第3～5周人胚肝的细胞特征和生长因子及受体表达的研究

The Characteristics of Hepatic Stem Cells and the Expression of Growth Factor and Their Receptors in the Early Embryonic Human Liver

用第 3～ 5周人胚 ,石蜡切片 ,免疫组化染色 ,光镜下观察人胚肝的细胞特征和HGF、IGF -I、TGFβ1等生长因子及其受体、PCNA、AFP、CK19等的表达。结果发现第 3周末肝芽形成 ,第 4周肝索开始形成 ,第 3～ 4周人胚肝由同一类具有幼稚细胞形态学特征的细胞构成。这些细胞为AFP、c Met阳性反应。第 5周时肝索细胞的数量增加 ,开始出现PCNA的表达 ,仍仅为同一类细胞。第 5周肝索细胞呈IGF -I、TGFβ1及其受体免疫反应阳性 ,HGF阴性 ,其周围的心肌细胞及间充质细胞为HGF阳性反应。结果提示第 3～ 5周 ,组成肝芽和肝索的细胞属于肝干细胞 ,其形态和因子表达的差异说明肝干细胞可能处于不同的发育阶段 ,AFP、c Met可以作为此阶段肝干细胞的标记物 ,HGF、IGF -I、TGFβ1及其受体可能参与对早期人胚肝发育的调节。

To study the morphological characteristics of hepatic st em cells and the expression of HGF, IGF-I, TGFβ1 and their receptors in human e mbryonic livers at 3-5 weeks of gestation. The SABC immunohistochemical met h od with HE counterstaining was employed. We found that the hepatic bud formed a t the end of the 3 rd week. At the 4 th week, the cells of hepatic bud migrated into the septum transversum mesenchyme and formed the hepatic cords. The hepatic cells at 3-4 weeks displayed the typical characteristics of immatur e cells: small size, a round or ovoid nucleus with dark color, scant cytoplasm w ith slight blue and a high ratio of nuclei/cytoplasm. They were positive for α -Fetoprotein (AFP), c-Met and negative for cytokertin 19 (CK19), and prolifera ting cell nuclear antigen (PCNA). At the 5 th week, compared to those at t he 4 th week, the number of cells within the hepatic cords increased. But the cells at the 5 th week were homogeneous and displayed the typical cha racteristic of immature cells. Those cells began to express PCNA at the 5 th week. The hepatic cells at the 5 th week were positive for insulin-li ke growth factor I (IGF-I), transforming growth factor β1 ( TGFβ1)and their r eceptors, and were negative for hepatocyte growth factor ( HGF), while HGF wer e positive in the cardiac cells and septum transversum mesenchyme. The results indicated that the cells of hepatic bud and cords were the hepatic stem cells. The difference of morphology and proteins expression at 3-5 weeks of gestation inferred that those stem cells belong to different developmental stage. AFP and c-Met were the markers of hepatic stem cells at the early stage of human embry o. HGF, IGF-I, TGFβ1 and their receptors may involve in regulating the develo pment of early embryonic human liver.