脂质-聚阳离子-CDKN1B质粒复合物的构建、特性和转染

目的 研究开发一种能有效转染CDKN1B基因进入肺和肝癌细胞的非病毒基因传递系统。方法 重组构建了含有CDKN1B序列和EYFP报告基因的质粒。该重组DNA与鱼精蛋白缩合后再与脂质体作用形成脂质-聚阳离子-DNA复合物（lipidspolycation-DNA-complex，LPDs），分别用激光粒度仪法和透射电镜法研究该LPDs的理化性质；用该LPDs转染几种肺癌、肝癌细胞；该LPDs中的EYFP在A549细胞中的表达情况用荧光显微镜和流式细胞仪观察和评价；在LLC肺癌细胞、Chang正常肝细胞和7721肝癌细胞中表达的CDKN1B蛋白用Western印迹方法分析。结果 该LPDs为凹陷的球状；平均粒径是167Bill，多分散指数为0．35；平均zeta电位为＋32．6mV；从A549细胞的荧光显微照片可清楚观察到EYFP的表达；A549细胞的流式细胞仪分析结果显示，LPDs的转染效率与阳性对照LipofectAMINE的转染效率相当；Western印迹法分析显示，以LPDs装载的CDKN1B质粒在LLC细胞、常细胞和7721细胞中表达CDKN1B蛋白，而裸CDKN1B质粒没有表达。结论脂质-聚阳离子-CDKN1B质粒复合物的构建是成功的。LPDs能够将CDKN1B质粒传递到肺癌细胞和肝癌细胞，并获得高效率的表达。因此，这种基因传递系统有望开发用作肺癌和肝癌的基因治疗传递系统。     

RNAi沉默WT1基因对人肝癌细胞HepG2的影响

目的:探讨利用RNA干扰沉默WT1基因对人肝癌细胞HepG2细胞生长,凋亡的影响,为肝癌的基因治疗提供理论依据。方法:利用脂质体将siRNA真核表达载体转入HepG2细胞中,并检测转染效率;利用免疫细胞化学染色方法检测HepG2细胞中WT1蛋白水平的表达,测定基因沉默效果;用MTT法测定HepG2细胞生长曲线;电镜下观察细胞凋亡形态,流式细胞仪检测凋亡率。结果:利用脂质体为载体将siRNA真核表达载体转染HepG2细胞,转染率达70%以上,转染后细胞中WT1蛋白表达水平下降;RNA干扰沉默WT1基因可抑制细胞增殖,促进细胞凋亡。结论:靶向WT1的序列特异性siRNA可显著抑制WT1基因的表达;下调HepG2细胞WT1基因表达可抑制细胞增殖,促进细胞凋亡。     

聚乙烯亚胺-聚乙二醇-siRNA纳米复合物的制备和理化性质的研究

目的 探索聚乙烯亚胺-聚乙二醇(PEI-PEG)-siRNA纳米复合物的制备方法及其理化性质,以提高siRNA的细胞转染率.方法 设计合成了PEI-PEG共聚物基因载体,使其与针对细胞表面受体CD44v6的siRNA形成纳米复合物.通过粒径与电位测定、凝胶阻滞电泳、扫描电镜、流式细胞仪测定等方法,观察不同N/P比的纳米复合物的复合效果、表面形态和大小、基因转染率等.结果 电镜下纳米复合物呈近球形、大小较一致、分散良好的纳米颗粒.N/P=5、10时复合物粒径分别为(174.6±1.2)nm,(267.7±1.8)nm.当N/P超过10时纳米复合物粒径减小,zeta电位为正值且增大.此时,siRNA被PEI-PEG完全复合,产生一种荧光淬灭作用.流式细胞仪结果表明纳米复合物的基因转染率随着N/P的增加而增大.当N/P比为30时,其转染率为(75.6±9.2)%.结论 PEI-PEG是一种有潜力的阳离子基因载体,它的制备为下一步体外实验及动物实验提供了条件.     

