转化生长因子β1基因缓释的壳聚糖纳米粒制备及体外检测***☆

背景：壳聚糖作为一种非病毒载体,具有低毒性、低免疫原性、良好的生物相容性以及带可高正电荷密度的特性,易与带负电荷的DNA通过静电作用形成相互作用体避免核酸酶的降解。 目的：构建负载重组人转化生长因子β1基因的壳聚糖纳米粒,检测其体外缓释转化生长因子β1基因及对软骨细胞基因转染等性能。 方法：将壳聚糖与负载增强型绿色荧光蛋白基因和转化生长因子β1基因的质粒DNA(pDNA)以复凝聚法制成壳聚糖/ pEGFP-TGF-β1纳米粒。 结果与结论：制备的壳聚糖/pEGFP-TGF-β1纳米粒呈球形,粒径、表面电位与pH值相关,随着pH值升高,粒径增大,表面电位减少。纳米粒可有效保护pDNA免受核酸酶的降解。纳米粒的pDNA包封率为(87.5±2.3)%;pDNA可从纳米粒中缓慢释放。体外转染实验证实壳聚糖/pEGFP-TGF-β1纳米粒能转染软骨细胞并在细胞内表达绿色荧光蛋白。提示壳聚糖/ pEGFP-TGF-β1纳米粒能有效保护pDNA免受核酸酶降解,具有良好的缓释转化生长因子β1基因的能力,并能介导基因转染软骨细胞。 关键词：转化生长因子β1;壳聚糖;软骨细胞;组织工程;基因载体 doi:10.3969/j.issn.1673-8225.2012.12.007     

脂质体介导pIDO-EGFP转染原代培养软骨细胞的初步研究

目的：检测脂质体介导pIDO-EGFP转染原代培养的C57小鼠关节软骨细胞的瞬时表达及转染效率，建立原代培养的小鼠关节软骨细胞转染方法。方法：大肠杆菌中扩增pIDO-EGFP质粒，在最优化条件下通过lipofectamine2000^TM转染试剂将pIDO-EGFP质粒转入原代培养的小鼠关节软骨细胞。应用荧光显微镜和激光共聚焦显微镜观察其转染过程及瞬时表达情况，流式细胞术检测其转染效率。结果：质粒携带的增强型绿色荧光蛋白在转染后24h得到了明显表达，48h后流式细胞术检测其转染效率为36．43％，未影响软骨细胞贴壁过程。结论：经绿色荧光蛋白检测表明，脂质体成功地将IDO基因转染进入原代培养的软骨细胞。转染后的软骨细胞在体外仍能存活，在最优化的条件下能达到良好的瞬时转染效率，为组织工程化软骨细胞基因导入和基因修饰提供了思路。     

十二烷基化壳聚糖基因支架血管内基因转运的实验研究

目的评估新型十二烷基化壳聚糖质粒DNA支架向局部动脉血管内转运基因的可行性及效果。方法十二烷基化壳聚糖同质粒DNA按文献制备纳米粒并进行表征。将纳米粒涂布于金属支架表面同时进行电镜观察。分别将十二烷基化壳聚糖质粒DNA支架进行细胞转染(pEGFP-C1)和兔颈动脉在体转染实验(pGL3-control),观察细胞转染效果。结果十二烷基化壳聚糖质粒DNA纳米粒为球形,稳定,平均粒径126nm,Zeta电位( 28±3)mV。该纳米粒涂布于支架表面,电镜下呈片状不规则粒子。细胞转染实验显示,支架表面细胞及支架邻近细胞大量转染,远离支架细胞未见转染。动物实验结果显示,支架植入部位荧光素酶高表达,同时有2只动物肝脏标本有微量表达,其他部位未见表达。结论十二烷基化壳聚糖质粒DNA支架是一种新型有效的血管内基因转运体系,可能对诸如再狭窄等心血管疾病有良好的应用前景,同时,这一基因运载思路可以广泛应用于各种质粒DNA的转运。     

