UC San Diego

Hypoplastic left heart syndrome is the leading cause of death among infants with congenital heart defects. Through analysis of wild type cells and cells exposed to a mechanically altered in-vivo environment across key developmental stages, we analyze how hemodynamic perturbations alter mechanosensitive cellular and nuclear remodeling.In this study, we assess morphological changes in cytoplasmic and nuclear areas, lamin A/C fluorescence, and yes-associated protein nuclear localization across substrate stiffness, developmental stage, and physiological state. We expose cells to an altered in-vivo mechanical environment, in the form of left-atrial ligation (LAL), and examine subsequent changes in cellular behavior on different substrate stiffnesses. We found that these three factors differentially regulated cell morphology. Mechanical perturbation of the in-vivo environment disrupted mechanosensation across gel stiffness conditions, often reducing sensitivity to developmental stage. The stiff 40 kPa condition caused cells to adopt wider spread triangular morphologies with less sensitivity to developmental stage or LAL due to high extracellular stress. The soft 0.3 kPa condition deviated from the native 1-2 kPa condition due to low extracellular tensile forces. These cells spread uniaxially as they developed, initially adopting more compact conformations than the 1-2 kPa cells but spreading farther at HH31. Lamin A/C intensity trends reflected this behavior, demonstrating relative insensitivity at 40 kPa and a reversal of stage-specific response at 0.3 kPa. An enhanced understanding of mechanosensitive responses across stiffness, stage, and physiological condition allows for better characterization of cardiac disease progression, which can improve detection and serve as a basis for regenerative strategies.