载药纳米粒透过血脑屏障机制的研究进展

血脑屏障是维持中枢神经系统内环境稳定的结构基础,有效保护脑组织避免外源性有害物质侵害,但也阻碍许多治疗药物进入脑内,限制了中枢神经系统药物的临床应用。如何有效透过血脑屏障成为此类药物发挥治疗作用的关键环节。纳米粒作为一种新型药物载体,能携载药物透过血脑屏障进入脑组织,提高脑内药物浓度,实现脑内靶向给药。本文对载药纳米粒及其透过血脑屏障机制的研究进展作一综述。     

纳米粒作为脑靶向给药系统的研究进展

中枢神经系统(Central nervous system,CNS)疾病,如脑肿瘤、老年痴呆、帕金森综合征、病毒感染等是威胁人类健康的一大类疾病。但血脑屏障(Blood brain barrier,BBB)的存在限制了许多有效的治疗药物从血液进入脑部而发挥作用。因此,解决通过BBB的药物传递问题已成为脑部疾病药物治疗的关键。纳米粒(Nanoparticle,NP)又称毫微粒,是粒径大小在10～1000nm的固态胶体颗粒,可作为传导或输送药物的载体[1]。广义的NP给药系统包括脂质体(Liopsomes)、固体脂质纳米粒(Solidlipid nanoparticles,SLN)、纳米囊(Nanocapsules)和纳米球(Nanospheres)以及聚合物胶束(Polymeric micelles),本文所述的NP特指纳米球和纳米囊。NP在体内具有长循环、隐形和立体稳定等特点,有利于靶向给药。对其进行表面修饰,能显著提高药物在脑内的浓度,改善药物对脑部疾病治疗的有效性。本文着重对NP的最新研究进展作如下综述。1BBB的主要生理特征CNS与体循环之间主要存在二重屏障:BBB与血-脑脊液屏障(B-CSF-B)。B...     

双配体修饰的阿霉素脂质体靶向于脑胶质瘤的体外研究

目的筛选和优化转铁蛋白、叶酸共同修饰的阿霉素脂质体的处方及制备工艺,以期得到具有良好的脑胶质瘤靶向治疗作用的给药系统。方法采用薄膜分散和硫酸铵梯度法制备阿霉素脂质体。将叶酸连接至二硬脂酸磷脂酰乙醇胺-聚乙二醇2000(DSPE-PEG2000-NH2)得到DSPE-PEG2000-Folic,考察不同磷脂种类、药脂比、水化介质和载药时间,对脂质体粒径、包封率和稳定性的影响,确定脂质体的处方工艺。以大鼠的脑毛细血管内皮细胞(bEnd3)和星形胶质细胞组成体外血脑屏障(blood-brain barrier,BBB),并结合大鼠胶质瘤C6细胞,构建体外模拟胶质瘤靶向治疗的复合BBB模型。考察阿霉素脂质体在bEnd3细胞中的摄取机制和透过BBB的转运速率及对C6细胞的毒性。结果确定了DSPC作为主要磷脂组分,并以120 mmol.L 1的硫酸铵作为水化介质,药脂比为1∶1 5,载药时间选择60 min,成功制备了高包封率和稳定性的双配体脂质体。其在bEnd3细胞中摄取远大于普通脂质体(P<0.05),摄取过程受网格蛋白和小窝内陷介导的细胞内吞作用,并受转铁蛋白和叶酸的影响;同时其在BBB模型中的药物透过速率、及其进一步透过BBB后对下层C6细胞的毒性,均显著高于其他脂质体组。结论转铁蛋白和叶酸共同修饰的阿霉素脂质体具有较好的体外脑胶质瘤靶向治疗作用。     

促进大分子药物跨血脑屏障转运多功能载体的研究进展

血脑屏障(Blood Brain Barrier，BBB)在防止异物入侵，保护脑功能正常方面起着非常重要的作用。促进药物特别是大分子药物跨过BBB入脑是脑疾病药物治疗学和脑药发展的重要研究领域之一。本文就近年促进药物跨BBB转运体系的研究进展作综述性介绍。     

