Lipid-based Nanoparticles for Nucleic Acid Delivery

Abstract Lipid-based colloidal particles have been extensively studied as systemic gene delivery carriers. The topic that we would like to emphasize is the formulation/assembly of lipid-based nanoparticles (NP) with diameter under 100 nm for delivering nucleic acid in vivo. NP are different from cationic lipid–nucleic acid complexes (lipoplexes) and are vesicles composed of lipids and encapsulated nucleic acids with a diameter less than 100 nm. The diameter of the NP is an important attribute to enable NP to overcome the various in vivo barriers for systemic gene delivery such as: the blood components, reticuloendothelial system (RES) uptake, tumor access, extracellular matrix components, and intracellular barriers. The major formulation factors that impact the diameter and encapsulation efficiency of DNA-containing NP include the lipid composition, nucleic acid to lipid ratio and formulation method. The particle assembly step is a critical one to make NP suitable for in vivo gene delivery. NP are often prepared using a dialysis method either from an aqueous-detergent or aqueous-organic solvent mixture. The resulting particles have diameters about 100 nm and nucleic acid encapsulation ratios are >80%. Additional components can then be added to the particle after it is formed. This ordered assembly strategy enables one to optimize the particle physico-chemical attributes to devise a biocompatible particle with increased gene transfer efficacy in vivo. The components included in the sequentially assembled NP include: poly(ethylene glycol) (PEG)-shielding to improve the particle pharmacokinetic behavior, a targeting ligand to facilitate the particle–cell recognition and in some case a bioresponsive lipid or pH-triggered polymer to enhance nucleic acid release and intracellular trafficking. A number of groups have observed that a PEG-shielded NP is a robust and modestly effective system for systemic gene or small interfering RNA (siRNA) delivery.     

Structural Requirements for Cationic Lipid Mediated Phosphorothioate Oligonucleotides Delivery to Cells in Culture

Abstract

A series of 2,3-dialkyloxypropyl quaternary ammonium lipids containing hydroxyalkyl chains on the quaternary amine were synthesized, formulated with dioleoylphosphatidylethanolamine (DOPE) and assayed for their ability to enhance the activity of an intercellular adhesion molecule 1 (ICAM-1) antisense oligonucleotide, ISIS 1570. Cationic liposomes prepared with hydroxyethyl, hydroxypropyl and hydroxybutyl substituted cationic lipid all enhanced the activity of the ICAM-1 antisense oligonucleotide. Cationic lipids containing hydroxypentyl quaternary amines only marginally enhanced the activity of ISIS 1570. Hydroxyethyl cationic lipids synthesized with dimyristyl (C_14:0) and dioleyl (C_18:1) alkyl chains were equally effective. Activity of cationic lipids containing saturated alkyl groups decreased as the chain length increased, i.e. the dimyristyl (C_14:0) was more effective than dipalmityl (C_16:0) lipid, which was more effective than distearyl (C_18:0). The phase transition temperature of cationic lipids containing saturated aliphatic chains was 56°C for the distearyl lipid, 42°C for the dipalmityl lipid and 24°C for the dimyristyl lipid. Cationic lipids with dioleyl alkyl chains required DOPE for activity, with optimal activity occurring at 50 mole%. In contrast, a dimyristyl containing cationic lipid did not require DOPE to enhance the activity of ISIS 1570. Formulation with different phosphatidylethanolamine derivatives, revealed that optimal activity was obtained with DOPE. These studies demonstrate that several cationic lipid species enhance the activity of phosphorothioate antisense oligonucleotides and provide further information on the mechanism by which cationic lipids enhance the activity of phosphorothioate oligodeoxynucleotides.     

壳聚糖及其衍生物在眼部给药系统中的研究进展

壳聚糖是一种阳离子型天然黏多糖,具有无毒、生物黏附性、生物相容性、促渗透性、生物可降解性和假塑性等优点,己被广泛应用于眼部给药系统中.本文综述了壳聚糖有关性质及其在眼部给药系统中的研究状况和局限性,旨在为壳聚糖在眼部给药系统中的进一步应用提供参考.     

