The Human Endometrium : Studies on Angiogenesis and Endometriosis

Angiogenesis is thought to play a pivotal role in the cycling endometrium. Coordinated by oestrogen and progesterone, endometrial blood vessel development is primarily mediated by vascular endothelial growth factor-A (VEGF-A), which promotes endothelial cell (EC) proliferation and protects ECs from induced apoptosis. Studying changes at transcript level in human endometrial endothelial cells (HEECs) in response to mitogenic and inhibitory stimuli is one way towards understanding the regulation of physiological endometrial angiogenesis. Endometriosis, the presence of endometrial-like tissue outside the uterine cavity, is a common gynaecological disorder in women of reproductive age, often causing pelvic pain and reduced fertility. Chronic inflammation in the peritoneal environment and defective endometrial protein expression are some of the contributors to the complex pathophysiology of endometriosis. The aim of this work was to study the changes in the transcriptome induced by VEGF-A and partial serum deprivation in primary HEECs, and to investigate biochemical factors associated with subfertility and chronic pelvic pain in endometriosis patients. Exposing primary HEECs to VEGF-A, and serum withdrawal was found to regulate transcripts associated with survival, migration, apoptosis and progression through the cell cycle, when assessed using microarray technology and bioinformatic tools. A subset of 88 transcripts was reciprocally regulated under the two experimental conditions; thus probably important in HEEC biology. Higher endometrial epithelial staining scores of oestrogen receptor-α and reduced staining of progesterone receptors were seen in subfertile endometriosis patients. Lower levels of the receptivity biomarker leukaemia inhibitory factor (LIF) and its receptor, as well as signs of dysregulated αB-crystallin expression and increased peritoneal fluid concentrations of interleukin (IL)-1α and IL-6 were associated with reduced pregnancy rates. Endometriosis patients with chronic pelvic pain had higher levels of vasoactive intestinal peptide (VIP) in eutopic endometria and in endometriotic lesions compared with patients without chronic pain. The presence of chronic pelvic pain was also associated with increased concentrations of VIP and IL-6 in peritoneal fluid. The present results may constitute a basis for further investigation of regulatory pathways in endometrial angiogenesis as well as for studies of endometrial receptivity and pain in women with endometriosis.