EXPRESSION OF ALPHA-FETOPROTEIN AND STEM-CELL FACTOR C-KIT SYSTEM IN BILE-DUCT LIGATED YOUNG-RATS/

The existence of a facultative hepatic stem cell compartment in bile d uctules that participates in the renewal process of epithelial cell po pulations in the liver is well documented, The present study was under taken to determine whether the immature bile epithelium responds diffe rently to growth stimulus induced by bile stasis to that seen in the a dult animal. In addition, the possible involvement of the growth facto r/receptor systems associated with early activation of hepatic stem ce lls in bile duct proliferation as also examined, Bile duct ligation wa s used to induce the proliferation of bile epithelial cells, The expre ssion of full-length alpha-feto-protein (AFP) was used as an indicator for activation of the stem cell compartment, AFP was highly and selec tively expressed in small bile ducts 7 days after bile duct Ligation i n immature rats up to 5 weeks of age, Although no significant increase in the expression of stem cell factor (SCF) c-kit, hepatocyte growth factor (HGF), and transforming growth factor-alpha (TGF-alpha) was obs erved 7 days after bile duct ligation in adult rats, the expression of all these growth factors was increased in bile duct ligated rats up t o 5 weeks of age. These results suggest that the bile ductular epithel ium in the young rats responds to bile stasis in a fashion that is phe notypically similar to that seen during early activation of hepatic st em cells in adult liver.