装载雷帕霉素的间充质干细胞外泌体缓释制剂在自身免疫性葡萄膜炎中的应用研究

Autoimmune uveitis is one of the leading causes of visual disability, and traditional long-term immune suppressive therapies often result in many adverse effects. Intravitreous injection of rapamycin has been proved to be effective in treating uveitis while reducing the usage of systemic medicine. However, repeated intravitreous injections increase the risk of infection and economic burden of the patients. Our previous study demonstrated that exosomes derived from mesenchymal stem cells (MSC-exosomes) can inhibit the development of experimental autoimmune uveitis (EAU) of rats. Exosomes are also believed to be ideal biological carriers due to their ability to migrate across tissues and biological barriers. In this study, we will use MSC-exosomes to carry rapamycin to increase its ocular penetrating ability and therapeutic efficacy. Sustained release preparation will be made by using alginate gel to package the rapamycin-loaded MSC-exosomes. The therapeutic effect of this biological compound will be verified on both recurrence and chronic EAU model of rats and mice induced by adoptive transfer of T cells. This new preparation will provide promising alternative for the therapy of autoimmune uveitis.

自身免疫性葡萄膜炎是常见的致盲性眼病，传统药物全身长期使用可导致多种副作用。雷帕霉素玻璃体腔注射可有效治疗葡萄膜炎，避免或减少全身药物使用，然而反复玻璃体腔注射增加了感染风险和患者负担。我们前期研究显示间充质干细胞来源的外泌体（MSC-exosomes）球周注射可以有效抑制大鼠实验性自身免疫性葡萄膜炎（EAU）。由于易于穿透组织和生物屏障，exosomes是良好的生物载体。本研究拟采用MSC-exosomes装载雷帕霉素以提高其眼球壁穿透效率和治疗作用，采用海藻酸凝胶包裹载药exosomes以实现缓释功能，制备可以进行眼周注射的复合缓释生物制剂，并验证其在T细胞过继转移诱导的大鼠复发EAU和小鼠慢性EAU模型中的治疗作用，从而开发适用于自身免疫性葡萄膜炎局部治疗的新型生物医学工程产品。

自身免疫性葡萄膜炎是一种常见的致盲性眼部疾病。糖皮质激素和免疫抑制剂是治疗此类疾病的传统药物，长期应用可导致较多副作用。雷帕霉素（Rapamycin，Rapa）是一种哺乳动物雷帕霉素靶蛋白（mammalian targets of rapamycin, mTOR）抑制剂，可抑制T细胞增殖，在葡萄膜炎中的应用受到广泛关注，但其穿透生物屏障能力较差。间充质干细胞（mesenchymal stem cells, MSCs）来源的小细胞外囊泡（small extracellular vesicles, sEVs）已被证实可以减轻大鼠实验性自身免疫葡萄膜炎（experimental autoimmune uveitis, EAU），同时也是一种天然的药物载体。本研究的目的是构建装载雷帕霉素的MSC-sEVs给药系统(Rapa-sEVs)，并探究其结膜下注射对EAU的治疗作用。通过超声制备Rapa-sEVs，使用纳米颗粒跟踪分析、透射电镜和western blotting进行表征。通过临床和组织病理学评分来评估治疗效果。采用流式细胞术检测炎性细胞浸润情况。结果表明，Rapa-sEVs在结膜下注射后可到达视网膜病灶。与单独的sEVs和雷帕霉素治疗组相比，Rapa-sEVs治疗效果更明显，可减少眼部炎症细胞浸润。MSC-sEVs装载雷帕霉素在治疗EAU方面具有巨大的潜力，可能为葡萄膜炎局部治疗带来更为安全有效的替代疗法。