AAV-based CRISPR-Cas9 genome editing: Challenges and engineering opportunities

Recent innovations in the field of gene therapy have paved the way for advances towards developing genome editing medicines. Despite these steps forward, challenges with viral delivery of genome editing tools persist. Efforts currently underway include developing next-generation genome editors, overcoming adeno-associated virus (AAV) packaging restrictions, improving AAV genome integrity, engineering novel AAV capsids, and minimizing the immune response. This review discusses current challenges in delivering CRISPR-Cas nuclease-based genome editing therapies using AAV and highlights emerging methods to overcome these obstacles. This includes developing smaller payloads and regulatory elements, advancing novel sequencing methods for vector characterization, engineering capsids with enhanced potency, tissue-selectivity, and ability to evade pre-existing antibodies, controlling transgene expression, and minimizing the immune response to Cas proteins.