Image-Guided Nanoparticle-Based siRNA Delivery for Cancer Therapy

With the discovery of RNA interference technology, small-interfering RNA (siRNA) has emerged as new powerful tool for gene therapy because of its high targeting specificity and selectivity. However, one of the limitations to successful gene therapy is the inability to monitor delivery of genes and therapeutic responses at the targeted site. Hence, a combinatorial approach of gene therapy with molecular imaging has been crucial in optimizing gene therapy. Recent advances in nanotechnology have made tremendous efforts to develop multifunctional nanoparticles that contain imaging and therapeutic agents together for image-guided therapy. The nanoparticles serve as contrast agents in imaging for disease detection with simultaneous delivery of therapeutics to cure the diseases. The therapy also helps to monitor the drug accumulation and assimilation in the body, thereby facilitating the evaluation of treatment effects. Here, we present an overview of polymer and lipid-based carriers for siRNA delivery, along with imaging agents as image guided therapy, in the treatment of breast, lung, liver, ovarian, cervical, and prostate cancers.

Trigger factor assisted soluble expression of recombinant spike protein of porcine epidemic diarrhea virus in Escherichia coli

BACKGROUND

Porcine epidemic diarrhea virus (PEDV) is a highly contagious enteric pathogen of swine. The spike glycoprotein (S) of PEDV is the major immunogenic determinant that plays a pivotal role in the induction of neutralizing antibodies against PEDV, which therefore is an ideal target for the development of subunit vaccine. In an attempt to develop a subunit vaccine for PEDV, we cloned two different fragments of S protein and expressed as glutathione S-transferase (GST)-tagged fusion proteins, namely rGST-COE and rGST-S1D, in E.coli. However, the expression of these recombinant protein antigens using a variety of expression vectors, strains, and induction conditions invariably resulted in inclusion bodies. To achieve the soluble expression of recombinant proteins, several chaperone co-expression systems were tested in this study.

RESULTS

We firstly tested various chaperone co-expression systems and found that co-expression of trigger factor (TF) with recombinant proteins at 15 °C was most useful in soluble production of rGST-COE and rGST-S1D compared to GroEL-ES and DnaK-DnaJ-GrpE/GroEL-ES systems. The soluble rGST-COE and rGST-S1D were purified using glutathione Sepharose 4B with a yield of 7.5 mg/l and 5 mg/l, respectively. Purified proteins were detected by western blot using mouse anti-GST mAb and pig anti-PEDV immune sera. In an indirect ELISA, purified proteins showed immune reactivity with pig anti-PEDV immune sera. Finally, immunization of mice with 10 μg of purified proteins elicited highly potent serum IgG and serum neutralizing antibody titers.

CONCLUSIONS

In this study, soluble production of recombinant spike protein of PEDV, rGST-COE and rGST-S1D, were achieved by using TF chaperone co-expression system. Our results suggest that soluble rGST-COE and rGST-S1D produced by co-expressing chaperones may have the potential to be used as subunit vaccine antigens.

Correction: Efficient gene transfection to liver cells via the cellular regulation of a multifunctional polylactitol-based gene transporter

Correction for 'Efficient gene transfection to liver cells via the cellular regulation of a multifunctional polylactitol-based gene transporter' by Young-Dong Kim et al., J. Mater. Chem. B, 2016, 4, 2208-2218.

Multifunctional Inorganic Nanoparticles: Recent Progress in Thermal Therapy and Imaging

Nanotechnology has enabled the development of many alternative anti-cancer approaches, such as thermal therapies, which cause minimal damage to healthy cells. Current challenges in cancer treatment are the identification of the diseased area and its efficient treatment without generating many side effects. Image-guided therapies can be a useful tool to diagnose and treat the diseased tissue and they offer therapy and imaging using a single nanostructure. The present review mainly focuses on recent advances in the field of thermal therapy and imaging integrated with multifunctional inorganic nanoparticles. The main heating sources for heat-induced therapies are the surface plasmon resonance (SPR) in the near infrared region and alternating magnetic fields (AMFs). The different families of inorganic nanoparticles employed for SPR- and AMF-based thermal therapies and imaging are described. Furthermore, inorganic nanomaterials developed for multimodal therapies with different and multi-imaging modalities are presented in detail. Finally, relevant clinical perspectives and the future scope of inorganic nanoparticles in image-guided therapies are discussed.

Gene therapy for bone tissue engineering

Gene therapy holds a great promise and has been extensively investigated to improve bone formation and regeneration therapies in bone tissue engineering. A variety of osteogenic genes can be delivered by combining different vectors (viral or non-viral), scaffolds and delivery methodologies. Ex vivo & in vivo gene enhanced tissue engineering approaches have led to successful osteogenic differentiation and bone formation. In this article, we review recent advances of gene therapy-based bone tissue engineering discussing strengths and weaknesses of various strategies as well as general overview of gene therapy.

Efficient gene transfection to liver cells via the cellular regulation of a multifunctional polylactitol-based gene transporter

A new polylactitol-based multifunctional gene carrier has shown low cytotoxicity, a high transfection efficiency, and liver cell targeting bothin vitroandin vivo.

Metabolic Syndrome Is not an Independent Risk Factor for Hearing Impairment

OBJECTIVE

We aimed to investigate the association between metabolic syndrome (MS) and hearing impairment (HI) using nationally representative data from Korean adults.

