装载PEDF-34的MSC-exosome在糖尿病视网膜病变中的作用及机制研究

Over-expression of VEGF, inflammation, and oxidative stress are the key pathogenic factors in diabetic retinopathy (DR). Though injection of anti-VEGF drugs generates reliable efficacy, long-term inhibition of VEGF may lead to neurodeatrophia. PEDF is an endogenous inhibitor of neovascularization that can balance VEGF expression without interfering its normal function. PEDF-34 is a PEDF-derived peptide with several merits, including low molecular weight, good water solubility, and low immunogenicity. However, the stability of PEDF-34 is less satisfactory. The results of our preliminary studies have demonstrated that the exosome derived from mesenchymal sem cells (MSC-exosome) exerts neuroprotective effects on retina. In addition, exosome also can serve as a natural drug carrier. In this study, the MSC-exosome will be used as a drug carrier to load PEDF-34 peptide, thereby increasing the stability and permeability of PEDF-34 in tissue, as well as its bioavailalbility in retina. Furthermore, a series of in vitro and in vivo experiments will be conducted to confirm the therapeutic effects of the PEDF-34-carrying MSC-exosome on DR and to investigate the underlying mechanisms. This study will provide the scientific basis for clinical application and translation of PEDF-34 and MSC-exosome in DR treatment.

VEGF的过量表达、炎症和氧化应激是糖尿病视网膜病变（DR）的关键致病因素。注射抗VEGF疗效可靠，但易引发视网膜神经萎缩。PEDF是内源性新生血管抑制因子，可同时平衡VEGF的表达。PEDF-34是由PEDF衍生的多肽片段，具有分子量小、水溶性好且免疫原性低等优点，但稳定性较差。我们前期研究显示间充质干细胞（MSC）来源的exosome具有视网膜神经保护作用，同时exosomes还可作为天然药物载体。本课题将采用MSC-exosome作为载体，构建装载PEDF-34多肽的MSC-exosome制剂，提高PEDF-34在组织中的稳定性和穿透性及其在视网膜的生物利用度。并通过一系列体内外实验，验证其在DR中的治疗作用和研究其机制，为PEDF-34和MSC-exosome治疗DR的临床应用转化提供科学依据。

目前，全球有2.2亿人患有糖尿病视网膜病变（diabetic retinopathy, DR），并且发病率正在迅速上升。DR的典型特征是视网膜炎症、神经变性和病理性新生血管的形成。目前临床治疗DR的方法虽疗效较好，但均存在一定缺陷，因此寻找新型可靠的治疗手段一直是临床研究的热点。色素上皮衍生因子（Pigment epithelial-derived factor, PEDF）具有抗血管生成、抗炎、抗氧化和神经保护的作用，然而由于生物稳定性较差限制了该药物的临床转化。小细胞外囊泡（small extracellular vesicles, sEVs）因其粒径小、免疫原性低、可生物降解等特点被认为是理想的药物载体，并且我们前期研究显示间充质干细胞（mesenchymal stem cells, MSCs）来源的sEVs具有抗炎和神经保护的作用。在这项研究中我们拟将 MSC-sEVs作为PEDF的运输载体合成 PEDF-sEVs，并在OIR小鼠模型和VEGF诱导的HRECs增殖模型中评估其效果。.本项目研究结果显示，对OIR小鼠模型和VEGF诱导的HRECs增殖模型的治疗效果，PEDF-sEVs组的较PEDF组和sEVs组的治疗效果更加明显，并且我们发现sEVs可以明确减少PEDF的降解来增强其作用效果。此外，Lucentis在炎症抑制、视网膜结构及功能的恢复方面没有表现出明显的治疗效果，而PEDF-sEVs 明显抑制了OIR 小鼠的无灌注区面积及新生血管的形成，并有助于炎症抑制、视网膜结构及功能的恢复，这些研究结果为DR的治疗提供了新的研究方向。