Cationic Liposomes and Gene Therapy for Solid Tumors

Cellular Alterations Due to Direct and Indirect Interaction of Nanomaterials with Nucleic Acids

Deoxyribonucleic acid (DNA) represents the main reservoir of genetic information in the cells, which is why it is protected in the nucleus. Entry into the nucleus is, in general, difficult, as the nuclear membrane is a selective barrier to molecules longer than 40 kDa. However, in some cases, the size of certain nanoparticles (NPs) allows their internalization into the nucleus, thus causing a direct effect on the DNA structure. NPs can also induce indirect effects on DNA through reactive oxygen species (ROS) generation. In this context, nanomaterials are emerging as a disruptive tool for the development of novel therapies in a broad range of biomedical fields; although their effect on cell viability is commonly studied, further interactions with DNA or indirect alterations triggered by the internalization of these materials are not always clarified, since the small size of these materials makes them perfectly suitable for interaction with subcellular structures, such as the nucleus. In this context, and using as a reference the predicted interactions presented in a computational model, we describe and discuss the observed direct and indirect effects of the implicated nanomaterials on DNA.

Chitosan Nanoparticles in Atherosclerosis-Development to Preclinical Testing

Chitosan is a natural biopolymer that is present in an abundant supply in sources such as crustacean shells, mushrooms, and insect exoskeletons. It can be used to make a variety of types of drug formulations and is generally safe to use in vivo; plus, it has inherent cholesterol-reducing properties. While an abundance of papers has tested this biopolymer in nanoparticles in cancer and diabetes research, there is a lag of usage, and hence the paucity of information, in the area of cardiovascular research, specifically in atherosclerosis, the topic of this review. This review highlights some of the deficiencies in this niche area of research, examines the range of chitosan nanoparticles that have been researched to date, and proposes several ways forward to advance this field. Nanoparticles used for both diagnostic and therapeutic purposes are reviewed, with a discussion on how these nanoparticles could be better researched in future and what lays ahead as the field potentially moves towards clinical trials in future.

Liposomes, new carriers for delivery of genes and anticancer drugs: a systematic review

Today, nanoscience has grown and developed in various fields of medicine and treatment, including cancer treatment. Currently, the existing treatments, including chemotherapy and radiotherapy, cause side effects that are unpleasant to the patient. Due to the fact that anticancer drugs cause severe and widespread side effects, liposomes are considered as new drug carriers to minimize the untimely destruction of the drug when it is delivered to the target tissue and to prevent the side effects of toxic drugs. This systematic review study examined the importance of using liposomes as new drug carriers for the delivery of genes and anticancer drugs. The articles published in English in the databases of Google scholar, WoS, PubMed, Embase, Scopus and science direct were reviewed. According to the results of this study, a new targeted nanosystem has been used for loading and delivering anticancer drugs, genes and controlled drug release which has a significant therapeutic effect compared to the same amount of free drug. In general, liposomal systems have been considered because of their capability in preserving the effect of the drug along with reducing the side effects and toxicity of the drug, especially in the case of anticancer drugs. Accumulation of the drug in a target tissue which results in a reduction of the drug entry into other tissues is the main reason for reducing the side effects of these drugs.

A novel method for the development of plasmid DNA-loaded nanoliposomes for cancer gene therapy

We aimed to develop a simple yet novel method to prepare plasmid DNA-loaded nanoliposomes for cancer gene therapy. Murine interleukin-12 (mIL-12) pDNA-loaded nanoliposomes were prepared via novel freeze-drying of a monophase solution method. The physicochemical characteristics, cytotoxicity, and transfection efficiency of the prepared nanoliposomes in murine CT-26 colon carcinoma cells were evaluated. Furthermore, tumor progression and survival rate in CT-26 colon carcinoma-bearing BALB/c mice subsequent to direct intratumoral injections were investigated over a period of 40 days. Using this preparation method, nanoliposomes with particle size of around 300 nm and zeta potential of 96.5 mV were obtained. The transmission electron microscope results showed that the liposomes were nano-sized and almost spherical. The agarose gel retardation assay revealed the pDNA encapsulation in the nanoliposomes. The nanoliposomes with 72.4% encapsulation efficiency and low cell toxicity could significantly improve mIL-12 expression by approximately 25-fold relative to the naked mIL-12 pDNA. There was a significant tumor growth inhibition after repeated injections of mIL-12 pDNA-loaded nanoliposomes. This is the first study on the freeze-drying of a monophase solution method as a simple yet novel technique for the preparation of pDNA-loaded nanoliposomes. Given the ease of preparation method and promising in vitro and in vivo characteristics, this investigation demonstrates advances in pDNA lipid formulation for cancer gene therapy.

