Atelocollagen-based gene transfer in cells allows high-throughput screening of gene functions

Multifunctional DNA-Collagen Biomaterials: Developmental Advances and Biomedical Applications

The complexation of nucleic acids and collagen forms a platform biomaterial greater than the sum of its parts. This union of biomacromolecules merges the extracellular matrix functionality of collagen with the designable bioactivity of nucleic acids, enabling advances in regenerative medicine, tissue engineering, gene delivery, and targeted therapy. This review traces the historical foundations and critical applications of DNA-collagen complexes and highlights their capabilities, demonstrating them as biocompatible, bioactive, and tunable platform materials. These complexes form structures across length scales, including nanoparticles, microfibers, and hydrogels, a process controlled by the relative amount of each component and the type of nucleic acid and collagen. The broad distribution of different types of collagen within the body contributes to the extensive biological relevance of DNA-collagen complexes. Functional nucleic acids can form these complexes, such as siRNA, antisense oligonucleotides, DNA origami nanostructures, and, in particular, single-stranded DNA aptamers, often distinguished by their rapid self-assembly at room temperature and formation without external stimuli and modifications. The simple and seamless integration of nucleic acids within collagenous matrices enhances biomimicry and targeted bioactivity, and provides stability against enzymatic degradation, positioning DNA-collagen complexes as an advanced biomaterial system for many applications including angiogenesis, bone tissue regeneration, wound healing, and more.

Self-Assembled DNA-Collagen Bioactive Scaffolds Promote Cellular Uptake and Neuronal Differentiation

Different modalities of DNA/collagen complexes have been utilized primarily for gene delivery studies. However, very few studies have investigated the potential of these complexes as bioactive scaffolds. Further, no studies have characterized the DNA/collagen complex formed from the interaction of the self-assembled DNA macrostructure and collagen. Toward this investigation, we report herein the fabrication of novel bioactive scaffolds formed from the interaction of sequence-specific, self-assembled DNA macrostructure and collagen type I. Varying molar ratios of DNA and collagen resulted in highly intertwined fibrous scaffolds with different fibrillar thicknesses. The formed scaffolds were biocompatible and presented as a soft matrix for cell growth and proliferation. Cells cultured on DNA/collagen scaffolds promoted the enhanced cellular uptake of transferrin, and the potential of DNA/collagen scaffolds to induce neuronal cell differentiation was further investigated. The DNA/collagen scaffolds promoted neuronal differentiation of precursor cells with extensive neurite growth in comparison to the control groups. These novel, self-assembled DNA/collagen scaffolds could serve as a platform for the development of various bioactive scaffolds with potential applications in neuroscience, drug delivery, tissue engineering, and in vitro cell culture.

Self-assembled VEGF-R2 targeting DNA aptamer-collagen fibers stimulate an angiogenic-like endothelial cell phenotype

Vascularization of engineered tissue is one of the hallmark challenges of tissue engineering. Leveraging self-assembled nucleic acid-collagen complexes (NACCs), we mixed a VEGF-R2 targeting aptamer or its receptor agonist divalent assembly with type I collagen to assemble NACC microfibers. Human umbilical vein endothelial cells (HUVECs) quickly remodeled these fibers into tubulogenic-like structures over 48 h. Moreover, NACCs made with the receptor agonist divalent aptamer assembly promoted enhanced expression of von Willebrand factor (vWF), angiopoietin-2 (ANGPT-2), and matrix metalloproteinase-2 (MMP-2) by HUVECs as measured by either immunocytochemistry or ELISA. The findings suggest, endothelial cell phenotype was directed by both biochemical cues afforded by the agonist behavior of the divalent aptamer assembly as well as by the biophysical cues afforded by the fibrous topography. Collectively, these results support the development of an angiogenic endothelial cell phenotype stimulated by the VEGF-R2 agonist NACC fibers. Thus, the combination of engineered DNA aptamer nanotechnology and DNA-collagen complexation phenomena is a promising biofunctional natural scaffold material system for tissue engineering and regenerative medicine applications.

Mineralized DNA-collagen complex-based biomaterials for bone tissue engineering

DNA is a highly polyanionic biomolecule that complexes with both collagen and hydroxyapatite. By combining these complexes, we synthesized nucleic-acid collagen complexes (NACC) mineralized with hydroxyapatite. The composite complexes were made using a short, monodisperse single-stranded DNA, type I collagen, and mineralizing medium. They rapidly self-assembled into both mineralized NACC microfibers and 3D NACC gels. At the nanoscale, these complexes are hierarchical, interwoven, curly nanofibrils resembling native extracellular matrix, which mineralized an interpenetrating nanocrystalline hydroxyapatite phase. Mineralization was able to be done either before or after NACC formation enabling temporal control of the process. In response to the NACC material, primary human osteoblasts took on an osteocyte-like morphology. Moreover, the cells agglomerated and remodeled the NACC gels into densified, tissue-like structures within 3 days. NACC fibers and gels have promise not only as osteoconductive coatings and scaffolds, but as coatings and scaffolds for any tissue using this new form of naturally-derived biomaterials.

