MK2 Inhibitory Nanoplexes to Enhance Long-Term Vascular Graft Patency

 描述(申请人提供)：冠状动脉搭桥术(CABG)与自体人大隐静脉(HSV)是治疗严重冠心病的最佳方法，但长期的移植物通畅性是有问题的。人均静脉移植失败12-18例 在最近的预防IV试验(N=1,920)中，冠状动脉搭桥术后6个月的死亡率为45%。静脉移植失败使患者易于接受额外手术、心肌梗死、复发性心绞痛、肢体丧失和死亡。移植物的失败主要是由于内膜增生(IH)，血管平滑肌细胞(VSMCs)通过这个过程迁移、增殖并沉积细胞外基质(ECM)到导致狭窄的新生内膜中。我们已经确定MAPKAP激酶II(MK2)是预防血管移植物IH的潜在药物干预靶点。MK2是由p38丝裂原激活的激酶(MAPK)直接激活的，而MAPK是由移植过程中移植物受到的机械和环境压力触发的。由于p38 MAPK的功能多样，p38抑制剂会引起不良的副作用。因此，MK2是抑制IH近端触发的合乎逻辑的靶点，该提议的中心假设是，持续的细胞内药物抑制MK2将预防IH并改善长期移植物通畅性。由项目合作者开发的一种“细胞穿透性”多肽MK2抑制剂(MK2I)具有高特异性和低毒性，但细胞内给药障碍阻碍了其疗效。机制研究支持这一观点，即MK2i具有良好的抗炎和抗纤维化活性，但其效力和作用寿命受到细胞内晚期内体囊泡的内化和隔离的限制。为了克服内体屏障，PI的实验室开发了一种新型的基于聚合物的MK2I“纳米网络”(MK2I-NP)设计，它可以改善MK2I多肽的细胞内化和内体逃逸。我们发表的数据证实，将MK2I制成内溶MK2I-NPs增加了多肽在细胞内的递送，并产生了比游离多肽治疗更有效和更持久的生物活性。MK2I-NPs的快速吸收和持久的细胞内滞留是这一应用的关键标准，因为在外科医生准备放置吻合口的位置期间，在移植时对HSV组织进行短暂(30分钟)处理，必须在手术后愈合阶段保护移植物。本项目旨在优化和更好地阐明MK2I-NPs的机制，然后在高级临床前模型中测试该疗法抑制IH发病的有效性。

 DESCRIPTION (provided by applicant): Coronary artery bypass grafting (CABG) with autologous human saphenous vein (HSV) is the best available treatment for severe coronary heart disease, but long-term graft patency is problematic. The per patient vein graft failure 12-18 months after CABG was 45% in the recent PREVENT IV trial (N=1,920). Vein graft failure predisposes patients to additional operations, myocardial infarction, recurrent angina, limb loss, and death. Graft failure is primarily attributable to intimal hyperplasia (IH), the process by whic vascular smooth muscle cells (VSMCs) migrate, proliferate, and deposit extracellular matrix (ECM) into a neointima that causes stenosis. We have identified MAPKAP kinase II (MK2) as a potential target for pharmacological intervention for preventing vascular graft IH. MK2 is activated directly by p38 mitogen activated kinase (MAPK), which is triggered by the mechanical and environmental stresses on the graft during transplant. Because p38 MAPK functions are diverse, p38 inhibitors cause undesirable side effects. Thus, MK2 is a logical target for inhibitin a proximal trigger of IH, and the central hypothesis of this proposal is that sustained intracellulr pharmacological inhibition of MK2 will prevent IH and improve long-term graft patency. A "cell- penetrating" peptidic MK2 inhibitor (MK2i) developed by project collaborators has high specificity and low toxicity, but barriers against intracellular delivery hinder its efficacy. Mechanistic studies support the notion that MK2i has promising anti-inflammatory and anti-fibrotic activity, but its potency and longevity of action are limited by internalization into and sequestration within intracellular late endosomal vesicles. To overcome the endosomal barrier, a novel polymer-based MK2i "nanoplex" (MK2i-NP) design has been developed in the PI's lab that improves cell internalization and endosomal escape of the MK2i peptide. Our published data verify that formulation of MK2i into endosomolytic MK2i-NPs increases peptide intracellular delivery and produces more potent and longer-lasting bioactivity relative to treatment with the free peptide. Rapid uptake and durable intracellular retention of MK2i-NPs are key criteria for this application because a brief (30 minute) treatment of the HSV tissue at the time of explant, during the period when the surgeon is preparing the site where the anastomosis will be placed, must protect the graft throughout the post-surgery healing phase. This project seeks to optimize and better elucidate the mechanism of MK2i-NPs and then to test this therapy for efficacy in inhibiting IH pathogenesis in advanced preclinical models.