新型非病毒载体聚乙烯亚胺介导基因转染参数的研究

聚乙烯亚胺是一种新型阳离子多聚物基因释放载体,可结合浓缩DNA,通过粘附内吞,进入细胞,使携带的质粒表达。本研究目的通过对聚乙烯亚胺各种转染参数的测定,为合成以聚乙烯亚胺为骨架的人工载体积累数据。方法:本研究利用聚乙烯亚胺分别结合含β半乳糖甙酶报告基因的pSVβ表达质粒、含绿色荧光蛋白报告基因的pEGFP质粒转染Cos-7细胞,通过组织化学法测定细胞抽提产物中β半乳糖甙酶的表达量、流式细胞仪法测定绿色荧光蛋白阳性细胞的表达比例,来测定影响转基因效率的各种参数。结果:在培养液中,6μg/ml聚乙烯亚胺作用24h,NIH 3T3细胞生存率为64.2%,7μg/ml聚乙烯亚胺细胞生存率为54.4%。电泳阻滞试验,聚乙烯亚胺在N/P比在3.0以上方可完全结合DNA。溶酶体抑制剂氯喹可增加聚乙烯亚胺的转染效率。培养液中的白蛋白、血清可降低转染效率。作为配制聚乙烯亚胺/DNA复合物的溶媒,HEPES缓冲液优于生理盐水,生理盐水优于5%葡萄糖。配制聚乙烯亚胺/DNA复合物的溶媒中加入Mg2+降低转染效率。聚乙烯亚胺转染效率优于SuperFectTM(断裂型树突状多聚物),而毒性低于SuperFectTM。结论:本研究首次报道了聚乙烯亚胺与DNA结合配伍的N/P比计算公式,N/P=7.75×b/c,这里b是PEI的质量(μg),c是质粒的质量(μg);PEI的工作终浓度应≤6μg/ml。通过体外细胞试验证明,聚乙烯亚胺是一种有效的真核细胞转染剂和人工合成基因载体的骨架。     

TAT-LHRH修饰的壳聚糖/DNA纳米粒的细胞内吞途径

目的 探索对肝癌细胞HepG2具有较高转染效率和靶向性的TAT-LHRH修饰的壳聚糖/DNA纳米粒的内吞途径.方法 采用复凝集法,将荧光标记的质粒DNA与壳聚糖或TAT-LHRH修饰的壳聚糖混合制备壳聚糖/DNA纳米粒(CDN)和TAT-LHRH修饰的壳聚糖/DNA纳米粒(TLCDN).观察3种内吞途径抑制剂Chlor...     

载表皮生长因子/壳聚糖纳米粒纤维蛋白胶胶联羊膜的制备及体外释药评价

背景：纤维蛋白胶胶联羊膜作为一种无需缝合生物移植材料还无法有效地在局部长时间缓释药物,特别是对于一些不稳定的生物活性蛋白药物。 目的：构建新型的能有效缓释蛋白药物的载表皮生长因子壳聚糖纳米粒纤维蛋白胶羊膜复合体。 方法：制备表皮生长因子/壳聚糖载药纳米粒并考察其表征,然后将载药纳米粒掺入纤维蛋白胶,再将载纳米粒的纤维蛋白胶和羊膜胶联黏合,制备出负载表皮生长因子/壳聚糖纳米粒纤维蛋白胶胶联羊膜,并进行形态学和体外释药观察,检测释放出的表皮生长因子生物活性。 结果与结论：表皮生长因子/壳聚糖纳米粒的粒径为(275.7±6.8) nm,Zeta电位为(32.7±0.6) mV,包封率为(67.03±1.22)%,多分散指数为0.23±0.04,形态圆形均一,载纳米粒纤维蛋白胶能够很好地与羊膜胶联黏合,表面呈网状结构,纳米粒充斥其中。载表皮生长因子/壳聚糖纳米粒纤维蛋白胶胶联羊膜体外释药可达14 d,释放的表皮生长因子生物活性可保持7 d以上。说明制备的载重组人表皮生长因子/壳聚糖纳米粒纤维蛋白胶胶联羊膜作为一种无缝合生物移植材料可在局部缓慢释放表皮生长因子。     

