Focal vascular endothelial growth factor correlates with angiogenesis in human endometrium. Role of intravascular neutrophils

Vascular endothelial growth factor (VEGF) is expressed in human endometrium , but the cellular source of VEGF for endometrial angiogenesis has not been determined. In the present study the relationship between focal VEGF assoc iated with microvessels and endothelial cell proliferation was examined in three layers of human endometrium at various stages of the menstrual cycle (menstrual, proliferative and secretory), Immunohistochemical analysis of f ull thickness endometrium from 18 hysterectomy samples without endometrial pathology were examined. The percentage of proliferating vessels was higher in proliferative compared to secretory endometrium, but this was only stat istically significant in the basalis layer. A significantly greater percent age of VEGF-expressing microvessels was observed in proliferative than secr etory endometrium (P < 0.05), The most VEGF-expressing microvessels were ob served in the subepithelial capillary plexus, followed by the functionalis and least were present in the basalis, There was a significant correlation between focal VEGF-expressing microvessels and proliferating vessels for th e subepithelial capillary plexus (R-S = 0.70, P = 0.008), the functionalis (R-S = 0.70, P = 0.001) and the basalis (R-S = 0.76, P < 0.001), Focal VEGF associated with microvessels was found in marginating and adherent neutrop hils, These data suggest that neutrophils in intimate contact with endometr ial endothelium may be a source of intravascular VEGF for vessels undergoin g angiogenesis by elongation or intussusception, particularly during the pr oliferative phase of rapid endometrial growth.