DESIGN, SETTING AND PARTICIPANTS

A total of 16,799 subjects (≥19 years old; 7,170 men and 9,629 women) who underwent pure tone audiometry testing were included in the analysis. Data were obtained from the fifth Korea National Health and Nutrition Examination Survey (2010-2012). Subjects were divided into two groups according to the presence of MS.

RESULTS

Among the subjects with MS, 47% had HI. Logistic regression analysis revealed that MS was not an independent risk factor for HI, although increased fasting plasma glucose (OR 1·4, 95% CI: 1·1-1·8) was independently associated with HI. In addition, older age, male sex, very low body mass index (≤17·5 kg/m2), lower education level, smoking history, and occupational noise exposure were independently associated with HI. For low-frequency HI, independent risk factors included older age, lower educational level, lower economic status, and very low BMI (≤17·5 kg/m2). For high-frequency HI, independent risk factors included older age, male sex, lower educational level, lower economic status, increased blood pressure, lower high-density lipoprotein cholesterol, and smoking history.

CONCLUSIONS

MS itself was not an independent risk factor for HI, and, among the individual metabolic components, only increased fasting plasma glucose was independently associated with HI.

Soluble RANKL expression in Lactococcus lactis and investigation of its potential as an oral vaccine adjuvant

BACKGROUND

To initiate mucosal immune responses, antigens in the intestinal lumen must be transported into gut-associated lymphoid tissue through M cells. Recently, it has been increasingly recognized that receptor activator of NF-kB ligand (RANKL) controls M cell differentiation by interacting with RANK expressed on the sub-epithelium of Peyer's patches. In this study, we increased the number of M cells using soluble RANKL (sRANKL) as a potent mucosal adjuvant.

RESULTS

For efficient oral delivery of sRANKL, we constructed recombinant Lactococcus lactis (L. lactis) IL1403 secreting sRANKL (sRANKL-LAB). The biological activity of recombinant sRANKL was confirmed by observing RANK-RANKL signaling in vitro. M cell development in response to oral administration of recombinant L. lactis was determined by 1.51-fold higher immunohistochemical expression of M cell marker GP-2, compared to that of non-treatment group. In addition, an adjuvant effect of sRANKL was examined by immunization of mice with M-BmpB as a model antigen after treatment with sRANKL-LAB. Compared with the wild-type L. lactis group, the sRANKL-LAB group showed significantly increased systemic and mucosal immune responses specific to M-BmpB.

CONCLUSIONS

Our results show that the M cell development by sRANKL-LAB can increase the antigen transcytotic capability of follicle-associated epithelium, and thereby enhance the mucosal immune response, which implies that oral administration of sRANKL is a promising adjuvant strategy for efficient oral vaccination.

Hyperosmotic polydixylitol for crossing the blood brain barrier and efficient nucleic acid delivery

Here, we introduce a polydixylitol based highly osmotic polymer that not only transmigrates the BBB by intra-arterial infusion of osmotic polyol but also triggers cellular uptake via modulation of caveolae mediated endocytosis.

Drug-conjugated polymers as gene carriers for synergistic therapeutic effect

The ability to safely and effectively transfer gene into cells is the fundamental goal of gene delivery. In spite of the best efforts of researchers around the world, gene therapy has limited success. This may be because of several limitations of delivering gene which is one of the greatest technical challenges in the modern medicine. To address these issues, many efforts have been made to bind drugs and genes together by polymers for co-delivery to achieve synergistic effect. Usually, binding interaction of drugs with polymers is either physical or chemical. In case of drug-polymer physical interaction, the efficiency of drugs generally decreases because of separation of drugs from polymers in vivo whenever it comes in contact with charged biofluid/s or cells. While chemical interaction of drug-polymer overcomes the aforementioned obstacle, several problems such as steric hindrance, solubility, and biodegradability hinder it to develop as gene carrier. Considering these benefits and pitfalls, the objective of this review is to discuss the possible extent of drug-conjugated polymers as safe and efficient gene delivery carriers for achieving synergistic effect to combat various genetic disorders.

Combinatorial Approach of Antigen Delivery Using M Cell-Homing Peptide and Mucoadhesive Vehicle to Enhance the Efficacy of Oral Vaccine

Orally ingested pathogens or antigens are taken up by microfold cells (M cells) in Peyer's patches of intestine to initiate protective immunity against infections. However, the uptake of orally delivered protein antigens through M cells is very low due to lack of specificity of proteins toward M cells and degradation of proteins in the harsh environment of gastrointestinal (GI) tract. To overcome these limitations, here we developed a pH-sensitive and mucoadhesive vehicle of thiolated eudragit (TE) microparticles to transport an M cell-targeting peptide-fused model protein antigen. Particularly, TE prolonged the particles transit time through the GI tract and predominantly released the proteins in ileum where M cells are abundant. Thus, oral delivery of TE microparticulate antigens exhibited high transcytosis of antigens through M cells resulting in strong protective sIgA as well as systemic IgG antibody responses. Importantly, the delivery system not only induced CD4(+) T cell immune responses but also generated strong CD8(+) T cell responses with enhanced production of IFN-γ in spleen. Given that M cells are considered a promising target for oral vaccination, this study could provide a new combinatorial method for the development of M-cell-targeted mucosal vaccines.

