Localization and possible role of membrane type metalloproteinase and tissue inhibitors of metalloproteinase-1 in early stages of placentation

Human placental tissues from the first and second trimesters of gestation h ave been investigated using riboprobe in situ hybridisation of mRNA sequenc es coding for membrane type metalloproteinase (MT-1-MMP) and tissue inhibit ors of metalloproteinase-l (TIMP-1). Results show that (i) both mRNAs expre ss at a relatively high level in the chorion laeve trophoblast cells and th e adjacent decidual cells of fetal membrane; (ii) the most abundant express ion of the two mRNAs was found in the extravillous trophoblast between Rohr s and Nitabuch striae of basal plate, trophoblast shell and gland cells of the decidua; (iii) isolated or small groups of cytotrophoblast cells in the chorionic villi and in the cells lining arterioles in decidua and stem vil li also expressed both MT-1-MMP and TIMP-1 at defferent extents. The data s uggest that the coordinated expression of the MT-MMP and its inhibitor TIMP in defferent cells of the placental tissue may play an essential role in t rophoblast invasion and angiogenesis related to placentation in the first t wo trimesters of gestation. They may also have an ability to effect separat ion of fetal from material tissue at a favorable junctional site during par turition.