多孔β-TCP负载PLGA抗结核药物缓释微球的构建及其抗结核成骨作用研究

In the management of bone and joint tuberculosis, the application of anti-tuberculosis chemotherapy and surgical removal of lesion is the main method presently. It is difficult for antituberculosis drugs to achieve bactericidal concentration because there are a large number of virulent bacteria in the TB lesion around which avasculrized osteosclerosis is. Because the chemotherapy is not less than 8 months and not less than three kinds of drugs, the adverse side effects are regularly harmful for the health of the patients. It is difficult to repair and reconstruct the segmental bone defects caused by tuberculosis during the removal surgery. Based on the previous researches, our aim of this project is to develop a novel biomaterial that will be designed to bave dual fuctions in the defect left after lesion removal. One fuction is acting as an local antitubercular agent, the other is to refill the defect caused by tubercular lesion. Firstly, rifampicin and isoniazid are encapsulated with poly lactic-co-glycolic acid (PLGA) to make drug control-release microspheres. Then, the latter are delivered into the powder of β-tricalcium phosphates (β-TCP), like the inlay and onlay of jujubes in cake, to produce the novel biomaterial that will be indicative for tubercular defect. The techinique to form the compound, the interface, the formula, the porosity and mechanical characteristics of the developing material will be studied. With drug-releasing and antibacterial experiments, the drug control-releasing and antitubercular property of the material will be tested. The ex-vivo culture of cells with the material will be used to detect the histocompatibility. The material will be implanted into animal models to observe the degradation, anti-tuberculosis and the repairing effects to bone defects. The results of this study will promote some new techniques and principles for the bone and joint tuberculosis, which is meaningful for the management of tuberculous bone defects.

外科病灶清除联合抗结核药物全身化疗是治疗骨关节结核的首选方法。因病灶组织内结核杆菌数量多、毒力强、周缘骨硬化增生以及小血管炎性损害致使药物不易进入结核病灶。目前至少三联以上的、疗程不短于8个月的化疗方案会严重损害患者肝、肾功能。多个椎体不规则的结核性骨质破坏可导致脊柱结构和功能的双重损坏。如何实现在结核病灶内持续、稳定的维持有效抗结核药物浓度，以及大段结核性骨缺损的一期修复与重建是目前研究的热点。本研究采用交联明胶作孔剂制备多孔β-磷酸三钙（β-TCP），在骨小梁水平上实现弹性模量的匹配和充填。将异烟肼、利福平用聚乳酸-羟基乙酸共聚物（PLGA）共包封制成缓释微球，并加载于多孔β-磷酸三钙构建植入型抗结核药物缓释骨修复材料。通过对所构建材料的理化特性、体内外药物缓释动力学、成骨作用的实验研究，验证其治疗效果，为材料最终应用于骨与关节结核的治疗，提供实验和理论支持。

外科病灶清除联合抗结核药物的全身运用是治疗骨关节结核的首选治疗方案，但骨结核的长期化疗方案严重损害患者肝、肾功能，且多个椎体及大段感染性骨缺损造成骨与关节结构和功能的双重损害，同时病灶组织内结核杆菌数量多、毒力强、周缘骨硬化增生及小血管炎性损坏导致抗结核药物不易进入结核病灶。因此，如何实现病灶内持续稳定的药物浓度以及大段感染性骨缺损的一期修复重建成为治疗感染性骨缺损的主要研究内容。本研究采用CAD制图及3D打印技术制备多孔β-TCP支架，在骨小梁水平上实现弹性模量的匹配与填充，同时将异烟肼、利福平及聚乳酸-羟基乙酸共聚物（PLGA）共包封制成缓释微球，并负载于多孔β-TCP支架构建植入型抗感染及骨修复材料。通过对材料的理化性质、体内外药物缓释研究、成骨作用研究评价，证实400um规格孔隙的3D打印β-TCP负载PLGA抗结核缓释微球复合支架力学特征达到松质骨强度，具有良好的体内外缓释特性，缓释时长可达12周，有较好的抗感染能力及体内成骨能力，其细胞毒性为0级。因此，该复合材料可以用于骨与关节感染的治疗，是一种理想的抗感染及一期成骨的骨修复材料。