Mannan-decorated thiolated Eudragit microspheres for targeting antigen presenting cells via nasal vaccination

Mucosal vaccination of protein as an antigen requires appropriate delivery or adjuvant systems to deliver antigen to mucosal immune cells efficiently and generate valid immune responses. For successful nasal immunization, the obstacles imposed by the normal process of mucociliary clearance which limits residence time of applied antigens and low antigen delivery to antigen presenting cells (APCs) in nasal associated lymphoid tissue (NALT) need to be overcome for the efficient vaccination. Here, we prepared mucoadhesive and mannan-decorated thiolated Eudragit microspheres (Man-TEM) as a nasal vaccine carrier to overcome the limitations. Mucoadhesive thiolated Eudragit (TE) were decorated with mannan for targeting mannose receptors (MR) in antigen presenting cells (APCs) to obtain efficient immune responses. The potential adjuvant ability of Man-TEM for intranasal immunization was confirmed by in vitro and in vivo experiments. In mechanistic study using APCs in vitro, we obtained that Man-TEM enhanced the receptor-mediated endocytosis by stimulating the MR receptors of APCs. The nasal vaccination of OVA-loaded Man-TEM in mice showed higher levels of serum IgG and mucosal sIgA than the soluble OVA group due to the specific recognition of MR of APCs by the mannan in the Man-TEM. These results suggest that mucoadhesive and Man-TEM may be a promising candidate for nasal vaccine delivery system to elicit systemic and mucosal immunity.

Biocompatible polymeric nanocomplexes as an intracellular stimuli-sensitive prodrug for type-2 diabetes combination therapy

Combination therapy is usually considered as a promising strategy owing to its advantages such as reduced doses, minimized side effects and improved therapeutic efficiency in a variety of diseases including diabetes. Here we synthesized a new highly intracellular stimuli-sensitive chitosan-graft-metformin (CS-MET) prodrug by imine reaction between oxidative chitosan and metformin for type 2 diabetes (T2D) therapy. Hypothetically, CS-MET functions dually as an anti-diabetes prodrug as well as a gene delivery vector without superfluous materials. CS-MET formed nanocomplexes with therapeutic gene through electrostatic interactions and entered cells by Organic Cation Transporter (OCT)-independent endocytosis. The incorporation of metformin into chitosan has been found to increase endosomal escape via the proton sponge effect. When vector carrying a short-hairpin RNA (shRNA) silencing sterol regulatory element-binding protein (SREBP), a major transcription factor involved in de novo lipogenisis, it reduced the SREBP mRNA and proteins efficiently. Furthermore, by intraperitoneal injection, CS-MET/shSREBP nanocomplexes effectively knocked down SREBP in livers of western-type diet (WD)-induced obese C57BL/6J mice, markedly reversed insulin resistance and alleviated the fatty liver phenotype without obvious toxic effects. Thus we were able to show that the intracellular stimuli-sensitive CS-MET prodrug renders a potential platform to increase the anti-diabetes activity with synergistic enhancement of gene therapy.

Suppression of tumor growth in lung cancer xenograft model mice by poly(sorbitol-co-PEI)-mediated delivery of osteopontin siRNA

Small interfering RNA (siRNA)-mediated gene silencing represents a promising strategy for treating diseases such as cancer; however, specific gene silencing requires an effective delivery system to overcome the instability and low transfection efficiency of siRNAs. To address this issue, a polysorbitol-based transporter (PSOT) was prepared by low molecular weight branched polyethylenimine (bPEI) crosslinked with sorbitol diacrylate (SDA). Osteopontin (OPN) gene, which is highly associated with non-small cell lung cancer (NSCLC) was targeted by siRNA therapy using siRNA targeting OPN (siOPN). Characterization study confirmed that PSOT formed compact complexes with siOPN and protected siOPN against degradation by RNase. PSOT/siOPN complexes demonstrated low cytotoxicity and enhanced transfection efficiency in vitro, suggesting that this carrier may be suitable for gene silencing. In the A549 and H460 lung cancer cell lines, PSOT/siOPN complexes demonstrated significant silencing efficiency at both RNA and protein levels. To study in vivo tumor growth suppression, two lung cancer cell-xenograft mouse models were prepared and PSOT/siOPN complexes were delivered into the mice through intravenous injection. The siOPN-treated groups demonstrated significantly reduced OPN expression at both the RNA and protein levels as well as suppression of tumor volume and weight. Taken together, siOPN delivery using PSOT may present an effective and novel therapeutic system for lung cancer treatment.

Biomedical Applications of Magnetically Functionalized Organic/Inorganic Hybrid Nanofibers

Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to a synergistic effect obtained from the unique properties of both the nanofibers and magnetic nanoparticles. These magnetic nanoparticle-encapsulated or -embedded nanofiber systems can be used not only for imaging purposes but also for therapy. In this review, we focused on recent advances in nanofibers loaded with magnetic nanoparticles, their biomedical applications, and future trends in the application of these nanofibers.

Dual expression of shAkt1 and Pdcd4 suppresses lung tumorigenesis in K-rasLA1 mice

BACKGROUND/AIM

Lung cancer has the highest mortality rate among cancers and current therapies are not efficient. Therefore, novel therapeutic methods are urgently needed. Here, we examined the effectiveness of simultaneous Akt1 inhibition and Pdcd4 over-expression using a dual expression system in suppressing tumorigenesis in K-ras(LA1) mice (a lung cancer model).

MATERIALS AND METHODS

An shRNA targeting Akt1 (shAkt1) and cDNA of programmed cell death protein 4 (Pdcd4) were inserted into a dual expression vector (shAkt1+Pdcd4). A sorbitol diacrylate-polyethylenimine (SDA-PEI) carrier was used because of low toxicity and high transfection efficiency. Aerosolized SDA-PEI/shAkt1+Pdcd4 complex was delivered to the mice twice a week for 4 weeks using a nose-only exposure inhalation chamber.

