Cell type-specific gene expression, mediated by TFL-3, a cationic liposomal vector, is controlled by a post-transcription process of delivered plasmid DNA

Non-viral suicide gene therapy in cervical, oral and pharyngeal carcinoma cells with CMV- and EEV-plasmids

BACKGROUND

Cervical cancer is the third most common cause of cancer in women. The 5-year survival rate in oropharyngeal squamous cell carcinomas is approximately 50% and this rate has not improved in recent decades. These cancers are accessible to direct intervention. We examined the ability of a highly efficient non-viral vector, TransfeX (ATCC, Manassas, VA, USA), to deliver the suicide gene HSV-tk to cervical, oral and pharyngeal cancer cells and to induce cytotoxicity following the administration of the prodrug, ganciclovir.

METHODS

HeLa cervical carcinoma, HSC-3 and H357 oral squamous cell carcinoma and FaDu pharyngeal carcinoma cells were transfected with cytomegalovirus (CMV)- or enhanced episomal vector (EEV)-driven HSV-tk plasmids and treated with ganciclovir for 24-120 h. Cell viability was assessed by Alamar blue.

RESULTS

The viability of HeLa cells was reduced to only 30-40%, despite the very high levels of transgene expression. By contrast, the viability of HSC-3 cells was reduced to 10%, although transgene expression was 18-fold lower than that in HeLa cells. An approximately five-fold higher transgene expression was obtained with the EEV-plasmid than from the CMV-plasmid. Nevertheless, HeLa cell viability after suicide gene + ganciclovir treatment was reduced by only 35% compared to 70% with the CMV-plasmid. For HSC-3 cells, the reduction was 40% for the EEV- and 80% for the CMV-plasmid. The lower efficiency of transfection with the EEV-plasmid may explain the lower cytotoxicity.

CONCLUSIONS

TransfeX-mediated gene delivery to cervical, pharyngeal and oral cancer cells may be used for suicide gene therapy. The levels of transgene expression, however, do not translate directly to cytotoxicity.

Integrating mitosis, toxicity, and transgene expression in a telecommunications packet-switched network model of lipoplex-mediated gene delivery

Gene delivery systems transport exogenous genetic information to cells or biological systems with the potential to directly alter endogenous gene expression and behavior with applications in functional genomics, tissue engineering, medical devices, and gene therapy. Nonviral systems offer advantages over viral systems because of their low immunogenicity, inexpensive synthesis, and easy modification but suffer from lower transfection levels. The representation of gene transfer using models offers perspective and interpretation of complex cellular mechanisms,including nonviral gene delivery where exact mechanisms are unknown. Here, we introduce a novel telecommunications model of the nonviral gene delivery process in which the delivery of the gene to a cell is synonymous with delivery of a packet of information to a destination computer within a packet-switched computer network. Such a model uses nodes and layers to simplify the complexity of modeling the transfection process and to overcome several challenges of existing models. These challenges include a limited scope and limited time frame, which often does not incorporate biological effects known to affect transfection. The telecommunication model was constructed in MATLAB to model lipoplex delivery of the gene encoding the green fluorescent protein to HeLa cells. Mitosis and toxicity events were included in the model resulting in simulation outputs of nuclear internalization and transfection efficiency that correlated with experimental data. A priori predictions based on model sensitivity analysis suggest that increasing endosomal escape and decreasing lysosomal degradation, protein degradation, and GFP-induced toxicity can improve transfection efficiency by three-fold. Application of the telecommunications model to nonviral gene delivery offers insight into the development of new gene delivery systems with therapeutically relevant transfection levels.

Multicomponent nanoparticles as nonviral vectors for the treatment of Fabry disease by gene therapy

Purpose:

Gene-mediated enzyme replacement is a reasonable and highly promising approach for the treatment of Fabry disease (FD). The objective of the present study was to demonstrate the potential applications of solid lipid nanoparticle (SLN)-based nonviral vectors for the treatment of FD.

Methods:

SLNs containing the pR-M10-αGal A plasmid that encodes the α-Galactosidase A (α-Gal A) enzyme were prepared and their in vitro transfection efficacy was studied in Hep G2 cells. We also studied the cellular uptake of the vectors and the intracellular disposition of the plasmid.

Results:

The enzymatic activity of the cells treated with the vectors increased significantly relative to the untreated cells, regardless of the formulation assayed. When the SLNs were prepared with protamine or dextran and protamine, the activity of the α-Gal A enzyme by the transfected Hep G2 cells increased up to 12-fold compared to that of untreated cells.

