RNA interference in vitro and in vivo using a novel chitosan/siRNA nanoparticle system

Combined silencing expression of MGMT with EGFR or galectin-1 enhances the sensitivity of glioblastoma to temozolomide

For several years, the first line of treatment of glioblastoma (GB) patients is based on surgical resection followed by fractioned radiotherapy with concomitant and adjuvant chemotherapy with temozolomide (TMZ). The effectiveness of this treatment is very limited due to the development by tumor cells of mechanisms of resistance to TMZ such as over-expression of O6-methylguanine DNA methyltransferase (MGMT), epidermal growth factor receptor (EGFR) and galectin-1. In this study, we hypothesized that the targeting of MGMT, EGFR and galectin-1 (alone or in combination) by specifics siRNAs carried by chitosan-lipid nanocapsules (chitosan-LNCs) could enhance the sensitivity of U87MG cells to TMZ. We showed in vitro that (i) anti-MGMT and (ii) anti-EGFR or anti-galectin-1 siRNAs decreased significantly the expression of their corresponding proteins and increased the sensitivity of U87MG cells to TMZ. Additionally, the sensitivity of U87MG/MGMT- cells to TMZ was significantly increased when anti-EGFR and anti-galectin-1 siRNAs were combined with a percentage of living cells of 17.8±1.6% at 0.5 mg/mL concentration of TMZ. The combination of anti-MGMT siRNAs with either anti-EGFR or anti-galectin-1 siRNAs enhanced the sensitivity of U87MG/MGMT+ cells to TMZ in comparison to their separately use. No difference was observed between the association of the three siRNAs and other associations. At 0.5 mg/mL concentration of TMZ, the percentage of living cells decreased from 55.1±1.9% to 36.0±4.1% for anti-MGMT alone and the combination of anti-MGMT/anti-galectin-1/anti-EGFR siRNAs, respectively. These siRNA nanovectors represent a good alternative to enhance the effectiveness of the standard treatment of GB. This method could be implemented in future preclinical models for experimental cancer treatment of GB.

Chitosan/siRNA nanoparticles targeting cyclooxygenase type 2 attenuate unilateral ureteral obstruction-induced kidney injury in mice

Cyclooxygenase type 2 (COX-2) plays a predominant role in the progression of kidney injury in obstructive nephropathy. The aim of this study was to test the efficacy of chitosan/small interfering RNA (siRNA) nanoparticles to knockdown COX-2 specifically in macrophages to prevent kidney injury induced by unilateral ureteral obstruction (UUO). Using optical imaging techniques and confocal microscopy, we demonstrated that chitosan/siRNA nanoparticles accumulated in macrophages in the obstructed kidney. Consistent with the imaging data, the obstructed kidney contained a higher amount of siRNA and macrophages. Chitosan-formulated siRNA against COX-2 was evaluated on RAW macrophages demonstrating reduced COX-2 expression and activity after LPS stimulation. Injection of COX-2 chitosan/siRNA nanoparticles in mice subjected to three-day UUO diminished the UUO-induced COX-2 expression. Likewise, macrophages in the obstructed kidney had reduced COX-2 immunoreactivity, and histological examination showed lesser tubular damage in COX-2 siRNA-treated UUO mice. Parenchymal inflammation, assessed by tumor necrosis factor-alpha (TNF-α) and interleukin 6 mRNA expression, was attenuated by COX-2 siRNA. Furthermore, treatment with COX-2 siRNA reduced heme oxygenase-1 and cleaved caspase-3 in UUO mice, indicating lesser oxidative stress and apoptosis. Our results demonstrate a novel strategy to prevent UUO-induced kidney damage by using chitosan/siRNA nanoparticles to knockdown COX-2 specifically in macrophages.

Self-assembly of bi-functional peptides on large-pore mesoporous silica nanoparticles for miRNA binding and delivery

Bi-functional peptide can bind both silica and miRNA, enabling non-covalent adsorption of miRNA on silica nanoparticles for delivery.

Cationic Polysaccharides in Gene Delivery

Approval of Glybera®, a gene therapy to treat lipoprotein lipase deficiency, by the European Union Marketing Authorization, and more than 1800 clinical trials in over 31 countries for the treatment of many incurable diseases, narrates the successful journey of gene therapy in the biomedical field. However, the undesired side effects of gene therapy using viral and other vectors have overshadowed the success story of gene therapy. Non-viral vectors, and more particularly cationic polysaccharides due to their non-toxicity, water solubility, biodegradability and excellent compatibility with body systems, provide an excellent alternative for gene delivery. This chapter highlights significant contributions made by cationic polysaccharides in gene delivery.

