Adenine Base Editing Reduces Misfolded Protein Accumulation and Toxicity in Alpha-1 Antitrypsin Deficient Patient iPSC-Hepatocytes

AbstractAlpha-1 antitrypsin deficiency (AATD) is most commonly caused by the Z mutation, a single base substitution, which leads to AAT protein misfolding and associated liver and lung disease. In this study, we apply adenine base editors to correct the Z mutation in patient-induced pluripotent stem cells (iPSCs) and iPSC-derived hepatocytes (iHeps). We demonstrate that correction of the Z mutation in patient iPSCs reduces aberrant AAT accumulation and increases its secretion. Adenine base editing (ABE) of differentiated iHeps decreases ER stress in edited cells as demonstrated by single-cell RNA sequencing. We find ABE to be highly efficient in iPSCs and do not identify off-target genomic mutations by whole genome sequencing. These results reveal the feasibility and utility of base-editing to correct the Z mutation in AATD patient cells.