Treatment of a Mouse Model of ALS by In Vivo Base Editing

• Published in: Molecular therapy Vol. 28; no. 4; pp. 1177 - 1189
• Main Authors: Lim, Colin K.W., Gapinske, Michael, Brooks, Alexandra K., Woods, Wendy S., Powell, Jackson E., Zeballos C., M. Alejandra, Winter, Jackson, Perez-Pinera, Pablo, Gaj, Thomas
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 08.04.2020; American Society of Gene & Cell Therapy
• Subjects: AAV; ALS; Amyotrophic Lateral Sclerosis - genetics; Amyotrophic Lateral Sclerosis - therapy; Animals; base editor; Codon, Nonsense; CRISPR-Associated Protein 9 - metabolism; CRISPR-Cas9; Dependovirus - genetics; Disease Models, Animal; Gene Editing; gene therapy; Genetic Vectors - administration & dosage; HEK293 Cells; Humans; Injections, Spinal; Inteins; Male; Mice; Mice, Transgenic; neurodegeneration; Original; SOD1; split intein; Streptococcus pyogenes - enzymology; Superoxide Dismutase-1 - genetics; Trans-Splicing; Treatment Outcome; base editor; CRISPR-Cas9; AAV; split intein; ALS; neurodegeneration; gene therapy; gene editing; SOD1
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2020.01.005

Amyotrophic lateral sclerosis (ALS) is a debilitating and fatal disorder that can be caused by mutations in the superoxide dismutase 1 (SOD1) gene. Although ALS is currently incurable, CRISPR base editors hold the potential to treat the disease through their ability to create nonsense mutations that can permanently disable the expression of the mutant SOD1 gene. However, the restrictive carrying capacity of adeno-associated virus (AAV) vectors has limited their therapeutic application. In this study, we establish an intein-mediated trans-splicing system that enables in vivo delivery of cytidine base editors (CBEs) consisting of the widely used Cas9 protein from Streptococcus pyogenes. We show that intrathecal injection of dual AAV particles encoding a split-intein CBE engineered to trans-splice and introduce a nonsense-coding substitution into a mutant SOD1 gene prolonged survival and markedly slowed the progression of disease in the G93A-SOD1 mouse model of ALS. Adult animals treated by this split-intein CRISPR base editor had a reduced rate of muscle atrophy, decreased muscle denervation, improved neuromuscular function, and up to 40% fewer SOD1 immunoreactive inclusions at end-stage mice compared to control mice. This work expands the capabilities of single-base editors and demonstrates their potential for gene therapy. Lim et al. establish a trans-splicing system to deliver CRISPR base editors in vivo that enables treatment of a mouse model of ALS. They show that base editing can increase survival and slow the progression of disease.