Non-viral siRNA and shRNA Delivery Systems in Cancer Therapy

RNA interference represents a promising therapeutic strategy for the silencing of specific target genes in cancer therapy. Small interfering RNAs and DNA-based vectors encoding short hairpin RNAs provide sequence-specific post-transcriptional gene silencing by binding to its complementary RNA. For the therapeutic use of siRNA in cancer, efficient intracellular delivery is necessary. The efficient cancer therapy with RNAi is not still accomplished because of internalization and intracellular trafficking problems such as low transfection efficiency, enzyme degradation, inappropriate subcellular localization, and endosomal trapping of siRNAs in cells. Cancer is a complex disease including multiple genes and pathways. The most important benefits of siRNA therapy are high target specificity and non-toxicity compared with chemotherapy. The uptake of siRNA by cells without a carrier system is possible, but naked siRNA is mostly degraded with nucleases and activates the immune responses. Development of appropriate delivery systems is an important issue in the use of siRNA-based therapeutics. Non-viral delivery systems have great potential for safe and effective delivery of siRNA therapeutics to tumor cells. Nanocarriers such as nanoplexes, lipoplexes, nanoparticles, and liposomes have been commonly used for siRNA delivery. This chapter highlights the importance of non-viral delivery systems in vitro and in vivo cancer therapy

Synthesis, structure elucidation and cytotoxic activities of 2,5-disubstituted-1,3,4-thiadiazole and l,2,4-triazole-3-thione derivatives

In this study, a series of 1,3,4-thiadiazole (1b-9b) and l,2,4-triazole-3-thione (1c-9c) derivatives were synthesized. The reaction proses was carried out with the cyclocondensation of suitable 1,4-disubstituted thiosemicarbazide derivatives (1a-9a). The structures of the synthesized compounds were confirmed by the data obtained from elemental analysis, HPLC, UV, IR,1H-NMR and MS spectra. All of the compounds were tested for their cytotoxic activities against L929 fibroblast cells by MTT method. It was determined that the tested compounds 1a-9a, 1b-9b and 1c-9c were not cytotoxic at the studied concentrations (5.0 µg/mL and 10.0 µg/mL) in L929 cell lines. Compounds 1a-c, 2a-c, 3a-c, 4a-c, 5a-c and 8a-c showed increased growth inhibition whereas compounds 6a-c, 7a-c and 9a-c showed decreased growth inhibition on L929 cell lines

Investigation of therapeutic effects in the wound healing of chitosan/pGM-CSF complexes

Granulocyte macrophage colony-stimulating factor (GM-CSF) has been shown to promote the growth, proliferation, and migration of endothelial and keratinocyte cells. Chitosan has been widely used as a biopolymer in wound-healing studies. The aim of this study was to investigate the in vitro proliferative effects of chitosan/pGM-CSF complexes as well as the therapeutic role of the complexes in an in vivo rat wound model. The effect of complexes on cell proliferation and migration was examined. Wounds were made in Wistar-albino rats, and examined histopathologically. The cell proliferation and migration were increased weight ratio- and time-dependently in HaCaT and NIH-3T3 cell lines. Wound healing was significantly accelerated in rats treated with the complexes. These results showed that the delivery of pGM-CSF using chitosan complexes could play an accelerating role in the cell proliferation, migration, and wound-healing process

siRNA’nın biyodağılımına kitozan komplekslerinin etkisi

Amaç: RNAi kanser dahil olmak üzere birçok hastalığın moleküler mekanizmasının analizinde ve gen susturulmasında hücresel proseslerin kontrolü için önemli bir araçtır. VEGF sinyali meme kanserinde siRNA taşınmasında önemli bir hedeftir. siRNA farklı hastalıklar için potansiyel bir ajan olmasına rağmen, siRNA’nın intrasellüler taşınması, terapötik olarak aktif bir moleküle dönüşmesindeki önemli engellerden biridir. Bugüne kadar birçok transfeksiyon yöntemi ve taşıyıcı sistem geliştirilmiştir. Bunlar arasında kitozan, biyouyumlu, biyoparçalanabilir olması, toksik ve immunojenik olmaması gibi özellikleri nedeniyle önemli bir gen taşıyıcısıdır. Bu çalışmanın amacı, meme kanserinde kitozan/VEGF-siRNA komplekslerinin tümör lokalizasyonunu ve biyodağılımını araştırmaktır. Yöntem: Çalışmamızda meme tümörü taşıyan sıçanlara serbest FITC-işaretli siVEGF (40 µg/sıçan) ve kitozan/ FITC-işaretli siVEGF (40 µg/sıçan) kompleksleri intravenöz olarak enjekte edildi. Bulgular: Kitozan/siVEGF komplekslerinin beyin ve kalbe biyodağılımı, serbest siVEGF ile hemen hemen benzerken, dalak, karaciğer, akciğer ve kasta biraz daha düşük ve böbrekte ise biraz daha yüksektir. Meme tümör dokusunda, kompleksler enjeksiyon sonrası 15 dakikada tümörde lokalize iken, serbest FITC-siVEGF tümör dokusunda lokalize değildir. Sonuç: Bu ön çalışmada, biz biyodağılım için VEGF siRNA taşıyıcı sistem olarak kitozanın umut verici olduğunu gösterdik