Nanoparticle Delivery Systems for DNA/RNA and their Potential Applications in Nanomedicine

The rapid development of nanotechnology has a great influence on the fields of biology, physiology, and medicine. Over recent years, nanoparticles have been widely presented as nanocarriers to help the delivery of gene, drugs, and other therapeutic agents with cellular targeting ability. Advances in the understanding of gene delivery and RNA interference (RNAi)-based therapy have brought increasing attention to understanding and tackling complex genetically related diseases, such as cancer, cardiovascular and pulmonary diseases, autoimmune diseases and infections. The combination of nanocarriers and DNA/RNA delivery may potentially improve their safety and therapeutic efficacy. However, there still exist many challenges before this approach can be practiced in the clinic. In this review, we provide a comprehensive summary on the types of nanoparticle systems used as nanocarriers, highlight the current use of nanocarriers in recombinant DNA and RNAi molecules delivery, and the current landscape of gene-based nanomedicine-ranging from diagnosis to therapeutics. Finally, we briefly discuss the biosafety concerns and limitations in the preclinical and clinical development of nanoparticle gene systems.

Oligomer Length Defines the Self-Assembly of Single-Stranded DNA-Collagen Complex Fibers

Collagen and single-stranded DNA (ssDNA) complex to self-assemble into fibers depending on the length of the ssDNA and the relative amounts of collagen and ssDNA in solution. We report for the first time that when monodisperse, random sequences of ssDNA in the range of 15-90 nucleotides and type I collagen were mixed together at room temperature, fibers several tens of micrometers in length and as large as 10 μm in diameter were formed. Fiber formation was rapid and spontaneous, requiring no further treatment after mixing. Most notably, more ssDNA oligomers were incorporated into the fibers formed using shorter ssDNA oligomers. Endothelial cells formed angiogenic-like structures using the fibers with elevated expression of von Willebrand factor for cells in direct contact with the fibers. These fibers open the door to future applications in the administration and functionality of ssDNA and collagen.

Development of magnetic anionic liposome/atelocollagen complexes for efficient magnetic drug targeting

Magnetic nanoparticle-incorporated liposomes (magnetic liposomes) are considered a promising site-specific drug delivery carrier vehicle. With regard to their surface charge, magnetic anionic liposomes (Mag-AL) demonstrate little toxicity in comparison with magnetic cationic liposomes (Mag-CL), whereas their cellular association and uptake efficiency are low. In the current study, we constructed complexes of Mag-AL and atelocollagen (ATCOL), which is a biocompatible and minimally immunogenic biomaterial, to improve the cellular uptake properties of Mag-AL in vitro and in vivo. The cellular association and/or uptake of Mag-AL in RAW264 cells, a murine macrophage-like cell line, under a magnetic field was significantly increased when Mag-AL was complexed with ATCOL, and the highest cellular association was observed with complexes constructed using 5 µg/mL of ATCOL. The complexes showed liposome concentration-dependent and time-dependent cellular association under a magnetic field, and their cellular uptake efficiency was comparable with that of Mag-CL. In addition, Mag-CL showed significant cytotoxicity in a liposome concentration-dependent manner, whereas Mag-AL/ATCOL complexes produced no cytotoxic effect against RAW264 cells. Furthermore, the efficient cellular association of Mag-AL/ATCOL complexes in RAW264 cells was observed even in the presence of serum, and their liver accumulation was significantly increased at a magnetic field-exposed region after intravenous injection in rats. These results indicate that Mag-AL/ATCOL complexes could be a safe and efficient magnetic responsive drug carrier.

An Atelocollagen Coating for Efficient Local Gene Silencing by Using Small Interfering RNA

In the last decades, many efforts have been made to counteract adverse effects after stenting atherosclerotic coronary arteries. A breakthrough in better vascular wall regeneration was noted in the new era of drug-eluting stents. A novel personalized approach is the development of gene-eluting stents promising an alteration in gene expression involved in regeneration. We investigated a coating system consisting of the polymer atelocollagen (ATCOL) and a specific small interfering RNA (siRNA) for intercellular adhesion molecule-1 (ICAM-1) found on the surface of defective endothelial cells (ECs). We demonstrated very high cell viability, in which EA.hy926 grew on 0.008% or 0.032% ATCOL layers. Additionally, hemocompatibility assays proved the biocompatibility of this coating. The highest transfection efficiency with EA.hy926 was achieved with 5 μg siRNA immobilized in ATCOL after 2 days. The release of fluorescent-labeled siRNA was about 9 days. Long-term knockdown of ICAM-1 was analyzed by flow cytometry, revealing that the coating with 0.008% ATCOL and 5 μg siICAM-1 provoked gene silencing up to 8 days. 5′-RNA ligase-mediated rapid amplification of cDNA ends PCR (RLM-RACE-PCR) demonstrated the specificity of our established ATCOL gene-silencing coating, meaning that our coating is well suited for further investigations in in vivo studies. Herein, we would like to demonstrate that our ATCOL is well-suited for better artery wall regeneration after stent implantation.

Efficient delivery of micro RNA to bone-metastatic prostate tumors by using aptamer-conjugated atelocollagen in vitro and in vivo

Bone is the primary site of skeletal metastasis in prostate cancer (PCa). Atelocollagen (ATE)-mediated siRNA delivery system can be used to silence endogenous genes involved in PCa metastatic tumor cell growth. However, we hope that the delivery system can target PCa cells to reduce damage to the bone tissue and improve the therapeutic effect. RNA aptamer (APT) A10-3.2 has been used as a ligand to target PCa cells that express prostate-specific membrane antigen (PSMA). APT was investigated as a PSMA-targeting ligand in the design of an ATE-based microRNA (miRNA; miR-15a and miR-16-1) vector to PCa bone metastasis. To observe the targeted delivery and transfection efficiency of ATE-APT in PSMA-overexpressing cells, luciferase activity and biodistribution of nanoparticles in Balb/c mice was analyzed. The anticancer effect of nanoparticles in vivo was investigated using the survival times of human PCa bone metastasis mice model. Luciferase assays of pGL-3 expression against PC3 (PSMA(-)) and LNCaP (PSMA(+)) cells showed that the transfection efficiency of the synthesized DNA/ATE-APT complex was higher than that of the DNA/ATE complex. The anticancer efficacy of miRNA/ATE-APT was superior to those of other treatments in vivo. This PSMA-targeted system may prove useful in widening the therapeutic window and allow for selective killing of PCa cells in bone metastatic foci.

