Submission Number: TIM-4-17-28

Abstract Number: 529

UTERO-PLACENTAL EXPRESSION OF BASIC FIBROBLAST GROWTH FACTOR (BFGF) IN SINGLE AND TWIN BEARING EWES IN AN OVINE MODEL OF PLACENTAL INSUFFICIENCY-INTRAUTERINE GROWTH RESTRICTION (PI-IUGR) DURING EARLY PLACENTAL GROWTH.

Timothy RH Regnault ¹, Randall B Wilkening ¹ and Russell V Anthony* ^1,2

Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO ¹
Department of Physiology, Colorado State University, Fort Collins, CO ²

Abstract:
Placental vasculature development requires organized invasion of a responsive uterine epithelium, through the actions of growth factors such as basic fibroblast growth factor (bFGF). bFGF has been well characterized in the middle to late term ovine placenta. Ovine placental growth is maximal at 55 days post coitus (dpc), and exposure to high ambient temperatures during this period results in decreased placental mass and fetal intrauterine growth restriction. This study examines placental tissue bFGF production of single and twin bearing ewes, following exposure to either hyperthermic (HT) conditions (402C 12 h/d, 352C 12 h/d; 30% relative humidity, RH), or thermoneutral (TN) conditions (202C), during early placental development. Ewes were exposed to either a HT (single n=5, twin n=7) or TN (single n=5, twin n=5) environment starting at 40 dpc, and placental tissue was collected at approximately 55dpc. Placental and fetal tissues were collected and weighed. Fetal cotyledonary tissue was manually separated from maternal caruncular tissue, and each tissue minced and placed in explant culture for 24 h. bFGF concentrations were evaluated by ELISA. Data were analyzed by analysis of variance and are presented as mean sem. Total twin HT placenta weight was similar to single placenta, but was reduced when compared to twin TN placenta (p<0.03). Individual twin fetal weights were reduced compared to singleton weights (p<0.02), though treatment had no effect. Liver weights were also reduced in twins, and HT twin liver weights were reduced compared to TN twin livers (p<0.05). Single and twin fetal cotyledon bFGF production was similar across temperature treatments. However, HT twin bFGF-caruncle production was greater than TN twin bFGF-caruncle production (HT; 3.81.0 vs. 2.10.3 pg/mg, p<0.002). Our data indicate that during maximal placental growth, the caruncle is the predominant source of placental bFGF. Maternal caruncle-derived bFGF could act in a paracrine fashion to promote proliferation and differentiation of maternal placental tissue, implicating bFGF's importance in the early establishment of the placenta. Furthermore, increased bFGF production by twin HT placenta, could act to stimulate increased angiogenesis, potentially compensating for reduced placental mass. .

Keywords: bFGF Placenta PI-IUGR

This abstract is being presented at: 8:00 AM in session:
Implantation and Early Development