Asymmetric Cellular and Structural Contributions to Cusp-Specific Remodeling and Malformation in the Aortic Valve

Abstract

The tricuspid aortic valve (AoV) comprises three cusps—left coronary (LCC), right coronary (RCC), and non-coronary (NCC)—that experience distinct hemodynamic environments, cellular distributions, and pathological susceptibilities. While the NCC consistently bears the highest calcific burden in calcific aortic valve disease (CAVD), the basis for this asymmetry remains poorly defined. Here, we investigated whether anatomical, hemodynamic, extracellular matrix (ECM), and transcriptomic differences contribute to asymmetric cusp remodeling and congenital bicuspid AoV (BAV) malformations.

Using a chronic kidney disease-induced mouse model of CAVD, we found no correlation between coronary ostium position and calcification burden. Instead, NCCs showed significantly greater calcification than LCCs, despite comparable or even lower wall shear stress. ECM analysis revealed that LCCs contain more elastin and collagen than NCCs or RCCs, yet these properties did not predict the observed asymmetry in calcification. Spatial transcriptomics demonstrated distinct gene expression profiles across cusps, with the LCC showing downregulation of melanocytic genes (Dct, Tyrp1, Pmel) and the NCC enriched in pro-calcific and contractile markers (Myh11, Palmd). These findings suggest that differential embryonic cell infiltration—particularly cardiac neural crest and second heart field populations—may impart lasting regional phenotypic differences. Additionally, genetic loss of melanocytic pigmentation reduced both BAV penetrance and calcification in eNOS-deficient mice, further implicating pigment-producing cells in AoV development and disease.

Together, these results highlight the critical role of asymmetric cellular composition in driving cusp-specific vulnerability to calcification and congenital malformation, offering new insights into non-mechanical contributors to AoV pathophysiology.