阳离子脂质体介导的基因转移机制

背景：与病毒载体相比,许多天然与合成的阳离子类脂以脂质体的形式用于基因转移,具有无免疫原性、易生产、质粒免受核酸酶降解和无致瘤性等优点,并且作为病毒载体的有效替代物,阳离子脂质体能用于细胞的体内和体外转染。 目的：介绍阳离子脂质体介导的基因转移机制研究进展。 方法：由第一作者用计算机检索中国期刊全文数据库(CNKI：1987/2010)和PubMed (1987/2010)数据库,检索词分别为“基因治疗、阳离子脂质体、基因转移、机制”和“gene therapy, cationic liposome, gene transfer, mechanism”,语言分别设定为中文和英文。从阳离子脂质体基因转染和基因转移机制进行总结,综述了阳离子脂质体介导的基因转移机制。 结果与结论：共检索到108篇,按纳入和排除标准对文献进行筛选,共纳入20篇文章。综述了阳离子脂质体介导的基因转移机制,包括阳离子脂质体/DNA复合物的形成、细胞吸收、内含体释放和复合物解体以及细胞核摄入等方面的研究内容。结果提示,对类脂构效关系和基因转移机制的研究,是提高阳离子脂质体转染效率和优化基因治疗的关键。     

Inhibition of nonviral cationic liposome-mediated gene transfer into primary human respiratory cells by interferon-gamma

The effect of interferon (IFN) gamma on cationic liposome-mediated gene transfer into primary respiratory epithelial cells was investigated. Treatment of primary respiratory epithelial cells with IFN-gamma resulted in a dose-dependent increase in the intermediate filament cytokeratin 13 and a decrease in cellular proliferation, indicating that respiratory cells underwent squamous differentiation. IFN-gamma pretreatment resulted in a dramatic inhibition of transfection efficiency mediated by a cationic liposome (DOTAP). Incubation of squamous nasal cells with DOTAP/DNA complexes for various periods at 4 degrees C and evaluation of luciferase levels suggested that IFN-gamma pretreatment inhibits complex binding to the cells. In primary nasal and bronchial cells cytofluorimetric analysis demonstrated that IFN-gamma reduces binding of FITC-labeled complexes. The data indicate that differentiation of respiratory epithelial cells to a squamous phenotype, which may occur in chronic respiratory diseases such as cystic fibrosis, induces a refractory condition to gene transfer by nonviral cationic liposomes.     

Studies on neutral, cationic and biotinylated cationic microbubbles in enhancing ultrasound-mediated gene delivery in vitro and in vivo

Ultrasound-mediated gene transfer is emerging as a practical means of facilitating targeted gene expression and is significantly enhanced in the presence of exogenously added microbubbles. This study explores the influence of microbubble surface modifications on their interaction with plasmid DNA and target cells, and the functional consequences of those interactions in terms of ultrasound-mediated gene transfer. Polyethylene glycol-stabilized, lipid-shelled microbubbles with neutral (SDM201), cationic (SDM202) and biotinylated cationic (SDM302) surfaces were compared in terms of their abilities to interact with a luciferase-encoding reporter plasmid DNA and with target cells in vitro. The results demonstrate that the biotinylated cationic microbubble>cationic microbubble>neutral microbubble, in terms of their abilities to interact with target cells and to enhance ultrasound-mediated gene transfer, particularly at low microbubble concentration. The presence of a net positive charge on both cationic microbubbles promoted the formation of microbubble-nucleic acid complexes, although preformation of the complexes prior to addition to target cells inhibited the interaction between the microbubbles and target cells in vitro. The impact of these findings on potential in vitro or ex vivo therapeutic applications of microbubble-enhanced ultrasound-mediated gene transfer is discussed. All three microbubble preparations could be used to facilitate gene transfer in vivo and the potential advantages associated with the use of the cationic microbubbles for targeted gene delivery are discussed.     

