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。     

反义寡核苷酸脂质体复合物性质对细胞摄入行为的影响

目的研究影响反义寡核苷酸脂质体复合物的性质和细胞摄取的因素。方法逆相蒸发法制备3种不同的空白脂质体,与反义寡核苷酸混合得到复合物,显微镜观察其形态,琼脂糖电泳分析载药量,流式细胞仪测定阳性细胞百分率和平均荧光强度。结果高电荷密度的脂质体和低离子强度介质可使复合物发生凝聚,载药量和细胞摄入量依赖于空白脂质体和药物的比例以及脂质体膜表面的电荷密度。结论阳离子脂质体可以提高载药量和细胞的摄入,其程度与复合物比例、脂质体膜表面电荷密度等有关。     

豆甾醇糖苷/聚乙二醇衍生物修饰的阳性脂质体体内分布和肝实质细胞靶向性

目的研究经豆甾醇糖苷 (sterylglucoside, SG) 修饰的以DC-Chol为阳性脂材的脂质体体内分布情况和达到小鼠肝实质细胞靶向的可能性。方法合成阳性脂材3β-［n-(n′,n′- 二甲基氨乙基) 氨基甲酰基］ 胆固醇(DC-Chol)，制备³H-胆固醇标记的阳性脂质体(caitonic liposome, CL)，SG和聚乙二醇-二硬酯酰磷酯酰乙醇胺(PEG-DSPE)修饰的阳性脂质体(SG/PEG-CL)，以及包封¹²⁵I标记的硫代反义寡核苷酸(asODN)的阳性脂质体(SG/PEG-CL-asODN)，分别测定CL,SG/PEG-CL,SG/PEG-CL-asODN和asODN溶液(asODN )在小鼠不同器官及CL,SG/PEG-CL肝内不同细胞中的分布。结果CL和SG/PEG-CL表现较高肝脏聚集性，SG/PEG-CL在肝实质细胞中浓度显著高于CL (P<0.01)， 非实质细胞中浓度明显小于CL(P<0.01)。SG/PEG-CL-asODN相对于asODN表现出明显的肝脾聚集性(P<0.01)。结论用阳性脂质体包载基因药物能改善药物的体内分布，SG的修饰则能提高脂质体肝实质细胞选择性。     

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。     

以叶酸受体为靶向的阳离子脂质体的制备与性质考察

为了研制一种能通过叶酸受体途径靶向肿瘤细胞的叶酸受体靶向脂质体，将叶酸(folate，folic acid，F)、 聚乙二醇二胺(polyoxyethylene-bis-amine，NH₂-PEG-NH₂)、 琥珀酸酐(succinic anhydride，SUC)和二硬脂酰磷脂酰乙醇胺(distearoylphosphatidylethanolamine，DSPE)按序共价连接， 并使用薄层色谱和飞行时间质谱确证合成产物为叶酸-聚乙二醇-二硬脂酰磷脂酰乙醇胺(folate-polyethyleneglycol-distearoylphosphatidylethanolamine，F-PEG-DSPE)。膜材选用二棕榈酰磷脂酰胆碱(dipalmitoylphosphatidylcholine，DPPC)， 3β-［N-(N′,N′-二甲基胺乙基)胺基甲酰基］胆固醇(3β-［N(N′,N′-dimethylaminoethane) carbamoyl］ cholesterol，DC-Chol)和F-PEG-DSPE，以10∶10∶0.75(摩尔比)的配比，以荧光素标记的阴离子葡聚糖(dextran fluorescein anionic，DFA)为模型，用薄膜分散法制备含DFA的叶酸受体靶向脂质体，其包封率较高(>55%)、稳定性好，平均粒径为144 nm，体外释放慢。MTT法考察其对细胞的毒性结果表明该阳离子脂质体具有一定的细胞毒性，在低浓度时(0.012 5～0.1 μmol·L^{-1)脂质体的细胞毒性与DC-chol浓度成正比。流式细胞技术检测KB细胞和HepG2细胞对DFA脂质体的摄取，结果表明叶酸受体靶向的长循环阳离子脂质体能提高细胞对脂质体的摄取。该研究为进一步研究叶酸受体靶向阳离子脂质体在肿瘤基因治疗中的应用提供了理论基础。}     

