ABSTRACT
Hereditary transthyretin amyloidosis (ATTR amyloidosis) is a multi-system, autosomal dominant protein folding disorder that results from over 100 described mutations in the transthyretin (TTR) gene. Here, we employed a universal gene editing strategy in patient-specific, induced pluripotent stem cells (iPSCs) that allows for the amelioration of all TTR genetic lesions, thereby eliminating the production of destabilized, disease-causing variants. Mass spectrometric analysis of corrected iPSC-derived hepatic supernatants revealed elimination of mutant TTR, resulting in diminished neuronal target cell toxicity. This procedure also allowed for the interrogation of global transcriptomic differences between control iPSC-derived hepatocyte-like cells (HLCs) and those expressing the most proteotoxic disease-causing TTR mutation. By employing single cell RNA sequencing (scRNAseq) to compare syngeneic corrected and uncorrected ATTR amyloidosis iPSC-derived HLCs, we found distinct transcriptional changes in cells expressing the disease-associated TTR mutant, including activation of unfolded protein response (UPR)-associated signaling pathways shown to protect the extracellular space from proteotoxic TTR aggregation. Results from these studies represent a potential cell-based therapeutic strategy for treating all forms of ATTR amyloidosis and challenge the notion that ATTR livers are unaffected in disease pathogenesis, highlighting possible biomarkers for this notoriously difficult to diagnose disease.