Characterization and isolation of ductular cells coexpressing neural cell adhesion molecule and Bcl-2 from primary cholangiopathies and ductal plate malformations

It has recently been shown that reactive bile ductules display neuroendocri ne features, including immunoreactivity for the neural cell adhesion molecu le (NCAM). In this study we have compared the immunohistochemical expressio n of NCAM with that of HEA-125 (biliary specific) and LKM-1 (hepatocyte spe cific) and other markers relevant to morphogenesis (Bcl-2, EMA) and cell pr oliferation (Ki-67) in cryostat sections from different chronic liver disea ses and from fetal livers at different gestational ages. In parallel, viabl e NCAM-positive ductular cells were purified from collagenase digests of ci rrhotic livers by immunomagnetic separation and characterized by immunocyto chemistry and transmission electron microscopy, We demonstrated that reacti ve ductules with atypical morphology coexpressed NCAM and Bcl-2 and were fo und mainly in congenital diseases associated with ductal plate malformation and in primary cholangiopathies. On the contrary, reactive ductules with t ypical morphology were negative for NCAM/Bcl-2 and positive for EMA. Reacti ve ductules coexpressing NCAM/Bcl-2 were negative for the proliferation mar ker Ki-67 and appeared to be directly connected with periportal hepatocytes , In fetal livers NCAM/Bcl-2 was transiently expressed during the early dev elopmental stages of ductal plate (10-16 weeks) and started to disappear as the ductal plate began duplicating. NCAM-positive ductal plate cells were Ki-67 negative, becoming positive in duplicated segments. Thus the histogen esis of ductular reactive cells seems to recapitulate the early stages of b iliary ontogenesis. In primary cholangiopathies and ductal plate malformati ons, these cells do not appear to maturate further, and thus abundant ductu lar structures coexist with vanishing mature ducts. These NCAM-positive duc tular cells were immunopurified from patients with chronic cholestatic live r diseases and showed ultrastructural features consistent with a less diffe rentiated phenotype than mature cholangiocytes, These belated cells represe nt a useful model for in vitro studies.