Substrate-mediated, high-efficiency siRNA electroporation

Here, we outline a method for surface-mediated transfection of small interfering RNA (siRNA) using electroporation. Cells are cultured on an electrode carrying siRNA. After the cells are adhered on the electrode surface, an electric pulse is applied to release siRNA from the surface and transfect it into the cells. A siRNA electroporation microarray is also presented for high-throughput screening of the functions of many siRNAs.

The use of gene activated matrix to mediate effective SMAD2 gene silencing against hypertrophic scar

Hypertrophic scar (HS) originates from the over-expression of transforming growth factor β (TGF-β) and downstream SMAD2. With attempts to rectify HS by RNA interference (RNAi) against SMAD2, we report the design of plasmid DNA encoding SMAD2 siRNA (pSUPER-SMAD2), and identify the optimal siRNA sequence toward maximal RNAi efficiency. To realize effective and sustained RNAi, we developed gene activated matrix (GAM) based on porous atelocollagen scaffold and embedded trimethyl chitosan-cysteine (TMCC)/pSUPER-SMAD2 polyplexes for promoting cell growth and gene transfection. The GAM exhibited porosity higher than 80%, pore size of 200-250 μm, desired mechanical strength, and sustained pSUPER-SMAD2 release profiles. Normal skin fibroblasts (NSFs) and hypertrophic scar fibroblasts (HSFs) were allowed to infiltrate and proliferate in GAM; at the meantime they were transfected with TMCC/pSUPER-SMAD2 polyplexes to display remarkably reduced SMAD2 levels that lasted for up to 10 days, consequently inhibiting the over-production of type I and type III collagen. We further unraveled the notably higher transfection levels of GAM in three-dimensional (3D) than in 2D environment, which was attributed to the improved cell-matrix interactions that promote cell proliferation and polyplex internalization. This highly safe and effective GAM may serve as a promising candidate towards HS treatment.

New aspects of gene-silencing for the treatment of cardiovascular diseases

Coronary heart disease (CHD), mainly caused by atherosclerosis, represents the single leading cause of death in industrialized countries. Besides the classical interventional therapies new applications for treatment of vascular wall pathologies are appearing on the horizon. RNA interference (RNAi) represents a novel therapeutic strategy due to sequence-specific gene-silencing through the use of small interfering RNA (siRNA). The modulation of gene expression by short RNAs provides a powerful tool to theoretically silence any disease-related or disease-promoting gene of interest. In this review we outline the RNAi mechanisms, the currently used delivery systems and their possible applications to the cardiovascular system. Especially, the optimization of the targeting and transfection procedures could enhance the efficiency of siRNA delivery drastically and might open the way to clinical applicability. The new findings of the last years may show the techniques to new innovative therapies and could probably play an important role in treating CHD in the future.

Y-box binding protein-1 regulates cell proliferation and is associated with clinical outcomes of osteosarcoma

Background:

Prognosis of osteosarcoma (OS) with distant metastasis and local recurrence is still poor. Y-box binding protein-1 (YB-1) is a multifunctional protein that can act as a regulator of transcription and translation and its high expression of YB-1 protein was observed in OS, however, the role of YB-1 in OS remains unclear.

Methods:

Y-box binding protein-1 expression in OS cells was inhibited by specific small interfering RNAs to YB-1 (si-YB-1). The effects of si-YB-1 in cell proliferation and cell cycle transition in OS cells were analysed in vitro and in vivo. The association of nuclear expression of YB-1 and clinical prognosis was also investigated by immunohistochemistry.

Results:

Proliferation of OS cell was suppressed by si-YB-1 in vivo and in vitro. The expression of cyclin D1 and cyclin A were also decreased by si-YB-1. In addition, si-YB-1 induced G1/S arrest with decreased cyclin D1 and cyclin A in OS cell lines. Direct binding of YB-1 in OS cell lines was also observed. Finally, the nuclear expression of YB-1 was significantly related to the poorer overall survival in OS patients.

Conclusion:

Y-box binding protein-1 would regulate cell cycle progression at G1/S and tumour growth in human OS cells in vitro and in vivo. Nuclear expression of YB-1 was closely associated with the prognosis of OS, thus, YB-1 simultaneously could be a potent molecular target and prognostic biomarker for OS.

Calcium phosphate composite layers for surface-mediated gene transfer

In this review, the surface-mediated gene transfer system using calcium phosphate composite layers is described. Calcium phosphate ceramics are osteoconductive bioceramics used typically in orthopedic and dental applications. Additionally, calcium phosphate particles precipitated by a liquid-phase process have long been used as a safe and biocompatible transfection reagent in molecular biology. Recently, calcium phosphate composite layers immobilizing DNA were fabricated on the surfaces of base materials through a biomimetic process using supersaturated solutions. These composite layers possess useful characteristics of both osteoconductive bioceramics and transfection reagents; they thus provide a biocompatible surface to support cell adhesion and growth, and can stimulate the cell effectively via surface-mediated gene transfer. By modifying the fabrication conditions, physicochemical and biological properties of the composite layers can be varied. With such an approach, these composite layers can be designed to have improved affinity for cells and to exhibit increased gene transfer efficiency over that of conventional lipid transfection reagents. The composite layers with the increased gene transfer efficiency induced specific cell differentiation and tissue regeneration in vivo. These composite layers, given their good biocompatibility and the potential to control cell behavior on their surfaces, have great potential in tissue engineering applications.

