Efficient and gentle siRNA delivery by magnetofection

Prospects for the potential of RNA interference in the treatment of autoimmune diseases: Small interfering RNAs in the spotlight

The identification of RNA interference (RNAi) has caused a growing interest in harnessing its potential in the treatment of different diseases. Modulation of dysregulated genes through targeting by RNAi represents a potential approach with which to alter the biological pathways at a post-transcriptional level, especially as it pertains to autoimmunity and malignancy. Short hairpin RNAs (shRNA), short interfering RNAs (siRNA), and microRNAs (miRNA) are mainly involved as effector mechanisms in the targeting of RNAi biological pathways. The manipulation and delivery of these molecules in an efficient way promotes the specificity and stability of RNAi-based systems, while minimizing the unwanted adverse reactions by the immune system and reducing cytotoxicity and off-target effects. Advances made to date in identifying the etiopathogenesis of autoimmune diseases has prompted the utilization of RNAi-based systems in vitro and in vivo. Future investigations aimed at deciphering the molecular basis of RNAi and optimizing the delivery of RNAi-based targeting systems will hopefully promote the applicability of such regulatory mechanisms and, ultimately, transfer the acquired knowledge from bench-to-bedside to ameliorate human diseases. In this review, we seek to clarify the potential of RNAi, with a focus on siRNAs, in designing therapeutics for potential treatment of human autoimmune disorders.

Electrotransfer of siRNA to Silence Enhanced Green Fluorescent Protein in Tumor Mediated by a High Intensity Pulsed Electromagnetic Field

The contactless high intensity pulsed electromagnetic field (HI-PEMF)-induced increase of cell membrane permeability is similar to conventional electroporation, with the important difference of inducing an electric field non-invasively by exposing a treated tissue to a time-varying magnetic field. Due to the limited number of studies in the field of electroporation induced by HI-PEMF, we designed experiments to explore the feasibility of such a contactless delivery technique for the gene electrotransfer of nucleic acids in tissues in vivo. By using HI-PEMF for gene electrotransfer, we silenced enhanced green fluorescent protein (EGFP) with siRNA molecules against EGFP in B16F10-EGFP tumors. Six days after the transfer, the fluorescent tumor area decreased by up to 39% as determined by fluorescence imaging in vivo. In addition, the silencing of EGFP to the same extent was confirmed at the mRNA and protein level. The results obtained in the in vivo mouse model demonstrate the potential use of HI-PEMF-induced cell permeabilization for gene therapy and DNA vaccination. Further studies are thus warranted to improve the equipment, optimize the protocols for gene transfer and the HI-PEMF parameters, and demonstrate the effects of HI-PEMF on a broader range of different normal and tumor tissues.

Magnetofection and isolation of DNA using polyethyleneimine functionalized magnetic iron oxide nanoparticles

This study was carried out to develop a simple and efficient method to isolate DNA directly from biological samples using iron oxide nanoparticles (IONPs) functionalized with polyethyleneimine (PEI). IONPs were synthesized via co-precipitation method followed with direct attachment of branched PEI. Nanoparticles were characterized using STEM, FT-IR spectroscopy and XRD analysis. The binding capacity of synthesized PEI-IONPs for plasmid and genomic DNA was assessed using purified DNA samples. In order to elute bound DNA, elution conditions were optimized, changing pH, salt concentration and temperature. Synthesized PEI-IONPs were subjected to isolation of DNA from bacterial cell culture and from human blood. PCR and magnetofection of the enhanced green fluorescence protein (EGFP) were carried out to verify the downstream applications of isolated DNA. The results indicated that the synthesized nanoparticles were of 5-10 nm. The binding capacity of PEI-IONPs for plasmid DNA and genomic DNA were 5.4 and 8.4 µg mg-1, respectively, which were even higher than the commercially available kits such as Mag-bind, MagJET and Magmax. The optimized condition for plasmid DNA elution was 0.1 M Tris HCl (pH 10.0), 1.5 M NaCl and 5% formamide, maintained at the temperature of 60°C. The optimized condition for genomic DNA elution was 0.1 M Tris HCl (pH 10.0), 1.5 M NaCl and 10% formamide, maintained at 60°C. PCR and magnetofection processes were successful. This study revealed that the magnetic separation of DNA using PEI-IONPs is a simple and efficient method for direct isolation of DNA from biological samples which can be then used in various downstream applications.

