Abstract
Background The recessive form of catecholaminergic polymorphic ventricular tachycardia 2 (CPVT2) is caused by mutations in cardiac calsequestrin (CASQ2), leading to protein deficiency. Objectives The aims of this study were to develop a viral-delivered gene therapy for CPVT2 and to determine the relationship between CASQ2 expression and antiarrhythmic efficacy in a murine model. Methods We used a murine model of CPVT2 caused by the D307H human mutation (CASQ2D307H) or CASQ2 knockout (CASQ2Δ/Δ). Adeno-associated virus (AAV) particles containing the CASQ2 gene (AAVCASQ2) were injected into the heart or intraperitoneally to 12-week-old mice. A telemetry device was implanted, and mice underwent provocation testing 7–8 weeks after gene therapy. Results CASQ2Δ/Δ mice injected intracardiacally with AAVCASQ2 expressed 40% ± 25% of the normal CASQ2 protein level, which was increased compared to untreated CASQ2Δ/Δ mice (n = 10; P <.05). Intraperitoneal therapy led to a significantly elevated expression of the CASQ2 protein, which was comparable in CASQ2D307H (n = 12) and CASQ2Δ/Δ (n = 4) mice. All control mice with CPVT2 had nonsustained ventricular tachycardia (VT) and 8 of 13 had sustained VT on provocation. Expressing ≥33% of the normal CASQ2 level was needed to protect from nonsustained VT as well as stress-induced premature ventricular contractions. Lower levels of expression prevented sustained VT in AAVCASQ2-treated mice (0 of 26; P <.001 vs controls). Conclusion AAVCASQ2 displays a long-lasting capacity to attenuate and potentially cure CPVT2. Systemic delivery is feasible and convenient, reproducibly providing adequate levels of transgene expression. Antiarrhythmic efficacy depends on the CASQ2 level: ≥33% of the normal CASQ2 level is needed to prevent arrhythmia. However, even lower levels of protein protect from sustained VT, thereby potentially reducing the risk of sudden death.
Original language | English |
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Pages (from-to) | 1053-1060 |
Number of pages | 8 |
Journal | Heart Rhythm |
Volume | 14 |
Issue number | 7 |
DOIs | |
State | Published - Jul 2017 |
Bibliographical note
Publisher Copyright:© 2017 Heart Rhythm Society
Funding
This work was supported by the Israel Science Foundation (grant no. 763/10).
Funders | Funder number |
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Israel Science Foundation | 763/10 |
Keywords
- Adeno-associated virus
- CPVT
- Calsequestrin
- Gene therapy
- Ventricular arrhythmia