靶向肿瘤新生血管的阿霉素阳离子脂质体的体外研究

本研究采用3β-［N-(N′,N′-二甲基胺乙基)胺基甲酰胺基］胆固醇(DC-Chol)和二棕榈酰磷脂酰胆碱为脂材制备了各种DC-Chol含量不同的阿霉素阳离子脂质体，考察了阿霉素阳离子脂质体的体外性质，同时以大鼠主动脉内皮细胞为模型，考察它们对不同阳离子脂质体的摄取情况，并采用静脉注射FITC-Dextran(M_r 500 000)标记体内肿瘤新生血管，为体内靶向肿瘤血管提供依据。结果表明阿霉素阳离子脂质体包封率均在90%以上，粒径在100~200 nm。随着DC-Chol含量的增加，zeta电位升高，但PEG的加入会降低zeta电位。DC-Chol含量的增加会增大阿霉素的释放量，同时也促进脂质体被内皮细胞的摄取，加快摄取速度。因此在进行体内靶向肿瘤血管考察时应充分关注这些体外实验结果。FITC-Dextran标记法可以显影体内新生血管，为体内肿瘤血管靶向实验提供直观的观察方法。     

联合包载阿霉素和siRNA阳离子脂质体的制备及体外评价

目的制备联合包载阿霉素和siRNA阳离子脂质体并进行体外评价。方法采用薄膜分散法制备载阿霉素阳离子脂质体(doxorubicin cationic liposomes,DCL),与siRNA静电复合得联合载药阳离子脂质体(liposome complexes,lipoplexes);动态激光散射法测定lipoplexes的粒径和zeta电位;透射电镜观察lipoplexes形态;超滤离心法测定lipoplexes中阿霉素和siRNA的包封率;琼脂糖凝胶阻滞实验考察lipoplexes中siRNA的结合能力;荧光显微镜观察MCF-7/ADR细胞对siRNA的摄取情况。结果所制备的lipoplexes外形圆整、分散均匀,当(2,3-二油氧基丙基)三甲基氯化铵与siRNA质量比为20时,其平均粒径为(125.7±2.7)nm,zeta电位为((45.8±1.5)m V,阿霉素包封率为(52.3±2.6)%,siRNA包封率为(88.1±1.8)%,且lipoplexes中siRNA可以紧密结合。与游离siRNA相比,lipoplexes可显著增加MCF-7/ADR细胞对siRNA的摄取。结论联合包载阿霉素和siRNA阳离子脂质体体外性质良好,能增加MCF-7/ADR细胞对siRNA的摄取,可用于小分子化疗药物和siRNA的共输送。     

载siRNA阳离子脂质体的制备

目的制备载siRNA阳离子脂质体并对其进行制剂学评价。方法利用siRNA与溴化乙锭结合能产生荧光的原理,采用预染溴化乙锭(Ethidium Bromide,EB)琼脂糖凝胶,氨基丁三醇-硼酸-乙二胺四乙酸(Tris-Boric acid-EDTA,TBE)电泳缓冲液将游离siRNA分离并通过凝胶成像分析系统转换数据进行定性和定量,计算载siRNA阳离子脂质体包封率,并考察其阴离子的抵御能力和血清稳定性;利用Malver粒径和zeta电位测定仪对不同载siRNA阳离子脂质体进行评价。结果琼脂糖凝胶电泳法的线性为0.665~13.30 mg·L-1(R2=0.988 3),回收率为97%~103%,精密度RSD<2%,阳离子脂质体对siRNA包封率较高,且具有良好的抵御阴离子能力和较强的血清稳定性;载siRNA阳离子脂质体的粒径和zeta电位变化与文献报道一致。结论所制备的载siRNA阳离子脂质体体外性质均良好。     

转铁蛋白修饰的载基因前阳离子脂质体制备及其表达研究

本文制备、优化转铁蛋白修饰的前阳离子脂质体，并研究其相关性质。通过薄膜分散膜挤压法制备空白前阳离子脂质体；以鱼精蛋白缩合质粒DNA与空白前阳离子脂质体作用形成载基因前阳离子脂质体(PLPD)；转铁蛋白(transferrin，Tf)再与PLPD作用形成转铁蛋白修饰的载基因前阳离子脂质体(Tf-PLPD)；中心组合设计优化制备工艺；以lacZ为报告基因转染人肝癌细胞株HepG2；测定形态、粒径、电位和转染效率。结果显示，PLPD形态近似于球体，平均粒径为(228.9±8.0) nm，多分散指数为0.122±0.020(n=3)；zeta电位为(-25.08±2.50) mV(n=3)，转染效率(12.18±3.80) mU·mg^-1(protein)。Tf-PLPD平均粒径为(240±12) nm，多分散指数为0.150±0.030(n=3)；zeta电位为(-24.10±2.50) mV(n=3)；转染效率(24.26±2.60) mU·mg^-1(protein)是裸质粒的20倍；实验结果也表明血清的存在不影响PLPD和Tf-PLPD的转染效率；PLPD和Tf-PLPD小于阳离子脂质体LPD对人肝癌细胞HepG2，SMMC7721和张氏正常肝细胞3种细胞株的毒性。由此可见，转铁蛋白修饰的前阳离子脂质体作为基因转运的非病毒载体具有良好的应用前景。     

