The functional regeneration of syncytiotrophoblast in cultured explants ofterm placenta

We have investigated the functional characteristics of term human placental villous explants kept in long-term (7-11 days) culture. Fragments of place ntal villous tissue ( similar to5-10 mg wet wt) were cultured in supplement ed CMRL-1066 culture medium for up to 11 days. After the first day of cultu re, the syncytiotrophoblast appeared vacuolated and eventually degenerated. However, a new syncytiotrophoblast developed by day 4, being indistinguish able from that of a fresh placenta by 11 days. Release of human chorionic g onadotrophin increased and activity of lactate dehydrogenase in culture med ium decreased with culture time. Transport variables were measured over the first 7 days of culture. Basal Rb-86 efflux was reduced with time in cultu re and was inhibited by Ba2+, suggesting the efflux was mediated by K+ chan nels. At all stages of culture, Rb-86 efflux was stimulated by ATP, hyposmo tic medium, and ANG II. A complex pattern of efflux changes with culture ti me and type of stimulator was observed, suggesting that several compartment s of the tissue contributed to stimulated efflux. This culture system provi des opportunities for studies of chronic regulation of placental function.