RESULTS

Simultaneous Akt1 inhibition and Pdcd4 over-expression synergistically induced potent antitumor effect. Analysis revealed significant reduction in lung tumor number.

CONCLUSION

Dual expression of shAkt1 and Pdcd4 effectively suppresses lung tumorigenesis.

Nanoparticle-mediated delivery of siRNA for effective lung cancer therapy

Lung cancer is one of the most lethal diseases worldwide, and the survival rate is less than 15% even after the treatment. Unfortunately, chemotherapeutic treatments for lung cancer are accompanied by severe side effects, lack of selectivity and multidrug resistance. In order to overcome the limitations of conventional chemotherapy, nanoparticle-mediated RNA interference drugs represent a potential new approach due to selective silencing effect of oncogenes and multidrug resistance related genes. In this review, we provide recent advancements on nanoparticle-mediated siRNA delivery strategies including lipid system, polymeric system and rigid nanoparticles for lung cancer therapies. Importantly, codelivery of siRNA with conventional anticancer drugs and recent theranostic agents that offer great potential for lung cancer therapy is covered.

Galactosylated poly(ethyleneglycol)-lithocholic Acid selectively kills hepatoma cells, while sparing normal liver cells

Delivering drugs selectively to cancer cells but not to nearby normal cells is a major obstacle in drug therapy. In this study, lithocholic acid (LCA), a potent anti-cancer drug, is converted to two forms of poly(ethyleneglycol) (PEG) conjugates, viz., PEG-LCA (PL) and lactobionic acid (LBA) conjugated PEG-LCA (LPL). The latter form contains a galactose ligand in LBA to target the hepatocytes. Both forms are self-assembled to form nanoparticle formulation, and they have high potency than LCA to kill HepG2 cancer cells, sparing normal LO2 cells. Besides, LPL has high specificity to mouse liver cells in vivo. Western blot results confirm that the cell death is occurred through apoptosis induced by LPL nanoparticles. In conclusion, the induction of apoptosis and cell death is much more efficient with LPL nanoparticles than LCA molecules.

Tuning the buffering capacity of polyethylenimine with glycerol molecules for efficient gene delivery: staying in or out of the endosomes

Endosomal escape is a major bottleneck for efficient non-viral gene delivery. This paper presents the development of two novel non-viral vectors by cross-linking glycerol molecules with low molecular weight polyethylenimine (PEI). The vectors, namely, HG-PEI (45 mol% glycerol content) and LG-PEI (9 mol% glycerol content) have apparently similar DNA binding, DNA unpacking and cellular uptake abilities but differ in buffering capacity. The cellular uptake and subsequent transfection efficiency of LG-PEI is superior to commercially available PEI 25 k. Interestingly, although the cellular uptake of HG-PEI is higher than that of PEI 25 k, the transgene expression by HG-PEI-mediated transfection is very low. Inhibitor and co-localization studies demonstrate the mechanism of endocytosis and formation of endosomes prone to lysosomal lysis of HG-PEI polyplexes as a consequence of its weak buffering capacity. Importantly, when the lysosomal lysis is inhibited, the transgene expression of HG-PEI-mediated transfection increases by 9-fold of its initial capacity which is comparable to the transfection efficiency of PEI 25 k. These results indicated that the buffering capacity of the polymers primarily impacts endosomal escape and subsequent transfection efficiency. Furthermore, this study highlights the significance of cross-linkers in optimizing the buffering capacity when designing polymers for gene delivery.

Release and Cytokine Production of BmpB from BmpB-Loaded pH-Sensitive and Mucoadhesive Thiolated Eudragit Microspheres

Swine dysentery is a contagious mucohaemorrhagic colitis of pigs that is caused by anaerobic intestinal spirochaete Brachyspira hyodysenteriae. Recently, an outer membrane lipoprotein of B. hyodysenteriae (BmpB) has been identified, and the mice or pigs immunized with a recombinant BmpB generated antibodies recognizing the native BmpB of B. hyodysenteriae. In this study, we cloned, expressed and purified BmpB protein from E. coli and used it as a vaccine candidate for oral delivery. The BmpB was encapsulated into the pH-sensitive and thiolated Eudragit microspheres (TEMS). The sizes of the microspheres ranged from 5-20 μ. About 22-34% of BmpB were released from the BmpB-loaded TEMS within 24 h at stomach pH 2.0 whereas the release of BmpB from the BmpB-loaded TEMS was 35% in the first one hour and reached 81% within 24 h at intestinal pH 7.2. These data revealed that the BmpB could be protected in the harsh gastric condition. Mucoadhesive experiment in vitro showed that TEMS have high binding affinity with the mucin glycoproteins of porcine intestine. Finally, in vitro production of cytokines from immune cells treated with the BmpB-loaded TEMS suggested that the TEMS would be a promising approach for oral delivery of BmpB as vaccine candidate.