Incorporation of osteogenic and angiogenic small interfering RNAs into chitosan sponge for bone tissue engineering

Engineered bone substitutes are being extensively explored in response to growing demand. However, the angiogenesis that occurs during bone formation is often overlooked in scaffold design. In this novel study, we incorporated two small interfering RNAs (siRNAs), ie, small interfering RNA targets casein kinase 2 interaction protein 1 (siCkip-1) and small interfering RNA targets soluble VEGF receptor 1 (siFlt-1), which can promote osteogenesis and angiogenesis, into a chitosan sponge. This scaffold could maintain siRNAs for over 2 weeks in neutral phosphate-buffered saline and degraded rapidly in the presence of lysozyme. The chitosan sponge with siCkip-1 and siFlt-1 in vitro bioactivity was investigated using mesenchymal stem cells. Target genes were significantly suppressed, and osteocalcin, alkaline phosphatase, and vascular endothelial growth factor were significantly upregulated. Alizarin Red staining revealed that mineralization of the extracellular matrix was markedly enhanced by dual transfection. Further analysis by immunofluorescence confirmed that the siRNA-modified scaffold simultaneously improved the expression of osteocalcin and von Willebrand factor. In vivo testing in a skull critical-size defect model showed marked bone regeneration in rats treated with siCkip-1 and siFlt-1. In conclusion, chitosan sponge containing osteogenic and angiogenic siRNAs may be used as a scaffold for bone regeneration. The dual siRNA concept may also be useful in the biofunctionalization of other materials.

Mucus barrier-triggered disassembly of siRNA nanocarriers

The mucus overlying mucosal epithelial surfaces presents not only a biological barrier to the penetration of potential pathogens, but also therapeutic modalities including RNAi-based nanocarriers. Movement of nanomedicines across the mucus barriers of the gastrointestinal mucosa is modulated by interactions of the nanomedicine carriers with mucin glycoproteins inside the mucus, potentiated by the large surface area of the nanocarrier. We have developed a fluorescence activation-based reporter system showing that the interaction between polyanionic mucins and the cationic chitosan/small interfering RNA (siRNA) nanocarriers (polyplexes) results in the disassembly and consequent triggered release of fluorescent siRNA. The quantity of release was found to be dependent on the molar ratio between chitosan amino groups and siRNA phosphate groups (NP ratio) of the polyplexes with a maximal estimated 48.6% release of siRNA over 30 min at NP 60. Furthermore, a microfluidic in vitro model of the gastrointestinal mucus barrier was used to visualize the dynamic interaction between chitosan/siRNA nanocarriers and native purified porcine stomach mucins. We observed strong interactions and aggregations at the mucin-liquid interface, followed by an NP ratio dependent release and consequent diffusion of siRNA across the mucin barrier. This work describes a new model of interaction at the nanocarrier-mucin interface and has important implications for the design and development of nucleic acid-based nanocarrier therapeutics for mucosal disease treatments and also provides insights into nanoscale pathogenic processes.

Mad2 checkpoint gene silencing using epidermal growth factor receptor-targeted chitosan nanoparticles in non-small cell lung cancer model

RNA interference has emerged as a powerful strategy in cancer therapy because it allows silencing of specific genes associated with tumor progression and resistance. Mad2 is an essential mitotic checkpoint component required for accurate chromosome segregation during mitosis, and its complete abolition leads to cell death. We have developed an epidermal growth factor receptor (EGFR)-targeted chitosan system for silencing the Mad2 gene as a strategy to efficiently induce cell death in EGFR overexpressing human A549 non-small cell lung cancer cells. Control and EGFR-targeted chitosan nanoparticles loaded with small interfering RNAs (siRNAs) against Mad2 were formulated and characterized for size, charge, morphology, and encapsulation efficiency. Qualitative and quantitative intracellular uptake studies by confocal imaging and flow cytometry, respectively, showed time-dependent enhanced and selective intracellular internalization of EGFR-targeted nanoparticles compared to nontargeted system. Targeted nanoparticles showed nearly complete depletion of Mad2 expression in A549 cells contrasting with the partial depletion in the nontargeted system. Accordingly, Mad2-silencing-induced apoptotic cell death was confirmed by cytotoxicity assay and flow cytometry. Our results demonstrate that EGFR-targeted chitosan loaded with Mad2 siRNAs is a potent delivery system for selective killing of cancer cells.

Effectiveness of local injection of lentivirus-delivered stathmin1 and stathmin1 shRNA in human gastric cancer xenograft mouse

BACKGROUND AND AIM

We have reported previously that RNA interference targeting stathmin1 (STMN1) gene in human gastric cancer cells inhibits proliferation in vitro and tumor growth in vivo. Based on these observations, in the present study, the possibility that local injection of lentivirus-delivered stathmin shRNA would induce regression of the established human gastric cancer xenograft in animal model was investigated.

METHODS

BALB/c nude mice were inoculated subcutaneously into the right armpit with human gastric cancer cells SGC-7901(2 × 10(6) cells in 200 μL phosphate-buffered saline) to develop a xenograft model of human gastric cancer. When tumor reached suitable size, mice were randomly divided into two groups. STMN1 shRNA group (n = 6) were given local injection of lentivirus-delivered STMN1 shRNA, and the non-silencing shRNA group (n = 6) were administered with local injection of lentivirus-delivered non-silencing shRNA. Quantitative reverse transcription-polymerase chain reaction and Western blot were used to verify the knockdown of the gene expression in dissected tumor at mRNA and protein level, respectively.

RESULTS

Experimental therapy on the nude mice model bearing subcutaneous tumor of SGC-7901 cells showed that local administration of STMN1 shRNA effectively regressed the pre-established tumors. Stathmin shRNA-treated tumors were significantly regressed as compared with that of the tumor injected with non-silencing shRNA (P < 0.05). Tumor weight was significantly decreased in STMN1-treated group as compared with non-silencing shRNA group (P < 0.05). Quantitative reverse transcription-polymerase chain reaction and Western blot showed downregulation of STMN1 gene expression in STMN1 shRNA group as compared with non-silencing shRNA group (P < 0.05).

