Objective: To identify a specific microenvironment in direct contact with fetal membranes where effector molecules acumulate, aiming to degrade the components of its extracellular matrix during labor.
Type of study: Experimental, analytic, longitudinal and prospective.
Materials and methods: Blood samples were collected from maternal, fetal and choriodecidual compartments, and mononuclear cells were isolated. Part of these cells was stained with antibodies to determine leukocyte subpopulations by flow cytometry. The other part was cocultured for 12 h with amniochorion explants. After coculture, MMP-9 was identified on the mononuclear cells by immunofluorescence. IL-1beta and TNF-alpha were determined in the supernatants by ELISA. Three independent experiments were carried out with duplicates and analyzed with Mann-Whitney's U test.
Results: Although there were no significant differences in the mononuclear cell subpopulations from the three compartments, MMP-9 production was higher in choriodecidual cells than in those of the maternal and fetal compartments. Furthermore, IL-1beta and TNF-alpha were significantly more abundant in cocultures with choriodecidual cells compared with the other two compartments.
Conclusions: During labor, choriodecidual cell subpopulations are not phenotypically different from those of the maternal or fetal compartments, but they are regarding MMP-9 production, which suggests that the environment surrounding chorioamniotic membranes enhances the synthesis of this enzyme, thus promoting degradation of connective tissue.