The synthesis of cholesterol-based cationic lipids with trimethylamine head and the effect of spacer structures on transfection efficiency

Five cholesterol-based cationic lipids were newly synthesized based on cholest-5-en-3β-oxyethane-N,N,N-trimethylammonium bromide (Chol-ETA) structure where the cholesterol backbone is linked to cationic head via various lengths of ether-linked carbon spacer. The transfection efficiency of these compounds was increased in order of three (Chol-PRO) < four (Chol-BTA) < two (Chol-ETA) methylene unit in their spacer, and was decreased by an addition of isomethyl group to Chol-PRO spacer. In case of the presence of multiple bonds in the spacer, it required the more cationic lipids in liposome formulation than single bond in the spacer to present similar transfection efficiency.     

Synthesis of diamine maleyl chitosans, and in vitro transfection studies

Three novel diamine-modified chitosan derivatives were synthesized from N-maleyl chitosan via Michael addition reaction with 1,2-diaminoethane, 1,4-diaminobutane, and 1,6-diaminohexane, respectively. These chitosan derivatives exhibited well binding ability of condensing plasmid DNA to form complexes with size ranging from 150 to 500 nm when the chitosan derivative/DNA weight ratios were above 10. The complexes observed by scanning electron microscopy (SEM) exhibited a compact and spherical morphology. The cytotoxicity of the chitosan derivatives presented a dependence on their side-chain structures. The gene transfection experiments were evaluated in 293 T and HeLa cells. The data obtained demonstrated that the gene transfection efficiencies of these chitosan derivatives were better than that of chitosan, suggesting these chitosan derivatives as potential gene vectors in vitro.     

Analysis of Novel Nonviral Gene Transfer Systems for Gene Delivery to Cells of the Musculoskeletal System

The aim of the present study was to evaluate the efficacy of novel nonviral gene delivery systems in cells of musculoskeletal origin. Primary cultures of lapine skeletal muscle cells, lapine articular chondrocytes, human cells from fibrous dysplasia and cell lines established from human osteosarcoma (SAOS-2), chondrosarcoma (CS-1), murine skeletal myoblasts (L8) and fibroblasts (NIH 3T3) were transfected with the P. pyralis luc or the E. coli lacZ genes using Nanofectin 1 and 2, Superfect, JetPEI, GeneJammer, Effectene, TransPass D2, FuGENE 6, Lipofectamine 2000, Dreamfect, Metafectene, Escort III, and calcium phosphate. Maximal transfection efficiency in lapine skeletal muscle cells was of 60.8 ± 21.2% using Dreamfect, 38.9 ± 5.0% in articular chondrocytes using Gene Jammer, 5.2 ± 8.0% in human cells from fibrous dysplasia using Lipofectamine 2000, 12.7 ± 16.2% in SAOS-2 cells using FuGENE 6, 29.9 ± 3.5% in CS-1 cells using Lipofectamine 2000, 70.7 ± 8.6% in L8 cells using FuGENE 6, and 48.9 ± 13.0% in NIH 3T3 cells using Metafectene. When the cells were transfected with a human IGF-I gene, significant amounts of the IGF-I protein were secreted. These results indicate that relatively high levels of transfection can be achieved using novel nonviral gene transfer methods.     

Bead transfection of adherent cells

Bead transfection is a simple, rapid, efficient, and cost-effective method of gene transfer into adherent mammalian cells. It involves a brief incubation of the cells with glass beads in a solution containing the DNA to be transferred. We have optimized this technique using COS-7 (an SV40 transformed monkey kidney cell line) and a transient expression assay for chloramphenicol acetyl transferase (CAT). Stable transfection efficiency assessed using the selectable marker gene neomycin phosphotransferase (NEO^R) was 27% in COS-7 cells. As this technique delivers high transfection efficiency with little manipulation of the exogenous DNA and does not require the use of any viral sequences, it may be a useful alternative method of gene delivery in the development of gene therapy protocols.     