CONCLUSION

These findings highlight the potential use of local injection of lentivirus-delivered shRNA for the treatment of early localized human gastric carcinoma.

Therapeutic potential of siRNA and DNAzymes in cancer

Cancer is characterized by uncontrolled cell growth, invasion, and metastasis and possess threat to humans worldwide. The scientific community is facing numerous challenges despite several efforts to cure cancer. Though a number of studies were done earlier, the molecular mechanism of cancer progression is not completely understood. Currently available treatments like surgery resection, adjuvant chemotherapy, and radiotherapy are not completely effective in curing all the cancers. Recent advances in the antisense technology provide a powerful tool to investigate various cancer pathways and target them. Small interfering RNAs (siRNAs) could be effective in downregulating the cancer-associated genes, but their in vivo delivery is the main obstacle. DNA enzymes (DNAzymes) have great potential in the treatment of cancer due to high selectivity and significant catalytic efficiency. In this review, we are focusing on antisense molecules such as siRNA and DNAzymes in cancer therapeutics development. This review also describes the challenges and approaches to overcome obstacles involved in using siRNA and DNAzymes in the treatment of cancers.

Convergence of nanotechnology and cancer prevention: are we there yet?

Nanotechnology is emerging as a promising modality for cancer treatment; however, in the realm of cancer prevention, its full utility has yet to be determined. Here, we discuss the potential of integrating nanotechnology in cancer prevention to augment early diagnosis, precision targeting, and controlled release of chemopreventive agents, reduced toxicity, risk/response assessment, and personalized point-of-care monitoring. Cancer is a multistep, progressive disease; the functional and acquired characteristics of the early precancer phenotype are intrinsically different from those of a more advanced anaplastic or invasive malignancy. Therefore, applying nanotechnology to precancers is likely to be far more challenging than applying it to established disease. Frank cancers are more readily identifiable through imaging and biomarker and histopathologic assessment than their precancerous precursors. In addition, prevention subjects routinely have more rigorous intervention criteria than therapy subjects. Any nanopreventive agent developed to prevent sporadic cancers found in the general population must exhibit a very low risk of serious side effects. In contrast, a greater risk of side effects might be more acceptable in subjects at high risk for cancer. Using nanotechnology to prevent cancer is an aspirational goal, but clearly identifying the intermediate objectives and potential barriers is an essential first step in this exciting journey.

Mannosylated chitosan nanoparticles for delivery of antisense oligonucleotides for macrophage targeting

The therapeutic potential of antisense oligonucleotides (ASODN) is primarily dependent upon its safe and efficient delivery to specific cells overcoming degradation and maximizing cellular uptake in vivo. The present study focuses on designing mannosylated low molecular weight (LMW) chitosan nanoconstructs for safe ODNs delivery by macrophage targeting. Mannose groups were coupled with LMW chitosan and characterized spectroscopically. Mannosylated chitosan ODN nanoparticles (MCHODN NPs) were formulated by self-assembled method using various N/P ratio (moles of amine groups of MCH to phosphate moieties of ODNs) and characterized for gel retardation assay, physicochemical characteristics, cytotoxicity and transfection efficiency, and antisense assay. Complete complexation of MCH/ODN was achieved at charge ratio of 1:1 and above. On increasing the N/P ratio of MCH/ODN, particle size of the NPs decreased whereas zeta potential (ZV) increased. MCHODN NPs displayed much higher transfection efficiency into Raw 264.7 cells (bears mannose receptors) than Hela cells and no significant toxicity was observed at all MCH concentrations. Antisense assay revealed that reduction in lipopolysaccharide (LPS) induced serum TNF-α is due to antisense activity of TJU-2755 ODN (sequence complementary to 3′-UTR of TNF-α). These results suggest that MCHODN NPs are acceptable choice to improve transfection efficiency in vitro and in vivo.

Chitosan hydrogel as siRNA vector for prolonged gene silencing

Background

The periodontitis is one of the most prevalent diseases with alveolar resorption in adult people and is the main cause of the tooth loss. To investigate the possibility for protecting the loss of alveolar bone in periodontal diseases, a RNAi-based therapeutic strategy is applied for silencing RANK signaling using thermosensitive chitosan hydrogel as siRNA reservoir and vector.

Results

The thermosensitive chitosan hydrogel was formed from solution (PH = 7.2, at 4°C) at 37°C within 8 minutes. The degradation rates of hydrogel were ~50% and 5% (W remaining/W beginning) in the presence and absence of lysozyme, respectively, over a period of 20 days. The concurrent cumulative in vitro release of Cy3-labeled siRNA from the hydrogel was 50% and 17% over 14 days, with or without lysozyme digestion, respectively. High cell viability (>88%) was maintained for cells treated with hydrogel loaded with RANK specific siRNA and RANK knockdown was prolonged for up to 9 days when cells were incubated with siRNA/hydrogel complex. In vivo release of siRNA was investigated in a subcutaneous delivery setup in mice. The fluorescent signal from siRNA within hydrogel was remained for up to 14 days compared to less than one day for siRNA alone.