新型阳离子脂质体制备及其体外转基因特征

背景:阳离子脂质体及胶束、纳米粒等转基因载体是目前非病毒转基因载体领域研究热点;而目前市售转基因试剂盒价格昂贵,并且基本上都是进口商品,如果能够开发一种价廉,转基因效率高,具有自主知识产权的转基因试剂盒将展现广阔市场前景。目的:合成一种新型阳离子脂质复合物,并制备相应阳离子脂质体,对其体外转基因效率进行考察。方法:以1-乙基-3-(3-二甲胺丙基)碳二亚胺、胆固醇、丁二酸酐为原料合成阳离子脂质复合物,采用薄层色谱、红外光谱等方法对产物进行结构表征。然后用薄膜分散法,将适当比例的二油酰磷脂酰乙醇胺和阳离子脂质复合物混合制备成阳离子脂质体,并用其包封含绿色荧光蛋白报告基因的真核表达质粒pEGFPC1,对人宫颈癌Hela细胞株进行体外转染。结果与结论:通过两步法合成了一种全新的阳离子脂质复合物——胆固醇-丁二酸酯-1-乙基-3-(3-二甲胺丙基)碳二亚胺,薄层色谱及红外光谱结果表明合成了预期产物。薄膜分散法制得阳离子脂质体,其中以这种阳离子脂质复合物和二油酰磷脂酰乙醇胺摩尔比为1:1左右所制备的脂质体颗粒较为均匀、细小,形态基本呈圆形。体外对质粒包裹实验结果表明,阳离子脂质体与质粒比为5:3,可完全包封质粒。用该阳离子脂质体对Hela细胞进行转染,24h后,瞬时转染效率达35.6%。从初步实验结果看,所合成的阳离子脂质复合物结构总体与市售阳性成分结构类似,合成方法简单、廉价,体外对质粒DNA有很好包裹性能,细胞毒性低,然而体外对Hela细胞的转染效率还明显偏低。     

MicroRNA-100对肝癌细胞增殖活力和细胞周期的影响

 目的：探讨microRNA-100(miR-100) 对肝癌细胞增殖活力和细胞周期的影响及其可能机制。方法：通过脂质体介导将人工合成的miR-100模拟物及其阴性对照转染人肝癌HepG2细胞,用细胞计数试剂盒8(CCK-8)方法检测转染后HepG2细胞的增殖活力,用流式细胞术判定细胞周期分布,并进一步用实时荧光定量RT-PCR和Western blotting分析Polo样激酶1(Plk1)的表达水平。结果：荧光显微镜下观察到经阳离子脂质体介导的细胞转染效率大于85%。转染miR-100模拟物的实验组细胞的增殖抑制率在24、48和72 h分别为(43.5±12.2)%、(46.5±3.7)%和(52.1±0.2)%,均显著高于对照组细胞（P<0.01）,并且在72 h实验组细胞增殖指数（35.8±1.4）低于阴性对照组（39.2±1.0）和单纯脂质体组（40.7±2.0）(P<0.05)。同时与对照组相比,实验组细胞Plk1　mRNA和蛋白表达水平在转染miR-100后 72 h明显降低（P<0.05)。结论：miR-100可抑制肝癌细胞增殖,其机制可能与其下调Plk1的表达有关。     

