Endocardial cell heterogeneity at the origin of valvular cell clones

Abstract

Valves are affected in 1/3 of cardiac congenital diseases. Cardiac valves derive from the process of endothelial-mesenchymal transition (EMT) of endocardial cells in the atrioventricular canal (AVC) and in the outflow tract of embryonic mouse hearts at E9.5 and E10.5, respectively. The origin and fate of endocardial cells as well as how EMT is specifically triggered in a subset of the latter are still poorly understood. To determine the extent of endocardial cells and valvular cells heterogeneity and in turn to assess whether endocardial cells are already committed to a valvular specific cell type. Clonal analysis: a genetic labeling of endocardial valve progenitors was performed using Brainbow and CAGERT2Cre mouse strains. Single cell sequencing: Tie2Cre/− male was bred with RosatdTomato females. AVC cells were dissected out from E9.5 embryos. Mitral valve leaflets were dissected out from both E16.5 and P0 mice. All cells were enzymatically dissociated and tomato+ cells sorted out by FACS and used for single cell RNA sequencing using the 10X genomics technology. Preliminary results point to a cell heterogeneity in each cell population so far investigated. A full panel of both clonal analysis and single cell RNA analysis will be presented.