Hepatic progenitor cells in chronic hepatitis C: a phenomenon of older age and advanced liver disease.

Hepatic progenitor cells (HPC) appear in a variety of liver diseases. Their occurrence in chronic hepatitis C (CHC) remains unclear, and triggering factors have to be elucidated. The presence of HPC in CHC was examined in relation to histological and virological parameters and patient age. Fifty liver biopsies of HCV-infected patients were examined. The presence of HPC was evaluated by immunohistochemical expression of keratin 7 (K7). Double immunostaining with K7 and cell proliferation marker Ki-67 was undertaken. Ductular reaction at the limiting plate, mean number of isolated progenitor cells (IPC) and isolated ductular structures (IDS) were quantified. The predominant distribution pattern of IPC and IDS and the presence of K7(+) hepatocytes were registered. Relationship between ductular reaction, IPC, IDS, presence of K7(+) hepatocytes, and patient age, hepatitis grade and stage, HCV RNA, and HCV genotype was examined. Prominent ductular reaction and increased numbers of IPC and IDS correlated significantly with older age and severe fibrosis/cirrhosis. The above HPC subtypes were not proliferating. Periportal/periseptal distribution pattern of IPC and IDS and presence of K7(+) hepatocytes were significantly more frequent in advanced hepatitis stages and in patients older than 40 years. Intraparenchymal distribution pattern correlated with younger age, lobular activity, and early fibrosis stage. K7(+) hepatocytes were encountered almost exclusively in the periportal pattern and in the presence of interface hepatitis and were more frequent among HCV genotype-1 patients. HPC activation in CHC is a common but diverse phenomenon closely related to patient age and hepatitis stage.