Immunolocalization of the Apoptotic Inhibiting Protein (bcl-2) in Early Normal Pregnancy and Abortion

ABSTRACT

BACKGROUND: The human placenta is an important organ in the maintenance of pregnancy, having functions in maturation and differentiation until the end of pregnancy. The bcl-2 protein is a proto-oncogene that prevents apoptosis and maintains cell survival. However, the mechanism through which bcl-2 inhibits apoptosis is unclear. The aims of this study are to localize bcl-2 at the placenta and to determine whether the expression of bcl-2 in early normal pregnancy is different from that of a missed abortion. METHODS: Immunohistochemistry was performed for bcl-2 in formalin-fixed chorionic villi and decidual tissue collected from five early normal pregnancies and eleven missed abortions having histories of recurrent abortions during the first trimester. RESULTS: The bcl-2 protein was observed in the syncytiotrophoblasts of chorionic villi and decidua in both the normal pregnancy and the missed abortion, and the expression of bcl-2 significantly increased in the missed abortion group (p<0.05). CONCLUSION: The bcl-2 may be necessary to maintain pregnancy through modulating the survival of the syncytiotrophoblast and decidua without affecting cell proliferation, and the increased bcl-2 expression is presumed to be a reparative process to the increased apoptotic activity.