Comparison of VEGF gene silencing efficiencies of chitosan and protamine complexes containing shRNA

VEGF is an angiogenic factor promoting the proliferation and migration of endothelial cells. Inhibition of VEGF by RNAi mechanism is one of the novel and the most important strategies in antiangiogenesis therapy. In this study, the tumor silencing efficiency of ternary complexes after addition of protamine to chitosan complexes containing VEGF targeting shRNA was investigated. Besides chitosan, protamine is an effective gene delivery material. Binary and ternary complexes consisting of chitosan, protamine, and shRNA were prepared to target VEGF, their morphology, size, and zeta potential of the complexes being measured. The average size of the complexes was between 173 and 284nm and zeta potential was between +10 and 16mV. In the ternary complexes, size decreased as the chitosan ratio increased; however, its molecular weight had no effect on the size of complexes. HeLa, HEK293, and MCF-7 cell lines were used for in vitro transfection. VEGF was assayed by ELISA. A higher silencing effect was obtained using ternary complexes. Transgene expression was increased by adding protamine to chitosan complexes. Gene inhibition values in cell lines followed the rank HEK293>HeLa>MCF-7. The addition of protamine to the chitosan/shRNA (VEGF) complexes increased the knockdown of VEGF genes in the cell lines, and no cytotoxicity was found after the complexes had been incorporated into the cells

Differences between Solution and Membrane Forms of Chitosan on the In Vitro Activity of Fibroblasts

Background: Chitosan, a linear polysaccharide, has been recently used in biomedical applications. In vitro studies have demonstrated its effect on cellular growth and its stimulatory action on cellular layer formation. Aims: The present study aims to compare the proliferative effects of chitosan in two forms, membranous and solution forms, on Swiss 3T3 mouse embryonic fibroblasts. Study Design: In vitro study. Methods: Three experimental groups were formed: cells were cultured in a normal medium without chitosan (Control Group); cells were cultured either in a medium containing 2.0% chitosan in membranous form (Membrane Group) or chitosan solution at a concentration of 2.0% (Solution Group). Two different methods were used in the experiments: cells cultured on the medium containing chitosan in solution or membranous forms (method 1); and chitosan solution or membranous forms were added into the medium containing previously cultured cells (method 2). Results: Scanning electron microscopic investigations of the experimental groups revealed cells with well-defined cellular projections, intact cellular membranes and tight intercellular junctions. They were especially prominent in the membrane group of method 1 and in the membrane and solution groups of method 2. Mouse monoclonal anti-collagen 1 primary antibody was used to indicate collagen synthesis. Prominent collagen synthesis was detected in the membrane groups on the 10th day of culture for both methods. Bromodeoxyuridine (BrdU) and MTT assays were performed in order to assess cellular proliferation and viability, respectively. BrdU labelling tests indicated a higher proliferation index in the membrane group of method 1 on the 5th and 10th days. For the second method, the membranous form on the 10th day and solution form on the 5th day were the most effective groups in terms of cellular proliferation. MTT results reflected a high cellular viability in method 1 on the 5th day of treatment with the membranous form, whereas cellular viability was highest in the solution form of method 2 on the 5th day. Conclusion: The membranous form of chitosan induced a significant proliferative effect and increased the ratio of cell-to-cell junctions of Swiss 3T3 mouse embryonic fibroblasts. Conveniently, the solution form also resulted in enhanced cell proliferation and viability compared to the control group. As the solution form is easy to prepare and apply to cells compared to the membrane form, the application of Chitosan directly to media appears to be a convenient alternative for tissue engineering approaches

Controlled release of interleukin-2 from chitosan microspheres

Chitosan microspheres were evaluated for sustained-release of recombinant human interleukin-2 (rIL-2) in this study. In addition, the effects of different formulation factors, such as chitosan and protein concentrations, the volume of sodium sulfate solution, addition technique of rIL-2, and presence of glutaraldehyde during the encapsulation process, on microsphere characteristics were investigated. Chitosan microspheres containing rIL-2 were prepared by using the precipitation technique. The average diameter of microspheres was between 1.11-1.59 mum. Recombinant IL-2 encapsulation efficiency in these micropheres was high (75-98%). Formulation factors had no effect on the microsphere size. Recombinant IL-2 had been released from chitosan microspheres over a period of 3 months. The encapsulated rIL-2 remained biologically active and could be completely recovered from the release medium. Briefly, rIL-2 was released from chitosan microspheres in a sustained manner. The efficacy of rIL-2 loaded chitosan microspheres was studied using two model cells, HeLa and L-strain cell lines. Chitosan microspheres were added to the cells at different concentrations, and the amount of rIL-2 was assayed using the ELISA kit. Cell culture studies indicated that microspheres were uptaken by cells, and rIL-2 was released from the microspheres. Cellular uptake of rIL-2-loaded microspheres was dose dependent. It can be said that chitosan microsphere is a suitable carrier for rIL-2 delivery. (C) 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association