Optimization of nonviral transfection: variables influencing liposome-mediated gene transfer in proliferating vs. quiescent cells in culture and in vivo using a porcine restenosis model

Cationic liposomes/DNA complexes are widely used vectors for delivering genes in clinical and experimental trials. Relatively low transfer efficiencies in vivo compared with viral gene transfer may be improved using local application. In addition, markedly increased transfer efficiency may be achieved in vitro and in vivo via optimization of known variables influencing liposomal transfection. Lipofection under different conditions was performed in various cell lines and primary porcine smooth muscle cells. Optimized conditions found in vitro were verified in vivo using a porcine restenosis model. Toxicity was monitored analyzing cell metabolism. Transfer efficiency and safety were determined using morphometry, histology, galactosidase assays, PCR, and RT-PCR. The most important variables enabling maximum transfer efficiency were firstly the appropriate selection of cationic lipids for the cell type to be transfected, secondly the DNA/liposome ratio chosen, which depended on the cell type and cationic lipids used, and thirdly the state of proliferation of the targeted cells. Transfection in vivo demonstrated two- to fivefold higher transfer efficiencies when transfer conditions were extrapolated from optimization experiments in stationary cells compared with the use of conditions established in proliferating cells. Application of the therapeutic gene for cecropin using optimized transfer conditions resulted in a significantly reduced neointima formation compared with the transfection using a control gene for ss-galactosidase. Thus, in this vascular model, initial optimization of lipofection in stationary cells in culture followed by local delivery in vivo and with selection of a suitable therapeutic gene led to markedly improved transfer efficiencies, gene expression, and biological effect. Stationary cell cultures simulate more realistically the in vivo situation and may therefore represent a better model for future in vivo experiments. In addition, the advantages of liposomes are easy handling, low toxicity, and the lack of carcinogenicity or immunogenic reactions.     

Expression of USP2‐69 in mesangial cells in vivo and in vitro

Ubiquitin‐specific protease 2 (USP2) is a member of a family of de‐ubiquitinating enzymes. It may play an important role in the regulation of cell growth and differentiation. It is known that expression of the isoform USP2‐69 kD is high in kidney tissue, but its role remains unclear. Mesangial cell proliferation is a prominent element of various types of glomerulonephritides. Therefore, whether USP2 plays a role in mesangial cell proliferation during glomerulonephritides is an interesting question to explore. The purpose of the present study was to evaluate USP2‐69 expression in needle biopsies of human kidneys and in cultured rat mesangial cells. On immunohistochemistry USP2‐69 was upregulated in some mesangial proliferative glomerulonephritides. The proportion of USP2‐69 positive area in the glomeruli was 3.90% in normal kidney, 4.96% in minimal change disease, and 4.39% in membranous glomerulonephritides, while it was 14.84% in IgA nephropathy (IgAN) (mesangial proliferative type), 16.18% in lupus nephritis (LN; diffuse proliferative type) and 15.54% in acute proliferative glomerulonephritides (APGN); the difference of the percentages between IgAN, LN (IV subtype) and APGN and normal kidney were statistically significant (P < 0.05). Additionally, the number of proliferating cell nuclear antigen (PCNA)‐positive nuclei in the glomeruli was statistically significantly higher in the various glomerulonephritides than in the normal kidney (P < 0.05). Immunohistochemistry showed that the distribution of the USP2⁺ area and PCNA⁺ nuclei overlapped in the glomeruli. Treatment with interleukin‐1β for 12 h and 24 h, or with anti‐thymocyte serum for 6 h and 12 h resulted in elevated USP2‐69 mRNA and protein expression in the rat mesangial cells. Also, PCNA expression increased and p27 expression decreased significantly in the treated mesangial cells. These findings suggest that USP2‐69 was upregulated in mesangial cells during mesangial proliferative glomerulonephritides in vivo and in vitro, which may relate to the proliferation of mesangial cells.     

脂质体介导的IL-2基因疗法增强机体巨噬细胞免疫功能的研究

本文报道了脂质体包裹的ＩＬ－２基因直接腹腔内注射后，巨噬细胞在介导该基因疗法中的作用及其功能变化。结果发现巨噬细胞是ＩＬ－２基因表达的主要靶细胞；巨噬细胞的吞噬功能、抗原提呈能力、Ｆｃ受体和Ｉａ抗原表达以及分泌ＩＬ－１、ＴＮＦ水平及杀伤肿瘤细胞的活性均明显提高。巨噬细胞功能的上述变化表明　，通过腹腔途径应用脂质体介导的ＩＬ－２基因疗法治疗腹部肿瘤可能具有一定的可行性。     

Rat mesangial cell lysis in vitro is induced by cationic polypeptides.

