A theranostic ultrasound approach to improve chronic wound treatment using phase-change contrast agents

摘要 慢性伤口是一个日益严重的公共卫生威胁，仅在美国就有超过650万人受到影响， 每年花费超过300亿美元。伤口愈合延迟的最重要的原因是细菌 感染，通常以生物膜的形式阻碍抗生素渗透并迫使细菌进入“休眠”状态， 说明他们对抗生素的耐受性。抗生素对生物膜感染的伤口效果很差， 1）差的药物渗透和2）生物膜内存在耐药持续细胞。这些因素 导致70%的感染复发率抗生素治疗期间未能完全根除生物膜 治疗可导致生活质量显著降低、住院、败血症、截肢和死亡。 合并症如糖尿病和心血管疾病进一步使治疗策略复杂化。每 在美国，每天有230名患者因慢性伤口感染而截肢，其中大多数是糖尿病患者。 足部感染迫切需要改进伤口护理疗法，但由于药物中的空白- 开发平台，创新主要围绕伤口闭合，而不是改进抗生素 功效近年来，声空化剂、微气泡和相变技术在声空化技术中得到了广泛的应用 用于超声介导的药物递送的造影剂（PCCA）已经取得了若干实质性进展， 目前正在进行其他应用的临床试验。在这项提案中，我们将开发一种非侵入性治疗诊断 超声平台，以改善抗persister药物进入生物膜感染伤口的输送。我们 在体内糖尿病小鼠模型中观察到令人鼓舞的初步数据， 在慢性伤口中，使用仅局部方法，MRSA生物膜的清除率为94%。重要的是，我们实现了 8只动物中有3只完全根除（低于检测限）。 在这个项目中，我们建议优化我们的声学响应生物相容性颗粒的功效， 治疗超声参数，以加强各种抗生素对生物膜的最常见的 慢性伤口感染的病原体（金黄色葡萄球菌、铜绿假单胞菌和肠球菌 faecalis），并通过定量治疗渗透来研究作用机制 和体外空化活性（具体目标1）。然后，我们将评估这种方法在多微生物糖尿病 慢性伤口感染模型（具体目标2）。为此，我们将重点关注铜绿假单胞菌， 金黄色葡萄球菌，这两种生物最常共同感染慢性伤口。伤口测量 将对愈合、伤口闭合和细菌负荷的减少进行量化，并以当前的 护理标准全身性抗生素给药，其中还将评价空化活性的能力 来预测对治疗的早期反应我们提出的方法有可能对以下方面产生重大影响： 治疗慢性伤口中的多微生物生物膜。

ABSTRACT Chronic wounds are a growing public health threat, with over 6.5 million people affected in the US alone, costing upwards of $30 billion annually. The single-most-important cause of delayed wound healing is bacterial infection, often in the form of biofilms that impede antibiotic penetration and force the bacteria into a “dormant” state where they are more tolerant to antibiotics. Antibiotics work so poorly against biofilm-infected wounds due to 1) poor drug penetration and 2) the presence of drug-tolerant persister cells within biofilms. These factors contribute to a 70% infection recurrence rate. Failure to completely eradicate biofilms during antibiotic therapy can result in significant quality-of-life reduction, hospitalization, sepsis, amputation and death. Comorbidities such as diabetes and cardiovascular disease further complicate therapeutic strategies. Every day in the US, 230 patients suffer an amputation due to a chronic wound infection, the majority due to diabetic foot infections. There is an urgent need for improved wound care therapies but with the void in the drug- development platform, innovation is mostly centered around wound closure rather than improving antibiotic efficacy. Recently, the technology of acoustically active cavitation agents, microbubbles and phase-change contrast agents (PCCA), for ultrasound-mediated drug delivery has made several substantial advances and is currently in clinical trials for other applications. In this proposal, we will develop a non-invasive theranostic ultrasound platform to improve delivery of anti-persister drugs into biofilm-infected wounds. Our encouraging preliminary data in an in vivo diabetic mouse model observed improved traditional therapeutic clearance of MRSA biofilms by 94% in chronic wounds using a topical-only approach. Importantly, we achieved complete eradication (below limit of detection) in 3 out of 8 animals. In this project, we propose to optimize the efficacy of our acoustically responsive biocompatible particles and therapeutic ultrasound parameters to potentiate various antibiotics against biofilms of the most common pathogens in chronic wound infections (Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis) in vitro, in conjunction with investigating mechanisms of action by quantifying therapeutic penetration and cavitation activity in vitro (specific aim 1). We will then evaluate this approach in a polymicrobial diabetic chronic wound infection model (specific aim 2). For this, we will focus on Pseudomonas aeruginosa and Staphylococcus aureus, the two organisms that most commonly co-infect chronic wounds. Measures of wound healing, wound closure and reduction in bacterial burden will be quantified and benchmarked against current standard of care systemic antibiotic administration, where cavitation activity will also be evaluated for its ability to predict early response to therapy. Our proposed approach has the potential to have a substantial impact on the treatment of polymicrobial biofilms in chronic wounds.