Expression of the vascular endothelial growth factor (VEGF) family in human endometrial blood vessels

Endometrial regrowth is associated with intense angiogenesis, for which vascular endothelial growth factor-A (VEGF-A) is an important regulator. However, the expression of other members of the VEGF family is less well documented. The aim of this study was to localize members of the VEGF family (VEGF-A, -B and -C), and their receptors (VEGFR1, 2 and 3) in human endometrial blood vessels. Endometrial biopsies collected from four healthy and fertile women were used for immunohistochemistry assessments. Co-localization of VEGF-family proteins with CD34 stained endothelial structures was determined by image analysis. We demonstrate here the marked expression of VEGF-A as well as VEGFR2 and 3 in capillaries. Arterioles expressed VEGF-B, VEGFR1, 2, and 3 moderately and VEGF-A variably. Venules expressed only VEGFR3 markedly. In contrast, VEGF-C was not expressed in the arterioles, but moderately in the capillaries and weakly in the venules. VEGF-B was expressed in all blood vessels; however, VEGF-B was weakly expressed in capillaries and arterioles and moderately expressed in venules and arterioles. Thus, expression of VEGF-A. B and C and VEGF receptors 1-3 in endometrial blood vessels indicates a highly structured involvement of VEGF in the regulation of angiogenesis in the human endometrium.