增强型绿色荧光蛋白基因转染对原代培养的人软骨细胞细胞周期的影响

目的:观察转染增强型绿色荧光蛋白 (EGFP) 基因后原代培养的人鼻中隔软骨细胞的细胞周期的变化,建立原代培养的人鼻中隔软骨细胞的示踪方法。方法:在大肠杆菌中扩增pEGFP-N1 质粒,通过Amaxa细胞核转染仪将pEGFP-N1质粒转入原代培养的人鼻中隔软骨细胞,应用激光共聚焦显微镜观察其转染过程及瞬时表达情况,流式细胞仪检测其转染效率和细胞周期的变化。结果:增强型绿色荧光蛋白基因在转染24 h后得到了明显表达,48 h后流式细胞仪检测其表达率为35.37％,细胞周期没有明显的改变,且未影响软骨细胞的贴壁过程。结论:经pEGFP-N1质粒转染的原代培养的人鼻中隔软骨细胞仍能在体外存活,对软骨细胞的生长没有明显的影响,pEGFP-N1是转染原代培养的人鼻中隔软骨细胞较为理想的瞬时表达载体,也是组织工程化软骨形成过程的良好示踪剂。     

重组人白细胞介素1受体拮抗蛋白荧光质粒在软骨细胞的表达

背景：白细胞介素1受体拮抗蛋白能延缓骨性关节炎进程,通过转基因方法可以使白细胞介素1受体拮抗蛋白表达的增加。 目的：观察重组人重组人白细胞介素1受体拮抗蛋白荧光质粒的构建及经脂质体转染软骨细胞的表达情况。 方法：双酶切法切取重组人白细胞介素1受体拮抗蛋白的c-DNA片段,通过T4DNA连接酶连接到pEGFP-C1载体上。体外分离培养兔关节软骨细胞,然后用构建的重组人白细胞介素1受体拮抗蛋白质粒经脂质体转染软骨细胞,通过荧光显微镜观察转基因的表达和荧光定量PCR检测其表达。 结果与结论：获得重组人pEGFP-C1-IL-1Ra真核表达载体质粒,酶切及测序结果证明表达质粒的DNA序列完全正确。荧光显微镜观察有绿色荧光蛋白表达,荧光定量PCR鉴定证实转染的软骨细胞基因得到表达。     

N-亚甲基磷酸化壳聚糖基因纳米粒子的体外细胞毒性及基因转染实验研究

目的 考察N-亚甲基磷酸化壳聚糖( NMPCS)基因纳米粒子的体外细胞毒性及基因转染效率.方法 采用均相反应法制备了NMPCS,用复凝聚法制备了NMPCS/DNA纳米粒子;通过MTT实验考察了NMPCS及其与DNA复合物对HeLa细胞的细胞毒性,以荧光索酶质粒为报告基因考察了NMPCS及NMPCS-CaZ+载体介导的体外基因转染效率.结果 NMPCS及其与DNA的复合物在体外表现出很小的细胞毒性,远远低于同等浓度时聚乙烯亚胺(PEI)的毒性.通过对壳聚糖进行亚甲基磷酸化修饰后,可大幅提高载体的基因转染效率.结论 N-亚甲基磷酸化壳聚糖有望成为一种新型、安全、高效的非病毒基因载体.     

PEG化壳聚糖质粒纳米粒的制备及其转染的研究

目的:制备壳聚糖纳米粒并构建聚乙二醇(PEG)化壳聚糖质粒纳米粒,研究其对大鼠主动脉内皮细胞的转染能力及细胞毒性.方法:采用离子交联法制备壳聚糖纳米粒,应用喷金扫描电子显微镜检测壳聚糖纳米粒粒径的分布与形态;通过静电吸附作用连接上pGenesil-1质粒(报告基岗);对壳聚糖质粒纳米粒进行PEG化的修饰;应用PEG化壳聚糖质粒纳米粒转染大鼠主动脉内皮细胞;采用噻唑蓝(MTT)法测定壳聚糖纳米粒对细胞的毒性作用.结果:喷金扫描电镜检测显示壳聚糖纳米粒呈均匀分散的球形颗粒,平均直径为5 nm;PEG化壳聚糖质粒纳米粒能转染大鼠主动脉内皮细胞;MTT结果显示壳聚糖纳米粒对细胞无毒性作用;壳聚糖质粒纳米粒对内皮细胞的转染效率为26%,PEG修饰壳聚糖质粒纳米粒转染细胞,转染率为63.4%.结论:对壳聚糖质粒纳米粒进行化学修饰不仅能提高其转染效率,且对细胞无毒性作用.     

