Biological pacemaker from proof-of-concept to clinic

项目摘要 该提案的总体目标是为首次人体生物学研究奠定临床前基础。 作为电子设备替代品的起搏器(BIOP)。基于基因的BIOP首次被描述的不止一个 十年前；各种结构的体细胞基因转移(内向整流的显性-负性突变 通道[Kir2.1AAA]、野生型HCN通道和转录因子[TBX18])都被证明 创建BIOP活动。然而，直到最近，体内临床前应用大多局限于高度- 侵入性模型。我们已经开发了一种临床上现实的微创递送技术，并将其用于 在猪的完全性心脏传导阻滞模型中建立BIOP。在这里，我们建议使用这种方法来比较两个 最终入围的治疗候选药物具有根本不同的作用机制。第一个是野生型的 离子通道(HCN_2)通过功能再灌流人工诱导心肌细胞自律性 工程学。我们的目标不是创造一个起搏器细胞的忠实复制品，而是操纵一个 膜通道谱系的成分，以在可兴奋的但是 通常处于静止状态的细胞。第二个候选治疗药物TBX18的活性成分重新编程 将心室肌细胞分化为窦房结(SAN)样起搏细胞(诱导窦房结[ISAN]细胞)。无名之辈 兴奋性的决定因素选择性地过度表达：整个基因表达程序被改变， 由此产生的基本细胞生理和形态的变化。该方案利用了上述内容 在心动过缓的大型动物模型中，经皮给药方法改进和验证这些方法 需要翻译到诊所。我们将对HCN的起搏效率和安全性进行表征和比较 和TBX18衍生的biop，检验了Isan细胞将提供优越的变时性支持的假设 与hcn2相比。我们将继续进行长期疗效、毒理学和生物分布研究 更有希望的治疗候选药物，然后制备并获得批准的研究新药 (IND)申请首次人类BIOP试验。虽然最终目标可能是使过时的 对于电子起搏器，重要的是要现实地考虑潜在的第一个人类应用。 因此，我们最初选择开发一种桥到设备的产品，该产品将暂时提供 对依赖起搏器的感染患者的非硬件变时性支持。制作围巾 暂时，我们通过腺病毒载体传递基因，依靠免疫清除来限制生物活性。 然而，我们将测试导管消融BIOP作为后备抢救策略，以防持续 不受欢迎的BIOP活动。本研究方案旨在为临床试验奠定基础。 最优化的BIOP最初是在贫困人口中进行的。

Project Summary The overall objective of the proposal is to lay the preclinical groundwork for first-in-human studies of biological pacemakers (BioP) as alternatives to electronic devices. Gene-based BioP were first described more than a decade ago; somatic gene transfer of various constructs (a dominant-negative mutant of the inward rectifier channel [Kir2.1AAA], wild-type HCN channels, and a transcription factor [Tbx18]) have all been shown to create BioP activity. However, until recently, in vivo preclinical applications have been mostly limited to highly- invasive models. We have developed a clinically-realistic minimally-invasive delivery technique and used it to create BioP in a porcine model of complete heart block. Here, we propose to use this approach to compare two “finalist” therapeutic candidates with fundamentally different mechanisms of action. The first one is a wild-type ion channel (HCN2) that artificially induces automaticity in ventricular cardiomyocytes by functional re- engineering. The goal is not to create a faithful replica of a pacemaker cell, but rather to manipulate a single component of the membrane channel repertoire so as to induce spontaneous firing in an excitable but normally-quiescent cell. The active principle of the second therapeutic candidate, Tbx18, reprograms ventricular cardiomyocytes into sinoatrial node (SAN)-like pacemaker cells (induced SAN [iSAN] cells). No one determinant of excitability is selectively over-expressed: the entire gene expression program is altered, with resultant changes in fundamental cell physiology and morphology. The proposal utilizes the abovementioned percutaneous delivery method to refine and validate, in a large-animal model of bradycardia, the approaches required for translation to the clinic. We will characterize and compare the pacing efficacy and safety of HCN2 and Tbx18-derived BioP, testing the hypothesis that iSAN cells will provide superior chronotropic support as compared to HCN2. We will go on to perform long-term efficacy, toxicology and biodistribution studies with the more promising therapeutic candidate, and then prepare, and obtain approval of, an Investigational New Drug (IND) application for a first-in-human BioP trial. While the ultimate goal may be to render obsolete the electronic pacemaker, it is important to be realistic in thinking about potential first-in-human applications. Therefore, we have chosen to develop, initially, a bridge-to-device product that will temporarily provide hardware-free chronotropic support in infected patients who are pacemaker-dependent. To make BioP temporary, we deliver the genes in adenoviral vectors, relying on immunological clearance to limit bioactivity. Nevertheless, we will test catheter ablation of the BioP as a backup rescue strategy in case of persistent undesired BioP activity. This research proposal is designed to lay the groundwork for clinical testing of an optimized BioP initially in a needy population.