新型负载VEGFR2靶向雷帕霉素纳米载体的聚乳酸羟基乙酸微球的抗血管瘤作用和机制研究

Rapamycin is a promising drug for the treatment of hemangiomas. To increase its targeting towards hemangiomas and reduce its side effects, we utilized the feature that vascular endothelial growth factor receptor 2 (VEGFR2) is overexpressed in hemangioma endothelial cells, and previsouly constructed VEGFR2-targeted rapamycin-loaed lipid polymer nanocarriers (rapamycin targeting nanocarriers) to achieve targeted therapy of rapamycin towards hemangiomas. In order to further extend the drug action time of the nanocarrier, we envisage that the rapamycin targeting nanocarrier is loaded on the polylactic acid glycolic acid microsphere to construct a novel rapamycin targeting nanocarrier microsphere. For the first time, the study used a novel strategy of rapamycin targeting nanocarrier microspheres to achieve multiple therapeutic efficacies towards hemangioma: long-time drug release, targeting hemangioma endothelial cells, and embolization of hemangioma microvessels. This study is intended to comprehensively explore the anti-hemangioma efficacy and mechanisms of rapamycin-targeted nanocarrier microspheres at the molecular, cellular and global experimental animal levels. This study is the first to use the new strategy of targeting nanocarrier microspheres to achieve the three aims of drug delivery, targeted therapy and vascular embolization, providing new ideas, important theoretical significance and potential clinical application values for the treatment of hemangiomas.

雷帕霉素是一种很有潜力的血管瘤治疗药物，为提高其对血管瘤的靶向性和降低其毒副作用，我们利用血管瘤内皮细胞过表达血管内皮生长因子受体2（VEGFR2）的特点，构建了VEGFR2靶向雷帕霉素脂质多聚物纳米载体（雷帕霉素靶向纳米载体）实现了雷帕霉素对血管瘤的靶向治疗。为进一步延长纳米载体的药物作用时间，我们设想将雷帕霉素靶向纳米载体负载于聚乳酸羟基乙酸微球以构建新型雷帕霉素靶向纳米载体微球。该研究首次采用雷帕霉素靶向纳米载体微球通过长效缓释维持稳定有效血药浓度、血管瘤内皮细胞靶向杀伤和微血管栓塞切断血管瘤营养供应的三重机制实现对血管瘤的高效杀伤。本研究拟在分子，细胞和整体实验动物水平，探讨雷帕霉素靶向纳米载体微球的抗血管瘤作用机制。本研究创新性的利用靶向纳米载体微球的全新策略实现针对血管瘤的药物缓释、靶向治疗和血管栓塞，为血管瘤治疗提供新思路，对血管瘤治疗具有重要理论意义和潜在临床应用价值。

我们之前开发了几种包封雷帕霉素的纳米颗粒，以实现雷帕霉素的持续释放来治疗血管瘤。然而，缺乏内在靶向性和容易被免疫系统清除是人工制造的纳米粒子必须克服的主要障碍。我们构建了包裹雷帕霉素的巨噬细胞衍生外泌体纳米微球(RNM)，以实现对血管瘤进行持续靶向治疗的目标。首先通过基于挤压的方法从U937细胞(人类巨噬细胞系)制备了雷帕霉素包封的外泌体纳米颗粒(RN)。然后，用PLGA(聚乳酸-羟基乙酸共聚物)微球包封RN以获得RNM。研究了RN和RNM在血管瘤干细胞上的释放特性、靶向性和生物活性。RN的直径大小为100纳米，雷帕霉素包封率(EE)为83%。制备的RNM的粒径约为30 μm，RNM的EE为34%。RNM的缓释可显著达到40天。正如预期的那样，RN和RNM在人胚胎干细胞中显示出有效的细胞增殖抑制，显著的细胞凋亡，以及显著的血管生成因子表达抑制。我们的结果表明，RNM是一种延长和有效地将雷帕霉素递送至血管瘤的有效方法。