Conclusions

Chitosan hydrogel can potentially serve as a suitable reservoir and vector for local sustained delivery of siRNA in potential therapy.

Modified-chitosan/siRNA nanoparticles downregulate cellular CDX2 expression and cross the gastric mucus barrier

Development of effective non-viral vectors is of crucial importance in the implementation of RNA interference in clinical routine. The localized delivery of siRNAs to the gastrointestinal mucosa is highly desired but faces specific problems such as the stability in gastric acidity conditions and the presence of the mucus barrier. CDX2 is a transcription factor critical for intestinal differentiation being involved in the initiation and maintenance of gastrointestinal diseases. Specifically, it is the trigger of gastric intestinal metaplasia which is a precursor lesion of gastric cancer. Its expression is also altered in colorectal cancer, where it may constitute a lineage-survival oncogene. Our main objective was to develop a nanoparticle-delivery system of siRNA targeting CDX2 using modified chitosan as a vector. CDX2 expression was assessed in gastric carcinoma cell lines and nanoparticles behaviour in gastrointestinal mucus was tested in mouse explants. We show that imidazole-modified chitosan and trimethylchitosan/siRNA nanoparticles are able to downregulate CDX2 expression and overpass the gastric mucus layer but not colonic mucus. This system might constitute a potential therapeutic approach to treat CDX2-dependent gastric lesions.

Amelioration of colorectal cancer using negative lipidoid nanoparticles to encapsulate siRNA against APRIL by enema delivery mode

A proliferation-inducing ligand (APRIL) is a key cell proliferation-regulatory molecule and have been investigated well enough in immunity regulation and a few of immune diseases. APRIL can stimulate tumor cell growth and is up-expressed in cancer tissues, especially in CRC (colorectal cancer). However, whether inhibition of APRIL can regulate tumor-relative genes expression in vivo and subsequently ameliorate the pathological progress of CRC remains obscure. To address this question, we developed a novel negative lipidoid nanoparticles (NLNs) encapsulating small interference RNA (siRNA) for selectively silencing APRIL in the parenchyma of CRC focus in vivo, which uptake proceeded through a lipid raft endocytotic pathway. Local enema delivery of APRIL-NLNs silenced APRIL in CRC cells and animal models, and then ameliorated experimentally the progress of CRC by suppressing CRC cell proliferation, metastasis, and apoptosis-related cytokine expression and did not affect the function of liver and kidneys and not trigger the immune response of CRC models. This study reveals APRIL to be a potential anti-CRC target by in vivo experiments, and suggests that the application of similar modes of siRNA delivery may be feasible in other therapeutic settings.

Quantitative assessment of inhalation exposure and deposited dose of aerosol from nanotechnology-based consumer sprays

This study provides a quantitative assessment of inhalation exposure and deposited aerosol dose in the 14 nm to 20 μm particle size range based on the aerosol measurements conducted during realistic usage simulation of five nanotechnology-based and five regular spray products matching the nano-products by purpose of application. The products were also examined using transmission electron microscopy. In seven out of ten sprays, the highest inhalation exposure was observed for the coarse (2.5-10 μm) particles while being minimal or below the detection limit for the remaining three sprays. Nanosized aerosol particles (14-100 nm) were released, which resulted in low but measurable inhalation exposures from all of the investigated consumer sprays. Eight out of ten products produced high total deposited aerosol doses on the order of 10¹-10³ ng kg^-1 bw per application, ~85-88% of which were in the head airways, only <10% in the alveolar region and <8% in the tracheobronchial region. One nano and one regular spray produced substantially lower total deposited doses (by 2-4 orders of magnitude less), only ~52-64% of which were in the head while ~29-40% in the alveolar region. The electron microscopy data showed nanosized objects in some products not labeled as nanotechnology-based and conversely did not find nano-objects in some nano-sprays. We found no correlation between nano-object presence and abundance as per the electron microscopy data and the determined inhalation exposures and deposited doses. The findings of this study and the reported quantitative exposure data will be valuable for the manufacturers of nanotechnology-based consumer sprays to minimize inhalation exposure from their products, as well as for the regulators focusing on protecting the public health.

Cationic bovine serum albumin based self-assembled nanoparticles as siRNA delivery vector for treating lung metastatic cancer

It is generally believed that intravenous application of cationic vectors is limited by the binding of abundant negatively charged serum components, which may cause rapid clearance of the therapeutic agent from the blood stream. However, previous studies show that systemic delivery of cationic gene vectors mediates specific and efficient transfection within the lung, mainly as a result of interaction of the vectors with serum proteins. Based on these findings, a novel and charge-density-controllable siRNA delivery system is developed to treat lung metastatic cancer by using cationic bovine serum albumin (CBSA) as the gene vector. By surface modification of BSA, CBSA with different isoelectric points (pI) is synthesized and the optimal cationization degree of CBSA is determined by considering the siRNA binding and delivery ability, as well as toxicity. The CBSA can form stable nanosized particles with siRNA and protect siRNA from degradation. CBSA also shows excellent abilities to intracellularly deliver siRNA and mediate significant accumulation in the lung. When Bcl2-specific siRNA is introduced to this system, CBSA/siRNA nanoparticles exhibit an efficient gene-silencing effect that induces notable cancer cell apoptosis and subsequently inhibits the tumor growth in a B16 lung metastasis model. These results indicate that CBSA-based self-assembled nanoparticles can be a promising strategy for a siRNA delivery system for lung targeting and metastatic cancer therapy.