壳聚糖载基因纳米粒子的研究

以壳聚糖为基质研究载基因纳米粒子的制备及其对血管平滑肌细胞的转染效率。制备载绿色荧光蛋白(Enhanced green fluorescen t prote in,EGFP)和组织因子途径抑制因子(T issue factor pathw ay inh ib itor,TFP I)质粒DNA的壳聚糖纳米粒子,透射电镜观察两种纳米粒子皆呈球形,光子相关色谱仪(PCS)测定显示纳米粒子的平均粒径为149 nm,粒径分布在80~250 nm之间;载基因纳米粒子的DNA包埋效率和DNA含量分别为96%±1.38%和37%±3.0%。载基因壳聚糖纳米粒子可以有效地保护DNA,防止核酸酶对其的降解作用。血管平滑肌细胞转染实验表明,纳米粒子对细胞基本无毒性,其转染效率与阳离子脂质体转染试剂L ipofectAM INETM相近。     

Plasmid size influences chitosan nanoparticle mediated gene transfer to chondrocytes

The objective of the present study was to prepare chitosan nanoparticles incorporating a relatively large plasmid encoding for osteogenic protein (OP)-1 and to determine the ability of these nanoparticles to transfect adult canine articular chondrocytes in vitro. The positive charge of chitosan acted to condense the relatively large negatively-charged OP-1 plasmid such that it could be incorporated into nanoparticles. Incorporation of the plasmid into the chitosan nanoparticles did not affect the structural integrity of the plasmid as demonstrated by gel electrophoresis. The morphology and size of the nanoparticles were found to vary with the chitosan:plasmid weight ratio. Nanoparticles formulated with a chitosan:plasmid ratio of 10:1 were of uniformly small size (less than 250 nm) and spherical shape. These nanoparticles had a positive charge of about 20 mV. FITC-labeled chitosan nanoparticles were found in virtually all of the cells after 24 h of incubation with the nanoparticles, and confocal microscopy revealed FITC-related fluorescence in the nucleus of the chondrocytes. Although transfection of the chondrocytes was demonstrated by the fluorescence of cells treated with chitosan nanoparticles containing the plasmid for the enhanced green fluorescence protein, cells transfected with nanoparticles incorporating the larger OP-1 plasmid did not show OP-1 expression measured by ELISA for up to 2 weeks in culture. These results indicate that although a large plasmid can be successfully incorporated within chitosan nanoparticles, the size of the plasmid incorporated within the nanoparticles may still significantly affect gene transfer to cells.     

Synergistic effects of conjugating cell penetrating peptides and thiomers on non-viral transfection efficiency

Nanoparticles generated by complex coacervation of plasmid DNA (pDNA) and modified chitosans namely chitosan-thioglycolic acid (TGA) conjugate and chitosan-HIV-1 Tat peptide conjugate were evaluated as gene delivery systems. In order to optimize transfection efficiency, chitosan-HIV-1 Tat peptide conjugate was combined with chitosan-TGA before its complexation with pDNA. Particle size and zeta potential measurements were performed to characterize the generated nanoparticles. The nanoparticles transfection efficiencies were assessed by exploitation of the green fluorescent protein (GFP) reporter gene. HEK293 cells were incubated for 24 h with the nanoparticles and the GFP positive cells were observed by fluorescence microscopy. The nanoparticles in the size range of 200-300 nm could transfect HEK293 cells as a model cell line with different transfection efficiencies. Unlike chitosan-TGA, chitosan-HIV-1 Tat peptide led to increased zeta potential of nanoparticles as compared to unmodified chitosan. The transfection efficiency of the nanoparticles generated by combination of chitosan-HIV-1 Tat peptide with chitosan-TGA was comparatively higher than that of the nanoparticles generated by either chitosan-TGA or the combination of chitosan-HIV-1 Tat peptide with unmodified chitosan. After 72 h of incubation, the combination of chitosan-HIV-1 Tat peptide with chitosan-TGA was found to be 7.12- and 67.37 times more efficient than unmodified chitosan and pDNA alone, respectively and showed a synergistic effect in transfection of pDNA into the cells. Moreover, none of the nanoparticles showed any severe cytotoxicity. Accordingly, this strategy might result in a potent carrier for gene delivery.     