The miRNA pathway in neurological and skeletal muscle disease: implications for pathogenesis and therapy

RNA interference (RNAi) represents a powerful post-transcriptional gene silencing network which fine-tunes gene expression in all eukaryotic cells. The endogenous triggers of RNAi, microRNAs (miRNAs), are proposed to regulate expression of up to a third of all protein-coding genes, and have been shown to have critical roles in developmental processes including in the central nervous system and skeletal muscle. Further, many have been reported to display differential expression in various disease states. Here we describe present understanding of the biogenesis and function of miRNAs, review current knowledge of miRNA abnormalities in both human neurological and skeletal muscle disease and discuss their potential as novel disease biomarkers. Finally, we highlight the many ways in which the miRNA pathway may be targeted for therapeutic benefit.

The living microarray: a high-throughput platform for measuring transcription dynamics in single cells

Background

Current methods of measuring transcription in high-throughput have led to significant improvements in our knowledge of transcriptional regulation and Systems Biology. However, endpoint measurements obtained from methods that pool populations of cells are not amenable to studying time-dependent processes that show cell heterogeneity.

Results

Here we describe a high-throughput platform for measuring transcriptional changes in real time in single mammalian cells. By using reverse transfection microarrays we are able to transfect fluorescent reporter plasmids into 600 independent clusters of cells plated on a single microscope slide and image these clusters every 20 minutes. We use a fast-maturing, destabilized and nuclear-localized reporter that is suitable for automated segmentation to accurately measure promoter activity in single cells. We tested this platform with synthetic drug-inducible promoters that showed robust induction over 24 hours. Automated segmentation and tracking of over 11 million cell images during this period revealed that cells display substantial heterogeneity in their responses to the applied treatment, including a large proportion of transfected cells that do not respond at all.

Conclusions

The results from our single-cell analysis suggest that methods that measure average cellular responses, such as DNA microarrays, RT-PCR and chromatin immunoprecipitation, characterize a response skewed by a subset of cells in the population. Our method is scalable and readily adaptable to studying complex systems, including cell proliferation, differentiation and apoptosis.

Patterned transgene expression in multiple-channel bridges after spinal cord injury

Patterning of gene delivery on sub-millimeter length scales within tissue engineering scaffolds is fundamental to recreating the complex architectures of tissues. Surface-mediated delivery of lipoplexes mixed with fibronectin was investigated to pattern vectors within 250 microm channels in poly(lactide-co-glycolide) (PLG) bridges. Initial studies performed in vitro on PLG surfaces indicated that a DNA density of 0.07 microg mm(-2) inside each channel with a weight ratio of DNA to fibronectin of 1:20 maximized the number of transfected cells and the levels of transgene expression. Patterned vectors encoding for nerve growth factor (NGF) resulted in localized neurite extension within the channel. Translation to three-dimensional multiple-channel bridges enabled patterned transfection of different vectors throughout the channels for DNA:fibronectin ratios of 1:4 and multiple DNA depositions, with a large increase of neural cell bodies and neurite extension for delivery of DNA encoding for NGF. In vivo, the immobilization of non-viral vectors within the channels resulted in localized transfection within the pore structure of the bridge immediately around the channels of the bridge containing DNA. This surface immobilization strategy enables patterned gene delivery in vitro and in vivo on length scales of hundreds of microns and may find utility in strategies aimed at regenerating tissues with complex architectures.

Regeneration of bone- and tendon/ligament-like tissues induced by gene transfer of bone morphogenetic protein-12 in a rat bone defect

Members of the bone morphogenetic protein (BMP) family have diverse physiological roles. For instance, BMP-2 stimulates osteogenesis, while BMP-12 induces the formation of tendon/ligament-like tissues. Here, we designed a study to determine whether BMP-12 has bone and/or cartilage regeneration abilities similar to those of BMP-2. We implanted plasmid vectors encoding either BMP-2 or BMP-12 in rats with femur defects, and monitored the bone healing process for 8-weeks. The BMP-12 transgene induced prominent fibrogenesis by 2 weeks, with bone substitution occurring by 8 weeks. BMP-2, however, was associated predominantly with osteogenesis throughout the 8 week period. Thus, we conclude that BMP-12 does not function similarly to BMP-2 during bone healing. Further work is needed to better understand the mechanisms by which it stimulates bony growths to replace the connective tissues formed during the first stages of bone healing.

