Endocrinology: The effects of natural and synthetic sex steroids on human decidual endothelial cell proliferation

The effects of natural and synthetic sex steroids on the proliferation of human decidual capillary endothelial cells in culture were investigated. Oestradiol at 5.0 ng/ml stimulated culture growth. Lower concentrations of oestradiol inhibited growth, while higher concentrations had no effect. Low concentrations of progesterone (5.0 and 10.0 ng/ml) had no effect on growth, while higher concentrations (20.0 and 40.0 ng/ml) inhibited growth. Combinations of oestradiol and progesterone usually reproduced the effects of progesterone alone. 3-Ketodesogestrel and levonorgestrel both inhibited endothelial cell growth, while medroxyprogesterone acetate had no effect. These findings suggest that (i) oestradiol and progesterone have direct effects on endothelial cells and are probably involved in the cyclical growth and regression of endometrial blood vessels in vivo, and (ii) the actions of certain progestogen-only contraceptives may have direct effects on endometrial blood vessels.