Recent advances in liposomal nanohybrid cerasomes as promising drug nanocarriers

Liposomes have been extensively investigated as possible carriers for diagnostic or therapeutic agents due to their unique properties. However, liposomes still have not attained their full potential as drug and gene delivery vehicles because of their insufficient morphological stability. Recently, a super-stable and freestanding hybrid liposomal cerasome (partially ceramic- or silica-coated liposome) has drawn much attention as a novel drug delivery system because its atomic layer of polyorganosiloxane surface imparts higher morphological stability than conventional liposomes and its liposomal bilayer structure reduces the overall rigidity and density greatly compared to silica nanoparticles. Cerasomes are more biocompatible than silica nanoparticles due to the incorporation of the liposomal architecture into cerasomes. Cerasomes combine the advantages of both liposomes and silica nanoparticles but overcome their disadvantages so cerasomes are ideal drug delivery systems. The present review will first highlights some of the key advances of the past decade in the technology of cerasome production and then review current biomedical applications of cerasomes, with a view to stimulating further research in this area of study.

Liposomal architecture boosts biocompatibility of nanohybrid cerasomes

Biomimetic cerasome has drawn much attention as a novel drug delivery system because its atomic layer of polyorganosiloxane surface imparts higher morphological stability than conventional liposomes and its liposomal bilayer structure reduces the overall rigidity and density greatly compared to silica nanoparticles. But, the issues about the interactions between cerasomes and biological systems have not been addressed as far as we could find. Herein, we reported cellular uptake of cerasomes and their biological effects toward human umbilical vein endothelial cells (HUVECs) compared with silica nanoparticles. The results indicated that the uptake of cerasomes by HUVECs was a concentration-, time-, and energy-dependent process and occurred probably through a process of clathrin-mediated endocytosis, which resulted in rearrangement of the cell cytoskeleton. Cerasomes affected different aspects of cell function to a smaller extent than silica nanoparticles, including cell proliferation, cell cycle, cell apoptosis, endogenous ROS level and pro-inflammatory molecular expression. In a word, cerasomes are more biocompatible than silica nanoparticles due to the incorporation of the liposomal architecture into cerasomes. The preliminary data will assist in the further development of new cerasome-based delivery systems.

Non-viral methods for gene transfer towards osteosarcoma therapy

Osteosarcoma, a class of cancer that originates from bone, afflicts mainly young people usually in their teenage years of life. Despite surgery and chemotherapy, the outlook for sufferers is not that positive, with a third of patients with metastatic disease not surviving past the 10-year mark. Like other neoplasms, other forms of therapeutics are being evaluated, and amongst these is gene therapy. This review discusses approaches for gene therapy of osteosarcoma using cationic liposomes and polyethylenimine in vivo. The field is still in its infancy as far as osteosarcoma is concerned and much more needs to be done to test its true potential as a feasible therapeutic modality.

Gene therapy for osteosarcoma: steps towards clinical studies

Gene therapy, an applied form of biotechnology, relies on the delivery of foreign DNA into cells. More than 50% of all reported clinical trials for gene therapy are for cancer, though only a scant number for osteosarcoma. Osteosarcoma is a neoplasm afflicting young adults, who in their prime years of life suffer debilitation if not death. The disease is not entirely curable, even with surgery combined with aggressive chemotherapy. Thus, other forms of therapies are being evaluated, including gene therapy. There exist two major forms of gene transfer: viral and non-viral. This review only covers proof-of-principle work carried out in cancer beyond the cell culture stage, in animals. Drawing from the experiences of gene therapy against other cancers, studies for which have already reached the clinical phase, the review discusses potential pitfalls and solutions to enhance gene therapy for osteosarcoma.

