阳离子膜融合脂质体介导反义寡核苷酸在Hela细胞中的转染实验研究

目的研究阳离子膜融合脂质体(CFL)介导反义寡核苷酸(ASON)的细胞转染效率及影响因素。方法 逆相蒸发法制备3种不同阳离子含量的脂质体(CL),在CL上引入仙台病毒形成CFL,将制得的阳离子膜融合脂质体与反义寡核苷酸混合得到复合物,考察形态学及载药量,用MTT法考察该载体的细胞毒性,流式细胞仪测定阳性细胞百分率和平均荧光强度。结果制得的CFL形态均匀,粒径为(168±65) nm。载药量随着磷脂/ASON(+/-)电荷比增加而增加。CFL细胞毒性明显低于相同电荷比的CL,细胞转染效率是随阳离子含量、磷脂/ASON(+/-)电荷比增加而增加,血清和低温均对CFL的细胞转染有影响。结论阳离子膜融合脂质体作为载体在低电荷比条件下可降低细胞毒性并可提高细胞转染效率,可作为该ASON的给药系统而进一步研究。     

寡核苷酸聚赖氨酸修饰物的脂质体制备及其对HepG2细胞的细胞毒活性研究

目的研究反义寡核苷酸的聚赖氨酸修饰物对脂质体包封率的影响及对HepG2细胞活性的初步测定。方法利用反义药物的聚赖氨酸修饰物,采用薄膜分散法制备反义寡核苷酸及其聚赖氨酸修饰物的脂质体;紫外分光光度法测定包封率的差异并考察对HepG2细胞细胞毒活性的影响。结果高密度正电荷的聚赖氨酸与带负电荷的反义寡核苷酸偶联后,脂质体的载药量大大增加,并且细胞的摄入量增加,对HepG2细胞生长具有抑制作用。结论聚赖氨酸修饰物增加了反义寡核苷酸的脂质体包封率,有效诱导人肝癌细胞的凋亡作用。     

反义寡核苷酸阳离子脂质体的制备和体外细胞摄取研究反义寡核苷酸阳离子脂质体的制备和体外细胞摄取研究

目的制备高效促进细胞摄取反义寡核苷酸(ASON)和保护ASON的脂质体。方法以3β［n-(n′,n′-二甲氨基乙基)氨甲酰基-胆固醇(DC-Chol)为类脂成分制备阳离子脂质体(以下简称DC-Chol脂质体),与ASON混合得到载药脂质体,测定载药率。用琼脂糖凝胶电泳分析载药脂质体的结构特点;流式细胞仪检测不同条件下细胞摄取荧光标记ASON的情况;变性聚丙烯酰胺电泳考察DC-Chol脂质体对ASON的保护作用。结果载药率与DC-Chol脂质体和药物的+/-电荷比有关,当+/-电荷比大于2时,载药率达90%以上;琼脂糖凝胶电泳显示ASON同时存在于DC-Chol脂质体的周围和包裹于其内部的两种形式;流式细胞仪测定结果表明,DC-Chol脂质体可明显增加细胞对ASON的摄取,阳性细胞染色率和胞内平均荧光强度均较对照组有明显增加,增加程度主要取决于+/-电荷比例,血清可降低细胞的摄取;变性聚丙烯酰胺电泳证实DC-Chol脂质体具有保护ASON的作用。结论DC-Chol脂质体具有显著增加细胞摄取ASON和保护ASON的作用,有望成为反义类药物的高效传递系统。     

