Hepatic stellate cells support hematopoiesis and are liver-resident mesenchymal stem cells.

Hematopoiesis can occur in the liver, when the bone marrow fails to provide an adequate environment for hematopoietic stem cells. Hepatic stellate cells possess characteristics of stem/progenitor cells, but their contribution to hematopoiesis is not known thus far. Isolated hepatic stellate cells from rats were characterized with respect to molecular markers of bone marrow mesenchymal stem cells (MSC) and treated with adipocyte or osteocyte differentiation media. Stellate cells of rats were further co-cultured with murine stem cell antigen-1(+) hematopoietic stem cells selected by magnetic cell sorting. The expression of murine hematopoietic stem cell markers was analyzed by mouse specific quantitative PCR during co-culture. Hepatic stellate cells from eGFP(+) rats were transplanted into lethally irradiated wild type rats. Desmin-expressing stellate cells were associated with hematopoietic sites in the fetal rat liver. Hepatic stellate cells expressed MSC markers and were able to differentiate into adipocytes and osteocytes in vitro. Stellate cells supported hematopoietic stem/progenitor cells during co-culture similar to bone marrow MSC, but failed to differentiate into blood cell lineages after transplantation. Hepatic stellate cells are liver-resident MSC and can fulfill typical functions of bone marrow MSC such as the differentiation into adipocytes or osteocytes and support of hematopoiesis.