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

Mol Ther. 2020 Apr 8;28(4):1177-1189. doi: 10.1016/j.ymthe.2020.01.005. Epub 2020 Jan 14.


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.

Keywords: AAV; ALS; CRISPR-Cas9; SOD1; base editor; gene editing; gene therapy; neurodegeneration; split intein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amyotrophic Lateral Sclerosis / genetics
  • Amyotrophic Lateral Sclerosis / therapy*
  • Animals
  • CRISPR-Associated Protein 9 / metabolism*
  • Codon, Nonsense
  • Dependovirus / genetics*
  • Disease Models, Animal
  • Gene Editing
  • Genetic Vectors / administration & dosage
  • HEK293 Cells
  • Humans
  • Injections, Spinal
  • Inteins
  • Male
  • Mice
  • Mice, Transgenic
  • Streptococcus pyogenes / enzymology
  • Superoxide Dismutase-1 / genetics*
  • Trans-Splicing
  • Treatment Outcome


  • Codon, Nonsense
  • Sod1 protein, mouse
  • Superoxide Dismutase-1
  • CRISPR-Associated Protein 9