Tenaya Therapeutics, Inc, South San Francisco, CA (H.Z., J.Y., C.S., A.Z., I.W., E.C.L., T.N.Q., C.A.R., E.R.N., E.X., Z.D., T.M.A.M., F.F., A.F., J. Liu, S.J., C.F., T.W.C., F.J., W.S.P., J. Lin, T.H., K.N.I., L.M.L.).
Gladstone Institutes, San Francisco, CA (P.Y., D.S.).
Circulation. 2023 Oct 3;148(14):1099-1112. doi: 10.1161/CIRCULATIONAHA.122.061542. Epub 2023 Aug 21.
Cardiac reprogramming is a technique to directly convert nonmyocytes into myocardial cells using genes or small molecules. This intervention provides functional benefit to the rodent heart when delivered at the time of myocardial infarction or activated transgenically up to 4 weeks after myocardial infarction. Yet, several hurdles have prevented the advancement of cardiac reprogramming for clinical use.
Through a combination of screening and rational design, we identified a cardiac reprogramming cocktail that can be encoded in a single adeno-associated virus. We also created a novel adeno-associated virus capsid that can transduce cardiac fibroblasts more efficiently than available parental serotypes by mutating posttranslationally modified capsid residues. Because a constitutive promoter was needed to drive high expression of these cell fate-altering reprogramming factors, we included binding sites to a cardiomyocyte-restricted microRNA within the 3' untranslated region of the expression cassette that limits expression to nonmyocytes. After optimizing this expression cassette to reprogram human cardiac fibroblasts into induced cardiomyocyte-like cells in vitro, we also tested the ability of this capsid/cassette combination to confer functional benefit in acute mouse myocardial infarction and chronic rat myocardial infarction models.
We demonstrated sustained, dose-dependent improvement in cardiac function when treating a rat model 2 weeks after myocardial infarction, showing that cardiac reprogramming, when delivered in a single, clinically relevant adeno-associated virus vector, can support functional improvement in the postremodeled heart. This benefit was not observed with GFP (green fluorescent protein) or a hepatocyte reprogramming cocktail and was achieved even in the presence of immunosuppression, supporting myocyte formation as the underlying mechanism.
Collectively, these results advance the application of cardiac reprogramming gene therapy as a viable therapeutic approach to treat chronic heart failure resulting from ischemic injury.
心脏重编程是一种使用基因或小分子将非心肌细胞直接转化为心肌细胞的技术。这种干预在心肌梗死时给予或转基因激活后 4 周内给予，可使啮齿动物心脏获得功能益处。然而，有几个障碍阻止了心脏重编程技术用于临床。
通过筛选和合理设计的结合，我们确定了一种心脏重编程鸡尾酒，它可以编码在单个腺相关病毒中。我们还创建了一种新型腺相关病毒衣壳，通过突变翻译后修饰的衣壳残基，可以比现有亲本血清型更有效地转导心脏成纤维细胞。由于需要组成型启动子来驱动这些改变细胞命运的重编程因子的高表达，我们在表达盒的 3'非翻译区中包含了与心肌细胞限制的 microRNA 的结合位点，从而将表达限制在非心肌细胞中。在优化了这个表达盒，使体外人类心脏成纤维细胞重编程为诱导性心肌样细胞之后，我们还测试了这个衣壳/盒组合在急性小鼠心肌梗死和慢性大鼠心肌梗死模型中赋予功能益处的能力。
我们在心肌梗死后 2 周的大鼠模型中，证明了心脏重编程具有持续的、剂量依赖性的改善心功能的作用，表明当在单个临床相关的腺相关病毒载体中给予时，心脏重编程可以支持重塑后心脏的功能改善。这一益处没有在 GFP（绿色荧光蛋白）或肝细胞重编程鸡尾酒中观察到，即使在免疫抑制存在的情况下，也支持心肌形成作为潜在机制。
总的来说，这些结果推进了心脏重编程基因治疗作为一种可行的治疗缺血性损伤引起的慢性心力衰竭的治疗方法的应用。
