Leviev Heart Center, Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Cardiac Research Lab, Felsenstein Medical Research Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Leviev Heart Center, Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Heart Rhythm. 2017 Jul;14(7):1053-1060. doi: 10.1016/j.hrthm.2017.03.025. Epub 2017 Mar 20.
The recessive form of catecholaminergic polymorphic ventricular tachycardia 2 (CPVT2) is caused by mutations in cardiac calsequestrin (CASQ2), leading to protein deficiency.
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.
We used a murine model of CPVT2 caused by the D307H human mutation (CASQ2) or CASQ2 knockout (CASQ2). Adeno-associated virus (AAV) particles containing the CASQ2 gene (AAV) 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.
CASQ2 mice injected intracardiacally with AAV expressed 40% ± 25% of the normal CASQ2 protein level, which was increased compared to untreated CASQ2 mice (n = 10; P < .05). Intraperitoneal therapy led to a significantly elevated expression of the CASQ2 protein, which was comparable in CASQ2 (n = 12) and CASQ2 (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 AAV-treated mice (0 of 26; P < .001 vs controls).
AAV 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.
儿茶酚胺多形性室性心动过速 2 型（CPVT2）的隐性形式是由心脏肌浆网钙结合蛋白（CASQ2）的突变引起的，导致蛋白缺乏。
本研究旨在开发 CPVT2 的病毒基因治疗方法，并确定 CASQ2 表达与在小鼠模型中的抗心律失常疗效之间的关系。
我们使用 CPVT2 的小鼠模型，该模型由人类突变（CASQ2）或 CASQ2 敲除（CASQ2）引起。含有 CASQ2 基因（AAV）的腺相关病毒（AAV）颗粒被注射到 12 周龄的小鼠心脏或腹腔内。植入遥测设备，在基因治疗后 7-8 周对小鼠进行激发试验。
心内注射 AAV 的 CASQ2 小鼠表达了正常 CASQ2 蛋白水平的 40%±25%，与未治疗的 CASQ2 小鼠（n=10；P<.05）相比有所增加。腹腔内治疗导致 CASQ2 蛋白的表达显著升高，在 CASQ2（n=12）和 CASQ2（n=4）小鼠中相当。所有 CPVT2 对照小鼠均发生非持续室性心动过速（VT），13 只中有 8 只在激发时发生持续 VT。表达≥正常 CASQ2 水平的 33%是预防非持续 VT 以及应激诱导的室性期前收缩所必需的。较低的表达水平可防止 AAV 治疗的小鼠发生持续 VT（26 只中 0 只；P<.001 与对照组相比）。
AAV 具有持久减轻和潜在治愈 CPVT2 的能力。系统给药是可行且方便的，可重复性地提供足够水平的转基因表达。抗心律失常疗效取决于 CASQ2 水平：需要正常 CASQ2 水平的≥33%来预防心律失常。然而，即使较低的蛋白水平也能防止持续的 VT，从而降低猝死的风险。