谷甾醇葡萄糖苷和卞泽双重修饰肝实质细胞靶向阳性脂质体介导的基因转染和抗乙肝病毒作用

目的研究载乙型肝炎病毒(HBV)反义寡核苷酸的双重表面修饰肝实质细胞靶向阳性脂质体的基因转染，抗乙肝病毒作用和其介导基因转染的机制。方法以3β-［N-(N′,N′-二甲氨基乙基)-氨甲酰基］胆固醇(DC-Chol)和二棕榈酰磷脂酰胆碱(DPPC)为脂材，分别以谷甾醇葡萄糖苷(sito-G)和卞泽(Brij 35)为膜表面修饰成分，制备载HBV反义寡核苷酸的阳性脂质体。采用大鼠原代肝实质细胞和人肝癌细胞HepG 2.2.15，通过流式细胞分析、荧光显微镜观察和酶联免疫吸附试验(ELISA)，考察脂质体对基因转染的促进作用及其病毒抑制作用；通过评价渥曼青霉素、尼日利亚菌素以及无涎胎球蛋白对其病毒抑制作用的影响，探讨其转染机制。结果以sito-G和Brij 35对脂质体进行双重表面修饰，显著提高了脂质体的转染率和病毒抑制作用；荧光显微镜下观察到较强转染，反义寡核苷酸的胞内分布以在细胞核中为主；渥曼青霉素、尼日利亚菌素和无涎胎球蛋白均不同程度地降低了载反义寡核苷酸脂质体的病毒抑制作用。结论Brij 35和sito-G双重修饰阳性脂质体显示出较高的基因转染效率和显著的病毒抑制作用，其基因转染过程以内吞和膜融合为主，并表现出肝实质细胞表面去唾液酸糖蛋白受体 (ASGPR)的靶向选择性。     

载基因纳米阳离子脂质体前体制剂的制备及性质研究

目的:制备稳定的载反义寡核苷酸的阳离子脂质体前体制剂。方法:以磷脂-二油酰磷脂酰乙醇胺(dioleoylphophatidylethanolamine,DOPE)-十八胺-胆固醇为类脂成分,采用薄膜超声-挤压制备空白阳离子脂质体,吸附-冷冻干燥法制备载反义寡核苷酸阳离子脂质体前体。激光粒度仪测定冷冻干燥前后脂质体Zeta电位及粒径,透射电镜观察其形态,葡聚糖凝胶柱分离未包封的反义寡核苷酸,紫外法测定冻干前后的载药率。结果:海藻糖与甘露醇及甘氨酸为较好的冻干保护剂,制得的阳离子脂质体前体带正电荷,规则球形,大小较均匀,海藻糖作为保护剂复溶前后平均粒径为175和320 nm左右,复融前后Zeta电位值在+32和+40 mV左右,脂质体的载药率复溶前后分别为87.6%与83.21%。结论:海藻糖作为冻干保护剂,薄膜超声挤压法与冷冻干燥法结合,可成功制备反义寡核苷酸阳离子脂质体前体制剂,稳定性大大改善。     

槐定碱阳离子脂质体的制备及体外抗肿瘤活性的研究

目的制备槐定碱阳离子脂质体,并探讨其对肿瘤细胞的抑制作用。方法采用主动载药法制备槐定碱阳离子脂质体,并对其进行表征研究,采用MTS方法考察槐定碱阳离子脂质体对3种肿瘤细胞的抑制作用。结果制备得到的槐定碱阳离子脂质体呈类圆形,表面光滑,其平均粒径和聚分散指数分别为242.2 nm和0.180,表面电荷为+32.5 m V,其包封率和载药量分别为88.62%和5.97%。槐定碱阳离子脂质体对3种肿瘤细胞的IC50值均明显高于槐定碱,而空白阳离子脂质体对细胞并无明显的抑制作用。结论采用阳离子脂质体作为槐定碱的载体有利于将药物透过细胞膜,提高抗肿瘤作用,值得进行深入的系统研究。     

