Successful stable xenograft of human fetal hemopoietic cells in preimmune fetal sheep.

Human fetal liver hemopoietic stem cells were transplanted into preimmune fetal sheep. Significant numbers of recipient fetuses showed evidence of engraftment of human stem cells which responded in vivo to human-specific hemopoietic growth factors. The chimerism has persisted now for > 2 years without significant graft loss. No evidence of GVHD has been noted. Successful engraftment was associated with the expression of human erythroid, myeloid, and lymphoid differentiation. This xenograft model offers useful possibilities for the study of the biology of human hemopoiesis in vivo.