Immunization and challenge with cationic proteins induces immune complex glomerulonephritis in rodents. Cationic (c) bovine gamma-globulin (BGG), when added to rat mesangial cells in vitro, induced release of lysosomal beta-glucuronidase, an enzyme capable of degrading basement membrane components. Native (n) BGG, alone or in the presence of specific antibody, did not. Morphological changes (cellular swelling) in response to cBGG suggested cell injury; indeed, significant lactate dehydrogenase (LDH) was released into the media, depending on dose, time, calcium, and temperature. Prior trypsinization of cBGG abrogated this response. The synthetic polycation, poly L-lysine > 50 kd, similarly elicited LDH release; 4-kd poly L-lysine or protamine sulfate had little or no effect. Anionic heparin sodium inhibited cBGG-induced morphological changes and, when coincubated with cBGG, significantly reduced LDH release (P < 0.0001) to levels equal to or less than those with the nBGG control. This heparin effect was lost if addition was delayed until 10 minutes after the addition of cBGG, indicating an irreversible effect of cBGG within this time. We conclude that charge alone is not sufficient for polycations to induce LDH release. Moreover, the cellular swelling and rapidity of LDH release suggest that cytotoxicity results from direct plasma membrane destruction, perhaps due to altered sodium ion concentrations.     

内皮抑素基因转移对乳腺癌细胞生长影响的体内和离体研究

目的：探讨内皮抑素(ES)基因转移在乳腺癌抗血管新生中的作用。 方法: 通过建立逆转录病毒介导的ES基因转移系统，用ES病毒转染人乳腺癌细胞系MDA-MB-231。以聚合酶链反应（PCR）、MTT法和裸鼠成瘤实验分析ES的生物学特性及其功能。 结果： 脂质体转染与交互感染策略获得ES病毒生产细胞；以ES病毒转染MDA-MB-231细胞后，经PCR分析显示其内有ES基因整合并持续表达，其分泌的ES能明显抑制内皮细胞EA.hy926的增殖(P<0.05)，但对肿瘤细胞的离体生长无明显影响（P>0.05）；裸鼠皮下移植瘤模型表明，ES基因表达可明显抑制MDA-MB-231细胞的生长(P<0.01)；实验组的肿瘤微血管密度（MVD）和血管内皮生长因子(VEGF)表达低于对照组(P<0.05)。 结论: 逆转录病毒载体介导的ES基因在乳腺癌细胞中可有效表达，能明显抑制血管内皮细胞生长，并通过旁分泌方式抑制血管新生，具有显著的抗肿瘤生长的作用。     

白细胞介素10基因转移抑制肾小球系膜细胞诱生炎症细胞因子

目的：通过建立白细胞介素１０（ＩＬ－１０）的重组逆转录病毒载体基因转移系统,观察ＩＬ－１０对脂多糖（ＬＰＳ）诱导的大鼠肾小球系膜细胞（ｇｌｏｍｅｒｕｌａｒｍｅｓｅｎｇｉａｌｃｅｌ,ＧＭＣ）中细胞因子的产生及其基因表达的影响。方法：通过构建的重组逆转录病毒载体ｐＬＸ（ＩＬ－１０）ＳＮ将外源基因ＩＬ－１０转移至大鼠ＧＭＣ：（１）应用聚合酶链反应（ＰＣＲ）,反转录聚合酶链反应（ＲＴ－ＰＣＲ）和ＥＬＩＳＡ检测ＩＬ－１０基因的整合和表达;（２）以ＲＴ－ＰＣＲ观察ＩＬ－１０基因转移对ＬＰＳ诱导的ＧＭＣ肿瘤坏死因子－α（ＴＮＦ－α）的ｍＲＮＡ表达的影响,以ＥＬＩＳＡ测定白细胞介素－１β（ＩＬ－１β）和ＴＮＦ－α的蛋白质表达。结果：外源性ＩＬ－１０基因已整合到靶细胞染色体ＤＮＡ并有效地表达,它能抑制ＬＰＳ诱生ＧＭＣ过度产生ＩＬ－１β,ＴＮＦ－α。结论：外源性ＩＬ－１０基因可以转移到ＧＭＣ并稳定表达,它能抑制ＧＭＣ炎症效应中细胞因子的产生及其基因表达。     

A cationic peptide consists of ornithine and histidine repeats augments gene transfer in dendritic cells

Condensing the plasmid with high molecular weight cationic polymers such as poly-L-lysine (PLL) and poly-L-ornithine (PLO) can enhance antigen-specific immunity generated from genetic vaccination with naked DNA encoding antigens. While these high molecular weight polymers are clearly effective in transfection experiments, clinical applications are limited by their physical heterogeneity and toxicity. Three chemically defined low molecular weight cationic peptides, K(16), K(10)H(6), and O(10)H(6), were examined in the context of DNA binding, toxicity, and efficiency of gene transfer in dendritic cells (DC). The results showed that while all three peptides can bind to a plasmid encoding a reporter gene with similar efficiency, in vitro transfection with DNA complexed with O(10)H(6) complexed resulted in the highest level of gene expression. Moreover, free O(10)H(6) was not toxic to DC, while the lysine-based peptides caused significant cell death in DC cultures. We also showed that DC transfected ex vivo with DNA complexed with O(10)H(6) was capable of eliciting antigen-specific INFgamma production in vivo. Taken together, these results indicate ornithine and histidine repeats are suitable building blocks of non-viral gene transfer vector for DC.     