Enhanced BBB permeability of osmotically active poly(mannitol-co-PEI) modified with rabies virus glycoprotein via selective stimulation of caveolar endocytosis for RNAi therapeutics in Alzheimer's disease

RNA interference (RNAi) holds one of the promising tools for Alzheimer's disease (AD) treatment by directly arresting the causative genes. For successful RNAi therapeutics for AD, limited access of therapeutic genes to the brain needs to be overcome by developing siRNA delivery system that could cross the blood-brain barrier (BBB). Here, we report a non-viral vector, rabies virus glycoprotein (RVG)-modified poly(mannitol-co-PEI) gene transporter (PMT), R-PEG-PMT. The RVG ligand directed the PMT/siRNA complexes toward the brain through binding to nicotinic acetylcholine receptors expressed on BBB. In mechanistic study using in vitro BBB model, we observed that osmotically-active PMT enhanced the receptor-mediated transcytosis by stimulating the caveolar endocytosis. The potential of RNAi therapeutics for AD using R-PEG-PMT/siBACE1 complexes was demonstrated in vitro and in vivo. Our results suggest that R-PEG-PMT is a powerful gene carrier system for brain targeted RNAi therapeutics with synergistic effect of RVG ligand and PMT on well-modulated receptor-mediated transcytosis through BBB.

Targeted gene delivery via N-acetylglucosamine receptor mediated endocytosis

Receptor-mediated endocytosis is a promising approach of gene delivery into the target cells via receptor-ligand interaction. Vimentins at the cell surface are recently known to bind N-acetylglucosamine (GlcNAc) residue, therefore, the cell surfaces of vimentin-expressing cells could be targeted by using the GlcNAc residue as a specific ligand for receptor-mediated gene delivery. Here, we have developed polymeric gene delivery vectors, based on poly(ethylene oxide)(PEO) and poly(aspartamide), namely poly[(aspartamide)(diethylenetriamine)]-b-[PEO-(GlcNAc)] (PADPG) and poly[(aspartamide)(diethylenetriamine)]-b-[PEO] (PADP) to elucidate the efficiency of GlcNAc ligand for gene delivery through receptor mediated endocytosis. To determine the efficiency of these polymeric vectors for specific gene delivery, the DNA condensation ability of PADPG and PADP and the subsequent formation of polymeric nanoparticles were confirmed by gel retardation assay and transmission electron microscopy respectively. Both PADPG and PADP had lower cytotoxicity than polyethylenimine 25 K (PEI 25 K). However, their transfection efficiency was comparatively lower than PEI 25 K due to hydrophilic property of PEO in the vectors. To observe the stability of polymeric nanoparticles, the transfection of PADPG and PADP was carried out in the presence of serum. Favorably, the interfering effect of serum on the transfection efficiency of PADPG and PADP was also very low. Finally, when the cell specificity of these polymeric vectors was investigated, PADPG had high gene transfection in vimentin-expressing cells than vimentin-deficiency cells. The high transfection efficiency of PADPG was attributed to the GlcNAc in the polymeric vector which interact specifically with vimentin in the cells for the receptor-mediated endocytosis. The competitive inhibition assay further proved the receptor-mediated endocytosis of PADPG. Thus, this study demonstrates that conjugation of GlcNAc is an effective and rational way to prepare a suitable vector for targeted gene delivery to vimentin-expressing cells.

MicroRNA delivery with osmotic polysorbitol-based transporter suppresses breast cancer cell proliferation

MicroRNAs (miRNA) are short oligonucleotides of endogenous origin involved in post-transcriptional regulation and are altered in disease, making them potential therapeutic targets. miRNA replacement is necessary in cells with downregulated miRNAs levels in response to disease. miRNA 145 is a novel tumor suppressor gene involved in cell suppression, invasion and migration of cancer cells; it is downregulated in most cancers. Delivery of therapeutic miRNA using nanoparticles enhances the chances of successful delivery and expression of genes at the target site. We evaluated polysorbitol-mediated transporter (PSMT) in the cellular delivery of miRNA 145. The polysorbitol backbone possesses osmotic properties and leads to enhanced cellular uptake. PSMT delivers genes into cells by a caveolae-mediated endocytic pathway. Caveolae expression is usually altered in transformed cancer cells. Physicochemical characterization, and the transfection efficiency and transgene expression capability of PSMT/reporter plasmid DNA nanoparticles, were determined. GFP-tagged miRNA 145 delivery with PSMT was confirmed by confocal microscopy and Western blotting. The functional effects of miRNA 145 delivered with PSMT were analyzed by confocal microscopy, as well as in apoptosis, proliferation and wound healing assays. Finally, the expression of an miRNA 145 target protein, c-myc, was determined by Western blotting after intracellular delivery of PSMT/miRNA 145 nanoparticle (NP).

Oral delivery of probiotic expressing M cell homing peptide conjugated BmpB vaccine encapsulated into alginate/chitosan/alginate microcapsules

Oral administration of live probiotics as antigen delivery vectors is a promising approach in vaccine development. However, the low survival of probiotics in the gastrointestinal tract limits this approach. Therefore, the aim of this study was the encapsulation of probiotic expressing vaccine into alginate/chitosan/alginate (ACA) microcapsules (MCs) for efficient oral vaccine delivery. Here, recombinant Lactobacillus plantarum 25 (LP25) expressing M cell homing peptide fused BmpB protein was used as a model probiotic. The viability of LP25 in ACA MCs was more than 65% in simulated gastric fluid (SGF, pH 2.0) and 75% in simulated small intestinal fluid (SIF, pH 7.2) up to 2h. Encapsulated LP25 was completely released from ACA MCs in SIF within 12h. When stored at room temperature (RT) or 4°C, the viability of LP25 in ACA MCs was higher than free LP25. Interestingly, the viability of LP25 in ACA MCs at 4°C for 5weeks was above 58%, whereas viability of free LP25 stored at RT up to 5weeks was zero. After 4weeks from the first immunization, LP25-M-BmpB-loaded ACA MCs induced a stronger BmpB-specific IgG and IgA production in mice. Collectively, these findings suggest that encapsulation of probiotic by ACA MCs is a promising delivery system for oral administration of probiotic expressing vaccine.