Transduction and transfection of difficult-to-transfect cells: Systematic attempts for the transfection of protozoa Leishmania

Cell-penetrating peptides (CPPs) are used to internalize different cargoes, including DNA, into live mammalian and plant cells. Despite many cells being easily transfected with this approach, other cells are rather "difficult" or "hard to transfect," including protist cells of the genus Leishmania. Based on our previous results in successfully internalizing proteins into Leishmania tarentolae cells, we used single CPPs and three different DNA-binding proteins to form protein-like complexes with plasmids covered with CPPs. We attempted magnetofection, electroporation, and transfection using a number of commercially available detergents. While complex formation with negatively charged DNA required substantially higher amounts of CPPs than those necessary for mostly neutral proteins, the cytotoxicity of the required amounts of CPPs and auxiliaries was thoroughly studied. We found that Leishmania cells were indeed susceptible to high concentrations of some CPPs and auxiliaries, although in a different manner compared with that for mammalian cells. The lack of successful transfections implies the necessity to accept certain general limitations regarding DNA internalization into difficult-to-transfect cells. Only electroporation allowed reproducible internalization of large and rigid plasmid DNA molecules through electrically disturbed extended membrane areas, known as permeable membrane macrodomains.

Transfection of Capsaspora owczarzaki, a close unicellular relative of animals

How animals emerged from their unicellular ancestor remains a major evolutionary question. New genome data from the closest unicellular relatives of animals have provided important insights into the evolution of animal multicellularity. We know that the unicellular ancestor of animals had an unexpectedly complex genetic repertoire, including many genes that are key to animal development and multicellularity. Thus, assessing the function of these genes among unicellular relatives of animals is key to understanding how they were co-opted at the onset of the Metazoa. However, such analyses have been hampered by the lack of genetic tools. Progress has been made in choanoflagellates and teretosporeans, two of the three lineages closely related to animals, whereas no tools are yet available for functional analysis in the third lineage: the filastereans. Importantly, filastereans have a striking repertoire of genes involved in transcriptional regulation and other developmental processes. Here, we describe a reliable transfection method for the filasterean Capsaspora owczarzaki. We also provide a set of constructs for visualising subcellular structures in live cells. These tools convert Capsaspora into a unique experimentally tractable organism to use to investigate the origin and evolution of animal multicellularity.

Summary: Development of genetic tools in a close unicellular relative of animals, the filasterean Capsaspora owczarzaki, will open new opportunities for functional studies to understand the transition to animal multicellularity.

Non-viral Gene Delivery

Although viral vectors comprise the majority of gene delivery vectors, their various safety, production, and other practical concerns have left a research gap to be addressed. The non-viral vector space encompasses a growing variety of physical and chemical methods capable of gene delivery into the nuclei of target cells. Major physical methods described in this chapter are microinjection, electroporation, and ballistic injection, magnetofection, sonoporation, optical transfection, and localized hyperthermia. Major chemical methods described in this chapter are lipofection, polyfection, gold complexation, and carbon-based methods. Combination approaches to improve transfection efficiency or reduce immunological response have shown great promise in expanding the scope of non-viral gene delivery.