人胰岛素样生长因子1基因转染脂肪源性干细胞的效应

背景：人胰岛素样生长因子1基因对脂肪源性干细胞的增殖和分化也可能会产生有效作用。 目的：验证人胰岛素样生长因子1基因转染对体外培养的脂肪源性干细胞的效应。 方法：构建含人胰岛素样生长因子1基因的双顺反子真核表达载体pIRES2-EGFP-hIGF-1,利用阳离子脂质体Lipofectamine 2000介导转染体外培养的人脂肪源性干细胞。观察基因转染后细胞增殖及形态的变化,倒置荧光显微镜观测标记基因增强绿色荧光蛋白的表达并计算转染效率,酶联免疫吸附试验检测培养上清中人胰岛素样生长因子1的浓度,免疫组织化学染色及RT-PCR检测人胰岛素样生长因子1的表达,流式细胞仪检测转染前后细胞周期的变化。 结果与结论：测序及酶切证实真核表达载体pIRES2-EGFP-hIGF-1构建正确。体外培养的脂肪源性干细胞为多种形态并存,转染后6 h检测到有EGFP的表达,至60 h达到高峰,转染效率为(16±3)%。细胞上清中人胰岛素样生长因子1的浓度在60 h达到22.65 μg/L。免疫组织化学染色及RT-PCR均检测到人胰岛素样生长因子1的表达。转染后的细胞分裂增殖加快,细胞群体倍增时间缩短,S期细胞比例增多。证实人胰岛素样生长因子1基因可有效转染脂肪源性干细胞并表达人胰岛素样生长因子1蛋白质,同时可促进细胞增殖。     

N-亚甲基磷酸化壳聚糖与DNA相互作用的研究

目的探讨双亲性壳聚糖衍生物与质粒DNA通过自组装的方式形成基因纳米粒子的可行性,考察载体与质粒DNA的相互作用机制,为开发安全高效的非病毒载体提供新的途径。方法合成了一种双亲性壳聚糖衍生物N-亚甲基磷酸化壳聚糖(NMPCS),利用复凝聚的方法制备NMPCS/DNA纳米粒子复合物。用傅立叶变换红外光谱、核磁共振谱等手段对NMPCS进行了表征,通过凝胶电泳阻滞实验、动态光散射、原子力显微镜、圆二色谱等实验对NMPCS与质粒DNA之间的相互作用进行研究。结果经傅立叶变换红外光谱及核磁共振谱分析表明,改性后的壳聚糖的特征基团有显著变化,证明了亚甲基磷酸基团成功的引入。NMPCS与DNA能自组装形成类似球形的基因纳米粒子。结论壳聚糖基双亲性分子可能与细胞膜中的双亲性分子具有潜在相容性,使得载体/DNA复合物通过一种膜的去组装过程跨越细胞膜而最终表达,从而有望研制出高效的非病毒载体。     