血管内皮生长因子反义寡核苷核对前列腺癌细胞PC3生长特性的影响

目的探讨血管内皮生长因子(VEGF)反义寡核苷核对前列腺癌细胞PC3生长特性的影响。方法采用新型脂质体Oligofectamine携带VEGF反义寡核苷酸转染激素非依赖性前列腺癌细胞PC3,实验分为对照组、反义寡核苷核苷酸组和正义寡核苷酸组。Western Blot杂交的方法检测细胞VEGF蛋白的表达,四甲基偶氮唑蓝法(MTT)检测细胞增殖变化,流式细胞仪检测细胞凋亡情况。结果新型脂质体可以携带VEGF反义寡核苷酸转染前列腺癌细胞PC3,与对照组和正义寡核苷酸组比较,反义寡核苷酸组细胞VEGF蛋白的表达明显下降,增殖受到明显抑制,凋亡率增加。结论新型脂质体Oligofectamine可以携带VEGF反义寡核苷酸成功转染前列腺癌细胞PC3,抑制VEGF的表达,进而抑制肿瘤细胞的增殖,促进其凋亡。     

mdr1反义寡核苷酸增强多药耐药肝癌细胞HepG2/ADM化疗敏感性的实验研究

目的：探讨在体外实验条件下mdr1反义寡核苷酸对多药耐药肝癌细胞株化疗敏感性的影响。方法以肝癌细胞HepG2/ADM为研究对象,设立mdr1反义寡核苷酸组和空白试剂组作对照,利用脂质体包载肿瘤耐药基因mdr1的反义寡核苷酸进行细胞转染,通过反转录聚合酶链反应（RT-PCR）、免疫印迹实验（Western blotting）分别检测mdr1基因mRNA和P-gp蛋白表达,通过MTT实验检测细胞转染前后对阿霉素（ADM）、顺铂（DDP）和5-氟尿嘧啶（5-FU）的化疗敏感性。结果 HepG2/AMD肝癌细胞经反义寡核苷酸处理后,mdr1 mRNA、P-gp蛋白表达水平均明显降低,对ADM、DDP 和5-FU的化疗敏感性明显增强。结论反义寡核苷酸能在体外有效增加肝癌细胞HepG2/ADM对化疗药物的敏感性。     

多胺胆固醇缀合物纳米粒作为反义核苷酸传递系统的研究

目的研究多胺胆固醇缀合物传递反义核苷酸的能力。方法通过对自制脂质体的载药量、红细胞毒性、M3骨髓瘤细胞的转染实验。结果自制脂质体具有比常规脂质体良好的载药量,并且对红细胞毒性相对偏小,对M3骨髓瘤细胞具有一定的转染能力。结论自制的脂质体具有一定的应用前景。     

脂质体Geneshuttle20对STAT6反义核酸转染小鼠脾淋巴细胞影响的研究

目的探讨阳离子脂质体Geneshuttle20对STAT6反义核酸在小鼠脾淋巴细胞摄入、分布的影响作用。方法采用阳离子脂质体介导STAT6反义核酸转染小鼠脾淋巴细胞,应用流式细胞仪、荧光显微镜分别观察反义核酸的细胞摄入和胞内分布。结果反义核苷酸与脂质体(W/W)为2∶4时,细胞摄入率可以达到67.7%,较单独加入反义核酸提高转染效率6倍,细胞内平均荧光强度最强,细胞核染色较深。结论Geneshuttle20提高了细胞对反义寡核苷酸的摄取,促使其进入细胞核内发挥作用。     

Synthesis of cholesterol modified cationic lipids for liposomal drug delivery of antisense oligonucleotides.

The paper describes a novel synthesis of cholest-5-en-3 beta-yl-6-aminohexyl ether (AH-Chol). AH-Chol was used to prepare positively charged liposomes. The liposomes consisted of phospholipon 90H and the cationic cholesterol derivative in an equimolar ratio. Liposome preparation was achieved by membrane homogenization after rehydration of a dry lipid film. Oligonucleotides (ODN) were adsorbed to the cationic liposomes very efficiently. At an ODN/liposome ratio of 1:5 (10:50 micrograms/ml) 84.2 +/- 5.4% of the ODNs were bound to the liposomal membrane. Within the range of 1:40 and 1:100 charge neutralization occurred and the liposome dispersion showed an increase in particle size due to aggregation. Below or above this range of charge neutralization the ODN loaded liposome preparation was physically stable, no sedimentation, increase of vesicle size or vesicle aggregation occurred.     

