Autologous hemopoietic reconstitution after fetal liver infusion in patients with bone marrow failure: consequence or coincidence?

In the past 4 years we have treated four patients with a total of 19 fetal liver infusions (FLI). Two cases of refractory anemia with excess blasts in transformation (RAEB-t) were conditioned with cyclophosphamide and total body irradiation (1400 cGy) and were treated with FLI. In spite of such intensive conditioning, one patient recovered autologous hemopoiesis 3 weeks later, remaining in remission 4 years after this procedure. The second patient died with aplastic marrow on day 154, and the third suffered from severe aplastic anemia refractory to several types of conventional treatment. After FLI and without previous conditioning therapy a partial fetal engraftment was documented. This was transient and followed by autologous hemopoietic recovery and cure of the disease. The fourth patient had bone marrow failure in the setting of a severe pneumonia following autologous bone marrow transplantation. Ten days after FLI the hematological parameters dramatically improved and the pneumonia resolved. Autologous reconstitution of hemopoiesis was demonstrated. These experiences suggest that FLI might stimulate autologous hemopoiesis. This therapeutic approach may be useful to treat bone marrow failure when there is no response to first-line therapy. In hematologic malignancies with an indication for stem cell transplantation, other sources such as allogeneic or autologous bone marrow seem preferable to fetal liver cells.