EXPRESSION OF STROMELYSIN-3 IN THE HUMAN PLACENTA AND PLACENTAL BED

Human placentation is mediated by fetal trophoblastic cells which pene trate into the decidualized uterine endometrium. Trophoblast invasion requires the precisely regulated secretion of specific proteinases abl e to degrade the endometrial basement membranes and extracellular matr ix. To document further the involvement of these proteinases during hu man placentation, we evaluated in vivo the expression of stromelysin-3 , a member of the metalloproteinase family, during the first and third trimesters of pregnancy, by means of immunohistochemistry, in situ hy bridization and Northern blot analysis. Human extravillous trophoblast s invading the maternal decidua produced stromelysin-3 during both, th e first and third trimesters of pregnancy, but to a lesser extent duri ng the latter. In floating villi, stromelysin-3 expression was restric ted to the syncytiotrophoblasts that line intervillous vascular spaces . In conclusion, stromelysin-3 is expressed by differentiated, non-pro liferative villous and extravillous trophoblastic cells in early and l ate placental beds and villi, and its pattern of expression evolves du ring pregnancy. Our observations suggest that stromelysin-3 could play a role in human placentation. (C) 1997 W. B. Saunders Company Ltd.