In utero transplantation of fetal liver stem cells in humans.

Following 15 years experience in postnatal fetal liver transplantation (FLT), we have developed a new therapeutical method, namely the in utero transplantation of stem cells from the human fetal liver. This early transplant takes advantage of the immunological tolerance that exists in young fetal recipients. The three fetuses that we treated were 28, 26, and 12 weeks of age (weeks after fecundation). The first two patients had immunodeficiencies, the third one had thalassemia major. Donor cells were obtained from 7- to 10-week-old fetuses, with conditions approved by the National Committee for Bioethics. Donors and recipients were not matched. The fetal cells were infused through the umbilical vein of the first two patients and injected intraperitoneally into the third one, under ultrasonic visualization. The first patient, born in 1988, has evidence of engraftment and reconstitution of cell-mediated immunity: initially 10% than 26% of lymphocytes of donor origin (with distinct phenotype), T cell responses to tetanus toxoid and candida antigens. This child, who had bare lymphocyte syndrome, has no clinical manifestation of the disease and lives normally at home. The second child was born in 1989 and it is too early for a thorough evaluation of the immunological effects of the transplant, although donor cell engraftment has been proven (Y chromosome in this female patient). The third patient has also evidence of donor cell take (Y chromosome in a female patient) but the effect on thalassemia has not yet been fully analyzed (donor hemoglobin present in small quantity). In all three cases, no side effect of any kind developed in the mother nor in the fetus.(ABSTRACT TRUNCATED AT 250 WORDS)