Human chorionic gonadotrophin release and tissue viability in placental organ culture

The use of human chorionic gonadotrophin (HCG) secretion as a measure of viability during the organ culture of human first trimester placental tissue has become a popular practice. It has been suggested that if cultured tissue is releasing large amounts of this protein hormone, there is a high level of viability. We have found, however, that the cytosolic enzyme L-lactate dehydrogenase is released into the culture supernatant in a similar daily pattern as HCG, suggesting that tissue disruption may be occurring, resulting in some of the observed hormone release. In addition, we have shown that the uptake of the fluorescent dye dansyl-L-lysine into the syncytium increases significantly from day 0 to day 4, suggesting a loss of syncytial membrane integrity. Electron micrographs show further evidence of the syncytial degeneration at the ultrastructural level, displaying extensive vacuolation and poor microvillous cover. In contrast to the degenerated state of the syncytiotrophoblast, a high level of bromodeoxyuridine incorporation is observed for cytotrophoblasts and, in particular, stromal cells up to 5 days in culture. Overall, the results suggest that the use of HCG release as a determinant of tissue viability in placental organ culture should be treated with a degree of caution.