Efficacy of immobilized polyplexes and lipoplexes for substrate-mediated gene delivery

Non-viral gene delivery by immobilization of complexes to cell-adhesive biomaterials, a process termed substrate-mediated delivery, has many in vitro research applications such as transfected cell arrays or models of tissue growth. In this report, we quantitatively investigate the efficiency of gene delivery by surface immobilization, and compare this efficiency to the more typical bolus delivery. The ability to immobilize vectors while allowing cellular internalization is impacted by the biomaterial and vector properties. Thus, to compare this efficiency between vector types and delivery methods, transfection conditions were initially identified that maximized transgene expression. For surface delivery from tissue culture polystyrene, DNA complexes were immobilized to pre-adsorbed serum proteins prior to cell seeding, while for bolus delivery, complexes were added to the media above adherent cells. Mathematical modeling of vector binding, release, and cell association using a two-site model indicated that the kinetics of polyplex binding to cells was faster than for lipoplexes, yet both vectors have a half-life on the surface of approximately 17 min. For bolus and surface delivery, the majority of the DNA in the system remained in solution or on the surface, respectively. For polyplexes, the efficiency of trafficking of cell-associated polyplexes to the nucleus for surface delivery is similar or less than bolus delivery, suggesting that surface immobilization may decrease the activity of the complex. The efficiency of nuclear association for cell-associated lipoplexes is similar or greater for surface delivery relative to bolus. These studies suggest that strategies to enhance surface delivery for polyplexes should target the vector design to enhance its potency, whereas enhancing lipoplex delivery should target the material design to increase internalization.

Gene delivery into hepatocytes with the preS/liposome/DNA system

Gene delivery into human hepatocytes remains a critical issue for the development of liver-directed gene therapy. Gene delivery based on non-viral vectors is an attractive approach relative to viral vectors. In this report, novel delivery system of preS/liposome/DNA virus-like particle (VLP) was developed for gene transfection into hepatocytes in vivo and in vitro. Plasmid pCMVbeta, expressing beta-galactosidase, was encapsulated with cationic liposome, and then the histidine-tagged preS domain of hepatitis B virus was coated on the surface of liposome/DNA to form preS/liposome/ DNA VLP. Transfection efficiencies of preS/liposome/DNA, liposome/DNA, naked DNA and preS were analyzed using several different human cell lines. The highest transfection efficiency was found using preS/liposome/DNA VLP as the transfection reagent in human hepatocyte (HH) cell line. Results show that preS domain of hepatitis B virus coated on liposome/DNA can be used for highly efficient gene transfection into human hepatocytes. Moreover, the target characteristic of preS/liposome/DNA was analyzed in vivo. After preS/liposome/DNA VLP was injected into immunocompromised (Nude) mice via the tail vein, most of beta-galactosidase was expressed in the liver; however, no significant target expression was found with the injection of liposome/ DNA or naked DNA. Our results show that preS/liposome/DNA VLP can be used as a novel liver-specific gene delivery system.

Reverse transfection using gold nanoparticles

Reverse transfection from a solid surface has the potential to deliver genes into various types of cell and tissue more effectively than conventional methods of transfection. We present a method for reverse transfection using a gold colloid (GC) as a nanoscaffold by generating nanoclusters of the DNA/reagent complex on a glass surface, which could then be used for the regulation of the particle size of the complex and delivery of DNA into nuclei. With this method, we have found that the conjugation of gold nanoparticles (20 nm in particle size) to the pEGFP-N1/Jet-PEI complex resulted in an increase in the intensity of fluorescence of enhanced green fluorescent protein (EGFP) (based on the efficiency of transfection) from human mesenchymal stem cells (hMSCs), as compared with the control without GC. In this manner, we constructed a method for reverse transfection using GC to deliver genes into the cells effectively.

Local and systemic delivery of siRNAs for oligonucleotide therapy

RNA interference (RNAi) is a relatively new found phenomenon of posttranscriptional gene silencing to regulate the expression of multiple genes involved in a wide range of biological processes. The gene-silencing technology via RNAi has also been developed into a commonly anti-gene method. Furthermore, in vivo data indicate that small interfering RNAs (siRNAs) may be used to treat human diseases. However, the most challenging issue to a successful in vivo application is the development of a delivery system that can transport siRNA molecules into the tissues and/or the cells of interest. Also, the evaluation of siRNA potency in vivo is central for the selection of therapeutic siRNAs. In this chapter, the effects of atelocollagen-delivered siRNAs in live animals were monitored using bioluminescence imaging.

In vivo silencing of a molecular target by short interfering RNA electroporation: tumor vascularization correlates to delivery efficiency

Screening for a molecular target for cancer therapy requires multiple steps, of which an important one is evaluation of the knockdown effect of the target molecule on pregrown xenograft tumors. However, methods currently used for local administration of knockdown reagents, such as short interfering RNA (siRNA), are not satisfactory as to simplicity and efficiency. We established an electroporation method involving a constant voltage and "plate and fork" type electrodes and used it for in vivo delivery of siRNA. The delivery efficiency correlated to the electric current. The electric current correlated to the microvascular density and vascular endothelial growth factor (VEGF) expression and exhibited a threshold that guaranteed efficient delivery. Consequently, we showed that the vascularization and VEGF expression in tumors determined the efficiency of delivery of siRNA by electroporation. VEGF was chosen as a model target. VEGF siRNA electroporation suppressed the growth of tumors exhibiting high VEGF expression to less than 10% of the control level, but it had no effect on low VEGF-expressing tumors. Notably, a long interval (20 days) of electroporation was enough to obtain a satisfactory effect. Systemically injected siRNA could also be delivered into tumors by this method. Our data will provide the technical basis for in vivo electroporation, and this simple and efficient siRNA delivery method is applicable to in vivo comprehensive screening for a molecular target.