Cationic liposomes for gene transfection

Cationic liposomes spontaneously interact with the negatively charged DNA to form a stable complex that promotes the gene transfer to cells. The mode of formation and the size of cationic liposomes/DNA complexes were investigated using the atomic force microscopy (AFM). Also the most important physical-chemical factors involved in cationic liposome-mediated gene transfection, e.g. size and lipidic composition, were evaluated through the transfection of complexes with different liposomes/DNA molar ratio into three types of cultured cells. Cationic liposomes, composed of a neutral lipid (phosphatidilcoline), a cationic lipid dimethyldioctadecylammonium bromide (DDAB), a co-lipid 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) and a phospholipid derivative of polyethylene glycol (DSPE-mPEG) at different molar ratio, were mixed with a plasmid pCMVbeta to form liposomes/DNA complexes. We have demonstrated that the complexes were made by complicated structures in which the liposomes tend to aggregate and the DNA is surrounded by lipidic material. In vitro transfection efficiency by liposomes/plasmid pCMVbeta complexes was found to depend on the kind of lipid associated in the liposomes and the liposomes/DNA mixing ratio. The importance of associating DOPE in cationic liposomes was confirmed; this co-lipid is able to improve the ability of cationic liposomes to transfect cells but in addition, the AFM images and the EtBr fluorescence experiments have suggested that this lipid can also play an important role to facilitate the formation of stable liposomes, which efficaciously protect the DNA by nuclease digestion.

Improving anti-angiogenic therapy via selective delivery of cationic liposomes to tumour vasculature

In the past three decades, two very important findings regarding tumour vasculature have been made. Firstly, it has been known a solid tumour has to establish an adequate blood supply to grow beyond a critical mass. Secondly, it has been proven that the tumour vasculature is relatively more aberrant, dynamic and permeable than healthy host tissue. This review discusses the potential of delivering therapeutic nucleic acids to tumour vasculature using cationic liposomes, vehicles recently demonstrated to be selectively delivered to tumour vasculature.

Gene therapy: theoretical and bioethical concepts

Gene therapy holds great promise. Somatic gene therapy has the potential to treat a wide range of disorders, including inherited conditions, cancers, and infectious diseases. Early progress has already been made in the treatment of a range of disorders. Ethical issues surrounding somatic gene therapy are primarily those concerned with safety. Germline gene therapy is theoretically possible but raises serious ethical concerns concerning future generations.

Enhancement of polyethylene glycol (PEG)-modified cationic liposome-mediated gene deliveries: effects on serum stability and transfection efficiency

In this study, we modified cationic liposomes either by polyethylene glycol (PEG)-grafting or PEG-adding methods, and compared the physical properties of transfection complexes and transfection efficiency in-vitro and prolonged circulation in-vivo. The PEG-grafted transfection complexes were prepared by mixing plasmid DNA with PEG-grafted cationic liposomes, which were composed of DSPE-PEG 2000 and cationic lipids. The PEG-added transfection complexes were prepared by adding DSPE-PEG 2000 to the mixture of cationic liposomes and plasmid DNA. The particle sizes of the PEG-modified transfection complexes (approximately 200 nm) changed a little over 4 weeks compared with the conventional transfection complexes. In the presence of serum, the transfection efficiency of the conventional transfection complexes was lowered whereas the transfection efficiency of the PEG-modified transfection complexes was maintained. Moreover, the transfection efficiency of the conventional transfection complexes was significantly reduced when they were stored. However, the transfection efficiency was stable for the PEG-modified transfection complexes, even after two weeks of storage. Of the in-vitro transfection efficiencies, there was no difference between PEG-grafted and PEG-added transfection complexes. When the conventional, PEG-grafted, and PEG-added transfection complexes were administered into mice by the tail vein, the PEG-added transfection complexes showed a prolonged circulation of plasmid DNA compared with other transfection complexes. These results suggest that the PEG-added transfection complexes could be a useful non-viral vector because of their simplicity in preparation, enhanced stability and prolonged circulation compared with the conventional transfection complexes.

Gene transfer in higher animals: theoretical considerations and key concepts

Gene transfer technology provides the ability to genetically manipulate the cells of higher animals. Gene transfer permits both germline and somatic alterations. Such genetic manipulation is the basis for animal transgenesis goals and gene therapy attempts. Improvements in gene transfer are required in terms of transgene design to permit gene targeting, and in terms of transfection approaches to allow improved transgene uptake efficiencies.