Distal enhancer of the mouse FGF-4 gene and its human counterpart exhibit differential activity: critical role of a GT box

Previous studies have shown that there is a strict requirement for fibroblast growth factor-4 (FGF-4) during mammalian embryogenesis, and that FGF-4 expression in embryonic stem (ES) cells and embryonal carcinoma (EC) cells are controlled by a powerful downstream distal enhancer. More recently, mouse ES cells were shown to express significantly more FGF-4 mRNA than human ES cells. In the work reported here, we demonstrate that mouse EC cells also express far more FGF-4 mRNA than human EC cells. Using a panel of FGF-4 promoter/reporter gene constructs, we demonstrate that the enhancer of the mouse FGF-4 gene is approximately tenfold more active than its human counterpart. Moreover, we demonstrate that the critical difference between the mouse and the human FGF-4 enhancer is a 4 bp difference in the sequence of an essential GT box. Importantly, we demonstrate that changing 4 bp in the human enhancer to match the sequence of the mouse GT box elevates the activity of the human FGF-4 enhancer to the same level as that of the mouse enhancer. We extended these studies by examining the roles of Sp1 and Sp3 in FGF-4 expression. Although we demonstrate that Sp3, but not Sp1, can activate the FGF-4 promoter when artificially tethered to the FGF-4 enhancer, we show that Sp3 is not essential for expression of FGF-4 mRNA in mouse ES cells. Finally, our studies with human EC cells suggest that the factor responsible for mediating the effect of the mouse GT box is unlikely to be Sp1 or Sp3, and this factor is either not expressed in human EC cells or it is not sufficiently active in these cells.     

Effect of interferon on the infectivity of Trypanosoma cruzi in cultured HeLa cells

Results are presented on the effects of human lymphoblastoid interferon (HUIFN-α-ly) on the infectivity of metacyclic culture forms of Trypanosoma cruzi in HeLa cells. When cells were pretreated with interferon the parasitisation ratios of the cultures increased with respect to controls. This phenomenon also occurs when interferon was added during the period of parasite-cell interaction. When parasites were pretreated with interferon but cells were not, no increase in the parasitisation ratios was observed.     

HMQ‐T‐F2 exert antitumour effects by upregulation of Axin in human cervical HeLa cells

Looking for novel, effective and less toxic therapies for cervical cancer is of significant importance. In this study, we reported that HMQ‐T‐F2(F2) significantly inhibited cell proliferation and transplantable tumour growth. Mechanistically, HMQ‐T‐F2 inhibited HeLa cell growth through repressing the expression and nuclear translocation of β‐catenin, enhancing Axin expression, as well as downregulating the Wnt downstream targeted proteins. Knock‐down of a checkpoint β‐catenin by siRNA significantly attenuated HeLa cell proliferation. Furthermore, XAV939, an inhibitor of β‐catenin, was used to treat HeLa cells and the results demonstrated that HMQ‐T‐F2 inhibited proliferation and migration via the inhibition of the Wnt/β‐catenin pathway.     

端粒酶shRNA慢病毒载体的构建及转染人类胚胎干细胞

目的：构建端粒酶shRNA慢病毒载体及建立端粒酶稳定干扰的人类胚胎干细胞系。方法：将端粒酶基因特异性shRNA靶序列与慢病毒载体PLKO.1-puro连接、转化、挑取阳性克隆进行PCR及测序鉴定;利用包装细胞293T获得重组的慢病毒,感染人类胚胎干细胞,分为干扰组ShTert、载体组vector和野生型组wt;Realtime-PCR检测端粒酶mRNA的表达。结果：经PCR和DNA测序鉴定,成功构建端粒酶特异性shRNA慢病毒载体,并感染人类胚胎干细胞;经检测shTert组端粒酶mRNA表达较vector和wt组明显降低,vector组和wt组之间无明显差异。结论：通过成功构建的端粒酶特异性shRNA慢病毒载体对人类胚胎干细胞的转染实现了对其端粒酶mRNA的调控。     

Therapeutic efficacy of natural dipeptide carnosine against human cervical carcinoma cells

