BCL-2 EXPRESSION IN THE HUMAN PLACENTA AND ITS CORRELATION WITH FIBRIN DEPOSITS

The human placenta performs numerous functions during its limited life span and its survival is a necessary prerequisite for fetal nutrition, even in unfavourable conditions. BCL-2 is a proto-oncogene implicated in the regulation of cell death and survival without affecting cell p roliferation. An extracellular matrix molecule involved in the reparat ive and degenerative processes in the human placenta is fibrin. We hav e analysed by immunohistochemistry the expression of BCL-2 and correla ted it with fibrin deposits in placental tissues. In first and third t rimester placentas BCL-2 was expressed in the syncytiotrophoblast. Onl y a few mesenchymal villi (first trimester) or terminal villi (third t rimester) showed no staining in the syncytiotrophoblast. Villous cytot rophoblast, mesenchymal cells of the villous cores and extravillous cy totrophoblast of cell columns and cell islands were all negative for B CL-2. BCL-2 expression was enhanced in the syncytiotrophoblast overlyi ng subtrophoblastic fibrin deposits. However, discontinuities and/or v ariations in intensity of BCL-2 expression characterized not only the villi showing perivillous fibrinoid but also those villi with a massiv e presence of fibrinoid in their cores. These data suggest that BCL-2 may be necessary for the preservation of the placenta during gestation as well as for the reparative processes of the trophoblast.