生物技术药物给药系统研究进展

生物技术药物给药系统按其途径分为注射和非注射两大结药系统。本文综述了国内外近年来生物技术药物新型给药系统的研究进展。     

多单元调释给药系统在复方制剂中的应用

复方制剂由2种或2种以上的药物组分进行配伍,通过协同、加合作用或拮抗不良反应,与单方制剂比较,疗效更加显著。将多单元调释给药系统应用于复方制剂中,能更灵活地调节释药方案,全方位、多靶点、多环节作用,使药物生物利用度提高,不良反应降低。本研究针对镇痛、抗感染、降糖和降压几种常见复方制剂及中药复方制剂的复方原理作一综述,并重点阐述多单元调释给药系统在复方制剂中应用的优势,以期为复方制剂的临床开发提供新的思路。     

生物素在肿瘤靶向递药中的研究进展

运用靶向递药系统给药是目前治疗癌症的有效方法,靶向配体的选择是靶向递药的关键。生物素受体在多数肿瘤细胞表面过表达,但在正常细胞中低表达或不表达,因此,生物素可作为配体与药物载体相连,用于肿瘤靶向递药。简述生物素及生物素受体,综述生物素修饰的脂质体、胶束、纳米粒等载药系统在肿瘤靶向诊断和治疗中的研究进展,以期为相关研究开发与临床应用提供参考。     

肝靶向微粒给药系统的研究进展

目的对近年来微粒给药系统在肝靶向治疗的研究进展做一综述。方法根据国内外文献资料进行整理归纳。结果纳米粒、微球、脂质体及微乳等微粒系统具有被动靶向于肝的趋势,利用肝细胞表面某些受体则可特异性靶向于肝达到主动靶向作用。结论微粒给药系统在肝靶向治疗领域具有重要意义。     

经鼻纳米递药系统在中枢神经系统疾病治疗中的研究进展

中枢神经系统疾病治疗药物的脑内递送通常受限于血脑屏障。经鼻给药作为脑靶向递药的一种无创给药方式,可绕开血脑屏障,实现药物至脑部的直接、高效靶向输送,在中枢神经系统疾病治疗中具有极大应用潜力。然而,鼻腔黏液纤毛清除力等屏障限制了经鼻给药递送效果。依托纳米递药技术的发展,经鼻纳米递药系统为中枢神经系统疾病的治疗带来了新的希望。本文综述了经鼻入脑递药通路、常见经鼻纳米递药系统及其特性和治疗应用进展,为基于中枢神经系统疾病治疗的经鼻纳米递药系统设计提供思路和方法。     

新型自乳化给药系统研究进展

自乳化给药系统因可提高药物的吸收速度和程度,增强难溶性药物的溶解能力,提高生物利用度而成为当前药剂研究的一大热点。本综述就近几年国内外关于自乳化给药系统的最新研究进展作一简要介绍。     

Enhanced Delivery and Antitumor Activity of Doxorubicin Using Long-Circulating Thermosensitive Liposomes Containing Amphipathic Polyethylene Glycol in Combination with Local Hyperthermia

