In Vitro Studies on Angiogenic Factors Produced by Human Endometrial Epithelial Cells

Objective: Endometrial growth and repair during the menstrual cycle are associated with angiogenesis. It is therefore important to understand which cells produce angiogenic factors and which factors regulate endometrial angiogenesis. Methods: After a collagenase digestion, stromal and epithelial cells were separated by filtration. The epithelial cells retained on the filter were cultured and identified by cytokeratin staining. The stromal cells which passed through the filter were cultured and identified by vimentin staining. The angiogenic activity in the conditioned medium of both cells was assessed by the enhancement of tube forming activity in 3‐dimensional culture of bovine endothelial cells. Results: The angiogenic activity in the epithelial cells was higher than that in the stromal cells and it was attenuated by the addition of the neutralized antibody to either b‐FGF (basic fibroblast growth factor) or VEGF (vascular endothelial growth factor) but, the b‐FGF content in the conditioned medium of the endometrial epithelial cells was less than that in the basal level of bovine endothelial cells used in this experiment. VEGF is therefore assumed to be the main angiogenic factor released from the epithelial cells. The amount of VEGF in the conditioned medium of the epithelial cells was higher than that of the stromal cells and significantly increased by the addition of pharmacological doses of 17 β‐estradiol. Conclusion: These results suggest that VEGF expression in endometrial epithelial cells plays a role in normal endometrial repair during the menstrual cycle.