Chitosan-coated liposomes for intracellular oligonucleotides delivery: characteristics and cell uptake behavior

Surface modification of liposomes with polymer to optimize drug delivery was well developed recently. The objective of the present work was to evaluate the feasibility of chitosan-coated liposomes (CSLP) as vehicles for anti-sense oligodeoxynucleotides (ASON). CSLP was obtained by adding chitosan dropwise to liposomes under magnetic stirring. The effect of chitosan content on size, zeta potential, and coating efficiency was investigated, which showed that chitosan increased the size and zeta potential of CSLP, and the coating efficiency increased with chitosan content increasing. Agarose gel electrophoresis was employed to evaluate the loading efficiency of CSLP for ASON, from which one could see ASON was completely combined to CSLP when the mass ratio of total lipids:ASON was more than 50:1. MTT assay showed that CSLP took on very low cytotoxicity, which is much lower than chitosan. At last, cell uptake behavior was investigated by a flow cytometer, which showed that CSLP enhanced significantly the COS7 cells uptake of ASON. All the results indicated that the CSLP could be a promising non-viral ASON vehicle.     

Chitosan-coated liposomes for intracellular oligonucleotides delivery: Characteristics and cell uptake behavior

Surface modification of liposomes with polymer to optimize drug delivery was well developed recently. The objective of the present work was to evaluate the feasibility of chitosan-coated liposomes (CSLP) as vehicles for anti-sense oligodeoxynucleotides (ASON). CSLP was obtained by adding chitosan dropwise to liposomes under magnetic stirring. The effect of chitosan content on size, zeta potential, and coating efficiency was investigated, which showed that chitosan increased the size and zeta potential of CSLP, and the coating efficiency increased with chitosan content increasing. Agarose gel electrophoresis was employed to evaluate the loading efficiency of CSLP for ASON, from which one could see ASON was completely combined to CSLP when the mass ratio of total lipids:ASON was more than 50:1. MTT assay showed that CSLP took on very low cytotoxicity, which is much lower than chitosan. At last, cell uptake behavior was investigated by a flow cytometer, which showed that CSLP enhanced significantly the COS7 cells uptake of ASON. All the results indicated that the CSLP could be a promising non-viral ASON vehicle.     

Studies on uptake, sub-cellular trafficking and efflux of antisense oligodeoxynucleotides in glioma cells using self-assembling cationic lipoplexes as delivery systems

The cellular uptake of antisense oligodeoxynucleotides (ODNs) may be enhanced by the use of carriers such as cationic liposomes or lipoplexes, but little is known about the intracellular fate and subcellular trafficking of these systems in target cells. In this study, we report on the cellular uptake and biodistribution of ODNs in the presence and absence of optimised self-assembled cationic lipoplexes using the C6 glioma cell line as an in vitro model. Biotin or radiolabelled 15-mer phosphorothioate (PS) ODNs were synthesised and their cellular uptake and subcellular biodistribution characterised in the presence and absence of an optimised cationic lipoplex delivery system using studies ranging from cellular association, cellular efflux and transmission electron microscopy (TEM). Ultrastructural studies clearly showed PS ODNs in the absence of liposomal delivery to be sequestered within endosomal and lysosomal vesicular bodies indicative of endocytic uptake. ODNs were also visible, to a lesser extent, in the nucleus and cytoplasm. By employing DOSPA (2'-(1",2"-dioleoyloxypropyldimethyl-ammonium bromide)-N-ethyl-6-amidospermine tetra trifluoroacetic acid) and DOPE (dioleoylphosphatidylethanolamine) complex in a 3 : 1 ratio, as a delivery system for ODNs at a optimal lipid/DNA charge ratio of 1 : 1, the level of ODN cellular association was significantly increased by approximately 10-12 fold with a concomitant change in subcellular distribution of PS ODN. TEM studies indicated enhanced penetration of ODN within the cytosol and the cell nucleus with reduced presence in vesicular compartments. Efflux studies confirmed that cationic lipoplexes promoted entry of ODNs into 'deeper' cellular compartments, consistent with endosomal release. Optimised cationic lipoplexes improved cellular delivery of ODNs by enhancing cell association, uptake and by favourably modulating the intracellular trafficking and distribution of ODNs into non-vesicular compartments including the cytosol and nucleus.     

