载氢气微泡的超声可视化传递及其治疗心肌缺血再灌注损伤的研究

Burst production of oxygen free radicals is one of the most important factors to induce myocardial ischemia-reperfusion injury. Evidences have demonstrated that hydrogen gas (H2) is a novel, simple and safe antioxidant. However, the poor solubility in water and difficulties to track by imaging and to release by a targeted and controllable manner limits its effect and applicability. Microbubbles (MBs) are ideal ultrasound contrast agents and ultrasound-activated drug carriers due to their characteristics of ultrasound imaging, drug carriers and ultrasound-activated drug release. In this project,we propose a novel approach to realise H2-visible targeted delivery via microbubbles. In brief, H2 will be encapsulated into the inner cavity of MBs to obtain the H2-loaded MBs(H2-MBs), The perfusion of H2-MBs at the damaged myocardial site can be observed by ultrasound imaging in a real-time manner and the H2 release can be achieved by ultrasound-targeted microbubble destruction technology. Our previous study demonstrated that the H2-MBs we prepared have excellent contrast effects under ultrasound imaging machine and can inhibit myocardial ischemia-reperfusion injury to some degree in rats by using of only H2-MBs. This project will further investigate the release performance and the effects on ultrasound-guided H2 targeted delivery for treatment of myocardial ischemia-reperfusion injury. Our study will provide a novel idea to realize the visible delivery of H2 and its therapy application.

氧自由基的爆发性增长是导致心肌缺血-再灌注损伤的重要因素之一。研究表明，氢气是一种新型、简单、安全的选择性抗氧化剂，然其水溶性低、难于实时追踪及定点可控释放在一定程度上限制了它的疗效和应用价值。微泡具有造影、载气及超声定点控释的特性。基于此，本项目提出一种基于微泡实现氢气可视化传递及其给药治疗心肌缺血-再灌注损伤的方法，拟通过制备载氢气的微泡，利用超声成像实时观察其在心肌组织的灌注，再通过超声击碎氢气微泡，定点可控地在缺血心肌部位释放氢气，以期达到氢气的可视化传递及治疗心肌缺血-再灌注损伤的目的。我们前期的研究已经制备获得了载氢气的微泡，初步证实氢气微泡具有较好的超声成像性能，单独使用氢气微泡具有一定地缓解心肌缺血-再灌注损伤的作用。本项目将进一步研究氢气微泡的超声释放性能以及超声定点给药治疗的效果、生物安全性及其相关的作用机制。本项目的研究将为氢气的可视化传递及其治疗提供一种新的思路。

制备载气量高、声学性能优良的氢气微泡是实现超声影像引导的氢气可视化递送用于疾病治疗的关键，在本项目中，我们利用微泡内部气室腔可携载气体的特性，制备获得了载氢气的超声微泡，并对其在可视化传递及其心肌缺血-再灌注损伤治疗应用方面进行了研究，我们的结果：（1）明确了超声微泡可以作为氢气的优良载体，对氢气的携载量可达1.46±0.08 μmol/108微泡；（2）实现了治疗性氢气的可视化体内示踪，利用体外仿体、体内动物证实了制备获得的氢气微泡具有较好的超声成像性能；（3）评价了氢气微泡联合超声对缺血心肌细胞的保护效果，发现超声爆破氢气微泡释放氢气可通过上调SOD活性，下调LDH和MDA的表达来缓解H2O2对心肌细胞的氧化损伤；（4）体内动物实验进一步验证了氢气微泡联合超声定点释放可显著缓解心肌缺血-再灌注给心肌细胞带来的损伤。我们的研究为探讨超声成像引导的治疗性气体的可视化给药治疗奠定了坚实的基础。综合上述结果，本研究制备获得了载氢气微泡，实现了氢气的超声可视化递送并显著抑制了心肌缺血-再灌注损伤，为探讨超声可视化氢气治疗奠定了坚实的基础。