TRANSFER OF ERYTHROPOIETIN ACROSS THE PLACENTA PERFUSED IN-VITRO

Objective: The purpose of this study was to investigate the placental passage of erythropoietin in a placental perfusion model ex vivo. Meth ods: In an open system 18 placentas were perfused on both the maternal and the fetal side. Erythropoietin and a reference substance were add ed to either the maternal or fetal perfusion medium. In the first seri es of experiments, radiolabeled erythropoietin was added to the perfus ion medium in four different concentrations to help determine the tran sfer rate of erythropoietin; Based on the results of these experiments unlabeled erythropoietin was added to the perfusate in three differen t concentrations. Radiolabeled erythropoietin was used in addition to erythropoietin because measuring radioactivity in a gamma counter is l ess expensive than measuring by immunoassay. Results: Accumulation of radioactivity in the venous portion of the fetal circuit was only 3.21 % of the activity added to the maternal circuit. No evidence of transf er of erythropoietin to the contralateral compartment was noted, regar dless of whether the test substance was added maternally or fetally. T hese results were independent of the concentration used. The reference compound antipyrine showed a mean transfer rate of 27.9%, which is in keeping with previous results. Conclusion: There is no transport of e rythropoietin across fetal membranes. This finding is particularly rem arkable in view of results published recently indicating the placenta as a site of erythropoietin production. The lack of its transport acro ss the human placenta is most likely due to its high molecular weight. (C) 1997 by The American College of Obstetricians and Gynecologists.