RAT-LIVER BILIARY EPITHELIAL-CELLS SUPPORT LONG-TERM PRODUCTION OF HEMATOPOIETIC PROGENITORS FROM HUMAN CD34(+) CELLS

In this study we report the supportive activity of rat liver epithelia l cells (RLEC) on human haemopoiesis in the absence of exogeneously su pplied growth factors. RLEC is a rat cell line derived from primitive biliary cells with epithelial characteristics which induce the long-te rm differentiation of hepatocytes through cell-cell contacts. We have established the ability of these cells to sustain long-term survival a nd multilineage differentiation of human haemopoietic progenitors from unfractionated bone marrow and growth-factor mobilized peripheral blo od cells, and from human CD34(+) and CD34(+) CD38(-) haemopoietic cell s, with a higher efficiency than the murine MS-5 stromal cell line: th e numbers of committed progenitors recovered from RLEC cocultures afte r 8 weeks were 3-fold higher than from MS-5 cocultures, with an unusua lly high BFU-E production. Furthermore, using diffusible insert cultur es, we demonstrated that, despite the lack of strong adhesive interact ion between haemopoietic cells and RLEC, physical proximity was absolu tely required for optimum stimulation of LTC-IC by RLEC. Taken togethe r these results show that biliary epithelial cells support human haemo poiesis and cause speculation that common mechanisms might be used by RLEC to regulate both the hepatocyte and the haemopoietic progenitors differentiation.