the First Trimester1

Matrix metalloproteinases (MMPs) are implicated in the deg-radation of extracellular matrix; they play important roles in the invasion of the trophoblast cell into the maternal endometrium during placentation. Previous studies have concentrated on comparison of MMP expression in trophoblast cells between the first and third trimester. But the dynamic expression of MMPs during the first trimester has not been reported. In the present study, the expression of MMP-2,-9, and-14 (membrane-type MMP-1) and the production of tissue inhibitors of metallopro-teinases (TIMP-1 and TIMP-2) by cultured human cytotropho-blast cells from 6 to 11 wk of gestation were investigated. The cells were cultured under serum-free conditions. There was no MMP-9 secretion by the cells at Week 6, but from Week 7 to 11 the MMP-9 secretion increased gradually. Week 11 cells secret