Atelocollagen-mediated local and systemic applications of myostatin-targeting siRNA increase skeletal muscle mass

RNA interference (RNAi) offers a novel therapeutic strategy based on the highly specific and efficient silencing of a target gene. Since it relies on small interfering RNAs (siRNAs), a major issue is the delivery of therapeutically active siRNAs into the target tissue/target cells in vivo. For safety reasons, strategies based on vector delivery may be of only limited clinical use. The more desirable approach is to directly apply active siRNAs in vivo. Here, we report the effectiveness of in vivo siRNA delivery into skeletal muscles of normal or diseased mice through nanoparticle formation of chemically unmodified siRNAs with atelocollagen (ATCOL). ATCOL-mediated local application of siRNA targeting myostatin, a negative regulator of skeletal muscle growth, in mouse skeletal muscles or intravenously, caused a marked increase in the muscle mass within a few weeks after application. These results imply that ATCOL-mediated application of siRNAs is a powerful tool for future therapeutic use for diseases including muscular atrophy.

Non-viral gene transfection technologies for genetic engineering of stem cells

The recent rapid progress of molecular biology together with the steady progress of genome projects has given us some essential and revolutionary information about DNA and RNA to elucidate various biological phenomena at a genetic level. Under these circumstances, the technology and methodology of gene transfection have become more and more important to enhance the efficacy of gene therapy for several diseases. In addition, gene transfection is a fundamental technology indispensable to the further research development of basic biology and medicine regarding stem cells. Stem cells genetically manipulated will enhance the therapeutic efficacy of cell transplantation. In this paper, the carrier and technology of gene delivery are briefly overviewed while the applications to the basic researches of biology and medicine as well as regenerative medical therapy are introduced. A new non-viral carrier and the cell culture system are described to efficiently manipulate stem cells.

An siRNA against JC virus (JCV) agnoprotein inhibits JCV infection in JCV-producing cells inoculated in nude mice

JC virus (JCV) is the etiological agent of the demyelinating disease progressive multifocal leukoencephalopathy (PML). Because JCV has a very narrow host range, it has been difficult to develop an animal model of JCV infection; as a result, no effective therapy for PML has been established. In this study, we have tried to create an animal model that replaces an in vivo JCV infection. As a result, we have obtained a stable persistence of JCV-infected human cells in the mouse brain by inoculating the virus-infected cells into the nude mice brains. In this model, the JCV-infected cells were well preserved in the nude mouse brains for 2 weeks. We then treated JCV-injected brains with an siRNA against the JCV agnoprotein that is known to be an effective inhibitor of JCV infection in vitro. A highly purified type I collagen, atelocollagen, was used as a carrier for the siRNA. The siRNA inhibited the expression of JCV protein in inoculated JCV-infected cells in the mouse brain, compared to the medium containing only atelocollagen used as a placebo. Thus, the combination of siRNA and atelocollagen might be a candidate therapeutic agent for the treatment of JCV infection.

Downregulation of monocyte chemoattractant protein-1 involving short interfering RNA attenuates hapten-induced contact hypersensitivity

Contact hypersensitivity (CHS) is a common skin disease, presenting clinically as allergic contact dermatitis. At inflammatory sites in a typical CHS model in the mouse ear, elevated expression of monocyte chemoattractant protein-1 (MCP-1) has been reported. MCP-1 is a potent chemotactic factor for many types of leukocytes including monocytes/macrophages and T cells. In this study, we aimed at developing a therapy for CHS involving RNA interference targeting MCP-1. A short interfering RNA (siRNA) to mouse MCP-1 successfully inhibited the secretion of MCP-1 by a fibroblastic cell line, L929, and RAW 264.7 cells derived from macrophages, and strikingly suppressed ear swelling in a CHS model. The siRNA systemically administered inhibited the infiltration of both monocytes/macrophages and T cells in the CHS model. Atelocollagen was used in this therapy as a delivery reagent for siRNA into the animal body. Atelocollagen facilitated the incorporation of the siRNA into macrophages/monocytes and fibroblasts, which vigorously secrete MCP-1 protein at inflammatory sites in CHS. This therapy had no adverse effects such as induction of interferon, or liver or renal damage. Our data indicate that the systemic delivery of siRNA targeting MCP-1 is a potent therapeutic strategy for CHS treatment.

Bioluminescence imaging for assessment and normalization in transfected cell arrays

Transfected cell arrays (TCAs) represent a high-throughput technique to correlate gene expression with functional cell responses. Despite advances in TCAs, improvements are needed for the widespread application of this technology. We have developed a TCA that combines a two-plasmid system and dual-bioluminescence imaging to quantitatively normalize for variability in transfection and increase sensitivity. The two-plasmids consist of: (i) normalization plasmid present within each spot, and (ii) functional plasmid that varies between spots, responsible for the functional endpoint of the array. Bioluminescence imaging of dual-luciferase reporters (renilla, firefly luciferase) provides sensitive and quantitative detection of cellular response, with minimal post-transfection processing. The array was applied to quantify estrogen receptor alpha (ERalpha) activity in MCF-7 breast cancer cells. A plasmid containing an ERalpha-regulated promoter directing firefly luciferase expression was mixed with a normalization plasmid, complexed with cationic lipids and deposited into an array. ER induction mimicked results obtained through traditional assays methods, with estrogen inducing luciferase expression 10-fold over the antiestrogen fulvestrant or vehicle. Furthermore, the array captured a dose response to estrogen, demonstrating the sensitivity of bioluminescence quantification. This system provides a tool for basic science research, with potential application for the development of patient specific therapies.

