Focal delivery of nitro-oleic acid using ultrasound targeted microbubble cavitation for the treatment of microvascular obstruction

随着再灌注治疗的引入，急性心肌梗死的死亡率显著下降，从1980年的20%下降到1998年的20%。 2008年为5%，但尽管我们的再灌注时间逐渐减少，但已达到稳定水平。现在，MI后 慢性心力衰竭（CHF）正在增加，并且与梗塞面积直接相关。微血管阻塞（MVO） 这是完全再灌注的主要障碍并限制了心肌挽救。这导致MI后射血减少 部分，并且被认为是MI后CHF的单一最重要的促成因素。 在他的第一个R 01中，PI证明了超声靶向微泡空化（UTMC）治疗 物理上缓解MVO和特定的机械机制，这种现象的基础。虽然UTMC可能 解决MVO的物理阻塞、相关炎症和缺血再灌注损伤 仍然存在并且可能对心肌环境显著有害。 本文提出应用基于硝基脂肪酸（NFA）的治疗策略，与 UTMC。NFA是内源产生的亲电子脂肪酸，其具有硝基烯烃取代基， 在介导多效性抗炎信号应答的调节中至关重要。目前，NFA 可以安全地用于人体（口服和静脉注射），并已进入2期临床试验。 然而，没有方法可以集中在特定的病理部位。由于两亲性，NFA 与大多数当前MB组合物中存在的磷脂具有有利的分子间相互作用。 因此，我们打算合成新的硝基脂肪酸MB（NFAB）与UTMC在MVO的动物模型中使用。 结合到MB中，当破裂时释放其壳内容物，允许快速和有针对性的释放 在MVO的网站上。NFAB-UTMC治疗策略的优点包括（a）快速、靶向递送， (b)初始NO供体作用，和（c）急性和慢性炎症反应的多效性调节 在MVO中发现我们假设，硝基脂肪酸微泡，通过超声靶向递送， 微泡空化，促进硝基脂肪酸靶向递送到微血管的部位， 并能改善治疗效果。这将在以下具体目标中进行测试： 目的1：合成新型超声靶向硝基脂肪酸微泡并对其进行表征 微泡空化体外表征需要分析硝基脂肪酸MB的化学组成 和声学行为。 目的2：确定硝基脂肪酸超声靶向微泡空化的功效 微泡用于治疗微血管阻塞。该策略的应用，沿着控制 条件下，将测试的假设，即UTMC与NFAB的结果，增加当地交付和行动的NFA 在健康啮齿类动物后肢模型中，与全身NFA递送相比（Aim 2A）。该模型还将测试 假设UTMC与NFAB可以减少MVO的持续时间和严重程度（目的2B）。

With the introduction of reperfusion therapy, mortality from AMI has decreased markedly, from 20% in 1980 to 5% in 2008, but has plateaued despite the fact that our time to reperfusion has progressively declined. Now, post MI chronic heart failure (CHF) is increasing and is directly related to infarct size. Microvascular obstruction (MVO) is a major obstacle to complete reperfusion and limits myocardial salvage. It results in lower post MI ejection fraction and is felt to be the single most important contributor to post MI CHF. In his first R01, the PI demonstrated that ultrasound targeted microbubble cavitation (UTMC) therapy physically relieves MVO and that specific mechanical mechanisms underly this phenomenon. While UTMC may address the physical obstruction of MVO, the associated inflammation and ischemia-reperfusion injury remain and can be significantly deleterious to the myocardial environment. It is proposed herein to apply a nitro-fatty acid (NFA)-based therapeutic strategy, in combination with UTMC. NFA are endogenously-produced electrophilic fatty acids having a nitroalkene substituent that is critical in mediating the modulation of pleiotropic anti-inflammatory signaling responses. Currently, NFA can be safely administered in humans (orally and intravenously) and have advanced to Phase 2 clinical trials. However, there is no method for concentrating at specific sites of pathology. Due to an amphipathic nature, NFA have favorable intermolecular interactions with the phospholipids present in most current MB compositions. Thus, we intend to synthesize novel nitro-fatty acid MBs (NFABs) for use with UTMC in an animal model of MVO. Incorporation into MBs, which release their shell contents when ruptured, allows for rapid and targeted release at the site of MVO. The advantages of a NFAB-UTMC therapeutic strategy, include (a) rapid, targeted delivery, (b) initial NO donor actions, and (c) pleiotropic modulation of both the acute and chronic inflammatory responses found in MVO. We hypothesize that nitro-fatty acid microbubbles, delivered via ultrasound-targeted microbubble cavitation, facilitates the targeted delivery of nitro-fatty acid to sites of microvascular obstruction and can improve therapeutic treatment. This will be tested in the following Specific Aims: Aim 1: Synthesize and characterize novel nitro-fatty acid microbubbles for ultrasound-targeted microbubble cavitation. In vitro characterization entails analysis of nitro-fatty acid MBs chemical composition and acoustic behavior. Aim 2: Determine the efficacy of ultrasound-targeted microbubble cavitation with nitro-fatty acid microbubbles for the treatment of microvascular obstruction. Application of this strategy, along with control conditions, will test the hypothesis that UTMC with NFABs results in increased local delivery and actions of NFA in a healthy rodent hindlimb model, compared against systemic NFA delivery (Aim 2A). This model will also test the hypothesis that UTMC with NFABs can lessen both the duration and severity of MVO (Aim 2B).