盐酸他克林前体药物的研究盐酸他克林前体药物的研究

目的制备盐酸他克林(THA)的酰化前体药物以提高其透过血脑屏障(BBB)的能力。方法THA和酸酐反应制得N-酰化-THA系列前体药物;考察了前体药物在不同介质中的降解情况,并以N-单丁酰-他克林(BTHA)为模型药物,考察其在小鼠体内的分布和降解情况。结果合成的化合物经¹HNMR,MS和IR鉴定为目标化合物。前体药物在不同介质中均较稳定。与原药相比,前药的脂水分布系数增大。BTHA主要分布于脑、血浆和肝脏中(最高浓度分别为17.572 5,13.140 0和22.827 9 mg·L^-1),在肺和心中的分布浓度很低(最高浓度分别为4.947 5和4.492 5 mg·L^-1)。BTHA在脑内的降解速率较慢,给药12 h后仍有较高浓度(2.415 9 mg·L^-1)。结论N-羧酰-THA系列前体药物提高了THA透过BBB的能力,有望成为脑内定向给药的有效途径。     

促进药物跨血脑屏障转运载体的研究进展

血脑屏障(BBB)主要由脑毛细血管内皮细胞构成,其阻止98%小分子和几乎全部大分子化合物入脑,是制约脑药发展的重要因素。目前将药物递送入脑的主要途径为神经外科学、药化和生理学途径,后者利用脑毛细血管内皮细胞膜受体介导的跨细胞系统(RMT)为载体携载药物经主动转运入脑。基于RMT可构建促进药物入脑的载药平台,该文重点介绍该平台的研究思路、方法技术和应用前景等方面的最新研究进展。     

PEG-胆固醇双重修饰PBCA纳米粒脑靶向机制

目的中枢神经系统疾病目前存在的主要问题是血脑屏障(BBB)通透性的问题,本实验期望通过制备PEG-胆固醇双重修饰PBCA纳米粒,提高难透过BBB的中枢神经系统疾病的治疗及早期诊断药物的治疗作用,并对其经过BBB进入脑组织的机制进行探讨。方法采用乳化聚合法制备双重修饰PBCA纳米粒并对其理化特性进行评价。(1)双重修饰PBCA纳米粒体内药动学及脑组织分布研究:实验前12小时大鼠进行颈静脉插管手术。实验时于插管处给予原药溶液,胆固醇单修饰及PEG-胆固醇双重修饰PBCA纳米粒。给药后不同时间点取血200μL,化学/发光分析仪测定血液中香豆素-6的含量。大鼠尾静脉分别给予原药溶液、胆固醇单修饰及PEG-胆固醇双重修饰PBCA纳米粒。给药后不同时间点处死大鼠,取脑组织测定香豆素-6的含量。(2)双重修饰PBCA纳米粒体外细胞摄取及转运机制研究:采用b End.3细胞模型(永生化小鼠脑内皮细胞株)评价了载体及纳米粒的体外细胞毒性,同时选用了巨胞饮介导的内吞作用(细胞松弛素D),网格蛋白介导的内吞作用(氯丙嗪),小窝蛋白介导的内吞作用(染料木素),胆固醇耗竭(MβCD和制霉菌素),高尔基体抑制剂(布雷菲德菌素A)和耗能(叠氮钠)等七种细胞摄取抑制剂来研究载药纳米粒的细胞摄取及转运机制。结果 (1)制备的纳米粒粒径为(191.1±1.22)nm、载药量约为1.97%,包封率大于98%。同时双重修饰PBCA纳米粒在体外具有更明显的缓释效果。(2)双重修饰PBCA纳米粒在体内具有更高的血药浓度及缓释效果,能持续释放12 h,而胆固醇单修饰纳米粒仅释放8 h,原药溶液仅4 h内能检测到药物。脑组织分布研究结果表明,双重修饰PBCA纳米粒静脉给药后脑组织中药物含量显著增高且成缓慢释放的过程,说明具有成为脑靶向制剂的研究潜力。(3)载体及载药纳米粒细胞安全性良好,纳米粒在实验范围内没有明显的细胞毒性,具有较好的安全性。选择不同类型的摄取和转运抑制剂研究了载药纳米粒的细胞摄取及转运机制。结果表明,参与细胞转运和摄取的机制可以是不同的,而胆固醇-PEG双修饰PBCA纳米粒在b End.3细胞中的转运机制,是一个包括巨胞饮介导、耗能、同时需要胆固醇参与等多种机制介导的复杂过程。结论本实验制备的PEG20000-胆固醇双重修饰PBCA纳米粒,可解决中枢神经系统疾病的治疗及诊断药物体内BBB通透率低、安全性差、缓释性差等瓶颈问题,具有重要应用前景。     

