Endothelial cell migratory signal produced by human endometrium during the menstrual cycle

Human endometrial explants were cultured in a three-dimensional collagen/bovine aortic endothelial cell (BAEC) matrix to measure angiogenic activity, as represented by migration of BAEC towards the explants. The 57 endometrial biopsies were classified by histological appearance into nine stages of the menstrual cycle; five proliferative groupings, three secretory groupings and one menstrual. The BAEC migratory score was taken as the average for 12 explants assayed from each biopsy. The results showed two significant peaks of BAEC migratory activity, one during the early proliferative phase and one during the mid--late proliferative phase. There was a significant drop in the BAEC migratory signal from early--mid-proliferative endometrial explants compared to most other stages of the cycle. The results also show a non-significant rise in BAEC migratory activity in the mid-secretory phase of the cycle. Overall, the results support the concept of two or three different endometrial angiogenic events during the human menstrual cycle, a post-menstrual repair, a mid--late proliferative growth and a lesser mid-secretory activity that may be associated with spiral arteriole growth. Each of these events occurs under different hormonal environments and will need to be investigated separately in terms of local mechanisms controlling angiogenesis.