Matrices and scaffolds for DNA delivery in tissue engineering

Regenerative medicine aims to create functional tissue replacements, typically through creating a controlled environment that promotes and directs the differentiation of stem or progenitor cells, either endogenous or transplanted. Scaffolds serve a central role in many strategies by providing the means to control the local environment. Gene delivery from the scaffold represents a versatile approach to manipulating the local environment for directing cell function. Research at the interface of biomaterials, gene therapy, and drug delivery has identified several design parameters for the vector and the biomaterial scaffold that must be satisfied. Progress has been made towards achieving gene delivery within a tissue engineering scaffold, though the design principles for the materials and vectors that produce efficient delivery require further development. Nevertheless, these advances in obtaining transgene expression with the scaffold have created opportunities to develop greater control of either delivery or expression and to identify the best practices for promoting tissue formation. Strategies to achieve controlled, localized expression within the tissue engineering scaffold will have broad application to the regeneration of many tissues, with great promise for clinical therapies.

Application of Atelocollagen-mediated siRNA Delivery for RNAi Therapies

RNAi has rapidly become a powerful tool for drug target discovery and validation in an in vitro culture system and, consequently, interest is rapidly growing for extension of its application to in vivo systems, such as animal disease models and human therapeutics. Novel treatments and drug discovery in pre-clinical studies based on RNAi are currently targeting a wide range of diseases, including viral infections and cancers by the local administration of synthetic small interfering RNA (siRNA) that target local lesions. Recently, specific methods for the systemic administration of siRNAs have been reported to treat non-human primates or a cancer metastasis model. In vivo siRNA-delivery technology is a key hurdle to the successful therapeutic application of RNAi. This article reviews the non-viral delivery system of atelocollagen for siRNA, which could be useful for functional screening of the genes in vitro and in vivo, and will provide a foundation for further development of RNAi therapeutics.

Method for reverse transfection using gold colloid as a nano-scaffold

DNA microarray of non-viral reverse transfection in cell engineering allows drastic downsizing of large-scale functional screening of genes and siRNAs. However the control of localizability and efficiency of the microarray is still considered as a critical barrier in practical use. One of the major breakthrough to increase the transfection efficiency may be control in the condition of DNA/transfection reagent complex on the microarray surface. In this paper, we showed that negatively charged gold colloid (GC) is successfully used to control the DNA/reagent complex on a glass surface. The conjugation of gold nanoparticles (20 nm in diameter) to the pEGFP-N1/Jet-PEI complex resulted in a more than 2.5-fold increase in the intensity of fluorescence of enhanced green fluorescent protein (EGFP) (based on the efficiency of transfection) from human mesenchymal stem cells (hMSCs), as compared to the control without GC. Our method for reverse transfection should be useful not only for cell array-based analyses but also as a novel gene-delivery method for gene therapy in regenerative medicine.

Atelocollagen-mediated systemic DDS for nucleic acid medicines

The goal of our research is to provide a practical platform for drug delivery in oligonucleotide therapy. We report here the efficacy of an atelocollagen-mediated oligonucleotide delivery system applied to systemic siRNA and antisense oligonucleotide treatments in animal disease models. Atelocollagen and oligonucleotides formed a complex of nanosized particles, which was highly stable against nucleases. The complex allowed oligonucleotides to be delivered efficiently into several organs and tissues via intravenous administration. In a tumor metastasis model, the complex successfully delivered siRNA to metastasized tumors in bone tissue and inhibited their growth. We also demonstrated that a single intravenous treatment of the antisense oligodeoxynucleotide complex suppressed ear dermatitis in a contact hypersensitivity model. These results indicate the strong potential of the atelocollagen-mediated drug delivery system for practical therapeutic technology.

Electrochemical Monitoring of Cellular Signal Transduction with a Secreted Alkaline Phosphatase Reporter System

Electrochemical monitoring of cellular signal transduction under three-dimensional (3-D) cell culture conditions has been demonstrated by combining cell-based microarrays with a secreted alkaline phosphatase (SEAP) reporter system. The cells were genetically engineered to produce SEAP under the control of nuclear factor kappaB (NFkappaB) enhancer elements, and they were embedded with a small volume of a collagen gel matrix on a pyramidal-shaped silicon microstructure. Cellular SEAP expression triggered by NFkappaB activation was assessed by two types of electrochemical systems. First, SEAP expression of a 3-D cell array on a chip was continuously monitored in situ for 2 days by scanning electrochemical microscopy (SECM). Since the SECM-based assay enables the evaluation of cellular respiratory activity, simultaneous measurements of cellular viability and signal transduction were possible. Further, we have developed an electrode-integrated cell culture device for parallel evaluation of cellular SEAP expression. The detector electrode was integrated around the silicon microhole. Two kinds of cells were immobilized on the array of microholes on the same chip for comparative characterization of their SEAP activity. This electrochemical microdevice can be applied to evaluate the SEAP expression activity in multiple cellular microarrays by a high-throughput method.

Bone Regeneration by Modified Gene-Activated Matrix: Effectiveness in Segmental Tibial Defects in Rats

Gene-activated matrix (GAM) is a matrix, such as collagen-containing plasmid vector, that encodes a protein to stimulate tissue regeneration. In the original GAM system, gene transfer efficiency was extremely low. We have recently reported that modifying GAM with calcium-phosphate precipitates (CaP) enhances the efficiency of gene transfer. The purpose of this study was to evaluate the effects of our modified GAM on tissue regeneration. We prepared critical size segmental bone defects in rat tibiae and transplanted GAM consisting of bovine atelocollagen and expression plasmid vector (bmp2), which encodes human BMP2, with or without CaP. The tibiae were later examined radiographically, histologically, and mechanically. Implantation of bmp2-CaP-collagen at 12 microg bmp2 bridged the bone defect at 4 weeks, and the strength of the bone was comparable to that of an intact tibia at 6 weeks. Implantation of bmp2-collagen at the same dose of bmp2 bridged the defect to a smaller extent. Neither collagen alone nor vacant vector-CaP-collagen bridged the defect. These results indicate that our modified GAM with CaP has the potential to be effective in tissue regeneration at lower plasmid DNA doses than used in previous studies.

