Micrococcal nuclease-triggered antibiotics release: a prophylactic implant coating against S. aureus infections

微球菌核酸酶触发的抗生素释放：针对金黄色葡萄球菌感染的预防性植入物涂层

基本信息

批准号：
10684948
负责人：
Jie Song
金额：
$ 48.94万
依托单位：
UNIV OF MASSACHUSETTS MED SCH WORCESTER
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-15 至 2025-07-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10684948
关键词：
Address Animals Antibiotics Bacteria Biological Assay Bone Cements Bypass Characteristics Chemicals Clinical Debridement Detection Development Dose Engineering Ensure Evaluation Femur Goals Growth Histology Hydrogels Implant In Vitro Incubated Infection Infection prevention Injections Invaded Location Mechanics Methylation Microbial Biofilms Micrococcal Nuclease Modeling Modification Monitor Mus Nucleotides Oligonucleotides Operative Surgical Procedures Organ Orthopedic Surgery Orthopedics Osteomyelitis Pathology Pharmaceutical Preparations Predisposition Prosthesis Prosthesis-Related Infections Rattus Replacement Arthroplasty Safety Saline Second Look Surgery Serum Staphylococcus aureus Staphylococcus aureus infection Surface Surgical Models System Systemic infection Technology Testing Thick Torsion Vancomycin aspirate bioluminescence imaging bone clinical translation clinically relevant comparative efficacy cortical bone drug resistance development efficacy evaluation ethylene glycol implant associated infection implant coating improved in vivo in vivo evaluation infection rate metallicity microbial nuclease operation phosphodiester phosphorothioate prevent prophylactic recurrent infection side effect standard care success surface coating translational potential

项目摘要

PROJECT SUMMARY/ABSTRACT Periprosthetic infections is one of the most serious complications in orthopedic surgeries, occurring in 1-4% of primary total joint replacement and up to 30% of revisions. Infections caused by Staphylococcus aureus (S. aureus), the most prevalent microbial culprit in orthopedic infections, are particularly hard to treat due to their tendency to form biofilms on implant and notorious ability to invade the canalicular network of surrounding bone. Existing prophylactic antibiotic deliveries involve high drug doses that are unsafe yet ineffective and could lead to the development of drug resistance. Utilizing an oligonucleotide linker labile to S. aureus micrococcal nuclease (MN) cleavage, we recently developed a hydrogel capable of on-demand release of covalently tethered vancomycin. When applied as a hydrogel coating to Ti6Al4V intramedullary (IM) pin and inserted to mouse femoral canal inoculated with S. aureus, the MN-triggered release of vancomycin timely killed the bacterial on implant surface and within IM space before they had a chance to colonize or invade surrounding bone, thereby preventing biofilm formation and osteomyelitis development in the 3 weeks examined. The covalent tethering dose of vancomycin in this coating was orders of magnitude lower than the typical prophylactic antibiotic content used clinically. The goal of the proposed study is to further engineer this exciting on-demand drug release system to enhance its serum stability and rigorously examine its efficacy in providing sustained protection against periprosthetic infections using two clinically relevant implant infection models. In Aim 1, the oligonucleotide linker is chemically modified by selective 2'-O-methylation and phosphorothioate modifications to achieved enhanced mammalian serum nuclease stability while maintaining necessary sensitivity to MN cleavage. In Aim 2, the in vitro optimized nucleotide linker will be implemented in MN-sensitive hydrogel coating and applied to Ti6Al4V IM pins for on-demand delivery of vancomycin. The efficacy and safety of this prophylactic coating in providing timely and sustained protection against S. aureus periprosthetic infections will be rigorously evaluated over 6 months using a rat femoral canal infection model. In Aim 3, the efficacy of this on-demand antibiotic release strategy in reducing the high periprosthetic infection rates following surgical debridement of previously infected rat femoral canal will be examined using a rat IM implant revision surgery model. The degree of infections as a function of pin coating and bioluminescent S. aureus inoculation are longitudinally monitored by bioluminescent imaging and µCT quantification of cortical bone thickening at 2 weeks, 1, 2, 3 and 6 months, and by end-point quantification of bacteria on the retrieved pin, torsion test of explanted femur and femoral histology at 1, 3 and 6 months. Long-term safety of the coating is examined by systemic organ pathology at the endpoints. Systemic injections of vancomycin at a dose several hundred-fold higher than that in the prophylactic coating are carried out in a subset of infected animals receiving uncoated IM pins to allow direct comparison of the efficacy of this prophylactic coating vs. that of the standard care. Achieving more sustained protection against periprosthetic infections or recurrent infections than systemic vancomycin injections will be considered a success while achieving extended protection for 6 months without local and systemic side effects will be considered exceptional. If successfully validated, the timely and sustained eradication of bacteria enabled by MN-triggered vancomycin release could bring together safety and efficacy in addressing the daunting challenge of orthopedic implant-associated infections by bypassing the notoriously hard-to-treat biofilms and osteomyelitis.

