Porcine and human aortic valve endothelial and interstitial cell isolation and characterization

Abstract

Background: Calcific aortic valve stenosis is defined by pathological changes in the aortic valve and their predominant cell types: valvular interstitial (VICs) and endothelial cells (VECs). Understanding the cellular and molecular mechanisms of this disease is a prerequisite to identify potential pharmacological treatment strategies. In this study, we present a unique aortic valve cell isolation technique to acquire specific human and porcine cell populations and compared VICs and VECs of these species with each other for the first time. Methods and Results: Aortic valve cells were isolated from human explants from patients undergoing surgical aortic valve replacement or porcine valvular tissue. Pure VEC and VIC populations could be verified by gene expression analysis and immunofluorescence staining showing a highly significant upregulation of endothelial markers in VECs and mesenchymal markers in VICs, respectively. Further analysis and comparison of cells in in vitro experiments revealed that endothelial-to-mesenchymal transition could be induced in hVECs, leading to significant increase of mesenchymal markers. In vitro calcification experiments of VICs induced by osteogenic medium or pro-calcifying medium demonstrated a pronounced calcification marker expression and visible calcific deposition in Alizarin red staining in both species. Conclusion: This study aims to initiate a first step towards standardization of a reproducible isolation technique for pure human and porcine VEC and VIC populations. A comparison of human and porcine aortic valve cells demonstrated that porcine cells might serve as an alternative cellular model system, in settings, where human tissues are difficult to obtain.