Placental matrix metalloproteinase--1 expression is increased in labor.

Matrix metalloproteinases (MMPs) are now known to process a broad spectrum of cell surface molecules and to function in several important biological processes. Testing for differences in gene expression in human placental chorionic villi in the absence or presence of labor, using cDNA microarray analysis, revealed that labor was associated with increased expression of MMP-1 gene expression in 5 placentas collected after term normal spontaneous deliveries compared with 5 placentas collected after term nonlaboring cesarean deliveries. Fibronectin 1 and collagen XVII, 2 other proteins involved in the homeostasis of the extracellular matrix, were also found to be upregulated in labor. MMP-1 was further tested in individual samples and found to be consistently overexpressed in labor. While previous microarray analyses have focused on either uterine tissue or the fetal membranes, the data presented here indicate for the first time that placental chorionic villus genes are likely to affect the initiation of parturition through altered processing of cell surface molecules by MMP-1.