Molecular Imaging of Targeted Cardiac Gene Therapy

描述（由申请人提供）：到目前为止，腺病毒介导的VEGF递送的大型II/III期临床试验的结果不确定，如果不是令人失望的话。我们认为一个更合理的策略可能是利用HIF-11上游转录调节因子，它可以激活几个下游基因，如VEGF、FGF、IGF、血管生成素和红细胞生成素。然而，HIF-11的生物半衰期很短，因为它可以被脯氨酸羟化酶-2 （PHD2）内源性降解。因此，我们假设短发夹抑制PHD2 （shPHD2）是一种诱导治疗性血管生成的新方法。另一方面，持续和不受调节的血管生成可能导致心脏血管瘤，因此需要以靶向和调节的方式控制基因表达。另一个重点是开发新的技术，可以用于无创、纵向和定量地跟踪活体受试者的基因表达。因此，本R01提案的主要目标是利用我们在载体设计，分子成像，血管生物学和转化模型方面的多学科专业知识来解决上述问题。我们的具体目标是：(1)开发具有稳健和长时间转基因表达的智能载体，(2)监测我们的新载体在体内的药代动力学和生物分布，(3)证明shPHD2介导的心肌缺血基因治疗机制，以及(4)评估安全性，有效性和翻译模型中的最佳递送条件。在5年后，我们希望将这些发现转化为我们的新型智能载体系统治疗冠状动脉疾病患者。公共卫生相关性：尽管心肌缺血患者的初始1期试验提供了令人鼓舞的结果，但最近的2期随机试验（AGENT， VIVA， KAT）仅产生了适度的益处。这些不一致归因于缺乏理想的递送载体，单一治疗基因（如VEGF）的作用不明确，次优剂量或给药途径，以及无法监测患者的基因转移。为了使该领域向前发展，需要解决的紧迫问题是：(i)找到一个合适的载体来克服物理障碍，（ii）开发一种新的方法来验证基因在体内的表达，（iii）解剖基因治疗的分子机制，以及（iv）在翻译模型中证明安全性和有效性。这个R01提案的意义是验证化学结合可以显著提高质粒的转染效率,新颖的分子成像平台将使我们能够监控基因治疗的药物动力学和biodistribution生活主题,一个“智能矢量系统”的设计可以组织特定和缺氧反应,最后,基因疗法可用于小动物,大型动物,人类被试在未来。

DESCRIPTION (provided by applicant): Recent results from large phase II/III clinical trials on adenoviral-mediated VEGF delivery have been inconclusive if not disappointing so far. We believe a sounder strategy may be to take advantage of the HIF-11 upstream transcriptional regulator that can activate several downstream genes such as VEGF, FGF, IGF, angiopoietin, and erythropoietin. However, HIF-11 has a short biological half-life due to endogenous degradation by prolyl hydroxylase-2 (PHD2). Therefore, we hypothesize that short hairpin inhibition of PHD2 (shPHD2) represent a novel approach to induce therapeutic angiogenesis. On the flip side, persistent and unregulated angiogenesis can lead to hemangioma in the heart and thus controlling gene expression in a targeted and regulatory fashion is needed. Another priority is to develop novel techniques that can be used to track gene expression in living subjects noninvasively, longitudinally, and quantitatively. Thus, the primary goal of this R01 proposal is to use our multi-disciplinary expertise in vector design, molecular imaging, vascular biology, and translational models to address the above questions. Our specific aims are to (1) develop smart vectors with robust and prolonged transgene expression, (2) monitor the pharmacokinetics and biodistribution of our novel vector in vivo, (3) demonstrate mechanisms of shPHD2 mediated gene therapy for myocardial ischemia, and (4) evaluate the safety, efficacy, and optimal delivery conditions in translational models. At the end of 5 years, we hope to translate these findings to treatment of coronary artery disease patients with our novel smart vector systems. PUBLIC HEALTH RELEVANCE: Although initial phase 1 trials in patients with myocardial ischemia provided encouraging results, recent phase 2 randomized trials (AGENT, VIVA, KAT) yielded only modest benefits. These inconsistencies have been attributed to lack of ideal delivery vectors, unclear role of single therapeutic gene such as VEGF, suboptimal dosing or route of administration, and inability to monitor gene transfer in patients. For the field to move forward, the pressing questions that need to be resolved are: (i) finding a suitable vector to overcome physical barriers, (ii) develop a novel method mean to verify gene expression in vivo, (iii) dissect the molecular mechanisms of gene therapy, and (iv) demonstrate safety and efficacy in translational models. The significance of this R01 proposal is to validate that chemical conjugation can be used to significantly improve the transfection efficiency of plasmid DNA, that novel molecular imaging platforms will allow us to monitor the pharmacokinetics and biodistribution of gene therapy in living subjects, that a "smart vector system" can be designed to be tissue specific and hypoxia responsive, and finally that gene therapy can be used in small animals, large animals, and human subjects in the future.