miRNAs and HIV: unforeseen determinants of host-pathogen interaction

Our understanding of the complexity of gene regulation has significantly improved in the last decade as the role of small non-coding RNAs, called microRNAs (miRNAs), has been appreciated. These 19-22 nucleotide RNA molecules are critical regulators of mRNA translation and turnover. The miRNAs bind via a protein complex to the 3' untranslated region (3' UTR) of mRNA, ultimately leading to mRNA translational inhibition, degradation, or repression. Although many mechanisms by which human immunodeficiency virus-1 (HIV-1) infection eventually induces catastrophic immune destruction have been elucidated, the important role that miRNAs play in HIV-1 pathogenesis is only now emerging. Accumulating evidence demonstrates that changes to endogenous miRNA levels following infection is important: in maintaining HIV-1 latency in resting CD4(+) T cells, potentially affect immune function via changes to cytokines such as interleukin-2 (IL-2) and IL-10 and may predict disease progression. We review the roles that both viral and host miRNAs play in different cell types and disease conditions that are important in HIV-1 infection and discuss how miRNAs affect key immunomodulatory molecules contributing to immune dysfunction. Further, we discuss whether miRNAs may be used as novel biomarkers in serum and the potential to modulate miRNA levels as a unique approach to combating this pathogen.

Current progress in gene delivery technology based on chemical methods and nano-carriers

Gene transfer methods are promising in the field of gene therapy. Current methods for gene transfer include three major groups: viral, physical and chemical methods. This review mainly summarizes development of several types of chemical methods for gene transfer in vitro and in vivo by means of nano-carriers like; calcium phosphates, lipids, and cationic polymers including chitosan, polyethylenimine, polyamidoamine dendrimers, and poly(lactide-co-glycolide). This review also briefly introduces applications of these chemical methods for gene delivery.

Polymers for nucleic acid transfer-an overview

For the last five decades cationic polymers have been used for nucleic acids transfection. Our understanding of polymer-nucleic acid interactions and their rational use in delivery has continuously increased. The great improvements in macromolecular chemistry and the recognition of distinct biological extra- and intracellular delivery hurdles triggered several breakthrough developments, including the discovery of natural and synthetic polycations for compaction of nucleic acids into stable nanoparticles termed polyplexes; the incorporation of targeting ligands and surface-shielding of polyplexes to enable receptor-mediated gene delivery into defined target tissues; and strongly improved intracellular transfer efficacy by better endosomal escape of vesicle-trapped polyplexes into the cytosol. These experiences triggered the development of second-generation polymers with more dynamic properties, such as endosomal pH-responsive release mechanisms, or biodegradable units for improved biocompatibility and intracellular release of the nucleic acid pay load. Despite a better biological understanding, significant challenges such as efficient nuclear delivery and persistence of gene expression persist. The therapeutic perspectives widened from pDNA-based gene therapy to application of novel therapeutic nucleic acids including mRNA, siRNA, and microRNA. The finding that different therapeutic pay loads require different tailor-made carriers complicates preclinical developments. Convincing evidence of medical efficacy still remains to be demonstrated. Bioinspired multifunctional polyplexes resembling "synthetic viruses" appear as attractive opportunity, but provide additional challenges: how to identify optimum combinations of functional delivery units, and how to prepare such polyplexes reproducibly in precise form? Design of sequence-defined polymers, screening of combinatorial polymer and polyplex libraries are tools for further chemical evolution of polyplexes.

Intranasal delivery of chitosan-siRNA nanoparticle formulation to the brain

Neurodegeneration is characterized by a progressive loss of neuron structure and function. Most neurodegenerative diseases progress slowly over the time. There is currently no cure available for any neurodegenerative disease, and the existing therapeutic interventions only alleviate the symptoms of the disease. The advances in the drug discovery research have come to a halt with a lack of effective means to deliver drugs at the targeted site. In addition, the route of delivering the drugs is equally important as most invasive techniques lead to postoperative complications. This chapter focuses on a non-invasive, intranasal mode of therapeutic delivery using nanoparticles, which is currently being explored. The intranasal route of delivery is a well-established route to deliver drugs via the olfactory and trigeminal neuronal pathways. It is known to be the fastest and most effective way to bypass the blood-brain barrier to reach the central nervous system. The presented chapter highlights the method of intranasal delivery in mice using chitosan-siRNA nanoparticle formulation, under mild anesthesia and the identification of successful siRNA delivery in the brain tissues, through histology and other well-established laboratory protocols.

Chitosan nanoparticles for siRNA delivery: optimizing formulation to increase stability and efficiency

This study aims at developing chitosan-based nanoparticles suitable for an intravenous administration of small interfering RNA (siRNA) able to achieve (i) high gene silencing without cytotoxicity and (ii) stability in biological media including blood. Therefore, the influence of chitosan/tripolyphosphate ratio, chitosan physicochemical properties, PEGylation of chitosan as well as the addition of an endosomal disrupting agent and a negatively charged polymer was assessed. The gene silencing activity and cytotoxicity were evaluated on B16 melanoma cells expressing luciferase. We monitored the integrity and the size behavior of siRNA nanoparticles in human plasma using fluorescence fluctuation spectroscopy and single particle tracking respectively. The presence of PEGylated chitosan and poly(ethylene imine) was essential for high levels of gene silencing in vitro. Chitosan nanoparticles immediately released siRNA in plasma while the inclusion of hyaluronic acid and high amount of poly(ethylene glycol) in the formulation improved the stability of the particles. The developed formulations of PEGylated chitosan-based nanoparticles that achieve high gene silencing in vitro, low cytotoxicity and high stability in plasma could be promising for intravenous delivery of siRNA.