Natural substances have been attracted several researchers in the recent years, because of its potential antioxidant, anti‐inflammatory and anti‐cancer properties. We have investigated the effect of carnosine on cell viability, apoptosis, DNA damage, reactive oxygen species (ROS) and caspase 3 enzyme expression in human cervical carcinoma and Madin‐Darby Kidney Cells (MDCK) cells . Carnosine inhibited cancer cell growth up to 23%. ROS level was increased up to 30 and 31% in MDCK and HeLa cells respectively. Tunnel assay showed 42 and 14% of positive apoptotic cells in cancer and normal cells respectively. The alteration in mitochondrial and nuclear morphology was determined. The extended lace‐like network of normal mitochondria found in control cells. Carnosine treatment significantly altered the mitochondrial morphology of normal cervical carcinoma cell. Mitochondria were condensed clump structures in carnosine treated cancer cells. Carnosine reduced the number of colonies of cervical carcinoma cells. Caspase 3 expression was corresponded to the appearance of immunofluorescence in the cytoplasm. Caspase 3 expression was gradually increased in cervical carcinoma cells. In Silico, docking study was performed to recognize the binding activity of carnosine against a subunit of the caspase 3 , and carnosine was able to bind to the drug binding pocket of caspase 3. The glide energy is ?5.2 kcal/mol, suggesting the high binding affinity of carnosine to caspase 3. Taking all these data together, the natural dipeptide L‐carnosine could be a suitable antiproliferative agent in cervical carcinoma cells. Copyright © 2016 John Wiley & Sons, Ltd.     

Modulation of uptake of organic cationic drugs in cultured human colon adenocarcinoma Caco-2 cells by an ecto-alkaline phosphatase activity

Alkaline phosphatase (ALP) refers to a group of nonspecific phosphomonoesterases located primarily in cell plasma membrane. It has been described in different cell lines that ecto-ALP is directly or indirectly involved in the modulation of organic cation transport. We aimed to investigate, in Caco-2 cells, a putative modulation of 1-methyl-4-phenylpyridinium (MPP(+)) apical uptake by an ecto-ALP activity. Ecto-ALP activity and (3)H-MPP(+) uptake were evaluated in intact Caco-2 cells (human colon adenocarcinoma cell line), in the absence and presence of a series of drugs. The activity of membrane-bound ecto-ALP expressed on the apical surface of Caco-2 cells was studied at physiological pH using p-nitrophenylphosphate as substrate. The results showed that Caco-2 cells express ALP activity, characterized by an ecto-oriented active site functional at physiological pH. Genistein (250 micro M), 3-isobutyl-1-methylxanthine (1 mM), verapamil (100 micro M), and ascorbic acid (1 mM) significantly increased ecto-ALP activity and decreased (3)H-MPP(+) apical transport in this cell line. Orthovanadate (100 micro M) showed no effect on (3)H-MPP(+) transport and on ecto-ALP activity. On the other hand, okadaic acid (310 nM) and all trans-retinoic acid (1 micro M) significantly increased (3)H-MPP(+) uptake and inhibited ecto-ALP activity. There is a negative correlation between the effect of drugs upon ecto-ALP activity and (3)H-MPP(+) apical transport (r = -0.9; P = 0.0014). We suggest that apical uptake of organic cations in Caco-2 cells is affected by phosphorylation/dephosphorylation mechanisms, and that ecto-ALP activity may be involved in this process.     

High efficiency transfection of porcine vascular cells in vitro with a synthetic vector system

Background

Gene therapy strategies for the treatment of vascular disease such as the prevention of post‐angioplasty restenosis require efficient, non‐toxic transfection of vascular cells. In vitro studies in these cells contribute to vector development for in vivo use and for the evaluation of genes with therapeutic potential. The aim of this project was to evaluate a novel synthetic vector consisting of a liposome (L), an integrin targeting peptide (I), and plasmid DNA (D), which combine to form the LID vector complex.

Methods

Cultures of porcine smooth muscle cells and endothelial cells were established and then transfected with the LID vector, using the reporter genes luciferase and green fluorescent protein and the metalloprotease inhibitor TIMP‐1.

Results

The LID vector system transfected primary porcine vascular smooth muscle cells and porcine aortic endothelial cells with efficiency levels of 40% and 35%, respectively. By increasing the relative DNA concentration four‐fold, incubation periods as short as 30 min achieved the same levels of luciferase transgene expression as 4 h incubations at lower DNA concentrations. The transfection did not affect cell viability as measured by their proliferative potential. Serum levels of up to 20% in the transfection medium had no adverse affect on the efficiency of transfer and gene expression in either cell type. Transfections with the cDNA for TIMP‐1 produced protein levels that peaked at 130 ng/ml per 24 h and persisted for 14 days at 10 ng/ml per 24 h.

