Differentiation potential of FDCPmix cells following injection into blastocysts

Factor-dependent cell Paterson mixed potential (FDCPmix) cells are murine, multipotent, interleukin-3 (IL-3)-dependent progenitor cells, established from long-term bone marrow cultures. They show multilineage myeloid/erythroid and osteoclast differentiation capacity in vitro. FDCPmix cells are neither immortalised, leukaemic nor transformed and have no detectable karyotypic abnormalities. To investigate the broader differentiation potential of FDCPmix cells in vivo, they were injected into murine blastocysts, and the engraftment of donor cells in developing chimaeric embryos was analysed. FDCPmix cell progeny was detected predominantly in haematopoietic tissues, and immunohistochemical analysis revealed that the majority of donor-derived cells expressed the pan-haematopoietic marker CD45. Albumin expression indicative of hepatocytes was not detectable in FDCPmix-derived cells in chimaeric foetal livers. However, analysis of foetal brains of developing embryos revealed a low frequency of neural cell adhesion molecule-positive donor cells. These results suggest that the majority of FDCPmix cells injected into blastocysts follow haematopoietic differentiation programs, but that a small number of cells can assume the expression of neural markers.