What is the role of matrix metalloproteinase-2 in placenta percreta?

This study compared the placental expression of the matrix metalloproteinase-2 (MMP-2) enzyme, which is thought to play a key role in the penetration of trophoblastic cells, in third-trimester placenta percreta (PP) patients with that of women with normal pregnancies.

Twenty-five pregnant subjects who underwent cesarean section due to PP and 25 term pregnant subjects who underwent cesarean section for obstetric reasons were included in the study. Demographic data, pathology reports, and histopathological samples were examined. Blocks containing samples of placenta underwent immunohistochemical analysis using the MMP-2 antibody. Immunohistochemical expression of placental samples obtained from both groups was examined and compared.

There were no statistically significant differences in the demographic data (P > 0.05). With regard to immunohistochemistry, cytoplasmic staining of trophoblastic cells was considered immunohistochemically positive. In the PP tissue samples, positive MMP-2 staining was detected as follows: 0 immunoreactivity, one patient (4%); 1(+), six patients (24%); 2(+), seven patients (28%); and 3(+), 11 patients (44%). In the term pregnant placental tissue samples, positive MMP-2 staining was detected in five patients (20%) at 0 immunoreactivity, 12 (48%) at 1(+) immunoreactivity, five (20%) at 2(+) immunoreactivity, and three patients (12%) at 3(+) immunoreactivity. Immunohistochemical expression was significantly different between the PP and normal term pregnancy placental tissues (P = 0.02).

The stronger expression of the MMP-2 enzyme in the PP as compared to the normal placental tissue suggests that this enzyme may be an effective mediator in the pathogenesis of PP.