TISSUE DISTRIBUTION OF TRANSPLANTED FETAL LIVER-CELLS IN THE HUMAN FETAL RECIPIENT

OBJECTIVE: Our purpose was to study the tissue distribution and concen trations of transplanted fetal liver cells in the human fetus. STUDY D ESIGN: Radiolabeled indium 111 fetal liver cells were injected in vivo under ultrasonographic guidance into 10 normal fetuses (13 to 17 week s of gestation) before a prostaglandin abortion. Six fetuses were inje cted intraperitoneally and four intracardially. Another two fetuses se rving as controls were injected with indium-labeled maternal plasma. T he fetuses were all alive, at least until 6 hours before expulsion. Af ter expulsion the fetuses were dissected, and radioactivity was measur ed in various fetal tissues. Results for each tissue were expressed as percentages of the total injected dose. RESULTS: Significantly greate r uptake of fetal liver cells in the liver, spleen, thymus, kidney, lu ng, and placenta was obtained with intracardiac than with intraperiton eal injection. Skeletal uptake did not differ in relation to mode of a dministration. With intracardiac injection uptake was greater in such parenchymal organs as the liver, spleen, and thymus (4.9%, 4.0%, and 3 .9%, respectively). Uptake in the rib, clavicle, humerus, and sternum was 2.7%, 1.8%, 2.1%, and 1.1%, respectively. Placental uptake was 0.1 %. The intracardiac route yielded a higher concentration of cells in d ifferent fetal organs than did injection of only radiolabeled material plasma, suggesting an active uptake of cells in different fetal hemat opoietic organs. CONCLUSION: The mode of administration of fetal liver dells seems to be a major determinant of donor cell concentration in the transplanted human fetus and may be a significant determinant of t he rate of successful engraftment.