Abstract 15406: Loss of Estrogen Receptor α Inhibits Angiogenic Function in Right Ventricular Endothelial Cells (RVECs)

Abstract

Introduction: Right ventricular failure (RVF) is the leading cause of death in patients with pulmonary hypertension (PH). While the pathophysiology of RVF is complex and multifactorial, insufficient angiogenesis and impaired RV endothelial cell (RVEC) function have been identified as key contributors. 17β-estradiol (E2), the most abundant female sex steroid, exerts RV-protective effects including stimulation of angiogenesis. However, the mechanism underlying E2’s pro-angiogenic function are unknown. Hypothesis: Estrogen Receptor (ER) α is necessary for RV angiogenesis. Methods: To identify the role of ERα in RVEC function and RV angiogenesis, ERα loss-of-function mutant (ERα Mut ) rats were generated by CRISPR-Cas9. In vivo studies were performed in both male and female wild-type (WT) and ERα Mut rats. RV capillary density was assessed by immunofluorescence. RVECs were isolated from male or female WT and ERα Mut rats. Angiogenic function was evaluated by matrigel tube formation assay at 10h. RVEC proliferation (at 24h) was measured by Incucyte image-based analysis and Thymidine incorporation assay. RVEC migration (at 24h) was examined by transwell migration assay. Angiogenesis mediators in RVECs were quantified via Western Blot. P<0.05 was considered significant. Results: Female WT rats exhibited increased RV capillary density compared to males (p<0.001). However, loss of functioning ERα decreased RV capillary density (p<0.05). Loss of ERα impaired proliferation (24h) capability in female, but not male, RVECs (p<0.001). On the other hand, male, but not female, ERα Mut RVECs exhibited reduced cell migration in response to VEGF-A (p<0.01). Loss of ERα reduced RVEC tube formation in both sexes (p<0.05). At a molecular level, male ERα Mut RVECs expressed less VEGF-A, angiopoietin-2, and Id1 than WT (p<0.01) . Conclusions: ERα is necessary for RVEC angiogenic function. However, ERα effects on angiogenesis are sexually dimorphic. Male ERα Mut RVECs exhibit reduced cell migration potential and less angiogenesis mediators, whereas female ERα Mut RVECs exhibit decreased proliferation potential in vitro and reduced female RV capillary density in vivo . Targeting ERα may allow for sex-specific therapies aimed at enhancing RV adaptation in PH.