MR分子成像引导下超声定点释药可视化靶向治疗RA的研究

Rheumatoid arthritis (RA) is a common severe autoimmune disease characterized by joint synovitis, pannus formation, bone destruction, with a high degree of disability. Althrough methotrexate (MTX) is widely accepted as the first choice of the drug for patients with rheumatoid arthritis, its side effects, such as hepatic lesion and myelosuppression, seriously affected the treatment of rheumatoid arthritis and eventually resulted in the discontinuation of clinical intervention and disease deterioration. It has become a difficult point of RA treatment to achieve the accurate targeting drug and response evaluation, reduce systemic dosage, relieve side effects, shorten the course under the condition of noninvasive treatment. Interestingly, echogenic liposomes are ideal ultrasound-activated drug carriers due to their characteristics of high loading efficiency and ultrasound-controlled drug delivery, which can better achieve MR-guided local drug delivery with the aid of magnetic nanoparticles(USPIO). Meanwhile, iRGD is a cell-penetrating peptide which can target over-expressed αvβ3 receptors of RA synovial vascular endothelial cells and enhance drug delivery inside synovial tissue. This study intends to regard over-expressed αvβ3 receptors closely related to the pathogenesis of rheumatoid arthritis as the target, and synthesize iRGD-modified echogenic liposomes loading MTX and USPIO to integrate their advantages between MR molecular imaging and low frequency ultrasound-controlled drug delivery. This project is expected to combine MR molecular imaging guidance with ultrasound-assisted drug delivery to achieve visual targeting treatment of RA and to enhance the effect of drugs. In the preliminary experiment, we briefly confirmed the validity of iRGD-modified liposomes in the treatment of RA, which will further provide favorable conditions for our next experiment.

类风湿关节炎(RA)是一种以关节滑膜炎、血管翳新生、骨破坏为基本病理改变的的高度致残性自身免疫性疾病，其治疗首选药甲氨蝶呤(MTX) 因有肝功损害、骨髓抑制等副作用常导致临床干预停止而发展为难治性RA。如何在非关节腔穿刺情况下实现病变关节的可视化精准靶向用药与疗效评估，减少全身用药量，降低副作用，缩短疗程是RA治疗的难点问题。本项目拟利用具有高载药量并可超声定点释药的声敏脂质体，借助可靶向滑膜血管内皮细胞整合素αvβ3受体并能加速药物递送的穿膜肽iRGD和MR造影剂超小超顺磁性氧化铁粒子(USPIO)，构建iRGD修饰的载USPIO和MTX声敏脂质体靶向传递体系，集MR分子成像和低频超声定点控释药物这两种无创技术于一体，有望实现MR分子成像引导下超声定点控释药物、可视化靶向治疗RA和疗效监测。我们前期初步证实靶向iRGD-MTX-脂质体治疗RA小鼠的疗效显著优于非靶向组和游离MTX组。

类风湿关节炎(RA) 是一种关节滑膜炎反复发作、关节破坏为主要特征的自身免疫性疾病。首选药物甲氨蝶呤（MTX）全身应用副作用大，局部药物药物浓度低。本项目旨在探索非关节腔穿刺等有创方法下，实现可视化药物在RA病变关节的精准定点靶向控释，提高药物局部浓度，增强疗效的同时降低全身副作用。.课题组通过特定磷脂配比构建iRGD-ICG-MTX-脂质体，利用真空冷冻干燥的技术使脂质体内形成空气腔隙，对声敏脂质体进行表征测定。利用人脐静脉内皮细胞（HUVEC）、类风湿关节炎滑膜成纤维细胞（MH7A）对其靶向性、杀伤性进行评价。用小鼠CIA模型模拟RA发病，根据超声、脂质体主动靶向性能、建模与否三个条件将成功建模的小鼠分为6组，利用近红外荧光成像技术对脂质体药物进行示踪并引导控释治疗，并在采用CT重建、组织病理学、免疫组化评价iRGD-ICG-MTX-声敏脂质体疗效及药物安全性检测。.制备的载MTX靶向声敏脂质体粒径为（106.32±0.46）nm，大小均匀，分散度、稳定性好 。在1.0MHz超声、0.30MPa、作用90s时，MTX释药率达（72.87±8.73）%，并随超声作用时间延长、声压增加递增。体外实验显示，载MTX靶向声敏脂质对人MH7A细胞增殖的抑制率达到（68.16±4.62）%。小鼠体内实验证实，利用近红外荧光对踝关节炎症部位进行成像，载MTX靶向声学脂质较对照组荧光聚集强度提升2.21倍。iRGD-ICG-MTX-声敏脂质体治疗组RA临床评分较低（平均4.19分），CT显示关节部位组织结构清晰、柔韧度佳，且小鼠皮毛光亮、精神状态佳，对照组织结构破坏与增生并存、结构紊乱、关节腔隙消失，iRGD-ICG-MTX-声敏脂质体治疗组与其他组疗效比较，差异具有统计学意义（P<0.05）。.该研究成功构建了iRGD靶向肽标记的载MTX声学脂质体，协同发挥穿膜肽iRGD的药物传递加速作用，同时借助近红外荧光分子成像技术可视化引导，实现局部低频超声定点控释MTX靶向治疗RA，将分子成像与超声控释治疗有机结合，为未来RA的早期诊断和靶向治疗奠定了一定的基础。