Conclusion

This novel vector system has potential for studies involving gene transfer to cardiovascular cells in vitro and in vivo. Copyright © 2002 John Wiley & Sons, Ltd.

     

Serum starvation improves transient transfection efficiency in differentiating embryonic stem cells

Control of genetic expression is a critical issue in the field of stem cell biology, where determining a cell fate or reprogramming adult somatic cells into pluripotent cells has become a common experimental practice. In turn, for these cells to have therapeutic clinical potential, techniques for controlling gene expression are needed that minimizes or eliminates the risk of oncogenesis and mutagenesis. Possible routes for achieving this outcome could come in the form of a transient nonviral gene delivery system. In this study, we improved the efficiency of transient gene delivery to differentiating murine embryonic stem (ES) cells via serum starvation for 3 days before transfection. The transient expression of a constitutively‐controlled plasmid increased from ～50% (replated control) to ～83% when transfected after 3 days of serum starvation but decreased to ～28% when transfected after 3 days in normal high serum‐containing media. When probed with a liver‐specific reporter, Cyp7A1, expression increased from ～1.4% (replated control) to ～3.7% when transfected after 3 days of serum starvation but decreased to ～0.7% when transfected after 3 days in high serum‐containing media. Cy3‐tagged oligonucleotides were used to rapidly quantify DNA uptake and predict ultimate transfection efficiency. This study suggests that modifications in media serum levels before transfection can have a profound effect on improving nonviral gene delivery. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

端粒酶shRNA 慢病毒载体的构建及转染人类胚胎干细胞

目的:构建端粒酶shRNA慢病毒载体及建立端粒酶稳定干扰的人类胚胎干细胞系。方法:将端粒酶基因特异性shRNA靶序列与慢病毒载体PLKO.1-puro连接、转化、挑取阳性克隆进行PCR及测序鉴定;利用包装细胞293T获得重组的慢病毒,感染人类胚胎干细胞,分为干扰组ShTert、载体组vector和野生型组wt;Realtime-PCR检测端粒酶mRNA的表达。结果:经PCR和DNA测序鉴定,成功构建端粒酶特异性shRNA慢病毒载体,并感染人类胚胎干细胞;经检测shTert组端粒酶mRNA表达较vector和wt组明显降低,vector组和wt组之间无明显差异。结论:通过成功构建的端粒酶特异性shRNA慢病毒载体对人类胚胎干细胞的转染实现了对其端粒酶mRNA的调控。     

Effects of bunaftine on morphology,microfilament integrity,and mitotic activity in cultured human fibroblasts and HeLa cells

Summary Human fibroblasts and HeLa cells were treated with bunaftine (N-butyl-N-/2-(diethylamino)ethyl/-1-naphthalenecarboxamide) in vitro. At concentrations of 0.5–2.0 mM, the drug caused contraction and rounding of the cells with loss of microvilli-like processes. Aggregates of dense, partly granular, partly fibrillar material formed in the cytoplasm and the rough endoplasmic reticulum became vesiculated. Immunofiuorescence microscopy with DNase I and anti-DNase I demonstrated that bundles of actin filaments were disrupted, forming rings, coils, and granules. Filaments stained with antibodies to vimentin (fibroblasts) and prekeratin (HeLa cells) showed less characteristic rearrangements, probably related to the rounding up of the cells. 0.4 mM bunaftine increased and 0.8–1.0 mM markedly decreased the percentage of mitotic cells, without accumulation of cells in any particular stage of mitosis. The drug may arrest the cell cycle at some point before mitosis; it may have a critical concentration above which the arrest becomes permanent.These results suggest that bunaftine interferes with the integrity of microfilament bundles in a different manner from that of cytochalasins. It does not cause any depletion of cellular ATP, indicating that its effect is not a result of inhibition of cell metabolism. It is proposed that bunaftine may be used as a complement to cytochalasins in studies of the microfilament system of the cell. The possible binding of bunaftine to actin or myosin and further details of its mechanism of action remain to be elucidated.