PROLONGED HEMATOPOIETIC CHIMERISM IN NORMAL MICE TRANSPLANTED IN-UTERO WITH HUMAN HEMATOPOIETIC STEM-CELLS

We have previously reported prolonged hematopoietic chimerism in norma l mice transplanted in utero with human fetal hematopoietic stem cells (HSC) by flow cytometry. We now further confirm the human origin of t hese cells by demonstrating human DNA in the marrow of one such chimer ic mouse. We also examined 42 mice born after in utero transplantation with HSC enriched from human adult marrow cells. All live-born mice w ere treated with recombinant human growth factors. Twelve had human ce lls in the peripheral blood (range: 01.-2.93%). Thymic samples were po sitive in 3 cases. The bone marrow of 2 mice contained cells expressin g human CD34 antigen. Light scatter characteristics support the presen ce of multilineage hematochimerism. Human IgM was present in 2 of 4 ch imeric sera tested. Thus, normal mice transplanted in utero with human HSC may permit long-term engraftment and differentiation of the human HSC.