项目概要/摘要假体周围感染是骨科手术中最严重的并发症之一，发生率为 1-4% 初次全关节置换术和高达 30% 的修复手术由金黄色葡萄球菌 (S. 金黄色葡萄球菌）是骨科感染中最常见的微生物罪魁祸首，由于其致病性而特别难以治疗在植入物上形成生物膜的倾向以及侵入周围小管网络的臭名昭著的能力现有的预防性抗生素给药涉及高剂量，不安全且无效。使用对金黄色葡萄球菌不稳定的寡核苷酸接头可能会导致耐药性的产生。微球菌核酸酶（MN）裂解，我们最近开发了一种水凝胶，能够按需释放当用作 Ti6Al4V 髓内 (IM) 针的水凝胶涂层时，共价连接万古霉素。插入接种有金黄色葡萄球菌的小鼠股管中，MN及时触发万古霉素的释放在细菌有机会定植或入侵之前杀死植入物表面和肌内空间内的细菌周围骨骼，从而在 3 周内防止生物膜形成和骨髓炎发展经检查，该涂层中万古霉素的共价束缚剂量比该涂层低几个数量级。临床上使用的典型预防性抗生素含量本研究的目标是进一步设计这一点。令人兴奋的按需药物释放系统，以增强其血清稳定性并严格检查其功效使用两种临床相关的种植体感染提供针对假体周围感染的持续保护在目标 1 模型中，寡核苷酸接头通过选择性 2'-O-甲基化进行化学修饰。硫代磷酸酯修饰可增强哺乳动物血清核酸酶的稳定性，同时保持在目标 2 中，将实施体外优化的核苷酸接头。 MN 敏感水凝胶涂层应用于 Ti6Al4V IM 针，用于按需输送万古霉素。这种预防性涂层在提供及时和持续的金黄色葡萄球菌保护方面的功效和安全性将使用大鼠股管感染模型在 6 个月内对假体周围感染进行严格评估。目标 3，这种按需抗生素释放策略在减少高假体周围感染方面的功效将使用大鼠 IM 检查对先前感染的大鼠股管进行手术清创后的比率种植体修复手术模型。感染程度作为针涂层和生物发光 S 的函数。通过生物发光成像和皮层 µCT 定量来纵向监测金黄色葡萄球菌接种 2 周、1、2、3 和 6 个月时的骨增厚，以及通过对回收的细菌进行终点定量销、外植股骨扭转测试和股骨组织学在 1、3 和 6 个月时的涂层的长期安全性。在终点处通过全身器官病理学检查万古霉素的剂量。在受感染动物的子集中进行的检测结果比预防性涂层高出数百倍接收未涂层的 IM 针，以便直接比较这种预防性涂层与其他涂层的功效标准护理实现更持久的保护，防止假体周围感染或复发感染。比全身注射万古霉素被认为是成功的，同时实现了对 6 的延长保护如果成功验证，几个月没有局部和全身副作用将被视为例外。 MN 触发的万古霉素释放能够及时、持续地消灭细菌，可以将细菌聚集在一起解决骨科植入物相关感染这一艰巨挑战的安全性和有效性绕过众所周知的难以治疗的生物膜和骨髓炎。