Fiber molecular model of atelocollagen–small interfering RNA (siRNA) complex

Previously we represented molecular model of collagen triple helix-DNA double helix complex [G.M. Mrevlishvili, D.V. Svintradze, Int. J. Macromol. 36 (2005) 324-326; G.M. Mrevlishvili, D.V. Svintradze, Int. J. Macromol. 35 (2005) 243-245]. We also proved that during the complex formation hydration of triple helix destroys and forms new water bridges maintaining the complex nano-structure. In this paper we demonstrate that small interfering RNA binds to atelocollagen directly to form siRNA-atelocollagen fiber complex.

Gene Delivery by Immobilization to Cell-Adhesive Substrates

Biomaterials can potentially enhance the delivery of viral and nonviral vectors for both basic science and clinical applications. Vectors typically consist of nucleic acids (DNA, RNA) packaged with proteins, lipids, or cationic polymers, which facilitate cellular internalization and trafficking. These vectors can associate with biomaterials that support cell adhesion, a process we term substrate-mediated delivery. Substrate immobilization localizes the DNA and the delivery vector to the cellular microenvironment. The interaction between the vector and substrate must be appropriately balanced to mediate immobilization, yet allow for cellular internalization. Balancing the binding between the biomaterial and the vector is dependent upon the surface chemistries of the material and the vector, which can be designed to provide both specific (e.g., biotin-avidin, the strongest known noncovalent interaction between a protein and its ligand) and nonspecific (e.g., van der Waals) interactions. In this review, we describe the biomaterial and vector properties that mediate binding and gene transfer, identify potential applications, and present opportunities for further development.

Substrate-mediated delivery from self-assembled monolayers: effect of surface ionization, hydrophilicity, and patterning

Gene transfer has many potential applications in basic and applied sciences. In vitro, DNA delivery can be enhanced by increasing the concentration of DNA in the cellular microenvironment through immobilization of DNA to a substrate that supports cell adhesion. Substrate-mediated delivery describes the immobilization of DNA, complexed with cationic lipids or polymers, to a biomaterial or substrate. As surface properties are critical to the efficiency of the surface delivery approach, self-assembled monolayers (SAMs) of alkanethiols on gold were used to correlate surface chemistry of the substrate to binding, release, and transfection of non-specifically immobilized complexes. Surface hydrophobicity and ionization were found to mediate both DNA complex immobilization and transfection, but had no effect on complex release. Additionally, SAMs were used in conjunction with soft lithographic techniques to imprint substrates with specific patterns, resulting in patterned DNA complex deposition and transfection, with transfection efficiencies in the patterns nearing 40%. Controlling the interactions between complexes and substrates, with the potential for patterned delivery, can be used to locally enhance or regulate gene transfer, with applications to tissue engineering scaffolds and transfected cell arrays.

Layer-by-layer assembly of poly(ethyleneimine) and plasmid DNA onto transparent indium-tin oxide electrodes for temporally and spatially specific gene transfer

The layer-by-layer assembly technique was used to adsorb alternately poly(ethyleneimine) and plasmid DNA onto the surface of a transparent electrode made of indium-tin oxide. The surface with adsorbed poly(ethyleneimine) and DNA was characterized by X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and contact angle measurements. These analyses revealed that the alternate adsorption process generated a multilayered assembly of cationic poly(ethyleneimine) and anionic DNA. For the spatially and temporally specific gene transfer, cells were cultured on the plasmid-loaded electrode and then a short electric pulse was applied to the cell-electrode system. It was shown that, upon electric pulsing, the plasmid was released from the electrode and transferred into the cells, resulting in efficient gene expression even in primary cultured cells. Transfection could be effected for hippocampal neurons after 3-day culture on the plasmid-loaded electrode, which indicated the feasibility of selecting the time of transfection. Our results also showed that electroporation could be performed in a spatially specific manner by using a plasmid-arrayed electrode, demonstrating the feasibility of the method for the fabrication of transfected cell microarrays.

Efficient delivery of small interfering RNA to bone-metastatic tumors by using atelocollagen in vivo

Silencing of gene expression by small interfering RNAs (siRNAs) is rapidly becoming a powerful tool for genetic analysis and represents a potential strategy for therapeutic product development. However, there are no reports of systemic delivery for siRNAs toward treatment of bone-metastatic cancer. Accordingly, we report here that i.v. injection of GL3 luciferase siRNA complexed with atelocollagen showed effective reduction of luciferase expression from bone-metastatic prostate tumor cells developed in mouse thorax, jaws, and/or legs. We also show that the siRNA/atelocollagen complex can be efficiently delivered to tumors 24 h after injection and can exist intact at least for 3 days. Furthermore, atelocollagen-mediated systemic administration of siRNAs such as enhancer of zeste homolog 2 and phosphoinositide 3'-hydroxykinase p110-alpha-subunit, which were selected as candidate targets for inhibition of bone metastasis, resulted in an efficient inhibition of metastatic tumor growth in bone tissues. In addition, upregulation of serum IL-12 and IFN-alpha levels was not associated with the in vivo administration of the siRNA/atelocollagen complex. Thus, for treatment of bone metastasis of prostate cancer, an atelocollagen-mediated systemic delivery method could be a reliable and safe approach to the achievement of maximal function of siRNA.