Novel Disulfide-Containing Poly(β-amino ester)-Functionalised Magnetic Nanoparticles for Efficient Gene Delivery

Poly(β-amino ester)s (PBAEs) have been proved to effectively transfer DNA to various cell types. However, PBAEs with high molecular weights also show considerable toxicities, partly resulting from inadequate degradation of their polyester backbone. In this study, we created novel poly(β-amino ester)s (SF-1, 2, 3, and 4; notation SFs refers to all the four polymers) which were characterised by the cleavable disulfide bonds. Moreover, a new technique, termed magnetofection that uses magnetic nanoparticles to enhance gene expression, has recently been well developed. The negatively charged magnetic nanoparticles (MNPs) with good biocompatibility in vitro were prepared here to subsequently combine with SFs and DNA via electrostatic interaction, leading to the formation of the magnetic gene complexes MNP/SFs/DNA. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and transfection experiments were performed in A549 cells to investigate all the resulting complexes. Studies indicated that the synthesised PBAEs exhibited good biodegradation and regulated release of DNA as a result of the reductive cleavage of the disulfide bonds, giving higher transfection efficiency along with much lower cytotoxicity compared with commercially available transfection agent polyethylenimine (Mw 25 kDa). Furthermore, when MNP was involved at a MNP/DNA weight ratio of 0.5, the magnetic gene complexes MNP/SFs/DNA showed enhanced levels of gene expression while maintaining low cytotoxicity.

Chemically tunable cationic polymer-bonded magnetic nanoparticles for gene magnetofection

This study evaluates the efficiency of novel non-viral vectors consisting of super paramagnetic iron oxide nanoparticles functionalized with the chemically tunable cationic polymer forin vitrogene magnetofection.

PSORS1C1 may be involved in rheumatoid arthritis

PSORS1C1/CDSN is a susceptibility gene for psoriasis. Both psoriasis and rheumatoid arthritis (RA) are autoimmune diseases. This study investigated whether PSORS1C1/CDSN was involved in RA. The TagSNPs rs3130983, rs3778638 and rs4959053 in the PSORS1C1/CDSN locus were shown to predict susceptibility to RA in two independent RA cohorts using a TaqMan genotyping assay and Sequenom MassARRAY. The expression of PSORS1C1/CDSN was determined with western blotting and ELISA. Cultured synovial fibroblasts from RA patients (RASF) were treated with anti-PSORS1C1 siRNA. The TaqMan genotyping assay demonstrated significant differences in the rs3130983 and rs4959053 allele frequencies (p = 0.002001 and 1.74E-07, respectively) and genotype frequencies (0.010503 and 1.07E-06, respectively) between the RA patients and controls. Sequenom MassARRAY results indicated that SNP rs3778638 allele frequency and genotype frequency were significantly associated with RA (p = 7.35E-05 and 0.000357, respectively). Western blotting revealed a significant increase in expression of PSORS1C1 in RA synovial tissues, and ELISA detected high levels of PSORS1C1 and CDSN in the blood of RA patients. PSORS1C1-siRNA treatment significantly decreased the PSORS1C1 expression, IL-17 level, Il-1β level and cell proliferation in RASF. These results suggest that PSORS1C1 might play an important role in the development of RA.

Delivery of short interfering ribonucleic acid-complexed magnetic nanoparticles in an oscillating field occurs via caveolae-mediated endocytosis

Gene delivery technologies to introduce foreign genes into highly differentiated mammalian cells have improved significantly over the last few decades. Relatively new techniques such as magnetic nanoparticle-based gene transfection technology are showing great promise in terms of its high transfection efficiency and wide-ranging research applications. We have developed a novel gene delivery technique, which uses magnetic nanoparticles moving under the influence of an oscillating magnetic array. Herein we successfully introduced short interfering RNA (siRNA) against green fluorescent protein (GFP) or actin into stably-transfected GFP-HeLa cells or wild-type HeLa and rat aortic smooth muscle cells, respectively. This gene silencing technique occurred in a dose- and cell density- dependent manner, as reflected using fluorescence intensity and adhesion assays. Furthermore, using endocytosis inhibitors, we established that these magnetic nanoparticle-nucleic acid complexes, moving across the cell surface under the influence of an oscillating magnet array, enters into the cells via the caveolae-mediated endocytic pathway.