Enhanced delivery of doxorubicin (DXR) to a solid tumor subjected to local hyperthermia was achieved by using long-circulating, thermosensitive liposomes (TSL) composed of dipalmitoyl phosphatidylcholine (DPPC)/distearoyl phosphatidylcholine (DSPC) (9:1, m/m) and 3 mol% amphipathic polyethylene glycol (PEG) in colon 26-bearing mice. Inclusion of 3 mol% of distearoyl phosphatidylethanolamine derivatives of PEG (DSPE-PEG, amphipathic PEG) with a mean molecular weight of 1000 or 5000 in DPPC/DSPC liposomes resulted in decreased reticuloendothelial system (RES) uptake and a concomitant prolongation of circulation time, affording sustained increased blood levels of the liposomes. Concomitantly, DXR levels in blood were also kept high over a long period. The presence of amphipathic PEG did not interfere with the encapsulation of DXR by the pH gradient method (>90% trapping efficiency) or with the temperature-dependent drug release from the liposomes. The optimal size of these liposomes was 180 – 200 nm in mean diameter for thermosensitive drug release and prolonged circulation time. The DXR levels in the tumor after injection of long-circulating TSL (DXR-PEG1000TSL or DXR-PEG5000TSL, at a dose of 5 mg DXR/ kg) with local hyperthermia were much higher than after treatment with DXR-TSL lacking PEG or with free DXR, reaching 7.0 – 8.5 DXR µg/g tumor (approximately 2 times or 6 times higher than that of DXR-TSL or free DXR, respectively). Furthermore, the combination of DXR-PEGTSL and hyperthermia effectively retarded tumor growth and increased survival time. Our results indicate that the combination of drug-loaded, long-circulating, thermosensitive liposomes with local hyperthermia at the tumor site could be clinically useful for delivering a wide range of chemotherapeutic agents in the treatment of solid tumors.     

多肽修饰脂质体靶向药物递送系统研究进展

目的介绍近年来多肽修饰脂质体靶向药物递送系统的研究进展。方法查阅和归纳总结近几年相关文献。结果阐述了精氨酸-甘氨酸-天冬氨酸（RGD）多肽、丙氨酸-脯氨酸-精氨酸-脯氨酸-甘氨酸（APRPG）多肽、细胞穿透肽（CPP）、血管活性肠肽（VIP）等修饰脂质体的研究进展。多肽修饰的包载药物的脂质体可以增加药物在体内的选择性,减少药物毒副作用,提高药物治疗指数。结论多肽分子是机体内一类重要的生物活性物质,将其作为导向物以配体-受体特异性结合的方式应用于靶向药物递送系统,具有良好的研究价值和应用前景。     

肿瘤微环境响应性纳米递药系统用于肿瘤免疫治疗的研究进展

在过去的几十年里,癌症免疫治疗取得了巨大的进步,但不尽如人意的患者应答率及潜在的免疫相关不良事件仍是临床上的主要挑战。纳米递药系统在癌症治疗方面具有独特的优势。基于肿瘤微环境缺氧、弱酸性、蛋白酶异常表达等特点,研究者们进一步设计了刺激响应性纳米递药系统,其已被广泛研究用于提高抗肿瘤免疫应答的效果和减少免疫相关的副作用。介绍了肿瘤微环境响应性纳米递药系统用于肿瘤免疫治疗的研究进展,并讨论了该类递药系统的应用前景和面临的挑战。     

黏膜疫苗传递系统的研究进展

黏膜疫苗能同时诱导系统和局部黏膜免疫应答,是预防感染性疾病最理想的一类疫苗.但黏膜疫苗存在两大障碍:抗原无效摄取和难以引发有效免疫反应.因此,研发新型黏膜疫苗传递系统必须要克服这些障碍.本文综述了黏膜免疫的作用机制、黏膜疫苗的特点及其传递系统的研究现状.     

ATP-Responsive Drug Delivery Systems

The combination of targeted drug delivery and controlled-release technology may pave the road for more effective yet safer chemotherapeutic options for cancer therapy. Drug-encapsulated polymeric nanoparticle–aptamer bioconjugates represent an emerging technology that can facilitate the delivery of chemotherapeutics to primary and metastatic tumours. Aptamers are short nucleic acid molecules with binding properties and biochemical characteristics that may make them suitable for use as targeting molecules. The goal of this review is to summarise the key components that are required for creating effective cancer targeting nanoparticle–aptamer bioconjugates. The field of controlled release and the structure and properties of aptamers, as well as the criteria for constructing effective conjugates, will be discussed.     

壳聚糖包覆脂质体递药系统的研究进展

脂质体在药物传递方面被广泛研究,但因结构稳定性差等因素使其应用受到了限制.壳聚糖是一种阳离子多糖,具有良好的生物相容性、生物降解性以及生物黏附性,并且可经化学改性成为性能更佳的壳聚糖衍生物.近年来,壳聚糖及其衍生物包覆脂质体在载药方面的研究得到了越来越多学者的关注.壳聚糖或其衍生物修饰脂质体,可提高其稳定性、黏附渗透性...     