聚酰胺-胺型树枝状高聚合物介导Survivin反义寡核苷酸抑制人肝癌裸鼠 移植瘤生长的作用*☆

背景：采用反义寡核苷酸等治疗方法可以抑制凋亡抑制因子Survivin 的表达,从而诱导肿瘤细胞凋亡。目前使用Survivin治疗恶性肿瘤仍存在基因载体转染效率低下、不能长期稳定表达、易被酶降解等难题。 目的：观察聚酰胺-胺型树枝状高聚合物(polyamidoamine,PAMAM)脂质体介导Survivin-反义寡核苷酸对人肝癌裸鼠移植瘤的抑制作用。 方法：以人肝癌细胞SMMC-7721裸鼠皮下注射建立人肝癌裸鼠皮下移植瘤模型,将PAMAM脂质体和PAMAM分别与Survivin-反义寡核苷酸混合得到载反义基因转染复合物。测定复合物的zeta电位及包封率。将两种载基因复合物注射道裸鼠移植瘤体内,观察两组移植瘤大小,检测移植瘤组织中survivin基因的表达。 结果与结论：PAMAM脂质体-survivin-反义寡核苷酸复合物的zeta电位高于PAMAM-survivin-反义寡核苷酸复合物(P < 0.05),基因包封率两组比较差异无显著性意义(P > 0.05)。PAMAM脂质体-survivin-反义寡核苷酸复合物治疗组裸鼠移植瘤质量及survivin蛋白表达低于PAMAM-survivin-反义寡核苷酸复合物组(P < 0.05)。提示PAMAM脂质体能将Survivin-反义寡核苷酸高效递送到人肝癌移植瘤细胞,降低survivin蛋白的表达,诱导移植瘤细胞凋亡。 关键词：聚酰胺-胺型树枝状高聚合物;脂质体;肝癌;反义寡核苷酸;Survivin doi:10.3969/j.issn.1673-8225.2012.12.020      

野生型p53基因在人肝癌细胞的表达及诱导其凋亡

目的:探讨外源性野生型p53基因(wt-p53)对人源性肝癌细胞系生物学的影响。方法:用脂质体转染法将真核表达质粒p53-pcDNA3转染人源性肝癌细胞系HepG2中,用G418筛选细胞;用生物素标记p53的cDNA探针,通过RNA原位杂交方法,检测p53-pcDNA3在细胞中的表达;用流式细胞术(FCM)检测细胞的凋亡指数。结果:G418筛选出了阳性转染细胞;RNA原位杂交显示HepG2的胞质成棕黄色,证明了p53的表达;FCM检测表明,转染p53-pcDNA3的HepG2细胞,其增殖能力下降,细胞凋亡指数由转染前的10.03%上升为54.17%。结论:外源性wt-p53可通过脂质体转染法在HepG2细胞中成功表达,并诱导其发生凋亡,有较好的临床应用前景。     

核转录因子HMBOX1对肝癌细胞生物学特征的影响

目的:比较肝癌细胞系与肝细胞系中HMBOX1的表达水平,探讨其在肝癌发生、发展中的作用。方法:RT-PCR检测HMBOX1在多种肝癌细胞系和正常肝细胞系中的表达。利用分子生物学方法构建pEGFP:HMBOX1融合表达载体,采用脂质体方法转染HepG2肝癌细胞系,MTT方法及流式细胞技术评价转染后细胞增殖和细胞周期的变化。基因芯片技术分析表达载体转染HepG2后肿瘤相关信号通路的变化。结果:PCR结果显示肝癌细胞系HMBOX1 mRNA表达水平明显低于正常肝细胞系;pEGFP:HMBOX1融合表达载体转染HepG2后,细胞的增殖能力和周期未出现显著变化;基因芯片的结果提示转染表达载体的HepG2细胞,肿瘤和免疫信号通路相关基因的表达发生显著变化。结论:HMBOX1在多种肝癌细胞系表达下调,可能参与了多条与肿瘤和免疫相关信号通路的调节,为进一步阐明肝癌的发生机制提供了新的实验依据。     