A universal protein tag for delivery of SiRNA-aptamer chimeras

siRNA-aptamer chimeras have emerged as one of the most promising approaches for targeted delivery of siRNA due to the modularity of their diblock RNA structure, relatively lower cost over other targeted delivery approaches, and, most importantly, the outstanding potential for clinical translation. However, additional challenges must be addressed for efficient RNA interference (RNAi), in particular, endosomal escape. Currently, vast majority of siRNA delivery vehicles are based on cationic materials, which form complexes with negatively charged siRNA. Unfortunately, these approaches complicate the formulations again by forming large complexes with heterogeneous sizes, unfavorable surface charges, colloidal instability, and poor targeting ligand orientation. Here, we report the development of a small and simple protein tag that complements the therapeutic and targeting functionalities of chimera with two functional domains: a dsRNA binding domain (dsRBD) for siRNA docking and a pH-dependent polyhistidine to disrupt endosomal membrane. The protein selectively tags along the siRNA block of individual chimera, rendering the overall size of the complex small, desirable for deep tissue penetration, and the aptamer block accessible for target recognition. More interestingly, we found that extending the c-terminal polyhistidine segment in the protein tag to 18 amino acids completely abolishes the RNA binding function of dsRBD.

Nanomedicine as an innovative therapeutic strategy for pediatric lung diseases

Nanomedicine is a rapidly emerging technology and represents an innovative field for therapy. Nanomaterials have intrinsically defined features for biomedical applications due to the high specific surface area, the amazing diversity, versatility in structure and function and the possibility of surface charge. In particular, the functionalization of targeting or stimuli-responsive unit on the surface of these materials gives them specific targeted therapeutic properties. There are many pediatric lung diseases that could potentially benefit from nanomedicine. Herein, we aim to review various drug carrier systems and release systems specifically targeting pediatric lung diseases. The injection of nanomedicine into in vivo models and their elimination will also be discussed. Finally, the potential toxicity of nanomaterials will be addressed.

Peritoneal macrophages mediated delivery of chitosan/siRNA nanoparticle to the lesion site in a murine radiation-induced fibrosis model

BACKGROUND

Radiation-induced fibrosis (RIF) is a dose-limiting complication of cancer radiotherapy and causes serious problems, i.e. restricted tissue flexibility, pain, ulceration or necrosis. Recently, we have successfully treated RIF in a mouse model by intraperitoneal administration of chitosan/siRNA nanoparticles directed towards silencing TNF alpha in local macrophage populations, but the mechanism for the therapeutic effect at the lesion site remains unclear.

METHODS

Using the same murine RIF model we utilized an optical imaging technique and fluorescence microscopy to investigate the uptake of chitosan/fluorescently labeled siRNA nanoparticles by peritoneal macrophages and their subsequent migration to the inflamed tissue in the RIF model.

RESULTS

We observed strong accumulation of the fluorescent signal in the lesion site of the irradiated leg up to 24 hours using the optical imaging system. We further confirm by immunohistochemical staining that Cy3 labeled siRNA resides in macrophages of the irradiated leg.

CONCLUSION

We provide a proof-of-concept for host macrophage trafficking towards the inflamed region in a murine RIF model, which thereby suggests that the chitosan/siRNA nanoparticle may constitute a general treatment for inflammatory diseases using the natural homing potential of macrophages to inflammatory sites.

Lipoplexes versus nanoparticles: pDNA/siRNA delivery

Small interfering RNA (siRNA) has been widely used as potential therapeutic for treatment of various genetic disorders. However, rapid degradation, poor cellular uptake and limited stability in blood limit the effectiveness of the systemic delivery of siRNA. Therefore, an efficient delivery system is required to enhance its transfection and duration of therapeutics. In the present study, plasmid DNA (pEGFPN3) expressing green fluorescent protein (GFP) was used as a reporter gene. Chitosan nanoparticles/polyplexes and cationic liposomes/lipoplexes were developed and compared for their transfectivity and therapeutic activity in mammalian cell line (HEK 293). The nanoparticulates were first characterized by assessing the surface charge (zeta potential), size (dynamic light scattering) and morphology (transmission electron microscope) followed by evaluation for their DNA retardation ability, transfection efficiency and cytotoxicity on HEK 293 cell line. The chitosan nanoparticles/plasmid DNA (pDNA) complex and liposomes/pDNA complex were co-transfected with GFP-specific siRNA into HEK 293 cells and it was found that both are efficient delivery vehicles for siRNA transfection, resulting in ~57% and ~70% suppression of the targeted gene (GFP), respectively, as compared with the mock control (cells transfected with nanocarrier/pDNA complexes alone). This strong inhibition of GFP expression indicated that cationic liposomes are better than chitosan nanoparticles and can be used as an effective carrier of siRNA in mammalian cells.

