Abstract 18558: Modeling Cardiac Amyloidosis: Insights Into Pathogenesis and Therapeutic Strategies

Abstract

Introduction: Cardiac transthyretin (TTR) amyloidosis is an underdiagnosed cause of heart failure and cardiac arrhythmias. The lack of relevant human cardiac tissue models hinders understanding of the underlying mechanisms and development of effective treatments. Hypothesis: We aimed to establish an in vitro model of cardiac amyloidosis using human-induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) and aggregated TTR and investigate cellular changes and potential therapeutic targets. Methods: Wild-type and mutated TTR proteins were aggregated and added to hiPSC-CM cultures directly or embedded in Matrigel used for culture-plate coating. Single-cell and two- and three-dimensional hiPSC-CM models were used for real-time microscopy, calcium and voltage imaging, immunostaining, apoptosis, ROS assays, and proteomics studies with mass spectrometry. Results: Immunohistochemical and histological staining confirmed the deposition of TTR aggregates within the hiPSC-CM tissue models. Cells exposed to TTR aggregates exhibited increased apoptosis and increased production of reactive oxygen species (ROS). TTR-treated cells also displayed irregular calcium transients, characterized by oscillating calcium peaks and double-humped signals. The presence of TTR also induced morphological changes, including cell shrinkage at the single-cell level and the formation of holes in 2D hiPSC-CM cell sheets due to cell migration and apoptosis. These holes led to conduction abnormalities and the development of reentrant arrhythmias, specifically spiral waves. The severity of these abnormalities was markedly increased when mutant TTR aggregates were used. Proteomics studies suggest a potential involvement of the mTOR signaling pathway in the pathogenesis of cardiac amyloidosis. Conclusions: Our in vitro model successfully recapitulated key features of cardiac amyloidosis and revealed significant protein expression changes. These findings provide valuable insights into disease pathogenesis and potential therapeutic targets and highlight the utility of our model for studying cardiac amyloidosis for the development and evaluation of novel therapeutic strategies.