阳离子脂质体介导IL-15基因治疗小鼠肺转移模型的实验研究

目的:用阳离子脂质体(CL)包裹pcDNA3.1-IL15制备阳离子脂质体质粒DNA复合物CL-IL15,观察其抗小鼠B16-F10肺转移瘤的治疗作用,并初步探讨其作用机制。方法:构建hIL-15真核表达载体,测定脂质体-质粒DNA复合物的最佳包封率;将该复合物转染CHO-K1细胞株,West-ern blott检测体外转染条件下IL-15蛋白的表达情况,MTT法检测细胞转染上清对CTLL-2细胞株的增殖刺激作用;建立B16-F10小鼠黑色素瘤肺转移模型,尾静脉给药,每隔1 d给药1次,共6次,治疗结束24 h后观察各组肿瘤肺转移情况;LDH释放法(乳酸脱氢酶释放法)检测脾淋巴细胞的杀伤作用,冰冻切片免疫荧光法观察NK细胞对肿瘤组织的浸润。结果:成功构建hIL-15表达载体,并验证其与阳离子脂质体的质量比为1∶5时,包裹后形成的复合物具有较好的包封率;可以在体外有效转染并表达具生物活性的分泌型IL-15蛋白;CL-IL15复合物治疗小鼠肿瘤肺转移模型,可以显著减少肿瘤肺转移结节数目,提高脾细胞对肿瘤细胞杀伤活性(P<0.05),增加NK细胞在肿瘤组织中的浸润比例。结论:阳离子脂质体质粒DNA复合物CL-IL15可有效地抑制小鼠B16-F10肺转移瘤,其作用机制可能与IL-15诱导脾细胞对肿瘤细胞的杀伤、激活NK(natural killer)细胞对肿瘤组织的浸润等机制有关。     

Gαs在肝癌中的表达情况及其高表达对肝癌细胞HepG2的影响

目的:探讨Gαs过表达对人类肝癌细胞HepG2生长、增殖的影响,及Gαs在人类肝癌中的表达情况,寻求有效的治疗靶点.方法:利用QpCR技术检测人类肝癌组织中Gαs基因水平的表达情况;利用Western blot检测人肝癌细胞HepG2及正常肝细胞HL-7702中Gαs蛋白水平的表达;利用脂质体法将Gαs质粒转染HepG2细胞;用MTT检测HepG2细胞增殖情况;流式细胞术检测细胞周期变化.结果:QPCR 结果显示在基因肝癌组织中Gαs表达高于癌旁组织;Western blot结果显示肝癌细胞中Gαs在蛋白水平表达高于肝正常细胞;Gαs质粒转染HepG2细胞后,Gαs表达增高,细胞增殖加快.结论:Gαs基因表达水平在肝癌组织中高于周围癌旁组织;Gαs的高表达可能与肝癌的发生发展相关联,其高表达促进HepG2细胞的生长与增殖.     

PEGylated guanidinylated polyallylamine as gene-delivery carrier

A novel cationic co-polymer was developed by grafting poly(ethylene glycol) (PEG) on guanidinylated polyallylamine (PAA) for gene delivery. Characterization of PEG-g-guanidinylated PAA/DNA complexes demonstrated that particle size increased and surface charge decreased with increasing the amount of PEG. The results of cytotoxicity assay proved that grafted PEG could effectively decrease the cytotoxicity of the complexes. In transfection efficiency assay, HeLa cells treated with PEG(2)-g-guanidinylated PAA (formed with 17.5 μmol guanidinylated PAA and 2 μmol PEG)/DNA (0.2 μg EGFP plasmid) complexes showed a very high level of EGFP expression. In conclusion, combination of guanidinylation and PEGylation could effectively decrease the cytotoxicity and significantly increase the transfection efficiency of PAA.     

In vitro and in vivo transfection efficiency of a novel ultradeformable cationic liposome

Cationic lipids have been often used as one of the major components in making most promising non-viral gene delivery systems, whereas sodium cholate, a surfactant so-called edge activator has been used in preparing ultradeformable and ultraflexible liposomes called Transfersomes. Using both a cationic lipid, DOTAP and sodium cholate, a novel formulation of ultradeformable cationic liposome (UCL) has been prepared. The average particle size of this formulation was approximately 80 nm. The physical and chemical stabilities at two different temperatures (4 degrees C and 20 degrees C) were also evaluated for 60 days. The ultradeformability of new formulation was also assessed, and it has been proved that the formulation is deformable. In vitro transfection efficiency of plasmid DNA/UCL was assessed by the expression of green fluorescent protein (GFP) in four cell lines, OVCAR-3 (human ovarian carcinoma cells), HepG2 (human hepatoma cells), H-1299 (human lung carcinoma cells) and T98G (human brain carcinoma cells). The optimal ratio of DNA to liposome for maximal transfection efficiency was 1:14 (w/w) in all the cell lines except for the human brain carcinoma cells. The same formulation was tested for in vivo transfection efficiency and its retention time within the organs by applying the DNA/UCL complexes on hair-removed dorsal skin of mice non-invasively. It was found that genes were transported into several organs for 6 days once applied on intact skin.     