A novel local anti-colorectal cancer drug delivery system: negative lipidoid nanoparticles with a passive target via a size-dependent pattern

The nontoxic, targeted and effective delivery of nucleic acid drugs remains an important challenge for clinical development. Here, we describe a novel negative lipidoid nanoparticle delivery system, providing entrapment-based transfection agents for local delivery of siRNA to the colorectal cancer focus. The delivery system was synthesized with lipidoid material 98N12-5(1), mPEG2000-C12/C14 glyceride and cholesterol at a desired molar ratio to realize the anionic surface charge of particles, which could alleviate to a larger degree the inflammatory response and immune stimulation of the organism, embodying dramatic biocompatibility. In particular, mPEG2000-C12/C14 glyceride was selected to ameliorate the stability of the delivery system and protection of nucleic acids by extending the tail length of the carbons, crucial also to neutralize the positive charge of 98N12-5(1) to form a resultant anionic particle. In vivo experiments revealed that a particle size of 90 nm perfectly realized a passive target in a size-dependent manner and did not affect the function of the liver and kidneys by a local delivery method, enema. We clarified that the uptake of negative lipidoid nanoparticles internalized through a lipid raft endocytotic pathway with low cytotoxicity, strong biocompatibility and high efficacy. This study suggests that negative lipidoid nanoparticles with enema delivery constitute, uniquely and appropriately, a local anti-colorectal cancer nucleic acid drug delivery platform, and the application of similar modes may be feasible in other therapeutic settings.

Intranasal, siRNA Delivery to the Brain by TAT/MGF Tagged PEGylated Chitosan Nanoparticles

Neurodegeneration is characterized by progressive loss of structure and function of neurons. Several therapeutic methods and drugs are available to alleviate the symptoms of these diseases. The currently used delivery strategies such as implantation of catheters, intracarotid infusions, surgeries, and chemotherapies are invasive in nature and pose a greater risk of postsurgical complications, which can have fatal side effects. The current study utilizes a peptide (TAT and MGF) tagged PEGylated chitosan nanoparticle formulation for siRNA delivery, administered intranasally, which can bypass the blood brain barrier. The study investigates the optimal dose, duration, biodistribution, and toxicity, of the nanoparticle-siRNA formulation, in-vivo. The results indicate that 0.5 mg/kg of siRNA is delivered successfully to the hippocampus, thalamus, hypothalamus, and Purkinje cells in the cerebellum after 4 hrs of post intranasal delivery. The results indicate maximum delivery to the brain in comparison to other tissues with no cellular toxic effects. This study shows the potential of peptide-tagged PEGylated chitosan nanoparticles to be delivered intranasally and target brain tissue for the treatment of neurological disorders.

Gadolinium embedded iron oxide nanoclusters as T1-T2 dual-modal MRI-visible vectors for safe and efficient siRNA delivery

This report illustrates a new strategy of designing a T1-T2 dual-modal magnetic resonance imaging (MRI)-visible vector for siRNA delivery and MRI. Hydrophobic gadolinium embedded iron oxide (GdIO) nanocrystals are self-assembled into nanoclusters in the water phase with the help of stearic acid modified low molecular weight polyethylenimine (stPEI). The resulting water-dispersible GdIO-stPEI nanoclusters possess good stability, monodispersity with narrow size distribution and competitive T1-T2 dual-modal MR imaging properties. The nanocomposite system is capable of binding and delivering siRNA for knockdown of a gene of interest while maintaining its magnetic properties and biocompatibility. This new gadolinium embedded iron oxide nanocluster provides an important platform for safe and efficient gene delivery with non-invasive T1-T2 dual-modal MRI monitoring capability.

Comparative characterization and cytotoxicity study of TAT-peptide as potential vectors for siRNA and Dicer-substrate siRNA

Recently, a newly discovered Dicer-substrate siRNA (DsiRNA) demonstrates higher potency in gene silencing than siRNA but both suffer from rapid degradation, poor cellular uptake and chemical instability. Therefore, Tat-peptide was exploited to protect and facilitate their delivery into cells. In this study, Tat-peptide was complexed with siRNA or DsiRNA through simple complexation. The physicochemical properties (particle size, surface charge and morphology) of the complexes formed were then characterized. The ability of Tat-peptide to carry and protect siRNA or DsiRNA was determined by UV-Vis spectrophotometry and serum protection assay, respectively. Cytotoxicity effect of these complexes was assessed in V79 cell line. siRNA-Tat complexes had particle size ranged from 186 ± 17.8 to 375 ± 8.3 nm with surface charge ranged from -9.3 ± 1.0 to +13.5 ± 1.0 mV, depending on the Tat-to-siRNA concentration ratio. As for DsiRNA-Tat complexes, the particle size was smaller than the ones complexed with siRNA, ranging from 176 ± 8.6 to 458 ± 14.7 nm. Their surface charge was in the range of +27.1 ± 3.6 to +38.1 ± 0.9 mV. Both oligonucleotide (ON) species bound strongly to Tat-peptide, forming stable complexes with loading efficiency of more than 86%. These complexes were relatively non cytotoxic as the cell viability of ∼90% was achieved. In conclusion, Tat-peptide has a great potential as siRNA and DsiRNA vector due to the formation of stable complexes with desirable physical characteristics, low toxicity and able to carry high amount of siRNA or DsiRNA.

