Late Breaking Abstract - Extracellular Vesicles as a Delivery System for Gene Editing to Cure Alpha 1 Antitrypsin Deficiency

Alpha1 antitrypsin (AAT) deficiency (AATD) is an autosomal codominant disease caused by mutations in the SERPINA1 gene, leading to liver and lung disease. Patients develop symptoms of lung involvement at older age and include shortness of breath, chronic bronchitis, bronchial obstruction with declining forced expiratory volume (FEV1), and progressive emphysematous lung destruction, as seen in decreasing CT lung density. Standard treatment involves weekly intravenous augmentation with plasma-purified human AAT. Our aim is to test a novel approach that uses Base Editors (BE) to correct the mutation and extracellular vesicles (EVs) to deliver them. To test our hypothesis, we employed different cell lines as in vitro model and Pallid mice as in vivo model. The protospacer adjacent motif (PAM) sequence was designed for DNA base editing to specifically recognize the mutation present in Pallid mice, facilitating the editing of the pathogenic base pair. PAM is encapsulated in EVs, which act as nanocarriers (approximately 100 nm in diameter) to specifically target hepatocytes. We have standardized the induction, isolation, storage, and engineering of EVs. We demonstrated homing properties in vitro using different cell types, in vivo on mice, and ex vivo on hepatocytes. We demonstrated efficient uptake within 24 to 48 hours, when labeled EVs can be specifically taken up by hepatocytes, transporting plasmids as nanocarriers. This study establishes a targeted, cell-specific, non-viral BE method for safe in vitro and in vivo gene editing. The non-viral, cell-specific gene editing technique holds promise for clinical application as a therapeutic option for patients with AATD.