Sendai F/HN Viroplexes for Efficient Transfection of Leukemic T Cells

Purpose

Most chemical transfection reagents are ineffective for the transfection of cells in suspension, such as leukemic cell and stem cell lineages. We developed two different types of viroplexes, cationic Sendai F/HN viroplexes (CSVs) and protamine sulfate-condensed cationic Sendai F/HN viroplexes (PCSVs) for the efficient transfection of T-leukemic cells.

Materials and Methods

The viroplex systems were prepared by reconstitution of fusogenic Sendai F/HN proteins in DMKE (O,O''-dimyristyl-N-lysyl glutamate) cationic liposomes. The viroplexes were further optimized for plasmid DNA and siRNA delivery to suspension cells. The particle size and surface charge of the viroplexes were analyzed with a ζ-sizer. Transfection of plasmid DNA (pDNA) and small interfering RNA (siRNA) by CSVs or PCSV was evaluated by measurement of transgene expression, confocal microscopy, FACS, and RT-PCR.

Results

The optimized CSVs and PCSVs exhibited enhanced gene and siRNA delivery in the tested suspension cell lines (Jurkat cells and CEM cells), compared with conventional cationic liposomes. In the case of pDNA transfection, the CSVs and PCSVs show at least 10-fold and 100-fold higher transgene expression compared with DMKE lipoplexes (or lipofectamine 2000), respectively. The CSVs showed more effective siRNA delivery to the suspension cells than cationic liposomes, as assessed by confocal microscopy, FACS, and RT-PCR. The effective transfection by the CSVs and PCSVs is presumably due to fusogenic activity of F/HN proteins resulting in facilitated internalization of pDNA and siRNA.

Conclusion

This study suggests that Sendai F/HN viroplexes can be widely applicable for the transfection of pDNA and siRNA to suspension cell lines.     

PEGylated Guanidinylated Polyallylamine as Gene-Delivery Carrier

A novel cationic co-polymer was developed by grafting poly(ethylene glycol) (PEG) on guanidinylated polyallylamine (PAA) for gene delivery. Characterization of PEG-g-guanidinylated PAA/DNA complexes demonstrated that particle size increased and surface charge decreased with increasing the amount of PEG. The results of cytotoxicity assay proved that grafted PEG could effectively decrease the cytotoxicity of the complexes. In transfection efficiency assay, HeLa cells treated with PEG(2)-g-guanidinylated PAA (formed with 17.5 μmol guanidinylated PAA and 2 μmol PEG)/DNA (0.2 μg EGFP plasmid) complexes showed a very high level of EGFP expression. In conclusion, combination of guanidinylation and PEGylation could effectively decrease the cytotoxicity and significantly increase the transfection efficiency of PAA.     

Endosomal escape and transfection efficiency of PEGylated cationic liposome-DNA complexes prepared with an acid-labile PEG-lipid

