PTEN Gene Therapy for Vein Graft Disease

描述(申请人提供)：在美国和其他发达国家，冠状动脉和外周动脉的动脉粥样硬化导致严重的发病率和死亡率。在冠状动脉和外周动脉疾病中，自体隐静脉是最常用的搭桥术管道，而自体静脉通常用于制造动静脉瘘(AVF)用于血液透析。由于闭塞性静脉移植物疾病的高发病率，这些管道的使用受到了影响，但目前还没有预防这一问题的治疗方法。静脉移植为基因治疗提供了理想的机会，因为静脉在移植前从其本土采集，可以在体外进行治疗，从而避免全身暴露于治疗剂。最近针对E2F转录因子的寡核苷酸诱骗的第三阶段临床试验表明，对于预防外周或冠状动脉旁路移植(CABG)中的静脉移植失败没有好处。因此，迫切需要新的方法来预防静脉移植失败。PTEN是一种脂质磷酸酶，能拮抗肌醇磷脂(PI)3-激酶的作用，PI是病理性血管平滑肌细胞(VSMC)生长的中枢调节因子。我们先前证明，PTEN在体外的过度表达抑制了血管SMC对内膜增生所必需的反应。更重要的是，腺病毒(Ad)介导的PTEN体外静脉移植可显著抑制犬冠状动脉旁路移植(CABG)模型的内膜增生。这些发现表明，PTEN基因治疗在预防临床静脉移植物疾病方面具有很大的前景。然而，腺病毒载体仅在数周内诱导转基因表达，并且与强烈的炎症反应有关。此外，目前尚不清楚AdPTEN的短期表达是否会导致长期的静脉移植开放。相比之下，较新的腺相关病毒(AAV)载体可实现持续数月至数年的表达，并且不会引发实质性炎症。我们假设，使用AAV获得的长期PTEN表达将导致长期静脉移植通畅率与使用AdPTEN获得的相当或更好。为了验证这一假说，这项建议的具体目的是：1)开发AAV-PTEN并优化血管平滑肌细胞和静脉移植物的转导；以及2)比较AdPTEN、AAV-PTEN或生理盐水对照体外静脉移植物治疗后6个月犬的主-冠状隐静脉移植物(SVG)通畅率和内膜增生情况。实现这些特定目标将确定进一步临床开发的最佳制剂，该制剂将随后在人体静脉移植物疾病的临床试验中进行测试。 公共卫生相关性：自体静脉通常用作冠状动脉和外周动脉疾病患者的搭桥管道，并用于血液透析的动静脉瘘(AVF)，然而这些管道由于内膜增生而失败率很高。PTEN基因治疗在预防静脉移植失败方面有很大的希望，这项建议的研究将确定这一治疗策略的最佳方法。这些研究的结果可能会对需要静脉旁路移植和动静脉动静脉瘘置入术的患者的预后产生重大影响。

DESCRIPTION (provided by applicant): Atherosclerosis of coronary and peripheral arteries results in significant morbidity and mortality in the U.S. and other developed countries. Autologous saphenous veins are the most commonly used conduits for bypass grafting in both coronary and peripheral artery disease, and autologous veins are commonly employed for creation of arteriovenous fistulas (AVFs) for hemodialysis. The utility of these conduits is compromised by a high incidence of occlusive vein graft disease, yet no treatments exist to prevent this problem. Vein grafting provides an ideal opportunity for gene therapy, since veins are harvested from their native territory prior to grafting and can be treated ex vivo, thereby avoiding systemic exposure to the therapeutic agent. Recent Phase III clinical trials of an oligonucleotide decoy targeting the E2F transcription factor demonstrated no benefit for the prevention of vein graft failure in peripheral or coronary artery bypass grafting (CABG). Thus, there is a critical need for novel approaches to prevent vein graft failure. PTEN is a lipid phosphatase that antagonizes the effects of phosphoinositide (PI) 3-kinase, a central regulator of pathological vascular smooth muscle cell (VSMC) growth. We demonstrated previously that overexpression of PTEN in vitro inhibits the VSMC responses necessary for intimal hyperplasia. More importantly, adenovirus (Ad)-mediated delivery of PTEN to vein grafts ex vivo resulted in significant inhibition of intimal hyperplasia in a canine model of coronary artery bypass grafting (CABG). These findings suggest that PTEN gene therapy holds great promise for the prevention of clinical vein graft disease. However, adenoviral vectors induce transgene expression only on the order of weeks and are associated with a robust inflammatory response. Moreover, it is unknown whether the short-term expression achieved with AdPTEN will result in long-term vein graft patency. In contrast, newer adeno-associated virus (AAV) vectors achieve expression that is sustained for months to years and do not induce substantial inflammation. We hypothesize that long-term PTEN expression achieved with AAV will result in long-term vein graft patency rates comparable to or better than those obtained with AdPTEN. To test this hypothesis, the Specific Aims of this proposal are to: 1) Develop AAV-PTEN and optimize transduction of vascular smooth muscle cells and vein grafts; and 2) Compare 6-month aortocoronary saphenous vein graft (SVG) patency rates and intimal hyperplasia in dogs following ex vivo vein graft treatment with AdPTEN, AAV-PTEN, or saline control. Accomplishing these Specific Aims will determine the optimal agent for further clinical development, and this agent will be subsequently tested in clinical trials of human vein graft disease. PUBLIC HEALTH RELEVANCE: Autologous veins are commonly used as bypass conduits in patients with coronary and peripheral arterial disease and to create arterio-venous fistulas (AVFs) for hemodialysis, however these conduits have a high rate of failure due to intimal hyperplasia. PTEN gene therapy holds great promise to prevent vein graft failure, and studies in this proposal will determine the optimal approach for this therapeutic strategy. The results of these studies may have a substantial impact on outcomes for patients requiring venous bypass grafting and AVF placement.