Prostacyclin production by human placental cells in short-term culture

Human placentae of varying gestational ages have been cultured in vitro with little variation in cell type and pattern of growth found. Cell types found are similar morphologically and histochemically to those previously described. The biological specificity of the cells in culture was also confirmed by human placental lactogen production. Placental cells in culture appear to synthesize and release PGI2 which can be identified by gas chromatography-mass spectrometry. Production of PGI2 was routinely measured by radioimmunoassay (RIA) for 6-oxo-PGF1alpha and 13,14-dihydro-6,15-dioxo-PGF1alpha in culture supernatants. Good agreement was found between RIA and gas chromatography-mass spectrometry measurements. PGI2 production in culture was not affected by mode of delivery, and synthetic capability was found to increase with gestational age. Production of PGI2 by cells from preterm and term placentae was similar but significantly greater than that of first-trimester cells. As the proportion of PGI2 produced in culture supernatants as 13,14-dihydro-6,15-dioxo-PGF1alpha changed with time of incubation, it appears pertinent to measure this metabolite when assessing total PGI2 production. Synthesis of PGI2 wa inhibited by the cyclo-oxygenase inhibitors indomethacin and aspirin and PGI2 synthetase inhibitor 15 hydroperoxyarachidonic acid. However, in the culture system tranylcypromine, a putative specific inhibitor of PGI2 synthetase, produced weak inhibition only before becoming cytotoxic. The cell culture system appears to offer a reliable and reproducible means for measuring placental PGI2 production in vitro and in which to study factors controlling its production and metabolism.