FETAL LIVER-CELL TRANSPLANTATION FOR THE CREATION OF LYMPHOHEMATOPOIETIC CHIMERISM IN FETAL BABOONS

OBJECTIVE: Our purpose was to create xenogeneic lymphohematopoietic ch imerism by in utero transplantation of human fetal liver cells in the midgestation fetal baboon. STUDY DESIGN: Human fetal liver cell suspen sions obtained from preimmune human fetuses (< 80 days' gestation) wer e injected into the peritoneal cavity of three fetal baboons (85, 95, and 104 days' gestation). A total of 9 x 10(6) cells, in a volume of 1 ml, were injected percutaneously into the fetal abdominal cavity unde r ultrasonographic guidance. The success of the injection was assessed by observing ascites and free loops of fetal bowel after injection. F etal umbilical cord blood (35 days posttransplantation) and neonatal b lood and bone marrow were obtained to be assayed for the presence of d onor hematopoietic cells. Chimerism was detected by fluorescence in si tu hybridization with a human Y-chromosome specific probe. RESULTS: Al l the animals survived the in utero procedures. Thirty-five days after transplantation engraftment was noted in one animal. Postnatally the same animal showed engraftment in both the peripheral blood and bone m arrow. The rate of chimerism was 1.5% (1.5% of the cells were human) i n both the peripheral blood and bone marrow. CONCLUSIONS: This study d emonstrates that creation of xenogeneic lymphohematopoietic chimerism is possible in the midgestation fetal baboon. However, the level of ch imerism was too low to study the biologic activity of the transplanted cells or to potentially ameliorate lymphohematopoietic disorders. Fut ure studies using allogeneic tissue, evaluating cells obtained from bo th fetal and adult donors, and comparisons between purified stem cells and fetal liver cells are needed.