Conclusion:

With this work we have revealed in Hep G2 cells the ability of a multicomponent system based on SLNs to act as efficient nonviral vectors to potentially correct low α-Gal A activity levels in FD with gene therapy.

Complexation of siRNA and pDNA with cationic liposomes: the important aspects in lipoplex preparation

In the last two decades, cationic liposomes have been investigated as vehicles for nucleic acids [plasmid DNA (pDNA) and small interfering RNA (siRNA)] delivery in vitro and in vivo. The formation of cationic liposomes-nucleic acids complexes, termed lipoplexes, depends on a number of experimental variables. The quality of the nucleic acid and the cationic liposome as well as the selection of diluents for diluting the concentrated stocks strongly affect the resulting lipoplexes and their efficiency of gene-expression or gene-silencing effect following transfection. In addition, the molar ratio of cationic lipid nitrogen (N) to siRNA or pDNA phosphate (P) (N/P ratio) influences the final characteristics of the lipoplexes, such as size, surface zeta potential, and reproducibility, thereby reflecting their efficiency following transfection. The methods presented in this chapter could be helpful to obtain reliable and reproducible lipoplexes and experimental results.

Solid lipid nanoparticles for retinal gene therapy: transfection and intracellular trafficking in RPE cells

Retinal pigment epithelial (RPE) cells are usually employed to study DNA systems for diseases related to problems in the retina. Solid lipid nanoparticles (SLNs) have been shown to be useful non-viral vectors for gene therapy. The objective of this work was to evaluate the transfection capacity of SLNs in the human retinal pigment epithelial established cell line (ARPE-19) in order to elucidate the potential application of this vector in the treatment of retinal diseases. Results showed a lower transfection level of SLNs in ARPE-19 cells than in HEK293 (2.5% vs. 14.9% EGFP positive cells at 72h post-transfection). Trafficking studies revealed a delay in cell uptake of the vectors in ARPE-19 cells. Differences in internalization process into the two cell lines studied explain, in part, the difference in the gene expression. The clathrin-mediated endocytosis in ARPE-19 cells directs the solid lipid nanoparticles to lysosomes; moreover, the low division rate of this cell line hampers the entrance of DNA into the nucleus. The knowledge of intracellular trafficking is very useful in order to design more efficient vectors taking into account the characteristics of the specific cell line to be transfected.

Serum decreases the size of Metafectene-and Genejammer-DNA complexes but does not affect significantly their transfection activity in SCCVII murine squamous cell carcinoma cells

Cationic liposome-DNA (lipoplexes) or polymer-DNA (polyplexes) complexes have been used to deliver therapeutic genes, both in vitro and in vivo. However, gene transfer by these non-viral vectors is usually inhibited by biological milieu. A relatively high efficiency of transfection could be achieved in human oral cancer cells transfected with the polycationic liposome, Metafectene, and the polyamine reagent, GeneJammer, in the presence of 60% fetal bovine serum (FBS) (Konopka et al., Cell. Mol. Biol. Lett.10 (2005) 455–470). Here, we examined the efficacy of these vectors to deliver β-galactosidase (β-gal), luciferase and Herpes Simplex Virus thymidine kinase (HSV-tk) genes to SCCVII murine squamous cell carcinoma cells, which are used to generate an orthotopic murine model of oral cancer. We also evaluated the hydrodynamic size and zeta potential of the vectors and the effect of FBS and mouse serum (up to 60%) on the size of Metafectene and GeneJammer complexes with the pCMV.Luc plasmid. Our results indicate that Metafectene and GeneJammer are highly effective in transfecting SCCVII cells. Approximately 60–70% of SCCVII cells transfected with pCMV.lacZ were positive for β-gal staining. The expression of β-galactosidase was essentially not affected by serum. Mouse serum (20–60%) reduced both Metafectene-and GeneJammer-mediated luciferase expression by ∼30–45%, while FBS did not affect transfection efficiency. The delivery of the HSV-tk gene by Metafectene or GeneJammer in the presence of 0% or 60% FBS, followed by GCV treatment for 6 days, resulted in over 90% cytotoxicity. The mean diameters of the DNA complexes of Metafectene and GeneJammer decreased significantly as a function of the serum concentration. The reduction in the size of the lipoplexes and polyplexes by serum was essentially not inhibitory to transfection of SCCVII cells. This is in contrast to previous hypotheses that serum-induced decrease in the size of lipoplexes is the primary cause of serum inhibition of transfection.