Application of ultrasound stimulation in bone tissue engineering

Many studies have been investigated on the effects of the low-intensity pulsed ultrasound (LIPUS) on bone healing, acceleration of bone mineralization and regeneration. Many researchers have focused on a more comprehensive understanding of the biological mechanism of the osteoblast by LIPUS because the osteoblast is an important cell in bone formation. The effects of LIPUS on the proliferation, gene expression of Runx2, Msx2, Dlx5, and AJ18, and the second messenger signaling of osteoblast were reported. Various parameters of LIPUS, such as intensity, frequency, duration and topology, were investigated to find appropriate conditions in osteoblast. Less than 120 mW/cm(2) of intensity and 1-3 MHz of frequency were considered good condition for regeneration of bone tissue. Increased osteoblast cells and higher mineralized nodule formation explain the enhancement of proliferation by LIPUS. In addition, LIPUS affects on differentiation of osteoblast cells, which is shown by increased ALPase, and transcriptional factors, Runx2. Ultrasound stimulates PEG2 and COX-2 in osteoblast, and the signals accelerates the bone regeneration in tissue engineering.

Stem Cell-assisted Approaches for Cartilage Tissue Engineering

The regeneration of damaged articular cartilage remains challenging due to its poor intrinsic capacity for repair. Tissue engineering of articular cartilage is believed to overcome the current limitations of surgical treatment by offering functional regeneration in the defect region. Selection of proper cell sources and ECM-based scaffolds, and incorporation of growth factors or mechanical stimuli are of primary importance to successfully produce artificial cartilage for tissue repair. When designing materials for cartilage tissue engineering, biodegradability and biocompatibility are the key factors in selecting material candidates, for either synthetic or natural polymers. The unique environment of cartilage makes it suitable to use a hydrogel with high water content in the cross-linked or thermosensitive (injectable) form. Moreover, design of composite scaffolds from two polymers with complementary physicochemical and biological properties has been explored to provide residing chondrocytes with a combination of the merits that each component contributes.

Roles of spheroid formation of hepatocytes in liver tissue engineering

The liver plays an important role in a broad spectrum of physiological functions and detoxifies endogenous and exogenous substances. The liver failure is associated with a high risk of mortality because it is one of important organs in our body. Various bioartificial liver (BAL) systems have been used for clinical trials as a bridge for liver transplantations in patients with liver failure. Long term and stable liver-specific functions of hepatocytes in the development of BAL support systems should be considered. Spheroid formation of hepatocytes enhances liver-specific functions. In this review, hepatocyte spheroid formation methods such as galactose density, topology of extracellular matrix, micro-molding technique, hanging-drop culture, non-adhesive surface, positive charged surface, spinner culture, rocked technique, medium component, external forces, coculture system and polymeric nanospheres are explained for enhancing liver-specific functions.

Selective transfection with osmotically active sorbitol modified PEI nanoparticles for enhanced anti-cancer gene therapy

Polysorbitol-mediated transporter (PSMT) has been previously shown to achieve high transfection efficiency with minimal cytotoxicity. Polysorbitol backbone possesses osmotic properties and leads to enhanced cellular uptake. The PSMT/pDNA nanoparticles were prepared and the particle size, surface charge of the nanoparticles was determined for the study. PSMT delivers genes into cells by the caveolae mediated endocytic pathway. Caveolae expression is usually altered in transformed cancer cells. Transfection through the caveolae may help PSMT to selectively transfect cancer cells rather than normal cells. Transfection of the luciferase gene by PSMT was tested in various cell types including cancer cell lines, primary cells, and immortalized cells. Luciferase transgene expression mediated by PSMT was remarkably increased in HeLa cells compared to expression using the control carrier Lipofectamine. Moreover, the toxicity of PSMT was comparable to the control carrier (Lipofectamine) in the same cells. Selective transfection of cancer cells using PSMT was further confirmed by co-culture of cancer and normal cells, which showed that transgene expression was pre-dominantly achieved in cancer cells. A functional p53 gene was also delivered into HeLa cells using PSMT and the selective transgene expression of p53 protein in cancer cells was analyzed through western blotting and confocal microscopy. HeLa cells transfected with PSMT/p53 plasmid nanoparticles showed cellular damage and apoptosis, which was confirmed through propidium iodide staining.

Exploring codon optimization and response surface methodology to express biologically active transmembrane RANKL in E. coli

Receptor activator of nuclear factor (NF)-κB ligand (RANKL), a master cytokine that drives osteoclast differentiation, activation and survival, exists in both transmembrane and extracellular forms. To date, studies on physiological role of RANKL have been mainly carried out with extracellular RANKL probably due to difficulties in achieving high level expression of functional transmembrane RANKL (mRANKL). In the present study, we took advantage of codon optimization and response surface methodology to optimize the soluble expression of mRANKL in E. coli. We optimized the codon usage of mRANKL sequence to a preferred set of codons for E. coli changing its codon adaptation index from 0.64 to 0.76, tending to increase its expression level in E. coli. Further, we utilized central composite design to predict the optimum combination of variables (cell density before induction, lactose concentration, post-induction temperature and post-induction time) for the expression of mRANKL. Finally, we investigated the effects of various experimental parameters using response surface methodology. The best combination of response variables was 0.6 OD600, 7.5 mM lactose, 26°C post-induction temperature and 5 h post-induction time that produced 52.4 mg/L of fusion mRANKL. Prior to functional analysis of the protein, we purified mRANKL to homogeneity and confirmed the existence of trimeric form of mRANKL by native gel electrophoresis and gel filtration chromatography. Further, the biological activity of mRANKL to induce osteoclast formation on RAW264.7 cells was confirmed by tartrate resistant acid phosphatase assay and quantitative real-time polymerase chain reaction assays. Importantly, a new finding from this study was that the biological activity of mRANKL is higher than its extracellular counterpart. To the best of our knowledge, this is the first time to report heterologous expression of mRANKL in soluble form and to perform a comparative study of functional properties of both forms of RANKL.

