EFFECT OF MATERNAL SERUM ON VIABILITY AND FUNCTION OF EARLY HUMAN PLACENTAL EXPLANTS

Fetal bovine serum (FBS) is frequently used to supplement chemically d efined media such as Ham's F10 when studying placental explant culture s. However in vitro production of hormones is usually declining by the 2nd or 3rd day and is short-lived (7 to 10 days). In this study we ex plored the use of human maternal serum (HMS) from early gestation as t he medium supplement to Ham's F10. Early placental hormone production was compared using two concentrations of FBS and HMS. On Day 3 of incu bation, progesterone production in 10% HMS was 12-fold increased over that in 10% FBS, estradiol production was increased 10-fold, and betah CG production more than 3-fold. When the serum concentrations were inc reased to 40%, the results in all cases were similar to those at 10%. Preliminary characterization studies revealed that the stimulatory act ivity of HMS is heat-labile, neither extractable into organic solvent (diethyl ether) nor dialyzable, suggesting that it is protein in natur e. In a long-term incubation, compared with FBS (7 days), HMS permitte d survival of culture up to 30 days, judged both histologically and bi ochemically. We conclude that HMS provides substance(s), probably prot ein in nature, not present in FBS or non-pregnant human serum, which a re important for human placental viability and function in vivo.