Perivascular smooth muscle α-actin is reduced in the endometrium of women with progestin-only contraceptive breakthrough bleeding

Abstract

It has been shown that the endometrium of women using progestin-only contraceptives has increased vascular fragility, although the structural basis for this weakness is unknown, as is its role in breakthrough bleeding (BTB). Perivascular cells such as pericytes and vascular smooth muscle cells surround capillaries during the maturation process following angiogenesis, and act to strengthen and stabilize the vessels. The aim of the present study was to quantify endometrial perivascular smooth muscle alpha-actin (alphaSMA) expression in women using Norplant with and without BTB problems, and compare it to controls. Using immunohistochemical techniques, vessels were classified as level 0, 1 or 2..