mPEG-CS纳米粒介导livin shRNA基因纳米复合物的制备及转染效率

背景：作为非病毒基因转染载体,由可降解的高聚物形成的纳米载体目前被广泛由于基因转染,因为他们具有良好的缓释性,靶向性和生物相容性。 目的：制备mPEG-CS纳米粒,探讨mPEG-CS作为Livin shRNA基因转染载体的可行性。 方法：通过离子交联法制备mPEG-CS纳米粒,利用聚乙二醇对壳聚糖进行改性,通过静电吸附法制备载livin shRNA的基因纳米复合物。Zeta-size分析仪和透射电镜检测空白纳米粒和载livin shRNA的基因纳米复合物的形态、粒径和zeta电位,测定基因纳米复合物的包封率,凝胶电泳阻滞实验和DNase I酶消化实验验证纳米粒对基因的保护作用。利用最佳条件下制备的基因纳米复合物,转染大肠癌HT-29细胞,考察转染效率。 结果及结论：成功制备出约60 nm的mPEG-CS纳米粒,当纳米粒与基因体积比为3∶1时,得到的基因纳米复合物形较规则,粒径100 nm左右;其包封率为(94.32±0.35)%。凝胶电泳阻滞实验表明纳米粒能够紧密结合DNA,对基因具有良好的基因保护作用。该基因纳米复合物转染大肠癌细胞的转染效率高,持续作用时间长。mPEG-CS纳米粒作为基因转染载体,对基因具有保护作用,能够将livin shRNA重组质粒高效转染入大肠癌细胞,能够在大肠癌细胞内长时间表达,克服了RNA干扰在基因治疗肿瘤中基因作用时间较短的缺点。     

Synthesis and efficient hepatocyte targeting of galactosylated chitosan as a gene carrier in vitro and in vivo

While chitosan (CS) has been researched widely as a non-viral vector, its usefulness has been limited by its low cell specificity and transfection efficiency. Therefore, we successfully synthesized galactosylated chitosan (GC) and complexed it with an enhanced green fluorescent protein plasmid (pIRES-EGFP) for transfection into cultured H22 cells (murine hepatic cancer cell line) using various GC/EGFP (N/P) charge ratios. Maximal gene transfection rates detected by flow cytometry occurred at an N/P ratio 5:1. Compared with those of lipofectin/EGFP and naked pIRES-EGFP, GC/EGFP complexes show a very efficient cell-selective transfection to hepatocytes. The MTT assay detected relatively low cytotoxicity in cells transfected with GC. A recombinant plasmid granulocyte-macrophage colony-stimulating factor (GM-SCF) and interleukin (IL) 21 (pIRES/GM-CSF-IL21) was successfully constructed and GC/GM-CSF-IL21 nanoparticles (average diameter, 82.1 nm) were administered via the tail vein of mice with liver metastasis of colon cancer model, for 5 consecutive days. The GC/GM-CSF-IL21 nanoparticles exhibited hepatocyte and passive tumor specificity, increased therapeutic efficacy compared to control groups, promoted leukocytes to aggregate in tumor tissues, and activated the cytotoxicity of natural killer (NK) cells and cytolytic T lymphocyte (CTL). Our results indicate that GC can be used in gene therapy to improve transfection efficiency and can be used as an immunological stimulant in vivo.     

A low-toxic and efficient gene vector: carboxymethyl dextran-graft-polyethylenimine

In this study, the low molecular weight branched polyethylenimine (PEI) (800 Da PEI) was grafted to the biodegradable and biocompatible carboxymethyl dextran (CMD) to obtain CMD-g-PEI, and the plasmid DNA was complexed with CMD-g-PEI polycation to form the polyion complex. The acid-base titration profile showed that the CMD-g-PEI had endosomal disruption capacity, and the agarose gel electrophoresis suggested that the CMD-g-PEI could condense DNA efficiently. The transfection efficiency of CMD-g-PEI/DNA complexes was measured by luciferase and green fluorescent protein assay in HEK293 cells. The results revealed that the transfection efficiency of CMD-g-PEI at the N/P ratios over 30-70 was higher than or comparable to that of the 25 kDa PEI at optimal ratio (N/P = 10). The cytotoxicity of CMD-g-PEI as well as 25 kDa PEI was evaluated in NIH3T3 and HEK293 cells, respectively, and it was also found that the cytotoxicity of CMD-g-PEI was much lower than that of 25 kDa PEI. The resulted CMD-g-PEI with high transfection efficiency and low cytotoxicity have promising applications when used as gene vector.