Antimicrobial activity of murine lung cells against Staphylococcus aureus is increased in vitro and in vivo after elafin gene transfer

Staphylococcus aureus is a pathogen often found in pneumonia and sepsis. In the context of the resistance of this organism to conventional antibiotics, an understanding of the regulation of natural endogenous antimicrobial molecules is of paramount importance. Previous studies have shown that both human and mouse airways express a variety of these molecules, including defensins, cathelicidins, and the four-disulfide core protein secretory leukocyte protease inhibitor. We demonstrate here by culturing mouse tracheal epithelial cells at an air-liquid interface that, despite the production of Defb1, Defb14, and Defr1 in this system, these cells are unable to clear S. aureus when exposed to this respiratory pathogen. Using an adenovirus (Ad)-mediated gene transfer strategy, we show that overexpression of elafin, an anti-elastase/antimicrobial molecule (also a member of the four-disulfide core protein family), dramatically improves the clearance of S. aureus. In addition, we also demonstrate that this overexpression is efficient in vivo and that intratracheal instillation of Ad-elafin significantly reduced the lung bacterial load and demonstrates concomitant anti-inflammatory activity by reducing neutrophil numbers and markers of lung inflammation, such as bronchoalveolar lavage levels of tumor necrosis factor and myeloperoxidase. These findings show that an increased antimicrobial activity phenotype is provided by the elafin molecule and have implications for its use in S. aureus-associated local and systemic infections.     

Binding capacity of in vitro deglycosylated IgA1 to human mesangial cells

IgA nephropathy (IgAN) is the most common glomerular disease and it is characterized by deposition of IgA1 molecules in mesangium. Recent studies had demonstrated that serum and mesangial IgA1 in IgAN were deglycosylated and IgA1 could bind to human mesangial cells (HMC) through a novel receptor. The aim of the current study is to investigate and compare the binding capacities of different in vitro deglycosylated IgA1 on human mesangial cells. Serum IgA1 was purified by jacalin affinity chromatography and then was desialylated (DesIgA1) and/or degalactosylated (Des/DeGalIgA1) with neuraminidase and/or beta-galactosidase. The efficacy of deglycosylations was assessed by Peanut agglutinin (PNA) and Vicia villosa (VV) lectin. The sizes of normal IgA1 and deglycosylated IgA1 were determined by Sephacryl S-300 chromatography and binding capacities to primary HMC were evaluated by radioligand binding assays. Normal IgA1 and deglycosylated IgA1 could bind to HMC in a dose-dependent, saturable manner. The maximal binding capacities and binding sites/cell of DesIgA1 and Des/DeGalIgA were significantly higher than that of normal IgA1. However, more aggregated IgA1 was found in DesIgA1 and Des/DeGalIgA1. Scatchard analysis revealed a similar Kd of normal IgA1 and deglycosylated IgA1. The current study suggested that the binding capacities of DesIgA1 and Des/DeGalIgA1 to HMC were significantly higher than that of normal IgA1, which at least in part was due to more macromolecular IgA1 in deglycoslated IgA1. However, there were no significant differences in the affinities of normal IgA1, DesIgA1 and Des/DeGalIgA1 with HMC. Deglycosylated IgA1 might play an important role in pathogenesis of IgAN.     

Interleukin-10 differentially modulates MHC class II expression by mesangial cells and macrophages in vitro and in vivo.

