利用分子探针Zn-DPA定位人工全膝关节置换术后关节内感染病灶的研究

Infection is one of the most serious complications after total knee arthroplasty (TKA). While the revision surgery is the gold standard for the therapy of chronic infection, the treatment for acute knee infection after TKA is currently under debate. The main treatment options for the acute knee infection after TKA include open debridement and implant retention, or implant exchange revision surgery. Compared to revision surgery, the open debridement and implant retention is quite less complex and is attractive for both patients and surgeons. Unfortunately, open debridement and implant retention does not provide satisfactory results in terms of infection control. The main reason might be that the open debridement and implant retention surgery could not eliminate the bacterias dwelling in the area of bone-cement interface. Therefore, the early diagnosis and location of the joint infection is critical for the treatment protocol planning and thorough elimination of bacterias during surgery. However, the anatomical imaging procedures like conventional radiography, CT or MRI frequently fail to differentiate aseptic and septic inflammation, and also could not locate infection. Recently, the imaging probe zinc-dipicolylamine(Zn-DPA) has been reported to selectively target the anionic surfaces of bacterial cells in vitro and in vivo, and not combine the exterior zwitterionic surfaces of most healthy animal cells. The current study will,for the first time as we know, evaluate the capability of radiolabeled Zn-DPA, combined with Single-photon emission computed tomography (SPECT/CT) techniques which has the superior anatomical location ability of pathological tracer accumulation, to provide specific physiological information about joint infection, and enable exact location of the infection. Based on the location of infection, the specific treatment were selected and the infected area would be accurately detected and thoroughly eliminated during surgery.

人工全膝关节置换（TKA）术后急性感染的治疗难点是选择治疗方法时没有客观、可靠的标准，清创保留假体术较翻修术相比优点众多，因而使用更为广泛，但其无法清除骨水泥-骨界面的感染，盲目使用必然导致高失败率。长期以来临床缺乏TKA术后关节感染早期诊断和定位的方法，无法准确判断感染是否侵及骨水泥－骨界面。本研究拟利用细菌示踪领域的前沿技术- - 分子探针Zn-DPA，经核素标记后在体内与细菌特异性结合，不与正常细胞结合，通过SPECT/CT对TKA术后急性感染进行早期诊断和感染病灶三维定位，根据感染累及部位选择针对性治疗方法，术中有的放矢地清除感染病灶，实现有效提高感染控制率的同时尽可能保护关节功能。

假体周围感染的诊断及预防是解决临床假体周围感染问题的根本和趋势，对于假体周围感染诊断，细菌的定位是关键，而决定细菌定位核心是具有高敏感性和高特异性的感染示踪物；对于假体周围感染的预防，构建抗感染的骨科植入物是有效手段。本课题基于体外体内对细菌的示踪剂进行研究,同时构建抗菌的骨科内植入物预防假体周围感染。.本课题开展的主要研究内容、重要结果包括：我们预实验比较了Zn-DPA和抗菌肽KR-12对细菌的亲和力与生物相容性，在细菌亲和力方面，小分子多肽KR-12具有明显的优势，因此本课题选择了KR-12作为细菌的示踪剂。我们研究了小分子抗菌肽KR-12对细菌亲和力和正常动物组织内细菌示踪敏感性和特异性及对骨髓间充质干细胞的粘附增殖、成骨分化及其机制。体外研究表明KR-12对金黄色葡萄球菌与大肠杆菌亲和力及体内能够定位示踪细菌并能够区分无菌性炎症。另外抗菌肽KR-12可以通过激活BMP/Smad通路促进人骨髓间充质干细胞成骨分化。在抗感染骨科植入物方面，我们研究了杆菌肽改性的骨科植入物对骨科常见的细菌粘附及生物膜形成的影响。杆菌肽修饰的钛合金亲水性得到极大的提高;抗菌试验表明具有优异的抗菌性能，能抑制金黄色葡萄球菌菌及耐药金黄色葡萄球菌的粘附和生物膜形成。同时提高骨髓间充质干细胞的黏附、增殖和成骨分化。大鼠体内实验表明杆菌肽修饰的钛合金能够预防假体周围感染同时具有促进骨整合。我们进一步通过骨科植入物表面依诺杀星共价接枝构建具有广谱抗菌的骨科植入物,依诺诺沙星修饰的钛表面可以有效地预防细菌的定植，包括金黄色葡萄球菌，耐甲氧西林金黄色葡萄球菌，表皮葡萄球菌，耐甲氧西林表皮葡萄球菌和大肠杆菌，并且对人骨髓间充质干细胞没有细胞毒性，体内能够预防耐甲氧西林金黄色葡萄球菌导致的假体周围感染。.我们的研究成果证明抗菌肽KR-12是一种优异的可以和UBI29-41媲美的细菌示踪剂，使细菌体内示踪成为可能。同时我们在抗感染骨科植入物方面做了大量研究，为研发抗感染骨科植入物提供了重要理论依据和方法。