Molecular Imaging of Targeted Cardiac Gene Therapy

描述（由申请人提供）：腺病毒介导的VEGF递送的大型II/III期临床试验的最新结果如果不是令人失望的话，也是不确定的。我们相信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，血管生成素和促红细胞生成素。然而，由于脯氨酰羟化酶-2（PHD 2）的内源性降解，HIF-11具有较短的生物半衰期。因此，我们假设短发夹抑制PHD 2（shPHD 2）代表一种新的方法来诱导治疗性血管生成。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方式控制基因表达。另一个优先事项是开发新的技术，可用于跟踪基因表达在活的主题非侵入性，纵向和定量。因此，R 01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）开发具有稳健和延长的转基因表达的智能载体，（2）监测我们的新型载体在体内的药代动力学和生物分布，（3）证明shPHD 2介导的心肌缺血基因治疗的机制，以及（4）评估翻译模型中的安全性、有效性和最佳递送条件。在5年结束时，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：尽管在心肌缺血患者中进行的初始I期试验提供了令人鼓舞的结果，但最近的II期随机试验（AGENT、VIVA、KAT）仅产生了适度的获益。这些不一致性归因于缺乏理想的递送载体、单一治疗基因如VEGF的作用不清楚、次优剂量或给药途径以及无法监测患者中的基因转移。为了使该领域向前发展，需要解决的紧迫问题是：（i）找到合适的载体来克服物理障碍，（ii）开发一种新的方法来验证体内基因表达，（iii）剖析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。该R 01提案的意义在于验证化学缀合可用于显著提高质粒DNA的转染效率，新型分子成像平台将允许我们监测基因治疗在活体受试者中的药代动力学和生物分布，“智能载体系统”可被设计为组织特异性和缺氧响应性，最后，基因治疗在未来可以用于小动物、大动物和人类受试者。

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.