Sexually Dimorphic Effect of Shear Stress Using Porcine Aortic Valve Endothelial Cells

Abstract

Congenital heart valve defects (CHVD) and their concomitant valvular diseases are increasingly considered sexually dimorphic. Bicuspid aortic valve (BAV), the most common CHVD, occurs in approximately 1.5% of individuals with a 46,XY karyotype, a threefold higher prevalence than those with 46,XX. Fibrosis is the most common valvular degenerative pathway in 46,XX patients while calcifications are more common in 46,XY with BAV. This suggests that sex chromosomes influence AV homeostasis and highlight the importance of considering biological sex for AV in-vitro studies. The objective of this investigation is to define functional and transcriptional differences between 46,XX and 46,XY porcine aortic valve endothelial cells (PAVECs). PAVECs were isolated from hearts of male and female young adult pigs and sorted for CD31 expression. Baseline properties and response of cell monolayers to shear stress using a cone-plate viscometer were characterized using microscopy, flow cytometry, qRT-PCR, and functional assays. We pooled 46,XY and 46,XX PAVECs from 6 hearts each and sorted them to at least 95% purity. 46,XX PAVECs showed less cellular alignment at all shear stress magnitudes compared to 46,XY. qRT-PCR after shear stress showed significant upregulation of vWF in 46,XY while being significantly downregulated in 46,XX. VCAM1 was significantly upregulated in both karyotypes but at different shear stress magnitudes. Despite similar baseline phenotypes, 45,XY PAVECs respond differently to shear stress than a 46,XX karyotype. This suggests that the karyotype may influence the cellular response to other functional assays and support the need to include biological sex as a factor in cardiovascular in-vitro studies.