Evaluation of ARMMs-mediated delivery of Cas9 protein complexed with gRNAs as a non-viral disease-modifying strategy for Friedreich’s Ataxia

Excision of the pathogenic GAA repeat expansion from at least one of the FXN alleles has the potential to be a transformative therapy for FA patients, as it does not carry the same potential for toxicity as gene therapy approaches delivering high levels of frataxin using Adeno-Associated Virus (AAV). Unfortunately, despite significant advances in gene editing technologies, like the ones using the CRISPR-Cas9 system, there are limited options for safe, transient, and targeted delivery to disease-affected cell types of these gene editing tools. ARRDC1-Mediated Microvesicles (ARMMs) are a distinct class of extracellular vesicles derived from the cell membrane that are produced through the activity of the protein ARRDC1. Vesigen Therapeutics has developed approaches to engineer their ARMMs to load a variety of cargos, including the tools necessary for genome editing of the GAA repeats. Payloads such as the gene editor Cas9 can be attached to ARRDC1, which actively recruits the cargo into engineered ARMMs. This proposal sets out to evaluate the use of ARMMs as a non-viral delivery vehicle for genome editing tools to excise the pathogenic repeat expansion in FXN. One challenge in this work will be successfully engineering ARMMs to target the tissues most affected in FA, specifically the proprioceptive system, which is responsible for the ability to sense body position and movement and whose early loss in FA leads to limited ambulatory capacity in patients.