应用强化材料修饰脂质体提高肝靶向性

介绍强化材料修饰脂质体以提高肝靶向性的应用及发展状况.围绕目前正在进行临床研究阶段的脂质体制剂,分析其用强化材料修饰脂质体后肝靶向性提高方面的情况.     

提高脂质体主动靶向性材料的研究进展

目的:为制备高效的脂质体提供参考。方法:以"材料""脂质体""Materials modified liposomes"等为关键词,组合查询2000-2016年在Pub Med、中国知网、万方、维普等数据库中的相关文献,对修饰脂质体材料的种类、特点及其在制剂中的应用研究进行综述。结果与结论:共检索到相关文献439篇,其中有效文献45篇。目前用于修饰脂质体的材料主要有糖类及其衍生物、配体类、聚合物类及肽类等。其中糖类及其衍生物、配体类和肽类修饰后的脂质体具有主动靶向性,能提高药物的生物利用度;聚合物类修饰后的脂质体可提高药物的稳定性。目前国内修饰脂质体材料还处在研发阶段,临床应用较少,存在经修饰的脂质体在体内外的靶向性是否具有可比性、各类材料是否能广泛用于不同含药脂质体的修饰、修饰后的脂质体能否实现大规模生产、修饰脂质体的设计与制备过程均较普通脂质体复杂等问题,有待今后去攻克。     

载基因脂质体用于治疗肿瘤的最新研究进展

基因传递是基因治疗中极具挑战性的领域,尤其是当全身给药时,生理学和生物学屏障是需要考虑的主要障碍。脂质体作为基因载体在治疗肿瘤中拥有独特优势,近几年备受关注。研究者们对脂质体的新制备材料、制备工艺、修饰方法等进行了广泛的研究,以期进一步提高其靶向性,降低其毒副作用。除了阳离子脂质体、长循环脂质体、pH敏感脂质体、免疫脂质体以及受体介导的脂质体,本文重点强调了新型的细胞穿膜肽修饰的脂质体在治疗肿瘤方面的最新研究进展。     

新型脂质体的研究进展

作为药物传递系统的载体,几种新型脂质体如膜融合脂质体、柔性脂质体、表面修饰脂质体等的研究己取得显著进展.本文归纳和分析了近期有关脂质体稳定性、靶向性及修饰材料的文献.     

脂质体修饰性材料应用研究进展

脂质体作为低毒性与免疫原性的药物载体已被应用于难溶性、不稳定、毒性等药物的递送,但传统脂质体仍存在稳定性差、体内循环时间不足、主动靶向性不明显等缺陷,因此选择适宜的修饰性材料制备脂质体已成为必要手段。修饰脂质体的方法主要有：在膜材中加入表面活性剂或改性物质,在膜表面嵌插靶向配体物质,将配体与膜材偶联共同组成脂质体结构。通过总结近年来脂质体常用的修饰性材料,阐释修饰原理并分析其优势及弊端,为脂质体的研究与开发提供借鉴。     

用于抗肿瘤药物递送的脂质体表面修饰策略

脂质体作为一种传统的药物传递系统,因其在药物及蛋白质、基因、核酸等生物活性物质的高效传递方面的应用而备受研究领域的关注。脂质体给药系统在抗肿瘤药物研究领域经历了常规脂质体、长循环脂质体、配体功能脂质体、刺激响应型脂质体等4个阶段。现结合相关文献,综述了这4种脂质体给药系统常用的表面修饰靶向策略和研究进展,以期为脂质体的进一步研究和基本靶向修饰提供参考。     

配体修饰脂质体的研究进展

目的:寻找较为稳定、有效且制备方法可靠的新的配体修饰脂质体(Ligand-modified liposomes,LML)。方法:查阅配体修饰脂质体的相关文献,综述了叶酸、甘露糖基、抗体、肽等不同配体修饰的脂质体的研究进展。结果与结论:配体修饰后的脂质体在靶向性与药效学方面有明显的提升,但也面临着巨大的挑战,如抗体和蛋白质等大分子配体会增加脂质体的免疫性,加快脂质体的循环清除等。配体修饰脂质体作为药物载体将会逐渐在疫苗接种、基因转染、靶向制剂方面发挥更加重要的作用。     