Cationic liposome-DNA (CL-DNA) complexes are being pursued as nonviral gene delivery systems for use in applications that include clinic trials. However, to compete with viral vectors for systemic delivery in vivo, their efficiencies and pharmacokinetics need to be improved. The addition of poly (ethylene glycol)-lipids (PEGylation) prolongs circulation lifetimes of liposomes, but inhibits cellular uptake and endosomal escape of CL-DNA complexes. We show that this limits their transfection efficiency (TE) in a manner dependent on the amount of PEG-lipid, the lipid/DNA charge ratio, and the lipid membrane charge density. To improve endosomal escape of PEGylated CL-DNA complexes, we prepared an acid-labile PEG-lipid (HPEG2K-lipid, PEG MW 2000) which is designed to lose its PEG chains at the pH of late endosomes. The HPEG2K-lipid and a similar but acid-stable PEG-lipid were used to prepare PEGylated CL-DNA complexes. TLC and dynamic light scattering showed that HPEG2K-CL-DNA complexes are stable at pH 7.4 for more than 24 h, but the PEG chains are cleaved at pH 5 within 1 h, leading to complex aggregation. The acid-labile HPEG2K-CL-DNA complexes showed enhanced TE over complexes stabilized with the acid-stable PEG-lipid. Live-cell imaging showed that both types of complexes were internalized to quantitatively similar particle distributions within the first 2 h of incubation with cells. Thus, we attribute the increased TE of the HPEG2K-CL-DNA complexes to efficient endosomal escape, enabled by the acid-labile HPEG2K-lipid which sheds its PEG chains in the low pH environment of late endosomes, effectively switching on the electrostatic interactions that promote fusion of the membranes of complex and endosome.     

Amphiphilic and biodegradable methoxy polyethylene glycol-block-(polycaprolactone-graft-poly(2-(dimethylamino)ethyl methacrylate)) as an effective gene carrier

A group of amphiphilic cationic polymers, methoxy polyethylene glycol-block-(polycaprolactone-graft-poly(2-(dimethylamino)ethyl methacrylate)) (PECD), were synthesized by combining ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) methods to form nanoparticles (NPs). The structures of these amphiphilic cationic polymers were characterized by (1)H NMR measurement. The PECD NPs have hydrophobic cores covered with hydrophilic PEG and cationic PDMAEMA chains. These self-assembly nanoparticles were characterized by dynamic light scattering (DLS) technique. PECD NPs can effectively condense DNA to form compact complexes of the size 65-160 nm suitable for gene delivery. The in vitro gene transfection studies of HeLa and HepG2 cells show that PECD NPs have better transfection efficiency compared to polyethylenimine (PEI) and Lipofectamine 2000 at low dose (N/P = 5). The cytotoxicity result shows that PECD NPs/DNA complexes at the optimal N/P ratio for transfection have comparable toxicity with PEI and Lipofectamine. These results indicate that PECD NPs have a great potential to be used as efficient polymeric carriers for gene transfection.     

Contribution of hydrophobic/hydrophilic modification on cationic chains of poly(ε-caprolactone)-graft-poly(dimethylamino ethylmethacrylate) amphiphilic co-polymer in gene delivery

Nanoparticles (NPs) assembled from amphiphilic polycations have been certified as potential carriers for gene delivery. Structural modification of polycation moieties may be an efficient route to further enhance gene delivery efficiency. In this study two electroneutral monomers with different hydrophobicities, 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA), were incorporated into the cationic poly(dimethylamino ethyl methacrylate) (PDMAEMA) side-chains of amphiphilic poly(ε-caprolactone)-graft-poly(dimethylamino ethylmethacrylate) (PCD) by random co-polymerization, to obtain poly(ε-caprolactone)-graft-poly(dimethylamino ethyl methacrylate-co-2-hydroxyethyl methacrylate) (PCD-HEMA) and poly(ε-caprolactone)-graft-poly(dimethylamino ethyl methacrylate-co-2-hydroxyethyl acrylate) (PCD-HEA). Minimal HEA or HEMA moieties in PDMAEMA do not lead to statistically significant changes in particle size, zeta potential, DNA condensation properties and buffering capacity of the naked NPs. However, the incorporation of HEMA and HEA lead to reductions and increases, respectively, in the surface hydrophilicity of the naked NPs and NPs/DNA complexes, which was confirmed by water contact angle assay. These simple modifications of PDMAEMA with HEA and HEMA moieties significantly affect the gene transfection efficiency on HeLa cells in vitro: PCD-HEMA NP/DNA complexes show a much higher transfection efficiency than PCD NPs/DNA complexes, while PCD-HEA NPs/DNA complexes show a lower transfection efficiency than PCD NP/DNA complexes. Fluorescence activated cell sorter and confocal laser scanning microscope results indicate that the incorporation of hydrophobic HEMA moieties facilitates an enhancement in both cellular uptake and endosomal/lysosomal escape, leading to a higher transfection efficiency. Moreover, the process of endosomal/lysosomal escape confirmed in our research that PCD and its derivatives do not just rely on the proton sponge mechanism, but also on membrane damage due to the polycation chains, especially hydrophobic modified ones. Hence, it is proved that hydrophobic modification of cationic side-chains is a crucial route to improve gene transfection mediated by polycation NPs.     

