c-kit(+) Stem cells and thymocyte precursors in the livers of adult mice

Livers of the adult mice contain c-kit(+) stem cells that can reconstitute thymocytes, multiple lineage cells, and bone marrow (BM) stem cells. Transfer of 1 X 10(7) hepatic mononuclear cells (MNC) and 5 X 10(4) hepatic c-kit(+) cells of BALB/c mice induced DP thymocytes with a a week ill four Gy-irradiated CB17/-SCID mice, but 2 wk were required for BM cells or BM c-kit(+) cells to produce DP thymocytes. Moreover, B cell-depleted BM cells or liver MNC of SCID mice that had bren rescued by hepatic MNC, of BALB/c mice again reconstituted thymus and B cells of other irradiated SCID mice. CD3(-)IL-2R beta(-) populations of both BM cells and hepatic MNC of C57BL/6 (B6) mice could generate T cells with intermediate TCR (mostly NK1.1(-)) in the liver of irradiated B6 SCID mice before thymic reconstitution (extrathymic T cells). Further-more, transfer of liver c-kit(+) cells of BG-Ly 5.1 mice into irradiated Bb SCID (Ly5.2) mice revealed that liver c-kit(+) cells can reconstitute myeloid and erythroid lineage cells. These results strongly suggest that the liver contains pluripotent stem cells and serves an important hematopoietic organ even into adulthood.