RVG29修饰脂质体对脑胶质瘤靶向性的初步研究

目的 研究一种新型配体RVG29修饰脂质体后,对体外脑胶质瘤的靶向性.方法 采用有机相合成法制备DSPE-PEG2000-RVG29 PPP(D-RVG29)材料,按照薄膜分散法制备脂质体,通过C6细胞和Hela细胞的细胞摄取考察D-RVG29修饰脂质体后,对体外脑胶质瘤的靶向性.结果 在脂质体处方中加入DSPE-PEG2000-OME(D-OME)可使D-RVG29修饰脂质体具有更好的粒径和分布范围,C6细胞对D-RVG29修饰脂质体的摄取强于未修饰D-RVG29的脂质体,Hela细胞对两种脂质体的摄取强度无明显区别.结论 D-OME可以提高D-RVG29修饰脂质体的稳定性,D-RVG29修饰脂质体具有体外脑胶质瘤细胞的靶向性.     

pH值敏感型脂质体表面修饰技术的研究进展

pH 值敏感型脂质体表面修饰已成为脂质体制剂的研究热点,经过表面修饰的pH值敏感型脂质体进入人体后,在此特异性片段的介导下,被靶细胞识别,达到在靶细胞有针对性地释放药物和减少对机体正常组织损害的目的.对pH值敏感型脂质体进行表面修饰的主要目的有3个:延长体循环时间、增强pH值敏感性和提高靶向性.主要从这3方面综述近十年来pH值敏感型脂质体表面修饰的研究进展,为pH值敏感型脂质体表面修饰的进一步研究提供参考.     

PCM和TAT双修饰脂质体的制备及心肌靶向性的初步评价

目的 研究心肌特异性靶向肽PCM和穿膜肽TAT双修饰的载荧光探针香豆素-6脂质体的制备工艺,并初步考察其心肌靶向性.方法 采用薄膜分散-超声法,以PCM和TAT为靶头,制备以大豆磷脂、胆固醇、DSPE-mPEG2000为载体材料的载香豆素-6的双修饰脂质体;优化香豆素-6用量、靶头连接方法及靶头用量,以形态、粒径分布、电位、包封率及体外稳定性对脂质体进行表征;考察心肌细胞H9C2对双修饰脂质体的摄取能力,表征其心肌靶向性.结果 PCM和TAT通过插入法连接,当PCM的用量为脂质的3％、TAT的用量为脂质的1％、香豆素-6的用量为20 μg时,所制得的双修饰脂质体的形态圆整,粒径分布为115.7 ±2.91 nm,Zeta电位为-13.1 ±1.81 mV,包封率为83.2％±3.1％,具有良好的体外稳定性,双修饰脂质体的心肌细胞摄取率明显高于未修饰和单修饰的脂质体.结论 双修饰脂质体的制备工艺简单,PCM和TAT双修饰可提高脂质体的心肌细胞靶向性.     

Effects of extrusion,lipid concentration and purity on physico-chemical and biological properties of cationic liposomes for gene vaccine applications

We developed cationic liposomes containing DNA through a conventional process involving steps of (i) preformation of liposomes, (ii) extrusion, (iii) drying and rehydration and (iv) DNA complexation. Owing to its high prophylactic potentiality against tuberculosis, which had already been demonstrated in preclinical assays, we introduced modifications into the conventional process towards getting a simpler and more economical process for further scale-up. Elimination of the extrusion step, increasing the lipid concentration (from 16 to 64?mM) of the preformed liposomes and using good manufacturing practice bulk lipids (96–98% purity) instead of analytical grade purity lipids (99.9–100%) were the modifications studied. The differences in the physico-chemical properties, such as average diameter, zeta potential, melting point and morphology of the liposomes prepared through the modified process, were not as significant for the biological properties, such as DNA loading on the cationic liposomes, and effective immune response in mice after immunisation as the control liposomes prepared through the conventional process. Beneficially, the modified process increased productivity by 22% and reduced the cost of raw material by 75%.     

