Lack of correlation between vascular endothelial growth factor production and endothelial cell proliferation in the human endometrium

Abstract

The role of vascular endothelial growth factor (VEGF) in endometrial angiogenesis was examined by measuring its production in human endometrial tissues from different stages of the menstrual cycle and relating these data to endothelial cell proliferation in the same tissues. Conditioned medium was collected from explant, and separated glandular epithelial and stromal cells cultured from 24 normal human endometrial biopsies and VEGF measured by enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry was also used to assess VEGF and the percentage of proliferating microvessels in the samples. Wide variation in results between individual endometrial samples at each stage of the menstrual cycle was observed for all parameters measured. There was no significant difference in VEGF secretion by explant, glandular epithelial or stromal cell cultures across the menstrual cycle, or in the percentage of proliferating vessels. VEGF immunostaining in the stroma was elevated during the early proliferative stage (P = 0.03). Epithelial cells secreted more VEGF than stromal cells (1.76 +/- 0.46 versus 0.46 +/- 0.06 ng per 10(5) cells; P = 0.002). There was no correlation between VEGF secreted by cultured explants, epithelial or stromal cells, VEGF immunostaining and the proportion of proliferating microvessels. These results show that the majority of endometrial VEGF is produced by glands, but neither total glandular nor stromal VEGF is correlated with endometrial endothelial cell proliferation. There is still no clear understanding on the regulation of human endometrial angiogenesis.

The relationship between microvessel density, proliferative activity and expression of vascular endothelial growth factor-A and its receptors in eutopic endometrium and endometriotic lesions

“…Moreover, the mitotic activity in blood vessels seemed to be higher in lesions with high proliferative activity, but the difference was not statistically significant. This may not be surprising, however, since it has been shown that angiogenic activity in eutopic endometrium assessed in terms of the number of proliferating endothelial cells is fairly constant during the menstrual cycle (Rogers et al 1993), although there are reports on peaks of blood vessel formation during the Angiogenic activity in endometriotic lesions menstrual cycle (Gargett et al 1999, Gargett & Rogers 2001. Several studies also indicate that endometrial angiogenesis does not occur according to the classical mechanism with sprouting of new capillary blood vessels from maternal blood vessels.…”

Correlation of endothelial cell proliferation with vascular endothelial growth factor in endometrium of women with menorrhagia

“…23 The percentage of proliferating vessels was higher in proliferative compared to secretory endometrium, but this was only statistically significant in the basalis layer. However, no statistical correlation was observed between VEGF production and endothelial cell proliferation in another study by Gargett et al 13 Mints et al observed that menorrhagia patients displayed statistically significantly more vessels/HPF in the secretory than in the proliferative phase measured in hot spots (P=0.011) and in random fields (P=0.007). 24 Studies concerning idiopathic menorrhagia suggested that the proliferative index of endothelial cells was increased in women with excess measured menstrual blood loss.…”

“…8,13 A significantly greater percentage of focal VEGF-expressing microvessels were found during the proliferative phase as compared to the secretory phase, with the greatest numbers of immunopositive vessels within the subepithelial capillary plexus. The focal VEGF associated with microvessels was localised within marginating and adherent neutrophils.…”

“…Studies on endometrial endothelial cell proliferation was done by Kooy et al, Rogers, Gargett et al using endometrial endothelial cell proliferation as a measure of angiogenesis. 5,13,19 To identify proliferating endothelial cells, a immunohistochemical double staining system was used Goodger (Macpherson) and Rogers. 20 On grading of endothelial cells positivity for VEGF we observed that the grade increased in menorrhagic patients along with progression of the cycle.…”

“…At least 100 microvessels were counted in sequential fields scanned at X400 magnification from the surface epithelium through the full depth of section. 13 The number of these vessels containing proliferative endothelial cells were determined and the percentage of microvessels containing proliferating endothelial cells were calculated. Immunohistochemistry determination of VEGF protein.…”