聚乳酸及其共聚物脑靶向载药纳米粒的研究进展

目的：综述聚乳酸及其共聚物（PLA/PLGA）脑靶向载药纳米粒（NP）的研究进展。方法：查阅2005-2012年来国内外有关文献,对PLA/PLGA脑靶向载药NP的作用机制、制备方法、功能分子的连接方式、体外体内作用效果评价方法进行综述。结果与结论：受体介导入脑是目前最为成熟的脑靶向给药机制,鼻腔给药也是一种有效的入脑机制;脂溶性载药NP和水溶性载药NP的制备分别采用乳化溶剂挥发法和复乳法;而溶剂扩散法可加快微球的形成,用于制备粒径较小的NP;功能分子主要利用其上的巯基、氨基、羧基或马来酰亚胺等活性基团与PLA或PLGA对应基团进行共价结合,或利用生物素-亲和素体系脑靶向递药;体外效果评价常用大鼠脑微血管内皮细胞（BMVEC）单层培养模型及BMVEC-星形胶质细胞共培养模型;体内效果评价常用荧光显微镜和活体荧光成像、放射自显影法,前者用于考察以荧光素和香豆素等荧光染料标记的脑靶向NP,后者用于以125I、3H、14C等放射性核素标记的脑靶向NP。提高脑靶向的靶向效率、提高载药量、减少PLA/PLGA的用量、改善PLA/PLGA纳米粒体内降解性能和增加稳定性,是今后脑靶向PLA/PLGA载药NP研究的重点方向。     

载药纳米粒的脑内递药系统

介绍了载药纳米粒在脑内药物传递系统中的应用 ,提出了其脑靶向性可能的影响因素和机制     

冰片在促进药物跨血脑屏障转运中的应用

中枢神经系统疾病的发病率与死亡率日渐增高,然而血脑屏障(blood brain barrier,BBB)的存在阻止了大部分药物进入脑内,达不到有效浓度,使得这类疾病的治疗效果不佳。冰片因其"芳香开窍"促进血脑屏障开放以及脑保护的性质,近年来越来越多地被用于脑靶向给药策略中。本文对冰片药理作用、在药物跨BBB转运中的应用、冰片修饰方法以及促透机制四个方面做一综述。     

The potential for nanoparticle-based drug delivery to the brain: overcoming the blood–brain barrier

The development of blood–brain barrier (BBB)-targeting technologies is a very active field of research: targeting therapeutic actives to the central nervous system by means of systemic administration means crossing the BBB, and this is now one of the most challenging problems in drug development. The BBB is a unique regulatory system that protects the brain environment by separating it from direct contact with the circulating blood. In doing so, it impedes at the same time the access of a large number of diagnostic and therapeutic agents into the brain parenchyma. One of the possibilities of bypassing this barrier relies on specific properties of nanoparticulate vectors designed to interact with BBB-forming cells at a molecular level, as a result of which the transport of drugs or other molecules (such as nucleic acids, proteins or imaging agents) could be achieved without interfering with the normal function of the brain. This article summarises several recent example applications, presents emerging work and highlights the directions for further developments in this area.     

经鼻脑靶向递药系统的研究进展

鼻腔与脑在解剖生理上的独特联系使得鼻腔给药作为脑内递药途径成为可能.鼻腔给药作为脑靶向的途径之一,可有效地使通过其他给药途径不易透过血脑屏障的药物绕过血脑屏障到达脑部,为中枢神经系统疾病的治疗提供了一种极有发展前景的脑内递药途径.就鼻腔给药脑靶向的依据、影响因素、评价方法、剂型等方面对经鼻脑靶向递药系统的研究现状进行总结.     

