Differentiation of hamster liver oval cell following Clonorchis sinensis infection

Oval cells which appear in the liver after hepatic injuries are suspected t o be progenitor cells for both hepatocytes and bile duct cells. Oval cell i solated from the livers of the hamsters treated with diethylnitrosamine and 2-acetylaminofluorene and infected with Clonorchis sinensis (CS), cultured for 2 weeks and evaluated for differentiation and plasticity by electron m icroscopy and immunohistochemistry. In the CS-uninfected group, glycogen gr anules and peroxisomes were noted in the cells that were cultured for 2 wee ks. Starting at 1 week postculture, immunoreactivity of the cells to cytoke ratin 19 markedly decreased but that to albumin and alpha-fetoprotein gradu ally increased. This means that oval cells isolated from hamsters that were not infected with CS differentiated toward hepatocyte lineage. However, in the CS-infected group, cultured cells contained numerous rough endoplasmic reticulum and showed immunoreactivity that was generally in reverse to tha t of CS-uninfected group, meaning that cells isolated following CS infectio n were primed by CS and differentiated toward bile duct cell lineage. The r esults of this study suggested that oval cells are indeed bipolar progenito r cells for hepatocytes and bile duct cells and can differentiate toward ei ther lineage depending upon the priming factor.