Expression of vascular endothelial growth factor-A and its receptor-1 in a luteal endometrium in patients with repeated in vitro fertilization failure.
To investigate temporal and spatial relationships of vascular endothelial growth factor (VEGF)-A and its receptor (VEGFR-1) expression in a luteal endometrium obtained from patients with repeated IVF failure. Immunohistochemical study. University hospital. Thirty-three regular-cycling infertile women (mean age, 34.4 years) who experienced three or more failed IVF cycles (range, 3-14 cycles). Endometrial samplings by silastic suction curette in the luteal phase of a spontaneous unmedicated cycle. Immunohistochemical intensity scoring after staining by monoclonal anti-VEGF-A and polyclonal anti-VEGFR-1. Microvascular density determined after staining by monoclonal anti-CD31 antibody. The data were compared in three phases; early (cycle day [CD]16-19) (n = 12), mid- (CD20-24) (n = 13), and late luteal phase (CD25-27) (n = 8). Expression of VEGF-A tended to be lower in midluteal endometrium at epithelial, stromal, and endothelial cells. Expression of VEGFR-1 at epithelial cells was highest in midluteal endometrium, but VEGFR-1 at stroma and endothelium and microvascular density continuously decreased throughout luteal-phase endometrium. In contrast to previous reports, VEGF-A expression was not highest in the midluteal phase in repeated IVF failure patients who had no apparent endometrial pathology. Further research is needed to determine whether different VEGF-A expression patterns in the luteal phase contribute to repeated IVF failure.