Inhibition of major histocompatibility complex (MHC) class II expression by macrophages is the primary mechanism by which interleukin-10 (IL-10) exerts immune suppression. Little, however, is known of the effects of IL-10 on other types of cells which can be induced to express MHC class II during an inflammatory response. We therefore studied the effects of IL-10 treatment on the expression of MHC class II molecules in a rat model of immunologically induced glomerulonephritis. MHC class II mRNA levels in whole kidney were increased in saline-treated (control) animals with glomerulonephritis (2.6-fold increase versus normal, P = 0.028) and this was partially inhibited by treatment with IL-10 (P = NS). Double immunostaining of tissue sections was used to compare MHC class II expression by infiltrating macrophages and resident glomerular cells. IL-10 treatment reduced the proportion of glomerular macrophages which expressed detectable MHC class II (70% reduction, P = 0.03). In contrast, IL-10 treatment was associated with an increase in the number of resident glomerular cells expressing MHC class II, particularly within mesangial areas. Therefore, the effects of IL-10 on macrophages and mesangial cells were compared in vitro. IL-10 reduced constitutive MHC class II mRNA and cell surface expression by peritoneal macrophages. In contrast, IFN-gamma-stimulated mesangial cells (1097 cell line) cultured with IL-10 for 24 hr showed increased MHC class II mRNA (26% increase) and surface expression (72% increase in percentage MHC II+ by flow cytometry, P = 0.04) as compared with cells stimulated with IFN-gamma alone. IL-10 also directly up-regulated expression of ICAM-1 by 1997 cells. In conclusion, IL-10 was found to have contrasting effects on the production and cell surface expression of MHC class II molecules by mesengial cells and by macrophages, both in vitro and in vivo. The implications of these findings for IL-10-mediated immunosuppression are discussed.     

Growth inhibitory effect on glioma cells of adenovirus-mediated p16/INK4a gene transfer in vitro and in vivo

The tumour suppressor gene p16/INK4a encodes a specific inhibitor of the cyclin D-dependent kinases CDK4 and CDK6. p16/INK4a prevents the association of CDK4 with cyclin D1, and subsequently inhibits phosphorylation of retinoblastoma tumour suppressor protein (pRb), thus preventing exit from the G1 phase. In human cancers, the estimated frequency of genetic alteration involving the p16/INK4a locus is believed to be second only to alteration of p53. A high frequency (greater than 50%) of homozygous p16/INK4a gene deletion has been demonstrated in glioblastoma tissues and p16/INK4a is altered in 80% of glioma cell lines. Therefore, restoration of p16/INK4a would suppress cell proliferation and induce cell growth arrest. We showed here that restoration of p16/INK4a expression in p16 negative U87MG, U251MG and partially deleted U373MG by Ad-CMV-p16/INK4a induced growth suppression in vitro and in vivo. Expression of p16 transferred by Ad-CMV-p16/INK4a in glioma cells was highly efficient and maintained for more than seven days. In addition, we found that the endogenous status of p16 and Rb might affect the expression of exogenous p16/INK4a gene and inhibitory effect of cell proliferation. Even though, there were several factors affecting the efficiency of Ad-CMV-p16/INK4 gene transfer, our results suggest that Ad-CMV-p16 gene therapy strategy is potentially useful and warrants further clinical investigation for the treatment of gliomas.     

SPARC is expressed by mesangial cells in experimental mesangial proliferative nephritis and inhibits platelet-derived-growth-factor-medicated mesangial cell proliferation in vitro.

Mesangial cell proliferation is a characteristic feature of many glomerular diseases and often precedes extracellular matrix expansion and glomerulosclerosis. This study provides the first evidence that SPARC (secreted protein acidic and rich in cysteine) could be an endogenous factor mediating resolution of experimental mesangial proliferative nephritis in the rat. SPARC is a platelet-derived-growth-factor-binding glycoprotein that inhibits proliferation of endothelial cells and fibroblasts. We now show that SPARC is synthesized by mesangial cells in culture and that SPARC mRNA levels are increased by platelet-derived growth factor and basic fibroblast growth factor. Recombinant SPARC or the synthetic SPARC peptide 2.1 inhibited platelet-derived-growth-factor-induced mesangial cell DNA synthesis in vitro. In a model of experimental mesangioproliferative glomerulonephritis, SPARC mRNA was increased 5-fold by day 7 and was identified in the mesangium by in situ hybridization. Similarly, SPARC was increased in glomerular mesangial cells and visceral epithelial cells by day 5 and reached maximal expression levels by day 7. Mesangial cell proliferation increased by 36-fold on day 5 and decreased abruptly on day 7. Maximal expression of SPARC was correlated with the resolution of mesangial cell proliferation. We propose that SPARC functions in part as an endogenous inhibitor of platelet-derived-growth-factor-mediated mesangial cell proliferation in glomerulonephritis and that it could account for the resolution of cellular proliferation in this disease.     