Synthesis and evaluation of stearylated hyaluronic acid for the active delivery of liposomes to liver endothelial cells

Hyaluronic acid (HA) is a naturally-occurring ligand that can be useful for targeting liver endothelial cells. We describe herein the development of a new HA-lipid conjugate for the efficient delivery of liposomes to liver endothelial cells. When free HA coated cationic liposomes were injected into mice, their accumulation in the liver was significantly decreased depending on the content of free HA, while accumulation in the lung was not significantly changed. When cationic liposomes modified with HA-stearylamine (HA-SA conjugate) were injected in mice, liver accumulation was increased depending on the amount of HA-SA conjugate and accumulation in the lung was drastically reduced, compared to non-modified liposomes. Confocal imaging analyses showed that HA-SA modified liposomes were accumulated to a greater extent along with blood vessels than non-modified liposomes, suggesitng that HA-SA modified liposomes are distributed in endothelial cells in the liver. Collectively, these findings indicate that an HA-SA conjugate is a useful material that can be used to modify liposomes and for delivering bioactive liposomal cargoes to liver endothelial cells.     

Prolonged circulation time of doxorubicin-loaded liposomes coated with a modified polyvinyl alcohol after intravenous injection in rats.

The purpose of this study was to evaluate the functions of a modified polyvinyl alcohol (PVA-R), which has a hydrophobic moiety, as a coating material for liposomes to be loaded with the anticancer drug, doxorubicin. The size controlled liposomes (egg phosphatidylcholine: cholesterol=1:1 molar ratio) were prepared by the hydration method followed by extrusion. Drug encapsulation and surface modification with polymers (PVA and PVA-R) were carried out simultaneously using a modified pH gradient method. The existence of a thick polymer layer on the surface of the liposomes was confirmed by an increase in particle size and the amount of polymer on the liposomal surface, especially for the PVA-R-coated liposomes. The effects of polymer coating on the behavior of the liposomes in vivo were evaluated by measuring the circulation time and biodistribution of the drug after i.v. administration of the liposomal drug in rats. The PVA-R-coated liposomes showed a more prolonged circulating time for the drug with less uptake by the reticuloendothelial system after i.v. administration in rats, compared with non-coated liposomes. These results confirm that polymer possessing a hydrophobic anchor at its end, like PVA-R, is a suitable material for modifying the surface of doxorubicin-loaded liposomes to improve their stability in the circulating blood.     

肺靶向吡非尼酮脂质体的制备及体外释药性质研究

目的：研究肺靶向吡非尼酮脂质体的制备方法并考察其体外释药性质。方法：采用薄膜分散法制备吡非尼酮脂质体;用D-甘露糖修饰脂质体并添加适量十八胺调节脂质体表面电荷;用紫外分光光度法测定包封率;用正交实验优化处方,用透析法考察药物体外释放性质。结果：制得的脂质体平均粒径为581.1nm,表面电荷为-20.61mV,包封率为81.1%,稳定性好。药物体外释药符合Weibull方程。结论：采用薄膜分散法,用D-甘露糖修饰并添加十八胺可制得具有较高包封率及稳定性的吡非尼酮脂质体,有助于提高吡非尼酮的肺靶向性。     

Uptake of liposomally entrapped fluorescent antisense oligonucleotides in NG108-15 cells: conventional versus pH-sensitive

Antisense oligodeoxynucleotides (asODN) are novel therapeutic agents designed to alter RNA metabolism, ultimately resulting in decreased production of disease-associated gene products. To investigate internalisation of liposomally delivered asODN in NG108-15 cells, a hybrid cell line of mouse neuroblastoma and rat glioma, and assure that uptake of marker corresponds to that of antisense, we compared the cellular uptake of fluorescently labelled marker (fluorescein isothiocyanate (FITC)-dextran) and antisense oligonucleotide (FITC-asODN), entrapped either in conventional soy phosphatidylcholine (SPC) liposomes or pH-sensitive liposomes (composed of dioleoylphosphatidylethanolamine and cholesteryl hemisuccinate in a molar ratio of 3 : 2). Both SPC and pH-sensitive liposomes were prepared by a modified freeze-thawing method. Entrapment efficiencies (about 20% of the original material) did not depend on the liposome compositions and fluorescent material used. Fluorescence activated cell sorting (FACS) analysis was used to quantify the association of fluorescent material with the NG108-15 cells, whereas confocal microscopy gave insight on the location of cell associated-fluorescence. Conventional liposomes failed to deliver fluorescent material into the cells, but in contrast, pH-sensitive liposomes significantly improved the uptake of both FITC-dextran and FITC-asODN, with the uptake of liposomal FITC-dextran being greater than the uptake of liposomal FITC-asODN. These results suggest that pH-sensitive liposomes can be applied as a carrier system in the delivery of genetic material into the cells.     