Low toxicity of cationic lipid-based emulsion for gene transfer

Cationic liposome has been studied as one of the most promising non-viral gene delivery systems. However, it has major drawbacks such as the formation of large aggregates at higher concentrations and the instability in the serum due to cationic lipid. As an alternative gene delivery system, cationic emulsion was formulated and transfection efficiency was evaluated in vitro and in vivo, in comparison with cationic liposome. Cationic emulsion was prepared with varying compositions of 3 beta [N-(N',N'-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol), dioleoylphosphatidyl ethanolamine (DOPE), caster oil and Tween 80. Cationic liposome was prepared with DC-Chol and DOPE. The particle size of all the DNA/lipid complexes varied from 150 to 230 nm. The in vitro transfection efficiency of plasmid DNA was assessed by the expression of green fluorescent protein as a reporter. Of various formulations, cationic emulsion E2 (DC-Chol/DOPE/Castor Oil/Tween 80 = 0.3:0.3:0.3:0.15) and cationic liposome L3 (DC-Chol/DOPE = 0.6:0.3) showed improved transfection. DNA/E2 complexes exhibited higher transfection efficiencies (17.39+/-0.58%) in comparison with DNA/L3 complexes (11.47+/-0.59%). DNA/E2 complexes also showed a better physical stability and a stronger serum resistance than DNA/L3 complexes. Moreover, the cytotoxicity of DNA/E2 complexes was comparable to that of DNA/L3 complexes. When DNA/lipid complexes were intravenously administered, DNA/E2 complexes showed a prolonged circulation in blood and mRNA expression in various tissues compared with DNA/L3 complexes. These results suggest that cationic emulsion E2 could be a potential gene delivery system in clinical approaches because of enhanced in vivo gene transfer with low toxicity.     

携带甲胎蛋白基因小干扰RNA慢病毒载体的构建及其对靶基因的沉默效率

目的构建携带甲胎蛋白（AFP）基因小干扰RNA（siRNA）的慢病毒载体并转染肝癌细胞,评价其对AFP基因的沉默效率。方法设计和构建针对AFP基因的阳性siRNA及不针对任何已知基因的阴性siRNA,将其分别插入携带绿色荧光蛋白（GFP）基因的重组慢病毒载体,然后转染到表达AFP基因的人肝癌细胞HepG2并筛选阳性表达细胞株,分别为慢病毒转染阳性siRNA组和慢病毒转染阴性siRNA组。同时设立脂质体转染阳性siRNA组、脂质体转染阴性siRNA组以及加AFPsiRNA而未用转染试剂的siRNA组、空白对照组。荧光显微镜观察评估转染效率,荧光定量PCR和免疫印迹法检测各组HepG2细胞APFmRNA及蛋白的相对表达量,比较不同转染方法对AFP基因表达的抑制率。结果慢病毒能够有效地转染siRNA到HepG2细胞内。荧光定量PCR显示慢病毒转染siRNA对AFPmRNA表达的抑制率显著高于脂质体转染siRNA（92．1％比74．3％,P〈0．05）。免疫印迹亦显示慢病毒转染siRNA对AFP蛋白表达的抑制率显著高于脂质体转染siRNA（88．2％比63．7％,P〈0．05）。结论慢病毒转染AFPsiRNA能够更有效地抑制HepG2细胞内AFP基因表达。