Nano carriers for drug transport across the blood–brain barrier

Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood–brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-brain delivery, which involves improving BBB permeability of the drug–carrier conjugate, can minimize side effects, such as being submicrometre objects that behave as a whole unit in terms of their transport and properties, nanomaterials, are promising carrier vehicles for direct drug transport across the intact BBB as a result of their potential to enter the brain capillary endothelial cells by means of normal endocytosis and transcytosis due to their small size, as well as their possibility of being functionalized with multiple copies of the drug molecule of interest. This review provids a concise discussion of nano carriers for drug transport across the intact BBB, various forms of nanomaterials including inorganic/solid lipid/polymeric nanoparticles, nanoemulsions, quantum dots, nanogels, liposomes, micelles, dendrimers, polymersomes and exosomes are critically evaluated, their mechanisms for drug transport across the BBB are reviewed, and the future directions of this area are fully discussed.     

In vivo monitoring of brain pharmacokinetics and pharmacodynamics with cerebral open flow microperfusion

In vivo investigation of brain pharmacokinetics and pharmacodynamics (PK/PD) is an integral part of neurological drug development. However, drugs intended to act in the brain may reach it at very low concentrations due to the protective effect of the blood–brain barrier (BBB). Consequently, very sensitive measurement methods are required to investigate PK/PD of drugs in the brain. Also, these methods must be capable of continuously assessing cerebral drug concentrations with verifiable intact BBB, as disrupted BBB may lead to compound efflux from blood into brain and to biased results. To date, only a few techniques are available that can sensitively measure drug concentrations in the brain over time; one of which is cerebral open flow microperfusion (cOFM). cOFM's key features are that it enables measurement of cerebral compound concentrations with intact BBB, induces only minor tissue reactions, and that no scar formation occurs around the probe. The membrane-free cOFM probes collect diluted cerebral interstitial fluid (ISF) samples that are containing the whole molecule spectrum of the ISF. Further, combining cOFM with an in vivo calibration protocol (e.g. Zero Flow Rate) enables absolute quantification of compounds in cerebral ISF. In general, three critical aspects have to be considered when measuring cerebral drug concentrations and recording PK/PD profiles with cOFM: (a) the BBB integrity during sampling, (b) the status of the brain tissue next to the cOFM probe during sampling, and (c) the strategy to absolutely quantify drugs in cerebral ISF. This work aims to review recent applications of cOFM for PK/PD assessment with a special focus on these critical aspects.     

Molecular mechanisms of drug influx and efflux transport at the blood-brain barrier

The blood-brain barrier (BBB) segregates the circulating blood from interstitial fluid in the brain and restricts drug permeability into the brain. Recent studies have revealed that the BBB exhibits not only blood-to-brain influx transport for the supply of nutrients, but also brain-to-blood efflux transport to excrete drugs and endogenous compounds. The influx transport system allows drugs to enter the brain. (L)-DOPA is transported into the brain by the large neutral amino acid transport system, system L. A cationic mu-opioid peptide analogue enters the brain by adsorptive-mediated endocytosis. In contrast, efflux transport limits the distribution of drugs in the brain. The ATP binding cassette transporter B1 (ABCB1) mediates the efflux transport of lipophilic drugs at the BBB by using ATP energy. Furthermore, organic anion transporter 3 (OAT3) is expressed at the BBB and mediates the efflux transport of homovanillic acid, a dopamine metabolite. This efflux transport is also likely to be involved in the transport of anionic drugs such as 6-mercaptopurine and acyclovir. Clarifying the BBB transport could give us important information allowing the development of better CNS drugs and improving our understanding of the relationship between CNS diseases and BBB functions.     