Effect of adenovector-mediated gene transfer of keratinocyte growth factor on the proliferation of alveolar type II cells in vitro and in vivo

Alveolar type II cell proliferation occurs after lung injury and is thought to minimize the subsequent fibrotic response. Keratinocyte growth factor (KGF) has been shown to be a potent growth factor for rat alveolar type II cells. In this study, we created a replication-deficient, recombinant human type 5 adenovirus vector expressing human KGF (Ad5-KGF) to produce alveolar type II cell hyperplasia in vivo. In rat type II cells in vitro, Ad5-KGF at a multiplicity of infection (MOI) of 2, 4, and 8 plaque-forming units (PFU)/cell increased thymidine incorporation 13.3-, 16.8-, and 20. 8-fold, respectively. The KGF concentration in the medium increased up to 26.0 +/- 1.0 ng/ ml. We then instilled 10(9) PFU of Ad5-KGF, Ad5-LacZ, or phosphate-buffered saline into Fischer 344 rats and analyzed the lungs 2, 3, 7, 14, 21, and 28 d later. Ad5-KGF produced extensive alveolar type II cell hyperplasia on Days 2, 3, and 7. Surfactant protein (SP)-A and SP-D in lavage and SP-D in serum increased more in the Ad5-KGF group than in the Ad5-LacZ and PBS groups on Days 2 and 3. KGF was readily detectable for up to 7 d in lavage fluid, although only a modest number of cells expressed KGF messenger RNA as detected by in situ hybridization. These data show that Ad5-KGF stimulates extensive alveolar type II cell proliferation in vivo.     

ABCE1基因在人肾小球系膜细胞中的表达

ATP结合盒转运子E1(ATP-binding cassette transporter E1,ABCE1)属ATP结合盒转运子基因亚家族成员之一,其表达定位于细胞质及线粒体.该基因在人体各组织器官表达具有特异性.     

稳定过表达饰胶蛋白聚糖基因对大鼠肾系膜细胞凋亡的影响

目的 观察稳定过表达饰胶蛋白聚糖(DCN)基因对大鼠肾系膜细胞(MsC)凋亡的影响.方法 采用脂质体介导法将pcDNA3.1A-DCN质粒稳定转染MsC,G418筛选阳性克隆.细胞免疫荧光法、逆转录-聚合酶链反应(RT-PCR)和Western印迹法鉴定并获得转染DCN阳性的细胞株(MsC/DCN);脂质体介导法将DCN-siRNA瞬时转染MsC/DCN以干扰DCN表达,Western印迹法鉴定.Hoechst染色和流式细胞仪观察细胞凋亡及比率,Western印迹法检测活性凋亡相关激酶半胱氨酸蛋白酶3(Caspase-3)蛋白的表达.结果 成功建立了过表达DCN基因的细胞株MsC/DCN.MsC/DCN中凋亡率为(20.40±8.01)%,显著高于MsC的凋亡率(2.07±0.99)%(P＜0.01),部分MsC/DCN发生典型的形态学改变.活性Caspase-3的蛋白表达也明显高于MsC(P＜0.01).DCN-siRNA瞬时转染不仅有效干扰了MsC/DCN中DCN的表达和降低了细胞凋亡率,而且显著下调了活性Caspase-3的蛋白表达.结论 大鼠MsC中DCN基因的过表达能诱导MsC发生凋亡,为肾小球疾病中调控MsC增生提供了新的实验依据.     

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.     

Nitric oxide induces metallothionein-I gene expression in mesangial cells

In various forms of injury involving the renal glomerulus, mesangial cells are exposed to potentially toxic concentrations of nitric oxide (NO) caused by activation of the inducible isoform of nitric oxide synthase (NOS). Whether mesangial cells possess systems that can defend against NO mediated oxidative injury is unknown. One putative system is Metallothionein (MT). Metallothioneins constitute a family of cysteine proteins and play a significant role as anti-oxidants. The authors assessed whether NO upregulates MT-I expression in cultured glomerular mesangial cells. Northern blot analysis revealed that steady state MT-I mRNA levels were increased by three different NO donors: sodium nitroprusside (SNP), S-nitroso-N-acetyl-DL-penicillamine (SNAP), and Spermine-NONOate (Sper/NO). The increase in MT-I mRNA levels induced by SNAP-derived NO was attenuated by the antioxidant N-acetylcysteine (NAC), a glutathione (GSH) precursor, which indicates that the mechanism of NO-mediated MT-I expression may involve an oxidative stress response. These observations identify MT-I as a putative antioxidant system in NO-mediated mesangial cell injury.