表达。结果：第3~5周甲胎蛋白、c-Met呈阳性反应，提示为肝干细胞；第10~12周甲胎蛋白、c-Met阳性细胞主要分布于汇管区周围，提示此时肝干细胞主要局限于汇管区周围的肝索内，与成年肝中卵圆细胞(成年肝干细胞)的分布一致。细胞角蛋白19阳性反应在第7周时开始出现；第10~11周时细胞角蛋白19阳性反应主要位于汇管区附近的肝索细胞和胆管板细胞及胆管上皮细胞；第12周时细胞角蛋白19阳性信号仅见于胆管板和胆管上皮细胞。此时所有的胆管板细胞及胆管上皮细胞均呈甲胎蛋白、c-Met和细胞角蛋白19阳性。结论：细胞角蛋白19在肝干细胞中无表达，仅在胆管上皮细胞及其祖细胞中有表达，可能不适合作为肝干细胞的标志物。所有的胆管板及胆管上皮细胞均呈甲胎蛋白、c-Met、细胞角蛋白19阳性反应，推测甲胎蛋白+/c-Met+/细胞角蛋白19+的细胞可能为胆管祖细胞。

Temporal spatial expression of alpha fetoprotein, cytokeratin-19 and c-Met during the process of human embryonic liver development of 3-12 weeks

BACKGROUND: There are few studies concerning morphological characteristics, space-time distribution and differentiation of hepatic stem cells during embryo liver development. OBJECTIVE: To understand the action of alpha fetoprotein, cytokeratin-19 (CK19) and c-Met in the liver through observing the expression of them. DESIGN, TIME AND SETTING: The in vitro cytological observational study was performed at the Central Laboratory of Weifang Medical College from June 2005 to December 2006. MATERIALS: A total of 40 embryo samples were obtained from 3-month aborted fetus, which were supplied by Hospital Affiliated to Weifang Medical College. METHODS: Aborted embryo was collected and made into sections within 30 minutes. Fetal age was defined according to embryonic layer formation, somite number and organ development under a microscope. Sample sections with fetal age of 3-12 weeks were selected. One was collected from every eleven sections and underwent immunohistochemical staining. MAIN OUTCOME MEASURES: Expression of alpha fetoprotein, CK19 and c-Met was measured in embryo hepatic stem cells aged 3-12 weeks. RESULTS: At 3-5 weeks, samples were positive for alpha fetoprotein and c-Met, which were indicated as hepatic stem cells. At 10-12 weeks, alpha fetoprotein- and c-Met-positive cells were mainly distributed surrounding the header, which suggested that hepatic stem cells were mainly located at hepatic cord of the header. This had similar distribution as adult hepatic oval cells (adult hepatic stem cells). CK19-positive reaction was found at week 7, and mainly at hepatic cord cells, bile duct sheet cells and bile duct epithelial cells at 10-11 weeks. CK19-positive reaction was only seen at the bile duct sheet and bile duct epithelial cells at week 12. At this time, all bile duct sheet cells and bile duct epithelial cells were positive for alpha fetoprotein, c-Met and CK19. CONCLUSION: CK19-positive reaction was not found in hepatic stem cells, but only detected in bile duct epithelial cells and progenitor cells. CK19 may be not fit for a marker of hepatic stem cells. All bile duct sheet and bile duct epithelial cells are positive for alpha fetoprotein, c-Met and CK19. It is assumed that alpha fetoprotein+/c-Met+/CK19+ may be bile duct progenitor cells.