Development of Human iPSC-based Microphysiogical Models of Transthyretin Amyloid Cardiomyopathy.

Transthyretin (TTR) amyloid cardiomyopathy (ATTR-CM) is a restrictive cardiac disease caused by the deposition of TTR in the heart. TTR is synthesized by hepatocytes and circulates as a homotetramer carrying complex for thyroxine and retinol. Mutations in TTR destabilize the tetramer promoting its dissociation into monomers that can enter the heart and aggregate into amyloid fibrils driving cytotoxicity, fibrosis, impaired electrical conductivity, and progressive cardiac dysfunction. Mechanistic studies and therapeutic development have been limited by the lack of physiologically relevant human preclinical models. Here we describe the creation of two in vitro models of ATTR-CM using human iPSC-derived cells. First, a custom microphysiological chip containing co-cultured hepatic and cardiac organoids in isolated chambers connected by microchannels enabling free passage, including hepatocyte synthesized TTR122VI, which diffuses to and is taken up by cardiac organoids recapitulating pathologic hepatic-cardiac crosstalk. Cardiac organoids exposed to TTRV122I exhibited increased oxidative stress, elevated cytotoxicity, and upregulation of fibronectin. Second, engineered heart tissues cultured with monomeric TTRV122I demonstrated TTR uptake, reduced contractility, and prolonged relaxation time that mirrors cardiac dysfunction observed clinically. These novel human-based models recapitulate key biochemical, cellular, and functional features of ATTR-CM, providing translational platforms to elucidate disease mechanisms and evaluate novel therapeutic strategies.