Physical non-viral gene delivery methods for tissue engineering

The integration of gene therapy into tissue engineering to control differentiation and direct tissue formation is not a new concept; however, successful delivery of nucleic acids into primary cells, progenitor cells, and stem cells has proven exceptionally challenging. Viral vectors are generally highly effective at delivering nucleic acids to a variety of cell populations, both dividing and non-dividing, yet these viral vectors are marred by significant safety concerns. Non-viral vectors are preferred for gene therapy, despite lower transfection efficiencies, and possess many customizable attributes that are desirable for tissue engineering applications. However, there is no single non-viral gene delivery strategy that "fits-all" cell types and tissues. Thus, there is a compelling opportunity to examine different non-viral vectors, especially physical vectors, and compare their relative degrees of success. This review examines the advantages and disadvantages of physical non-viral methods (i.e., microinjection, ballistic gene delivery, electroporation, sonoporation, laser irradiation, magnetofection, and electric field-induced molecular vibration), with particular attention given to electroporation because of its versatility, with further special emphasis on Nucleofection™. In addition, attributes of cellular character that can be used to improve differentiation strategies are examined for tissue engineering applications. Ultimately, electroporation exhibits a high transfection efficiency in many cell types, which is highly desirable for tissue engineering applications, but electroporation and other physical non-viral gene delivery methods are still limited by poor cell viability. Overcoming the challenge of poor cell viability in highly efficient physical non-viral techniques is the key to using gene delivery to enhance tissue engineering applications.

Intracellular Delivery of siRNA by Polycationic Superparamagnetic Nanoparticles

The siRNA transfection efficiency of nanoparticles (NPs), composed of a superparamagnetic iron oxide core modified with polycationic polymers (poly(hexamethylene biguanide) or branched polyethyleneimine), were studied in CHO-K1 and HeLa cell lines. Both NPs demonstrated to be good siRNA transfection vehicles, but unmodified branched polyethyleneimine (25 kD) was superior on both cell lines. However, application of an external magnetic field during transfection (magnetofection) increased the efficiency of the superparamagnetic NPs. Furthermore, our results reveal that these NPs are less toxic towards CHO-K1 cell lines than the unmodified polycationic-branched polyethyleneimine (PEI). In general, the external magnetic field did not alter the cell's viability nor it disrupted the cell membranes, except for the poly(hexamethylene biguanide)-modified NP, where it was observed that in CHO-K1 cells application of the external magnetic field promoted membrane damage. This paper presents new polycationic superparamagnetic NPs as promising transfection vehicles for siRNA and demonstrates the advantages of magnetofection.

Cellular signaling of amino acids towards mTORC1 activation in impaired human leucine catabolism

The regulation of cell growth and protein biosynthesis is triggered by the mammalian target of rapamycin complex 1 (mTORC1) responding to amino acids, especially leucine. The molecular mechanisms linking leucine to mTORC1 activation are not well understood. We analyzed whether the free intracellular leucine availability, a metabolite of leucine catabolism or the process of leucine oxidation activates mTORC1 signaling. We further investigated whether mTORC1 signaling is subject to altered regulation in disturbed leucine metabolism. Human fibroblasts with deficiencies in leucine catabolic steps and those from healthy control subjects were utilized. In all cells, leucine-induced mTORC1 signaling was significantly related to leucine pool size and leucine repletion capacity. The leucine/glutamine antiporter SLC7A5/SLC3A2 and the amino acid sensor MAP4K3 were identified as crucial determinants of signaling leucine availability to downstream targets. In cells with defective leucine catabolism, mTORC1 signaling towards phosphorylation of ribosomal protein S6 kinase 1 (S6K1) was significantly increased, whereas transcriptional down-regulation of MAP4K3 upon reduced amino acid supply was abrogated. Remarkably, these effects were observed irrespective of the localization of the enzymatic blockage. Our data provide evidence that mechanisms determining intracellular leucine availability and the amino acid sensor MAP4K3 are key upstream modulators of nutrient-sensitive mTORC1 signaling, whereas specific leucine metabolites or leucine oxidation rates do not play a role. In human fibroblasts deficient in leucine catabolic steps, we observed regulation consistent with sustaining a more efficient MAP4K3 and mTOR-S6K1 signaling. Such regulatory circuit might serve to protect cells against detrimental consequences of reduced nutrient utilization in human conditions associated with disturbed leucine metabolism.