Chemical modification of chitosan with pH-sensitive molecules and specific ligands for efficient DNA transfection and siRNA silencing

Successful gene therapy depends on the development of efficient and cell-specific gene delivery systems. Currently, animal viral vectors have been mostly used for in vivo and in clinical trials owing to their high transduction efficiency. However, they suffer from numerous limitations such as biosafety, immunogenicity, gene packaging capacity, complicated production and cell specificity. Therefore non-viral vectors are attractive alternatives to viral gene delivery systems due to their low toxicity, relatively easy production and greater diversity. Among non-viral vectors, chitosan and chitosan derivatives have been extensively utilized as gene carriers owing to their low immunogenicity, biocompatibility, biodegradability, low toxicity and ease of chemical modifications. However, low transfection efficiency of DNA (or low gene silencing of siRNA) and low cell specificity of chitosan should be overcome before clinical trials. The objective of this review is to summarize several parameters affecting the transfection efficiency of DNA (or gene silencing of siRNA) for the promising use of chitosan as gene carriers. Besides, chemical modifications of chitosan with pH-sensitive molecules and specific ligands so as to enhance the transfection efficiency of DNA (or gene silencing of siRNA) and cell specificity will be covered.

Dynamic chemotactic response of fibroblasts to local stimulation using EGF-immobilized microbeads

Directional cellular migrations as a chemotactic response to spatially inhomogeneous growth factor stimulation play an important role in establishing physiological mechanisms and pathological events in cells. We developed epidermal growth factor (EGF)-immobilized microbeads by photoreaction and evaluated its local stimulatory effects on the dynamic chemotactic motility of fibroblasts. The local stimulation resulted in global activation of ERK 1/2 and directionality of cellular migration. The cellular migration by stimulation using 3-μm diameter EGF-immobilized microbeads persisted for a longer time, were involved a wider field and their number were further increased with stimulation. This effective technique allows cellular migration and biochemical analyses that will help elucidate the mechanisms involved in signal transduction by spatially inhomogeneous stimulation of the growth factor.

Chemical modification of chitosan for efficient gene therapy

Gene therapy involves the introduction of foreign genetic material into cells in order to exert a therapeutic effect. Successful gene therapy relies on effective vector system. Viral vectors are highly efficient in transfecting cells, but the undesirable complications limit their therapeutic applications. As a natural biopolymer, chitosan has been considered to be a good gene carrier candidate due to its ideal character which combines biocompatibility, low toxicity with high cationic density together. However, the low cell specificity and low transfection efficiency of chitosan as a gene carrier need to be overcome before undertaking clinical trials. This chapter is principally on those endeavors such as chemical modifications using cell-specific ligands and stimuli-response groups as well as penetrating modifications that have been done to increase the performances of chitosan in gene therapy.

Carbohydrate-based nanogels as drug and gene delivery systems

Nanogels are hydrogels with nanometer-scale three-dimensional networks of physically or chemically cross-linked chains. Nanogels have attracted much interest in recent years for various biomedical applications such as drug delivery systems and bioimaging owing to their specific properties of size tunability and intrinsic hydrophilic surfaces. Nanogels are generally classified either as natural polymer-based or synthetic polymer-based nanogels. Natural polymer-based nanogels are considered better candidates for drug delivery than synthetic polymer-based nanogels. This review summarizes the role of natural polymer-based nanogels, especially carbohydrate-based nanogels as drug and gene delivery systems.

The effect of RNAi silencing of p62 using an osmotic polysorbitol transporter on autophagy and tumorigenesis in lungs of K-rasLA1 mice

Treating cancer patients by conventional chemotherapy to achieve prolonged survival still remains complicated. Autophagy is a topic of considerable interest in recent times, as it may contribute greatly to tumor suppression. Recent studies indicate that autophagy-deficient cells accumulate high levels of p62, an ubiquitin-binding scaffold protein, involved greatly in tumorigenesis. Here, we synthesized an osmotically active polysorbitol-mediated transporter (PSMT) to downregulate p62 using an RNAi strategy and described the mechanism of how p62 silencing using PSMT/siRNA p62 system activates autophagy and contributes to tumor suppression in the lungs of K-ras(LA1) mice. Downregulation of p62 by PSMT/siRNA p62 activated autophagy confirmed by the formation of autophagosomes and swelling of Golgi apparatus with a decreasing level of GM130, a cis-Golgi matrix protein. Activation of osmotic PSMT-mediated autophagy remarkably reduced the size and number of tumors by suppressing proliferative cell nuclear antigen, cluster of differentiation 31, and vascular endothelial growth factor levels. Furthermore, an increase in apoptosis was observed in the lungs of PSMT/siRNA p62-delivered K-ras(LA1) mice.

