Advanced Disease Models of Amyloid Cardiomyopathy: From 2D In Vitro Systems to 3D Engineered Tissues and In Vivo Models

Cardiac amyloidosis is characterized by the deposition of misfolded light chain (AL) or transthyretin (TTR) fibrils. These fibrils are extremely insoluble, rigid and resistant to proteolytic cleavage, and their accumulation in the extracellular space results in altered cardiac tissue architecture and heart dysfunction. However, definitive diagnosis of cardiac amyloidosis remains challenging because of non-specific clinical manifestations, multi-organ involvement and the lack of specific biomarkers. Also, a lack of representative preclinical models that recapitulate cardiac amyloidosis pathophysiology has hindered the understanding of disease mechanisms and the development of effective therapies.
This thesis describes the development and characterization of novel in vitro (2D and 3D) and in vivo (mouse) models for both AL and ATTR amyloid cardiomyopathy. We utilized human induced pluripotent stem cell (iPSC)-derived cardiomyocytes, iPSC-derived fibroblasts, and endothelial cells in 2D and 3D (spheroid and cardiac microtissue) levels. These models revealed cell-type-specific cytotoxicity from patient-derived LCs (AL) and TTR fibrils (ATTR). Notably, 3D ATTR microtissues incorporating patient-derived amyloid seeds successfully modeled native-like fibril aggregation and recapitulated key aspects of both early and late disease stages.
Furthermore, we established novel humanized knock-in mouse models (hTTRwt and hTTRV122I) that developed progressive ATTR cardiomyopathy. Mechanistic studies in these mice identified the accessory protein Vitronectin (VTN) as a key driver for cardiac TTR deposition. This VTN-promoted deposition disrupts integrin αvβ3/FAK/Akt signaling, leading to mitochondrial dysfunction.
Collectively, these advanced preclinical models provide crucial insights into the complex cellular and molecular mechanisms of cardiac amyloidosis, offering robust platforms for the discovery and validation of novel diagnostic and therapeutic targets.