基于光触发同步释放ROS与药物的眼内长效植入系统的构建及其用于后囊浑浊防治的评价

Posterior capsule opacification (PCO) is a common complication after cataract surgery. The occurrence of PCO is mainly attributed to the proliferation of residual lens epithelial cells (LECs) in the ambitus of capsule bag. The proliferative LECs would move towards to posterior capsule and become fibrosis, leading to a result of losing vision again. According to the mechanism of PCO, our group had designed relevant systems previously to prevent PCO [Asian J of Pharm Sci, 2013. Biomaterials, 2016. Int J Pharm., 2016]. One of the systems could release drug at specific location [Biomaterials, 2016.] while another one could generate ROS with in-vitro control [Int J Pharm., 2016]. Both of the system showed great potential for PCO prevention. However, they had their own disadvantages respectively. Therefore, this project is going to establish an implant system to integrate the advantages of the two system, which could make PCO prevention more effective and safe. In this project, photosensitizers were loaded and drug was covalently connected to the implant through a ROS-sensitive bond. When irradiated by laser, the implant could generate a large amount of ROS. On one hand, ROS could directly contact with LECs, leading the cells to apoptosis or necrosis. On the other hand, ROS-sensitive bonds would be degraded rapidly with ROS existence and the connected drug would be released. Accordingly, both ROS and drug could be controlled released simultaneously by laser irradiation in vitro and they could play their roles together to make a stronger and safer inhibition to LECs. The monomer CPBA which drug was covalently connected to through ROS-sensitive bonds had been synthesized in our pre-experiment. The synergistic effect of simultaneous releases of ROS and drug would be investigated through MTT assay and ex vivo capsule bag culture. Pharmacodynamics and pharmacokinetics experiments would be conducted to evaluate the efficacy and safety of the implant. We hope this project could put forward a new idea for PCO prevention.

后囊浑浊（PCO）是白内障术后常见并发症，是因位于晶体囊袋赤道部的上皮细胞发生增殖并向后囊移行，继而发生纤维化使后囊皱缩，导致视力再次下降。基于PCO发生机制，本课题组前期分别设计了可定点释放药物[Biomaterials,2016]和体外可控产生活性氧（ROS）[Int J Pharm,2016]的植入体系并获得良好体内疗效。基于前期研究结果，我们拟利用两种治疗模式的优势，将光敏剂与药物以ROS敏感键结合于植入剂中，经激光触发产生ROS，继而触发ROS敏感键释放药物，实现外界可控制ROS与药物在体内的同步释放，进而协同起效。我们在预实验中已设计并合成出以ROS敏感键连接药物的单体CPBA。随后将通过体外细胞及离体囊袋对光触发释放ROS与药物，阐明光照剂量与ROS及药物释放量的相关性及协同机制，构建光触发同步释放ROS和药物的体系，并于体内考察其安全、有效及合理性。探索PCO防治新方法。

针对晶状体后囊浑浊（PCO）防治的两大难点：１）如何使药物长期持续定位于眼内囊袋中，２）如何实现时空可控的治疗。本课题设计并合成了近红外光（NIR）可控激活产生活性氧（ROS）并同步释放药物的植入剂。结果表明，所制备的ROS敏感光控材料可于NIR触发下产生ROS，一方面使材料中ROS敏感的缩硫酮键或苯硼酸酯键断裂，使得填充材料具有NIR敏感的释药或降解特性；另一方面ROS可杀伤细胞，实现长效可控的化疗/光动力联合治疗。为了进一步增加PCO防治的长效性及安全性，又进一步构建了基于光触发条件下具有同步、可持续释放ROS功能的的复合材料长效眼内植入剂囊袋张力环（CTR），用于PCO的防治。将光敏剂原卟啉（PpIX）共价连接到CTR上以克服因光敏剂释放导致的疗效不足或其它副作用，同时共价接枝单线态氧储存器2-羟基吡啶酮（Py）于CTR表面，制备在短暂光触发后，可持续产生ROS的长效眼内植入剂（CTR-P-P），以达到无光照条件下ROS的持续释放，实现持续杀死LECs，最终防治PCO的目的。结果表明，在短暂（5min）光触发下，PpIX产生的ROS与Py形成内过氧化物，实现ROS的存储。在撤去光源后，内过氧化物通过逆D-A反应持续地产生ROS。体外长期稳定性、单次及重复光触发实验表明，CTR-P-P在短时光照条件下具有稳定的ROS释放能力，撤去光源后仍保持自身产生ROS的能力，表现出良好的光动力稳定性和单线态氧储存释放稳定性。实验证实，CTR-P-P在短时间光照后能持续产生并储存ROS，撤去光源后储存的ROS能持续释放，所产生的ROS能将晶状体上皮细胞（HLECs）膜脂质过氧化，实现对HLECs的持续杀伤。经体外细胞培养以及兔晶状体离体囊袋考察了所构建制剂对LECs的增殖抑制作用，证实了所构建晶状体囊袋植入剂用于PCO防治的有效性和安全性。综上，本研究成功合成了NIR触发同步产生ROS的植入剂材料，论证了PDT产生的ROS触发药物释放的可行性，实现了时空可控的定位治疗，并初步阐明了基于ROS的治疗策略防治PCO发生的机制，为临床PCO的防治提供新的策略与思路。