O-63: Angiogenesis factors in human ovarian follicular development: The presence of vascular endothelial growth factor and placental growth factor in follicular fluid

Abstract

It has been demonstrated that angiogenesis plays an important role in normal cyclical ovarian function. In particular, follicular growth is dependent upon the proliferation of new capillary vessels, and, it has been proposed that the process of selection of a dominant follicle is likely to be associated with angiogenesis. Vascular endothelial growth factor (VEGF) and its homolog the placental growth factor (PlGF) are vascular cell-specific mitogen factors with a key function in angiogenesis. Their role in human follicular growth and oocyte maturation however, is less well-understood and the presence of PlGF in human follicles has not been previously demonstrated. This study sought to determine the content of both VEGF and PlGF within the follicular fluid (FF) of large and small follicles of women undergoing in vitro fertilization (IVF) and to relate their content to patient age A prospective laboratory-based study at an academic center. Women between the ages of 25 - 43 years old undergoing IVF were enrolled under IRB approval during the time of oocyte retrieval. Follicles were measured by transvaginal ultrasound in 2 dimensions prior to aspiration. FF from lead (>14mm) and small (< 12mm) follicles was collected by transvaginal aspiration. Cellular components and immunoglobulins were removed by centrifugation and protein A/G chromatography. VEGF and PlGF concentration in FF were then analyzed via enzyme-linked immunosorbent assay (ELISA) on lead and small follicles from young (</= 34 years) and old (>/= 40 years) samples and confirmed by western blot with specific antibodies. Results were analyzed with students’t test and statistical significance was set at a p value of < 0.05. The results of the Western Blot analysis showed the presence of both VEGF and PlGF within the FF. The mean concentration of PlGF in lead follicles was 42.41 pg/ml and the mean concentration in small follicles was 55.91 pg/ml (p= 0.10). The mean concentration of VEGF in lead follicles was 5,745.76 pg/ml whereas the mean concentration in small follicles was 3,485.70 pg/ml (p<0.01). The concentration of VEGF and PlGF did not vary with respect to age. This study demonstrated a significantly increased concentration of VEGF in the follicular fluid of lead follicles compared with smaller follicles irrespective of age, lending proof to the idea that angiogenesis is an important part of lead human follicle development. The trend of our results for PlGF supports findings suggesting that PlGF may act as a natural VEGF antagonist. Additionally, our western blot and ELISA results are the first demonstration of the presence of PlGF in human FF. Overall, this study demonstrates that angiogenesis factors are important in follicular development in women undergoing IVF.