Effect of surface ligand density on cytotoxicity and pharmacokinetic profile of docetaxel loaded liposomes

Various biotin-modified liposomes incorporated with docetaxel (DTX) were prepared to study the effect of surface biotin density on the pharmacokinetic profile of the liposome. Four types of liposomes such as PEG modified liposome (PDL), 0.5% (mol) biotin modified liposome (0.5BDL), 1% (mol) biotin modified liposome (1BDL) and 2% (mol) biotin modified liposome (2BDL) were prepared using thin film dispersion method. The prepared liposomes were characterized by measuring encapsulation efficiency (EE), particle size, Zeta-potential, physical stability and drug release profiles in vitro. MTT assay was performed to elevate the cytotoxicity of liposomes on MCF-7 cells. In vivo evaluation was further performed to investigate the effect of biotin surface density on the pharmacokinetic profiles. All the prepared liposomes exhibited high encapsulation efficiency, small particle size, narrow particle distribution and sustained release profiles in vitro. In MTT assay, 0.5BDL showed largest tumor cell toxicity, compared with DTX solution. All liposomes containing DTX showed prolonged blood circulation in vivo, and 0.5BDL showed the longest circulation time among the biotin modified liposome. Surface modification of liposome had a negative impact on the circulation of liposomes in the blood, which needs to be considered when designing the ligand mediated targeting delivery systems. A proper amount of biotin liposome with 0.5% molar ratio is expected to produce the best anti-tumor effect.     

The use of a new functional glucose conjugate material,TPGS1000-Glu,in treatment of brain glioma by incorporating into epirubicin liposomes

Most of anticancer agents can not be used for treatment of brain glioma due to the existence of the blood brain barrier (BBB). The over-expression of glucose transporters (GLUTs) on the BBB and brain glioma cells enables the possibility that the GLUTs ligand modified drug carrier transports across the BBB, and targets to the brain glioma cells. The objectives of the present study were to synthesize a new glucose conjugate material, TPGS₁₀₀₀-Glu, develop a kind of TPGS₁₀₀₀-Glu modified epirubicin liposomes, and evaluate their efficacy. The studies were performed on the BBB co-culture model and brain glioma cells in vitro. TPGS1000-Glu was synthesized by conjugating TPGS_1000-COOH with 4-aminophenyl-β-D-glucopyranoside (Glu), and confirmed by MALDI-TOF-MSspectrum. TPGS₁₀₀₀-Glu modified epirubicin liposomes were prepared with a high drug encapsulation efficiency (>97%), a nanosize (approximately 90 nm), and a minimal drug leakage in fetal bovine serum (FBS)-containing buffer system. The BBB co-culture model was established, and after applying TPGS₁₀₀₀-Glu modified epirubicin liposomes to the model, transport of liposomal drug across the BBB was evidenced. Besides, TPGS₁₀₀₀-Glu modified epirubicin liposomes showed the strongest cellular drug uptake and anti-glioma efficacy after transport across the BBB in vitro. The synthesized TPGS1000-Glu material could offer a new targeting ligand for the BBB, while the developed TPGS₁₀₀₀-Glu modified epirubicin liposomes might provide a potential anticancer formulation for treatment of brain glioma.     

卡波姆包衣姜黄素脂质体的制备及体外黏附性考察

目的探讨提高难溶性药物口服生物利用度的方法。方法采用薄膜分散法制备姜黄素脂质体,采用孵育法对姜黄素脂质体进行卡波姆包衣并考察姜黄素脂质体包衣前后稳定性、包封率及相对包衣率的变化,采用离体大鼠小肠孵育法考察卡波姆包衣姜黄素脂质体体外黏附性。结果卡波姆包衣对脂质体的稳定性影响较大,当卡波姆的质量浓度为5.0 g.L-1时脂质体最稳定;脂质体包衣后包封率略有下降,相对包衣率随着卡波姆质量浓度的增大而增大;质量浓度同为5.0 g.L-1的条件下,卡波姆包衣脂质体的体外生物黏附性比壳聚糖包衣的体外生物黏附性大,未包衣的脂质体体外生物黏附性很小。结论作为药物载体,卡波姆包衣脂质体具备了难溶性药物姜黄素口服给药的条件,将有很好的应用前景。