Plasmid-DNA loaded chitosan microspheres for in vitro IL-2 expression

Interleukin-2 (IL-2) expression plasmid (pCXWN-hIL-2) loaded chitosan microspheres were evaluated for using in gene-based immumotherapy. Chitosan microspheres containing pCXWN-hIL-2 were prepared by using a precipitation technique. In addition, the effects of different factors such as the concentration (0.35-0.70%) and the molecular weight of chitosan (low and medium molecular weights), the plasmid amount (5-10 mug/ml) and the presence of glutaraldehyde during the encapsulation process, on microsphere characteristics were investigated. The size of microspheres changed between 1.45 and 2.00 mum. All the formulation factors affected the size of microspheres. The structure of plasmid remained unchanged during the encapsulation process and the release studies. Plasmid encapsulation efficiency of chitosan microspheres was high (82-92%). The zeta potential values of microspheres was approximately +5.2 to +12.4 mV. In vitro release properties of microspheres changed with formulation variables. In vitro release of DNA changed with the concentration and molecular weight of chitosan and initial plasmid amount. Addition of glutaraldehyde is not necessary for a formulation. MAT-LyLu, the rat prostate adenocarcinoma cell line, was used for the determination of the in vitro transfectional activity of IL-2 encoding plasmid DNA loaded chitosan microspheres and the level of IL-2 expressed into the cells was assayed using a ELISA kit. High level of IL-2 expression was obtained with plasmid-loaded chitosan microspheres. Microspheres showed similar IL-2 production as lipofectin. The molecular weight of chitosan used and the amount of plasmid influenced the in vitro IL-2 production in the cells. Encapsulation of IL-2 encoding gene into chitosan microspheres might be a useful strategy to increase the expression and to control the delivery of cytokine gene to cells. (C) 2004 Elsevier B.V. All rights reserved

Effects of different forms of chitosan on intercellular junctions of mouse fibroblasts in vitro

Chitosan is a linear polysaccharide that has many biomedical applications. We compared the effects of chitosan, in both solution and membranous form, on intercellular adhesion of Swiss 3T3 mouse fibroblasts. Cells were grown as spheroidal cell cultures. Some control cell spheroids were cultured without chitosan and two experimental groups were cultured with chitosan. Chitosan in solution was used for one experimental group and chitosan in membranous form was used for the other. For each group, intercellular adhesion was investigated on days 5 and 10 of culture. Transmission electron microscopy revealed well-defined cellular projections that were more prominent in cells exposed to either membranous or solution forms of chitosan than to the chitosan-free control. Immunocytochemical staining of ICAM-1 and e-cadherin was used to determine the development of intercellular junctions. Compared to the weakly stained control, strong reactions were observed in both chitosan exposed groups at both 5 and 10 days. Cells were treated with 5-bromo-2-deoxyuridine (BrdU) and incubated with anti-BrdU primary antibody to assess proliferation. Both the solution and membranous forms of chitosan increased proliferation at both 5 and 10 days. Cellular viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide (MTT). The MTT assay indicated high cell viability; maximum viability was obtained with the solution form of chitosan at day 5. Chitosan exposure increased the number of intercellular junctions and showed a significant proliferative effect on 3T3 mouse fibroblasts

Plasmid DNA-loaded chitosan/TPP nanoparticles for topical gene delivery

Topical application of plasmid DNA represents an attractive route of gene delivery. Although chitosan (CS) has been widely investigated as a gene-carrier, there is very limited information about the skin application of CS-based systems for DNA. This study evaluated pDNA-loaded chitosan nanoparticles (CS-NPs) for skin gene delivery. NPs were prepared by inducing the gelation of CS upon interaction with sodium tripolyphosphate. pSV-beta-Gal was used as a reporter gene. The size, surface charge, and the other in vitro characteristics of CS-NPs were examined. Primary human dermal fibroblast cells (HDF) and mouse fibroblast NIH 3T3 cell lines (ATCC CCL-92) were used for in vitro transfection studies. In in vivo study, CS-NPs were applied to the skin of baby and adult Sprague Dawley rats by spreading on the shaved area of the back of animals. During a week animals were sacrificed and skin biopsies were taken for beta-Gal expression. beta-galactosidase enzyme activity was determined spectrophotometrically at 420 nm. The distribution of beta-galactosidase expressing cells within the skin tissue was observed by X-gal histochemical method. beta-galactosidase was continuously expressed at the nanoparticle-treated skin during the 7 days. High and continuous beta-Gal expressions were obtained with CS-NPs, although it was low in the first day. When a comparison was made between the data of baby and adult rats, markedly high transfection were measured in the skin samples of the baby rats. NPs protected pDNA against the enzyme and serum attacks. In conclusion, CS-NPs showed in vivo transfection potential in rats for skin gene delivery