Poster abstracts

Poster number 10 submitted by Madeline Burghaze

Right Ventricle Fibroblasts Display a Hyperfibrotic Phenotype In Vitro

Madeline Burghaze (Department of Surgery, Ohio State University Wexner Medical Center), Matthew Gorr (Department of Surgery, Ohio State University Wexner Medical Center)

Abstract:
Pulmonary hypertension (PH) is a disease that can lead to right ventricular (RV) fibrosis and failure due to pressure overload. The RV develops more severe fibrosis in response to pressure overload than the left ventricle (LV), which may contribute to the fact that clinical outcomes of RV failure are worse than those of LV disease. As the RV has been found to contain a unique molecular and cellular makeup, we hypothesize that RV fibroblasts (RVfibs) carry out distinct mechanisms of disease that lead to exaggerated fibrosis. To characterize fibroblast activation at baseline and during PH, we used the Sugen-Hypoxia (SuHx) rat model (20 mg/kg SU5416 and 3 weeks of hypoxia at 10% O2) to recapitulate PH at both the compensatory stage of cardiac remodeling (3 weeks post-hypoxia, SuHx 3(+3)) and the point of failure (6 weeks post-hypoxia, SuHx 3(+6)), which was confirmed by echocardiography and invasive pressure catheter measurements. RVfibs and LV fibroblasts (LVfibs) isolated by enzymatic digestion were cultured separately for analysis of fibrotic gene expression by qPCR, oxygen consumption rate (OCR) by Seahorse assay, and proliferation by CyQuant assay. We found RVfibs display higher TGFβ-induced fold-change in periostin expression versus LVfibs and increase in cell number twice as much as LVfibs over a 3 day period (p<0.05 via t-test). The proliferation rate of LVfibs isolated from SuHx 3(+3) and SuHx 3(+6) rats do not change from that of baseline LVfibs, while SuHx 3(+3) and SuHx 3(+6) RVfibs appear to match LVfibs in proliferative rate as opposed to baseline RVfibs. RVfibs also trended towards having a greater OCR than LVfibs. Thus, RVfibs exhibit amplified proliferation, fibrotic gene expression, and OCR, suggesting an elevated capacity for fibrotic response compared to LVfibs. Future experiments will focus on determining the mechanisms of this phenotype and may identify therapeutic targets for PH treatment that lessen the severity of RV fibrosis.

Keywords: Cardiac Fibrosis, Right Ventricle, Pulmonary Hypertension