Transplantation of DLA-compatible and incompatible fetal liver hematopoietic cells in dogs.

Requirements for sustained engraftment of fetal liver hematopoietic stem cells were evaluated in 45 dogs. Pretransplant preparative treatment with total-body irradiation, 14.7 Gy, permitted engraftment of DLA-compatible fetal liver cells. Radiation alone was inadequate in DLA-haploidentical or DLA-mismatched transplants; none of 5 dogs had engraftment. Addition of cyclosporine facilitated engraftment. The combination of 14.7 or 16.1 Gy total-body irradiation (TBI) and cyclosporine allowed engraftment in 15 of 19 (78%) dogs receiving DLA-histoincompatible grafts and 11 Gy TBI plus cyclosporine allowed engraftment in 4 of 10 dogs. Restoration of granulopoiesis and thrombopoiesis was rapid; recovery of lymphocytes was relatively delayed, especially in recipients of incompatible fetal liver cells. Cumulative one-year survival was decreased in recipients of incompatible grafts due to early posttransplant infections. These data suggest that fetal liver transplantation is a potential approach in patients who lack an HLA-identical donor for bone marrow transplantation.