Experimental aspects of transplantation of haemopoietic cells of fetal liver.

About 25% mice treated for radiation-induced bone marrow aplasia with allogeneic transplantation of histoincompatible fetal liver cells survived four months. The same survival time was observed in 80% of mice after transplantation of syngeneic fetal liver cells. Mice irradiated and not treated and those receiving transplants of allogeneic histoincompatible bone marrow died within a few weeks after transplantation. This observation confirms the reports on the therapeutic superiority of transplantation of haemopoietic fetal liver cells over transplantation of bone marrow of similar tissue incompatibility and reports on the usefulness of tissue matching, if possible. Another observation was an absence of inactivation of the haemopoietic stem cells in mixtures of genotypically different fetal liver cells. The animals receiving these cell mixtures showed survival rates similar to those of the animals receiving genetically homogenous cells. This opens theoretical possibilities for undertaking clinical trials of transplantation of cells from several fetal livers, especially in view of the accumulating reports that one human fetal liver may be too small to serve as a source of stem cells for ensuring successful transplantation.