RESUMEN
Objective: To investigate the immunohistochemical characterization of hepatic stem cells in the developing human liver, so as to study the origin, differentiation and migration of hepatic stem cells. Methods: H-E staining and immunohistochemical methods were used to observe the expression of hepatic/cholangiocellular differentiation markers (AFP, GST-π, CK7, CK19) and hematopoietic stem cell markers (CD34 and c-kit) in several kinds of cells obtained from thirty 4- to 35-week old fetal liver samples. Results: AFP expression appeared in fetal liver at 4 weeks' gestation, peaked during 16-24 weeks' gestation and decreased gradually afterwards; finally weak signals were only found in some ductal plate cells and a few limiting plate cells. GST-π was detected in hepatic cord cells from the 6th week and in the ductal plate cells from the 8th week; 26 weeks later, only some ductal plate cells and a few limiting plate cells showed positive signals. CK19 expression peaked during 6th to 11th week in hepatic cord cells and decreased gradually afterwards, except for that in the ductal plates. CK7 expression was limited in the ductal plate cells and bile duct cells from the 14th week. CD34 and c-kit were detected at the 8th week in some ductal plate cells and a few mononuclear cells in the hepatic cords/mesenchymal tissue of portal area; after 21 weeks, CD34 and c-kit were found only in ductal plate cells and a few mononuclear cells in the hepatic mesenchymal tissue of portal areas. Conclusion: Fetal hepatocytes at 4-16 weeks' gestation are mainly constituted by hepatic stem cells with bi-potential differentiation capacity. At 16 weeks' gestation, most hepatic cord cells begin to differentiate into hepatocytes and abundant hepatic stem cells remain in the ductal plate (the origin site of Hering canals). It is also indicated that the hematopoietic stem cells may give rise to some hepatic stem cells in embryonic liver. These indirectly support the hypothesis about the location and origin of liver stem cells in "liver valley hypothesis" reported previously.
RESUMEN
Objective:To investigate the immunohistochemical characterization of hepatic stem cells in the developing human liver, so as to study the origin, differentiation and migration of hepatic stem cells. Methods: H-E staining and immunohistochemical methods were used to observe the expression of hepatic/cholangiocellular differentiation markers (AFP,GST-?,CK7,CK19) and hematopoietic stem cell markers (CD34 and c-kit) in several kinds of cells obtained from thirty 4-to 35-week old fetal liver samples. Results: AFP expression appeared in fetal liver at 4 weeks’ gestation,peaked during 16-24 weeks’ gestation and decreased gradually afterwards; finally weak signals were only found in some ductal plate cells and a few limiting plate cells. GST-? was detected in hepatic cord cells from the 6th week and in the ductal plate cells from the 8th week; 26 weeks later, only some ductal plate cells and a few limiting plate cells showed positive signals. CK19 expression peaked during 6th to 11th week in hepatic cord cells and decreased gradually afterwards, except for that in the ductal plates. CK7 expression was limited in the ductal plate cells and bile duct cells from the 14th week. CD34 and c-kit were detected at the 8th week in some ductal plate cells and a few mononuclear cells in the hepatic cords/mesenchymal tissue of portal area; after 21 weeks, CD34 and c-kit were found only in ductal plate cells and a few mononuclear cells in the hepatic mesenchymal tissue of portal areas. Conclusion: Fetal hepatocytes at 4-16 weeks’ gestation are mainly constituted by hepatic stem cells with bi-potential differentiation capacity. At 16 weeks’ gestation, most hepatic cord cells begin to differentiate into hepatocytes and abundant hepatic stem cells remain in the ductal plate (the origin site of Hering canals). It is also indicated that the hematopoietic stem cells may give rise to some hepatic stem cells in embryonic liver. These indirectly support the hypothesis about the location and origin of liver stem cells in “liver valley hypothesis” reported previously.