Poly(ester amine) synthesized from trimethylolpropane triacrylate and spermine as an efficient siRNA carrier

Small interfering RNA (siRNA) is a promising candidate for gene therapy due to the strong and specific gene silencing effects. However, to effectively silence any protein, lack of an efficient delivery system is major obstacle for siRNA therapeutics. In the present study, we report on the development of a novel poly(ester amine) (PEA) as an efficient siRNA carrier. The PEA was prepared by a Michael addition reaction between trimethylolpropane triacrylate (TT) and spermine (SPE). The composition of the PEA was characterized by 1H nuclear magnetic resonance (1H NMR) and the molecular weight was measured using gel permeability chromatography (GPC). This TT-SPE effectively condensed siRNA into a compact nanoscale structure (size: 76 nm) with homogenous size distribution and provided superior protection of siRNA from RNase A enzyme. Furthermore, TT-SPE/ siRNA complexes showed good intracellular uptake and had efficacious gene silencing effect with low toxicity compared to PEI 25K. These findings demonstrated that TT-SPE has potential as an alternative to PEI 25K for siRNA-based gene therapy.

Recent advances in 2D and 3D in vitro systems using primary hepatocytes, alternative hepatocyte sources and non-parenchymal liver cells and their use in investigating mechanisms of hepatotoxicity, cell signaling and ADME

This review encompasses the most important advances in liver functions and hepatotoxicity and analyzes which mechanisms can be studied in vitro. In a complex architecture of nested, zonated lobules, the liver consists of approximately 80 % hepatocytes and 20 % non-parenchymal cells, the latter being involved in a secondary phase that may dramatically aggravate the initial damage. Hepatotoxicity, as well as hepatic metabolism, is controlled by a set of nuclear receptors (including PXR, CAR, HNF-4α, FXR, LXR, SHP, VDR and PPAR) and signaling pathways. When isolating liver cells, some pathways are activated, e.g., the RAS/MEK/ERK pathway, whereas others are silenced (e.g. HNF-4α), resulting in up- and downregulation of hundreds of genes. An understanding of these changes is crucial for a correct interpretation of in vitro data. The possibilities and limitations of the most useful liver in vitro systems are summarized, including three-dimensional culture techniques, co-cultures with non-parenchymal cells, hepatospheres, precision cut liver slices and the isolated perfused liver. Also discussed is how closely hepatoma, stem cell and iPS cell-derived hepatocyte-like-cells resemble real hepatocytes. Finally, a summary is given of the state of the art of liver in vitro and mathematical modeling systems that are currently used in the pharmaceutical industry with an emphasis on drug metabolism, prediction of clearance, drug interaction, transporter studies and hepatotoxicity. One key message is that despite our enthusiasm for in vitro systems, we must never lose sight of the in vivo situation. Although hepatocytes have been isolated for decades, the hunt for relevant alternative systems has only just begun.

Effect of microencapsulation of Lactobacillus plantarum 25 into alginate/chitosan/alginate microcapsules on viability and cytokine induction

Lactobacillus plantarum 25 (LP25) encapsulated into alginate/chitosan/alginate (ACA) microcapsules (LP25-ACA MCs) prepared by an extrusion methods were characterized to assess their efficacy in oral delivery. The particle sizes of LP25-ACA MCs were 1.11 +/- 0.32 mm. The loading content of LP25 was 1.11 x 10(7) colony forming unit (cfu)/microcapsule and encapsulation efficiency was above 98%. The viability of LP25 in ACA MCs was more than 65% in simulated gastric fluid (SGF, pH 2.0) and 75% in simulated small intestinal fluid (SIF, pH 7.2) up to 2 h. Encapsulated LP25 were completely released from LP25-ACA MCs in SIF and simulated colon fluid (SCF, pH 6.0) within 12 h and 8 h respectively. The viability of LP25 in ACA MCs till 5 weeks was above 58%, whereas viability of free LP25 stored at room temperature up to 5 weeks was zero. Besides, LP25-ACA MCs induced the secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) from macrophages and dendritic cells showing the immunomodulatory effect of LP25. These findings demonstrate that the encapsulation of LP25 by ACA is a suitable strategy for oral delivery of probiotics.

Nanoparticle-mediated delivery of therapeutic genes: focus on miRNA therapeutics

INTRODUCTION

Micro RNAs (miRNA) are 21 - 23 nucleotides long and regulate the expression of coding genes by binding imperfectly with their 3' UTR region. The miRNA profile is altered in pathological processes, making miRNAs good targets for drug therapy. Restoration of down-regulated miRNA or inhibition of overexpressed miRNA to return miRNA to its normal state is the basis of miRNA-based therapy. This review focuses on nanocarriers used for the delivery of miRNA that confer physical stability to the unstable RNA structure, protect the RNA from nuclease degradation and aid in effective silencing of target genes.

AREAS COVERED

The necessity of the nanocarrier for the delivery of the miRNA is emphasized and the recent research on liposome-, metal- and polymer-mediated miRNA delivery for the inhibition or replacement of the disease-related miRNA is summarized.

EXPERT OPINION

The size, charge and surface properties of nanocarriers have to be tuned to ensure effective and safe delivery of the miRNA in clinical practice. The immune responses related to the nanocarriers and the double-stranded nucleotide delivery remain to be addressed. Also, the binding of miRNAs to non-specific targets has to be studied in more detail because miRNAs have multiple targets due to partial binding unlike siRNA.