Endothelial Notch signaling as a target for aortic valve calcification

Introduction Calcific aortic valve disease (CAVD) is the third most common type of heart disease in developed countries, and no medical treatment is currently available. The Notch signaling pathway is among the molecular pathways implicated in CAVD pathogenesis and may represent a potential therapeutic target. However, its exact role remains incompletely understood. Objective The study evaluated Notch-dependent regulatory mechanisms of cross-talk between aortic valve endothelial cells and aortic valve interstitial cells in pathological osteogenic differentiation. Methods Primary human aortic valve endothelial and interstitial cells (VEC and VIC) were isolated from patients with CAVD and healthy donors. Notch was activated by lentiviral transduction with Notch1 intercellular domain (NICD). shRNA-mediated knockdown of RBPJ (DNA-binding protein for NICD interaction) was employed to inhibit Notch activity. Osteogenic differentiation was induced by cultivating the cells in osteogenic medium. Results This report shows that activating Notch in VEC when co-culturing them with VIC leads to an increase in osteogenic differentiation, while inhibiting Notch by small hairpin RNA to the RBPJ gene (shRBPJ) suppresses osteogenic differentiation. VEC from CAVD patients, have dysregulated Notch signaling and significantly enhance osteogenic differentiation when co-cultured with VIC. Conclusion Notch signaling pathway is dysregulated in VEC from patients with CAVD. This contributes to disruption of normal cross-talk between endothelial and interstitial cells in the valve and increases sensitivity to pro-osteogenic stimuli. The effect on Notch in VEC may be a powerful target for treatment of CAVD.