Vehicles for oligonucleotide delivery to tumours

The vasculature of a tumour provides the most effective route by which neoplastic cells may be reached and eradicated by drugs. The fact that a tumour's vasculature is relatively more permeable than healthy host tissue should enable selective delivery of drugs to tumour tissue. Such delivery is relevant to carrier-mediated delivery of genetic medicine to tumours. This review discusses the potential of delivering therapeutic oligonucleotides (ONs) to tumours using cationic liposomes and cyclodextrins (CyDs), and the major hindrances posed by the tumour itself on such delivery. Cationic liposomes are generally 100-200 nm in diameter, whereas CyDs typically span 1.5 nm across. Cationic liposomes have been used for the introduction of nucleic acids into mammalian cells for more than a decade. CyD molecules are routinely used as agents that engender cholesterol efflux from lipid-laden cells, thus having an efficacious potential in the management of atherosclerosis. A recent trend is to employ these oligosaccharide molecules for delivering nucleic acids in cells both in-vitro and in-vivo. Comparisons are made with other ON delivery agents, such as porphyrin derivatives (< 1 nm), branched chain dendrimers (approximately 10 nm), polyethylenimine polymers (approximately 10 nm), nanoparticles (20-1,000 nm) and microspheres (> 1 microm), in the context of delivery to solid tumours. A discourse on how the chemical and physical properties of these carriers may affect the uptake of ONs into cells, particularly in-vivo, forms a major basis of this review.

Apolipoprotein A-I, cyclodextrins and liposomes as potential drugs for the reversal of atherosclerosis. A review

Several studies have revealed that high-density lipoprotein (HDL) is the most reliable predictor for susceptibility to cardiovascular disease. Since apolipoprotein A-I (apoA-I) is the major protein of HDL, it is worthwhile evaluating the potential of this protein to reduce the lipid burden of lesions observed in the clinic. Indeed, apoA-I is used extensively in cell culture to induce cholesterol efflux. However, while there is a large body of data emanating from in-vitro and cell-culture studies with apoA-I, little animal data and scant clinical trials examining the potential of this apolipoprotein to induce cholesterol (and other lipid) efflux exists. Importantly, the effects of oxysterols, such as 7-ketocholesterol (7KC), on cholesterol and other lipid efflux by apoA-I needs to be investigated in any attempt to utilise apoA-I as an agent to stimulate efflux of lipids. Lessons may be learnt from studies with other lipid acceptors such as cyclodextrins and phospholipid vesicles (PLVs, liposomes), by combination with other effluxing agents, by remodelling the protein structure of the apolipoprotein, or by altering the composition of the lipoprotein intended for administration in-vivo. Akin to any other drug, the usage of this apolipoprotein in a therapeutic context has to follow the traditional sequence of events, namely an evaluation of the biodistribution, safety and dose-response of the protein in animal trials in advance of clinical trials. Mass production of the apolipoprotein is now a simple process due to the advent of recombinant DNA technology. This review also considers the potential of cyclodextrins and PLVs for use in inducing reverse cholesterol transport in-vivo. Finally, the potential of cyclodextrins as delivery agents for nucleic acid-based constructs such as oligonucleotides and plasmids is discussed.

Apolipoprotein A-I, phospholipid vesicles, and cyclodextrins as potential anti-atherosclerotic drugs: delivery, pharmacokinetics, and efficacy

High-density lipoprotein (HDL) is a reliable predictor for susceptibility to cardiovascular disease. Since apolipoprotein A-I (apoA-I) is the major protein of HDL, it is worthwhile to evaluate the potential of this protein to reduce the lipid burden of lesions observed in the clinic. While a large body of data emanates from in vitro and cell culture studies with apoA-I, few animal and lesser clinical trials examining the potential of this apolipoprotein to induce cholesterol (and other lipid) efflux exist. Lessons may be learned from studies with other lipid acceptors such as phospholipid vesicles (PLVs, liposomes) and cyclodextrins (CDs). Additionally, the combination of apoA-I with other effluxing agents, alteration of the composition of the lipoprotein, or a remodeling of the protein structure of the apolipoprotein to be administered in vivo may result in increased efficacy. The usage of this apolipoprotein in a therapeutic context has to follow the conventional sequence of events: an evaluation of the biodistribution, safety, and dose-response of the protein in animal trials before clinical trials. The review also considers the potential of cyclodextrins and PLVs to induce reverse cholesterol transport in vivo and discusses the potential of CDs as delivery agents for genetic constructs, such as plasmids and oligonucleotides.