A4 - AAV Vectors - Preclinical and Proof-of-Concept In-Vivo Studies (Excluding Non-Human Primates)
1002: Gene Editing Strategies to Treat Spinocerebellar Ataxia Type 1
Type: Poster Session
Poster Board Number: 1002
Presentation Details
Session Title: Thursday Posters: AAV Vectors - Preclinical and Proof-of-Concept In Vivo Studies
Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurogenetic disease caused by expansion of the polyglutamine repeat region in ATXN1. Normal ATXN1 alleles contain 6-42 CAG repeats with interspersed CAT nucleotides, while disease alleles have 39-100+ uninterrupted CAG repeats. SCA1 patients present with cerebellar Purkinje cell (PC) loss, progressive loss of motor coordination, respiratory issues and eventual death. Currently there are no disease modifying treatments; however, previous work from our laboratory has demonstrated the potential of gene therapy as a treatment modality, specifically RNAi. Here, we tested two CRISPR-Cas9 strategies aimed to reduce ATXN1; a single guide RNA (gRNA) that targets near the exon-exon junction to induce nonsense mediated decay and a second approach which employs a dual guide system to excise the CAG repeat region. Both single and dual gRNA strategies significantly reduced ATXN1 RNA by 56% and 57%, respectively when screened in HEK-Cas9 cells. Next, we tested for editing in human cells and in mice models. SCA1 patient iPSCs and unaffected matched sibling donors were differentiated into neuronal progenitor cells and transgenes expressing SpCas9 and dual gRNAs were delivered via AAV1. Treated experimental cells showed full CAG deletion. In B05 mice, a transgenic model of SCA1 that expresses human ATXN1 (hATXN1) with 82 uninterrupted CAG repeats under a PC-specific promoter, co-delivery of Cas9 and gRNA reduced ATXN1 mRNA levels by 36% (dual gRNAs) and 54% (single gRNA), respectively. Additionally, rotarod performance by B05 mice treated with the single gRNA strategy was significantly better than vehicle-treated B05 mice and not statistically different from wild-type animals. Importantly, there was no increase in inflammatory markers in treated animals. In combination, these data present CRISPR-Cas9 as a potential approach for SCA1 therapy.
Plain Language Summary
In this study, two CRISPR-Cas9 strategies successfully reduced ATXN1 RNA in cell lines and induced a full CAG deletion in patient-derived cells. Mouse models exhibited reduced ATXN1 levels and improved motor coordination. No increased inflammation was observed. These findings suggest CRISPR-Cas9 as a potential therapeutic avenue for SCA1.
Kelly Fagan1, Guillem Chillon1, Ellie Carrell2, Beverly L. Davidson2
1University of Pennsylvania, Philadelphia, PA,2Children's Hospital of Philadelphia, Philadelphia, PA"
Find This Session