低频超声联合人β-防御素3纳米脂质体-微泡复合载体用于内植物生物膜感染的早期诊断及靶向治疗的实验研究

Bone and joint infections, including chronic implant-related infection are refractory to treatment. The most important mechanism of chronic infection is the existence of bacterial biofilms and bacterial internalization in osteoblasts which can evade most of antibiotics and the immune systems. Our previous studies provided encouraging evidences that ultrasound-targeted microbubble destruction may enhance endogenous antibiotic polypeptides, human β-defensin-3, activity against antibiotic-resistant biofilm cells, and biofilm-associated and methicillin-resistance genes. Our research group independently prepared and characterized the complex of microbubble conjugated to nanosized liposomes with human β-defensin-3. The significantly increased release of payloads from liposome-microbubble complexes was achieved upon US exposure. Subsequently, we observed therapeutic effects of infection under the conditions of human β-defensin-3-loaded liposomes-microbubble complexes conjugated to fluorescent dye combined with ultrasound radiation. Meanwhile, it is essential to optimize the ultrosound exposure parameters in order to treat efficiently bacterial biofilm infections and bacterial internalization in osteoblasts in vitro. Next, the same findings were observed in vivo and revealed its possible mechanism. We design a multifunctional durg-loaded liposomes-microbubble complex delivery system for early detection (fluorescence and ultrosound trimodal imaging) and targeted therapy (ultrosonic-acivated) in a murine model of biofilm infection. It will establish the foundation for the integrated application of the ultrasonic imaging diagnosis, drug delivery and therapy.

内植物感染的诊疗是困扰骨科医生的难题，早期诊断尤其困难，而晚期迁延不愈最主要机制包括细菌生物膜的形成及细菌内化进入成骨细胞，从而逃避抗生素和体内的免疫机制。课题组前期研究表明，低频超声联合靶向微泡可以使内源性抗菌肽人β-防御素3对生物膜内耐药葡萄球菌的杀灭作用明显增强，并抑制细菌成膜及耐药基因表达。本项目拟将人β-防御素3包裹于高载药量的纳米级脂质体中，进而耦联到微米级的微泡表面，获得具有超声爆破靶向释放性能的载药脂质体-微泡复合物；再将荧光染料与微泡、脂质体耦联，赋予其炎症部位特异性的靶向显影。在优化的超声参数条件下，体外联合低频超声，明显增强复合物对成骨细胞内金葡菌及生物膜感染的杀菌效果，体内亦证实可以显著提高复合物在炎症部位的浓度及抗感染疗效，并分析其作用机制。本课题组提出一种多功能的载药纳米脂质体-微泡荧光复合载体诊疗剂，为超声敏锐成像诊断、给药、治疗一体化的临床应用奠定基础。

内植物感染的诊疗是困扰骨科医生的难题，早期诊断尤其困难，而晚期迁延不愈最主要机制包括细菌生物膜的形成及细菌内化进入成骨细胞，从而逃避抗生素和体内的免疫机制。课题组前期研究表明，低频超声联合靶向微泡可以使内源性抗菌肽人β-防御素3对生物膜内耐药葡萄球菌的杀灭作用明显增强，并抑制细菌成膜及耐药基因表达。本项目已将人β-防御素3包裹于高载药量的纳米级脂质体中，进而耦联到微米级的微泡表面，获得具有超声爆破靶向释放性能的载药脂质体-微泡复合物；再将荧光染料与微泡、脂质体耦联，赋予其炎症部位特异性的靶向显影。在优化的超声参数条件下，体外联合低频超声，明显增强复合物对成骨细胞内金葡菌及生物膜感染的杀菌效果，体内亦证实可以显著提高复合物在炎症部位的浓度及抗感染疗效，并分析其作用免疫调节机制。本课题组提出一种多功能的载药纳米脂质体-微泡荧光复合载体诊疗剂，为超声敏锐成像诊断、给药、治疗一体化的临床应用奠定基础。