Epimorphin is involved in differentiation of rat hepatic stem-like cells through cell-cell contact

Epimorphin, a mesenchymal cell surface-associated molecule, is detected on hepatic stellate cells (HSCs) in the liver. Here, we show the involvement of epimorphin in differentiation of rat hepatic stem-like cells (HSLCs) through contact with HSCs. HSLCs, isolated from adult rats, cultured in stellate cell-conditioned medium had no phenotypic and morphological changes, whereas HSLCs co-cultured with HSCs expressed albumin, transferrin, and tyrosine aminotransferase. An anti-epimorphin antibody inhibited hepatocytic differentiation of HSLCs in co-culture. Furthermore, epimorphin induced mRNA expression of albumin, transferrin, tyrosine aminotransferase, and gamma-glutamyl transpeptidase with decrease of c-kit and musashi-1. Morphologically, HSLCs piled up when co-cultured with HSCs, which was dramatically inhibited by an anti-epimorphin antibody. HSLCs contact with epimorphin started piling up, changed their shape from flat to cuboidal, and subsequently developed bile-canaliculi-like structures. In conclusion, epimorphin is a factor that induces differentiation of hepatic stem-like cells through epithelial-mesenchymal cell contact.