替诺福韦阳离子脂质体的制备及其对人体肝细胞SMMC-7721摄取和细胞毒性研究

目的:研究替诺福韦阳离子脂质体的制备及其促进肝实质细胞摄取的情况和细胞毒性作用。方法:采用叔丁醇冻干法制备替诺福韦阳离子脂质体,测定其包封率及理化性质;以SMMC-7721细胞为模型,研究脂质体对肝实质细胞摄取替诺福韦的促进作用,MTT法检测不同条件下载药脂质体对细胞的毒性情况。结果:制备的脂质体包封率为(88.3±1.6)%,粒径为(278.4±67.6)nm,Zeta电势为(31±5)mV;经半乳糖基及PEG修饰的脂质体较游离药物进入肝实质细胞的浓度明显升高,且时间延长;当替诺福韦脂质体、脂质浓度分别为7.5、30μg·mL-1时,细胞存活率在80%以上,毒性较小。结论:所制备的阳离子脂质体具有显著增加细胞摄取替诺福韦和保护替诺福韦的作用,有望成为抗病毒药物如替诺福韦等的高效传递系统。     

Effect of Pluronic on cellular uptake of cationic liposomes- mediated antisense oligonucleotides

Cationic liposomes modified by different Pluronic block copolymers were prepared. The influence of Pluronic on the cellular uptake of antisense oligonucleotides (ODN) based on cationic 3beta[N-(N', N'-dimethylaminoethan)-carbamoyl] cholesterol (DC-Chol) liposomes was studied by flow cytometric analysis. It showed that DC-Chol liposomes containing Pluronic gave 1.7-2.3 times higher capacity of cellular uptake of ODN, despite the diminution of ODN loading efficiency. The level of improvement by Pluronic is related to the hydrophobic propylene oxide (PO) units Pluronic contains as well as the lipophile/hydrophile value of the molecule. This preliminary study indicated that modifying liposomes with another excipient is a useful pharmaceutical technique to improve ODN delivery.     

新型阿霉素隐形阳离子脂质体的制备及体外细胞实验

目的制备阿霉素隐形阳离子脂质体(DOX-SCL),并与中性脂质体(DOX-SNL)比较在体外小鼠乳腺癌4T1细胞实验上的差异。方法采用薄膜超声法制备空白脂质体,硫酸铵梯度法包载盐酸阿霉素(DOX);引入赖氨酸-胆固醇酯(Chol-lys)制成阳离子脂质体(CL),同时引入聚乙二醇-胆固醇琥珀酸酯(CHEMS-PEG)制成隐形阳离子脂质体(SCL);采用凝胶柱-UV法测定包封率;采用MTT法测定细胞毒性及体外抗肿瘤活性;通过流式细胞试验考察4T1细胞对脂质体的摄取情况。结果 SCL粒径约为100 nm,Zeta电位约为15.2 mV,对DOX的包封率大于95%;CHEMS-PEG的引入可以有效地降低CL的细胞毒性;与DOX-SNL相比,4T1细胞对DOX-SCL的摄取有所增加,DOX-SCL对4T1细胞的抑制率也更高。结论 SCL作为新型药物载体,可有效地促进DOX在肿瘤细胞中的传递。     

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.     

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。     

Monosialoganglioside containing cationic liposomes with a cationic cholesterol derivative promote the efficiency of gene transfection in mammalian culture cells

We have studied the effects of monosialoganglioside (GM1)-containing cationic liposomes with a cationic cholesterol on the liposome-mediated gene transfection into mammalian culture cells. The results showed that both cationic liposomes with either a cationic cholesterol derivative of a hydrophobic amino head group (I) and a hydrophilic amino head group (II) promoted the transfection of luciferase plasmids (pGL3) into HeLa and CHO-K1 cells more than the control cationic liposomes without GM1. In addition, we found that cationic liposomes with a cationic cholesterol derivative (II) were about ten times as effective as that by commercially available cationic liposome Lipofectin. Confocal fluorescence microscopy showed that the liposome/DNA complex was transferred more efficiently into the target cells by the GM1-containing liposomes than by the liposomes without GM1. In proportion to the above results, free antisense DNAs were also more efficiently transferred into the nucleus of the target cells by the GM1-containing liposomes. When there was 100 mM galactose in the transfection medium, the luciferase activity by the GM1-containing liposomes was reduced to the level of the control liposomes. The results suggest that GM1-containing cationic liposomes with a cationic cholesterol derivative of a hydrophobic amino head group or a hydrophilic amino head group should significantly increase the transfection efficiency of plasmid DNAs and antisense DNAs by galactose receptor-mediated endocytosis. This means that the GM1-containing liposomes described here should be very promising for gene transfection in vitro.