基于缺血性脑卒中炎症反应构建白细胞介导的中药有效组分多级脑靶向递药系统

The existence of blood brain barrier and inadequate blood flow make it difficult to delivery therapeutic molecules to the lesions in the brain for the treatment of cerebral ischemic stroke. A typical feature of neuroinflammation response, which occurs under cerebral ischemia, is the recruitment of leukocytes (mainly neutrophils and monocytes) to the lesions in the brain. The phagocytic and exclusive extravasation of leukocytes offers a unique opportunity to develop a targeting and cascade delivery system that can effectively deliver drugs to the inflammation sites in the brain. In present study, salvianolic acid B and puerarin, two effective neuroprotectant isolated from Salvia Miltiorrhiza Bge. and Puerariae Lobatae Radix, were encapsulated into liposomes synchronically by remote loading method. cRGD and N-Ac-PGP, two kind of peptides with high affinity to neutrophils and monocytes, respectively, were exploited as ligands and decorated on the surface of liposomes. When the liposomes are injected into the animals with ischemic stroke, they will be selectively and rapidly phagocytosed by the neutrophils and monocytes in the circulation. Then, the leukocytes will carry liposomes passing through the BBB, targeting to ischemic brain by inflammatory immigration, and finally entering the cerebral neurocytes by transient intercellular connection and exosome. The preparation, modification and characterization of liposomes, the binding efficiency of liposomes with leukocytes, the delivery mechanisms, brain targeting and therapeutic efficacy of liposomes-loaded cells will be studied comprehensively. Considering neuroinflammation occurs under many neurological disorders, the strategy developed in the study is not only promising for the efficient delivery of active components of traditional Chinese medicines to the brain, but also an effective approach for the treatment of various CNS diseases related to inflammation.

脑卒中严重威胁人类健康。中药由于多成分多靶点的综合作用，在脑卒中治疗中具有独特的优势，其中丹参-葛根药对以确切的疗效广泛应用，其主要活性成分丹酚酸B和葛根素从不同机制和靶点发挥对脑缺血损伤的治疗作用。但由于血脑屏障及脑卒中独特的病理特点，药物难以到达脑病变部位而发挥作用。本项目巧妙利用脑缺血时炎症反应募集的白细胞为载体，使载药脂质体实现BBB穿透、脑内组织选择性、进入病变细胞的多级靶向目的，提高药物治疗效果。首先将丹酚酸B和葛根素同步共载入脂质体中，采用可与白细胞特异性结合的cRGD和N-Ac-PGP肽对脂质体进行修饰，静注后脂质体迅速被白细胞摄取，进而随其被递送至脑病变部位和靶细胞，释放有效组分发挥配伍协同作用。本项目从分子、细胞、动物水平对递送过程与机制进行了深入研究，研究结果不仅将为脑卒中的治疗提供新方法，也为多种炎症相关脑部疾病的组分中药靶向递送和治疗提供了科学依据和理论基础。

脑卒中严重威胁人类健康。中药由于多成分多靶点的综合作用，在脑卒中治疗中具有独特的优势，其中丹参-葛根药对以确切的疗效广泛应用，其主要活性成分丹酚酸B和葛根素从不同机制和靶点发挥对脑缺血损伤的治疗作用。但由于血脑屏障及脑卒中独特的病理特点，药物难以到达脑病变部位而发挥作用。本项目巧妙利用脑缺血时炎症反应募集的白细胞为载体，使载药脂质体实现BBB穿透、脑内组织选择性、进入病变细胞的多级靶向目的，提高药物治疗效果。首先将丹酚酸B和葛根素同步共载入脂质体中，二者包封率均达到80%以上；采用可与白细胞特异性结合的cRGD和PGP肽对脂质体进行修饰，以增加脂质体与靶细胞（白细胞）结合率，其中cRGD可与单核细胞表面整合素受体结合，PGP可与中性粒细胞表面CXCR2受体结合。静注后脂质体迅速被白细胞摄取，能随着中性粒细胞和单核细胞携带cRGD与PGP共修饰载Sal-B和Pue的脂质体跨越BBB而浸润至缺血区，进一步通过与神经元细胞融合方式促进脂质体转移至神经元细胞内，脂质体在神经元细胞内缓慢释放有效组分发挥配伍协同作用，达到持续治疗的目的。药效学试验结果证明，cRGD与PGP共修饰可显著降低脑梗死面积和脑水肿，明显提高治疗效果。本项目从分子、细胞、动物水平对递送过程与机制进行了深入系统研究，显示cRGD与PGP的共修饰脂质体可将中药小分子配伍组合高效脑内递送至脑缺血区，并完整以配伍形式释放于脑缺血区，大幅度提高中药的治疗效果。研究结果不仅将为脑卒中的治疗提供新方法，也为多种炎症相关脑部疾病的组分中药靶向递送和治疗提供了科学依据和理论基础。