Current strategies for targeted delivery of bio-active drug molecules in the treatment of brain tumor

Brain tumor is one of the most challenging diseases to treat. The major obstacle in the specific drug delivery to brain is blood–brain barrier (BBB). Mostly available anti-cancer drugs are large hydrophobic molecules which have limited permeability via BBB. Therefore, it is clear that the protective barriers confining the passage of the foreign particles into the brain are the main impediment for the brain drug delivery. Hence, the major challenge in drug development and delivery for the neurological diseases is to design non-invasive nanocarrier systems that can assist controlled and targeted drug delivery to the specific regions of the brain. In this review article, our major focus to treat brain tumor by study numerous strategies includes intracerebral implants, BBB disruption, intraventricular infusion, convection-enhanced delivery, intra-arterial drug delivery, intrathecal drug delivery, injection, catheters, pumps, microdialysis, RNA interference, antisense therapy, gene therapy, monoclonal/cationic antibodies conjugate, endogenous transporters, lipophilic analogues, prodrugs, efflux transporters, direct conjugation of antitumor drugs, direct targeting of liposomes, nanoparticles, solid–lipid nanoparticles, polymeric micelles, dendrimers and albumin-based drug carriers.     

葡萄糖转运体1研究进展

葡萄糖转运体(glucose transporter,GLUT)家族是葡萄糖转运的主要媒介,目前发现有13个成员。其中GLUT1以异构体的形式广泛表达于多种细胞,是介导葡萄糖经过血脑屏障的主要转运体。疾病可以改变GLUT1介导的葡萄糖转运过程,糖转运受到干扰能使脑功能受损,甚至导致脑死亡。近来研究显示,GLUT1能介导一些神经活性药物的转运,如糖基化的神经肽、低分子量肝素及D-葡萄糖衍生物等。因此,依赖于葡萄糖转运体的葡萄糖运载方法有可能是一个选择性药物运输系统,通过此高效转运系统,可调节药物进入大脑。     

泊洛沙姆在药物穿越血脑屏障中的重要作用

泊洛沙姆是一种具有药理活性的多功能药用辅料，在药剂学中应用广泛。近年来，研究发现泊洛沙姆可以通过多种作用机制帮助药物穿越血脑屏障，抑制血脑屏障上的P-糖蛋白、多药耐药相关蛋白等外排泵系统；吸附血浆中的不同载脂蛋白后，通过与血脑屏障上相应受体的结合，使泊洛沙姆包被的纳米粒主动转运入脑；连接各种配体及单克隆抗体等导向性分子，使其通过受体介导的转运进入脑部。本文综述了泊洛沙姆在促进药物穿越血脑屏障的重要作用，对设计脑靶向药物传递系统具有重要意义。     

Borneol,a novel agent that improves central nervous system drug delivery by enhancing blood–brain barrier permeability

The clinical application of central nervous system (CNS) drugs is limited by their poor bioavailability due to the blood–brain barrier (BBB). Borneol is a naturally occurring compound in a class of ‘orifice-opening’ agents often used for resuscitative purposes in traditional Chinese medicine. A growing body of evidence confirms that the ‘orifice-opening’ effect of borneol is principally derived from opening the BBB. Borneol is therefore believed to be an effective adjuvant that can improve drug delivery to the brain. The purpose of this paper is to provide a comprehensive review of information accumulated over the past two decades on borneol’s chemical features, sources, toxic and kinetic profiles, enhancing effects on BBB permeability and their putative mechanisms, improvements in CNS drug delivery, and pharmaceutical forms. The BBB-opening effect of borneol is a reversible physiological process characterized by rapid and transient penetration of the BBB and highly specific brain regional distribution. Borneol also protects the structural integrity of the BBB against pathological damage. The enhancement of the BBB permeability is associated with the modulation of multiple ATP-binding cassette transporters, including P-glycoprotein; tight junction proteins; and predominant enhancement of vasodilatory neurotransmitters. Systemic co-administration with borneol improves drug delivery to the brain in a region-, dose- and time-dependent manner. Several pharmaceutical forms of borneol have been developed to improve the kinetic and toxic profiles of co-administered drugs and enhance their delivery to the brain. Borneol is a promising novel agent that deserves further development as a BBB permeation enhancer for CNS drug delivery.