The gene-silencing effect of siRNA in cationic lipoplexes is enhanced by incorporating pDNA in the complex

Efficient delivery is a key issue in translating interference RNA technology into a feasible therapy. The efficiency of carrier systems used for this technology is commonly tested by co-transfection, i.e. simultaneous transfection with an exogenous gene and with the siRNA. Two approaches can be distinguished: (1) with the two transfectants in the same carrier complex (siRNA/pDNA/carrier) and (2) with the two transfectants in different carrier complexes (pDNA/carrier and siRNA/carrier). The process to prepare the nucleic acid(s)-carrier complexes and the transfection procedure may affect the effectiveness of the gene-silencing process. In this study, two preparation methods were compared, namely the co-preparation of an siRNA/pDNA/liposome lipoplex (Method I) and the separate preparation of an siRNA/liposome lipoplex and a pDNA/liposome lipoplex (Method II). siRNA in the lipoplex produced by Method I showed a stronger gene-silencing effect than that in the lipoplexes prepared by Method II. There was no significant difference between the two methods in the amount of siRNA delivered to cells. Cellular entry and intracellular trafficking of siRNA/pDNA/liposome lipoplex is likely to differ from those of the separate lipoplexes. When in Method II non-transcriptional pDNA was included in the complex with siRNA, the gene-silencing effect was significantly enhanced. If and to what extent the experimental design is suitable to quantify RNA interference remains to be demonstrated.

Increased gene expression by cationic liposomes (TFL-3) in lung metastases following intravenous injection

We recently showed that size, not surface charge, is a major determinant of the in vitro lipofection efficiency of pDNA/TFL-3 complex (lipoplex), even in the presence of serum. In this study, the effect of lipoplex size as a result of interaction with serum proteins on in vitro lipofection and the relationship of this with in vivo lipofection was examined in a murine lung metastasis model. As previously described, the pDNA to lipid ratio (P/L ratio) affected both the size and zeta potential of the lipoplex. In vitro studies also indicated that transgene expression in B16BL6 cells was largely dependent on the size of the lipoplex, both in the absence or presence (50% (v/v)) of serum. An in vivo lipofection experiment showed that predominant gene expression in lungs occurred only in tumor-bearing mice, not in normal mice. Based on the in vitro study, this tumor-related gene expression was not related to lipoplex size in the presence of serum (50% (v/v)), suggesting that the size alteration, as the result of interactions with serum proteins in the blood stream may not play an important role in the case of systemic injections. In addition, the efficient gene expression in tumor-bearing lung was not related to the progression of lung metastases. The area-specific gene expression in tumor-bearing lungs, which was largely dependent on the P/L ratio of the lipoplexes, was observed by fluorescent microscopy. Although the underlying mechanism for the area-specific transgene expression is not clear, it may be related to the interaction of lipoplexes with tumor cells, vascular endothelial cells under angiogenesis and normal cells in the lungs. The possibility that TFL-3 is a useful utility to the targeted delivery of pDNA to lungs and tumor-related lipofection is demonstrated. This result suggests that area-specific gene expression in lung metastases may be achieved by controlling the physicochemical properties of the lipoplex, i.e. the P/L ratio.

Gene Expression in Primary Cultured Mouse Hepatocytes with a Cationic Liposomal Vector, TFL-3: Comparison with Rat Hepatocytes

We recently reported that a cationic liposomal vector, TFL-3, could be used to achieve significant gene expression in primary cultured rat hepatocytes (Nguyen et al., Biol. Pharm. Bull., 26, 880-885 (2003)). A combination of hepatocyte transplantation and hepatocyte-targeted gene transfer represents a potentially important strategy for expanding treatment options for liver disease. A widely applied approach to support cross-species is necessary before human applications can be realized. Therefore, in this study, we examined the utility of TFL-3 in another species of rodent hepatocytes, namely mouse hepatocytes. Gene expression in mouse hepatocytes by TFL-3 was successful and the level was higher than those in rat hepatocytes that we recently reported on. Interestingly, it appears that both the degree and rate of gene expression were dependent on the incubation time prior to lipofection as well as on the density of cells per dish, but these parameters were independent of the amount of pDNA associated with the cells. These significantly suggest that the culture time prior to and following lipofection, which are related to the biological condition of the cells, may be one of major factors that affect gene expression in hepatocytes and non- or less dividing cells.