2-Dioleoyl-sn-glycero-3-phosphocholine-based nanoliposomes as an effective delivery platform for 17β-estradiol

The high loading efficiency and controlled release of hydrophobic drugs is still an unmet goal in the development of drug delivery systems. In the present study, liposomes were developed to encapsulate 17β-estradiol (E2), which is a sex steroid shown to confer protective effects in the cardiovascular system. Egg phosphatidylcholine (EPC), 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) were used to prepare liposomes by thin film hydration and tested for their ability to load E2 with a high efficiency. DOPC-based liposomes were found to improve E2 encapsulation efficiency and loading capacity compared to those composed of EPC and DPPC. In addition, neutral liposomes, liposomes prepared with the cationic charging agent DDAB, and liposomes prepared with the anionic charging agent DMPG, were characterized with regard to their E2 encapsulation efficiency, loading capacity, particle size, zeta potential, and in vitro drug release. A human coronary artery endothelial (HCAE) cell model was used to further evaluate liposome effects on cytotoxicity and relative cellular uptake efficiency of each formulation. Results showed that DOPC liposomes composed of DDAB had the highest E2 loading capacity and improved cellular uptake compared to uncharged and DMPG-based liposomes, demonstrating the greatest potential to be used in future cardiovascular therapeutic applications.     

阳离子脂质材料和聚乙二醇对脂质体细胞转染率及膜流动性的影响阳离子脂质材料和聚乙二醇对脂质体细胞转染率及膜流动性的影响

目的制备包封荧光素钠（FS）的脂质体，考察阳离子脂质材料（DC-chol）和聚乙二醇（PEG）对脂质体包封率、细胞转染率及膜流动性的影响。方法以FS作为模型物质，制备并分离脂质体，测定脂质体包封率；通过观察荧光光谱的变化考察FS与脂质体膜之间的相互作用；以HepG₂ 2.2.15为细胞模型观察脂质体对FS细胞转染率的影响；通过荧光偏振技术考察阳离子脂质材料和PEG对脂质体膜流动性的影响。结果阳离子脂质材料和PEG能提高脂质体包封率（0.64％～86.57％）、细胞转染率（2.18％～48.46％）及脂质体膜流动性，PEG分子质量的增大有利于包封率、转染率的提高，并增加脂质体膜的流动性。结论在脂质体处方中加入阳离子脂质材料和高分子量的PEG有利于提高包封率、细胞转染率及增加脂质体膜的流动性。     

Modeling cytoplasmic release of encapsulated oligonucleotides from cationic liposomes

Transfection activity of antisense oligodeoxynucleotides (ODN)-loaded cationic liposomes is mainly restricted by uptake and ODN release into cytoplasm, which is difficult to evaluate in cell culture studies. Well-designed models of cellular membranes, aim of the present study, might facilitate investigation of such processes. In this investigation, a phosphorothioate ODN was actively encapsulated in a DODAP-containing cationic liposome by ethanol injection with 73% efficiency. ODN release was determined by fluorescence dequenching of FITC-ODN upon incubation of liposomes with early endosomal (EE), late endosomal (LE) and plasma membranes (PM) models. LE provided the highest release (up to 76%) in a temperature-dependent manner. Release by EE (<16%), total PM (<11%) and PM external layer ( approximately 0) were not temperature sensitive. These differences are attributed to lipid charge, chain mobility, critical packing parameter and cholesterol content of the models. Intracellular distribution of FITC-ODN, determined by fluorescence microscopy and flowcytometry in the presence and absence of sodium azide, confirmed that liposomes were internalized mainly via endocytosis; hence inability of our PL models to simulate such active processes. Instead, release of ODN from endosomes into cytoplasm was pH-sensitive and in good agreement with model membrane studies in terms of amount and mechanism.