壳聚糖在新型给药系统中的应用

综述壳聚糖的物理化学和生物特性及在基因转染和不同给药系统中的应用研究近况。壳聚糖作为新型药用辅料,已受到越来越多的关注,对其应用的开发和研究已渗透到药剂学的多个领域。壳聚糖用作非病毒基因载体,也已成为近年来的研究热点之一。它也被广泛研究应用于眼部、鼻腔、口腔、胃内、小肠和结肠等靶向给药载体。     

Liposomes Dispersed Within a Thermosensitive Gel: A New Dosage Form for Ocular Delivery of Oligonucleotides

Purpose. The main goal of this study was to develop an ocular controlled release formulation of a model oligonucleotide (pdT16), contained within liposomes dispersed within a thermosensitive gel composed by poloxamer 407. Methods. The influence of the poloxamer concentration 2% or 27% on the stability of the liposomes (PC: CHOL and PC: CHOL: PEG-DSPE) was investigated. The in vitro release profiles of pdT16 from various poloxamer formulations (free pdT16 dispersed within 20% and 27% poloxamer gels, pdT16 encapsulated within liposomes dispersed within 20% and 27% poloxamer gels) were realized using a membrane-free release model. Results. The dispersion of liposomes within a dilute 2% poloxamer solution resulted in a great leakage of pdT16 from liposomes. However, the destabilization effect of poloxamer was reduced when higher concentration (27%) was used. Poloxamer dissolution was found to control the release process of pdT16, whereas the dispersion of liposomes within 27% poloxamer gel was shown to slow down the diffusion of pdT16 out from the gel. Conclusions. The dispersion of liposomes within a 27% poloxamer gel presented an interesting system to control the release of a model oligonucleotide compare to a simple gel.     

疫苗和基因给药系统的研究进展

简述了当前疫苗和基因给药系统的研究进展，包括注射、口服、鼻腔和透皮等给药系统，并介绍了以转基因植物作为疫苗以及基因给药系统的病毒载体和非病毒载体系统。     

壳聚糖纳米粒作为药物递送系统在癌症治疗中的应用

癌症是威胁人类生存的恶性疾病之一。近年来,利用纳米技术将药物靶向递送到肿瘤部位,可以增加疗效并降低毒性,为癌症治疗带来了新希望。壳聚糖是自然界唯一存在的碱性多糖,具有良好的生物相容性和生物可降解性。此外,其反应位点多,可制成不同性质的衍生物,广泛用于药物递送系统和组织工程支架,在生物医药领域具有重要的应用价值。本综述对近年来壳聚糖纳米粒在抗癌药物递送方面的研究进展进行介绍,重点介绍了壳聚糖纳米粒的制备、被动靶向、主动靶向和刺激-响应药物递送系统方面的研究进展。     

Prodrugs of Gestodene for Matrix-Type Transdermal Drug Delivery Systems

Purpose. The aim of this study was to enhance the transdermal absorption of the highly active progestin gestodene from matrix type transdermal delivery systems (TDDS) by formation of prodrugs with improved matrix solubility. Methods. Gestodene esters were synthesized via acylation of the drug with the respective carboxylic anhydrides. Subsequently TDDS were produced using the solvent cast method. Selected formulations were examined with in vitro diffusion experiments using skin of nude mice. Results. One prodrug, gestodene caproate proved to be an oil at ambient temperature and showed a very high solubilty of over 10.5% in the TDDS matrix. Within in vitro penetration studies using those systems the prodrug exhibited a significantly higher transdermal penetration rate than gestodene from reference systems. Furthermore, the prodrug was hydrolyzed to the parent drug to a high extent during the passage of the skin. Conclusions. Designing prodrugs to the requirements of matrix TDDS is an efficient way of enhancing the transdermal drug flux rate.