Chitosan-based siRNA delivery systems

Recently, chitosan has attracted significant attention in the formulation of small interfering RNA (siRNA). Because of its cationic nature, chitosan can easily complex siRNA, thus readily forming nanoparticles. Moreover, chitosan is biocompatible and biodegradable, which make it a good candidate for siRNA delivery in vivo. However, chitosan requires further development to achieve high efficiency. This review will describe the major barriers that impair the efficiency of the chitosan-based siRNA delivery systems, including the stability of the delivery system in biological fluids and endosomal escape. Several solutions to counteract these barriers have been developed and will be discussed. The parameters to consider for designing powerful delivery systems will be described, particularly the possibilities for grafting targeting ligands. Finally, optimized systems that allow in vivo therapeutic applications for both local and systemic delivery will be reviewed. This review will present recent improvements in chitosan-based siRNA delivery systems that overcome many of these system's previous pitfalls and pave the way to a new generation of siRNA delivery systems.

Click conjugated polymeric immuno-nanoparticles for targeted siRNA and antisense oligonucleotide delivery

Efficient and targeted cellular delivery of small interfering RNAs (siRNAs) and antisense oligonucleotides (AONs) is a major challenge facing oligonucleotide-based therapeutics. The majority of current delivery strategies employ either conjugated ligands or oligonucleotide encapsulation within delivery vehicles to facilitate cellular uptake. Chemical modification of the oligonucleotides (ONs) can improve potency and duration of activity, usually as a result of improved nuclease resistance. Here we take advantage of innovations in both polymeric delivery vehicles and ON stabilization to achieve receptor-mediated targeted delivery of siRNAs or AONs for gene silencing. Polymeric nanoparticles comprised of poly(lactide-co-2-methyl, 2-carboxytrimethylene carbonate)-g-polyethylene glycol-furan/azide are click-modified with both anti-HER2 antibodies and nucleic acids on the exterior PEG corona. Phosphorothioate (PS), 2'F-ANA, and 2'F-RNA backbone chemical modifications improve siRNA and AON potency and duration of activity. Importantly, delivery of these nucleic acids on the exterior of the polymeric immuno-nanoparticles are as efficient in gene silencing as lipofectamine transfection without the associated potential toxicity of the latter.

Polysaccharide-based nucleic acid nanoformulations

Therapeutic application of nucleic acids requires their encapsulation in nanosized carriers that enable safe and efficient intracellular delivery. Before the desired site of action is reached, drug-loaded nanoparticles (nanomedicines) encounter numerous extra- and intracellular barriers. Judicious nanocarrier design is highly needed to stimulate nucleic acid delivery across these barriers and maximize the therapeutic benefit. Natural polysaccharides are widely used for biomedical and pharmaceutical applications due to their inherent biocompatibility. At present, there is a growing interest in applying these biopolymers for the development of nanomedicines. This review highlights various polysaccharides and their derivatives, currently employed in the design of nucleic acid nanocarriers. In particular, recent progress made in polysaccharide-assisted nucleic acid delivery is summarized and the specific benefits that polysaccharides might offer to improve the delivery process are critically discussed.

Chitosans for delivery of nucleic acids

Alternatives to efficient viral vectors in gene therapy are desired because of their poor safety profiles. Chitosan is a promising non-viral nucleotide delivery vector because of its biocompatibility, biodegradability, low immunogenicity and ease of manufacturing. Since the transfection efficiency of chitosan polyplexes is relatively low compared to viral counterparts, there is an impetus to gain a better understanding of the structure-performance relationship. Recent progress in preparation and characterisation has enabled coupling analysis of chitosans structural parameters that has led to increased TE by tailoring of chitosan's structure. In this review, we summarize the recent advances that have lead to a more rational design of chitosan polyplexes. We present an integrated review of all major areas of chitosan-based transfection, including preparation, chitosan and polyplexes physicochemical characterisation, in vitro and in vivo assessment. In each, we present the obstacles to efficient transfection and the strategies adopted over time to surmount these impediments.

Nebulised siRNA encapsulated crosslinked chitosan nanoparticles for pulmonary delivery

PURPOSE

To explore the potential of crosslinked chitosan nanoparticles as carriers for delivery of siRNA using a jet nebuliser.

MATERIALS AND METHODS

Nanoparticles encapsulating siRNA were prepared using an ionic crosslinking technique at chitosan to siRNA weight/weight ratios of 10:1, 30:1 and 50:1. Particles were characterised for their size, charge, morphology, pH stability and siRNA encapsulation efficiency. Gel electrophoresis was used to assess the association and stability of siRNA with nanoparticles, including after aerosolisation using a Pari LC Sprint jet nebuliser. The aerosolisation properties of FITC labelled chitosan nanoparticles were investigated using a two-stage impinger. Cell viability was performed with H-292 cells using a WST-1 assay.

RESULTS

Positively charged spherical nanoparticles were produced with mean diameters less than 150 nm, at all chitosan to siRNA ratios. Nanoparticles were non-aggregated at the pH of the airways and showed high siRNA encapsulation efficiency (>96%). Complete binding of siRNA to chitosan nanoparticles was observed when the w/w ratio was 50:1. Nebulisation produced fine particle fractions of 54±11% and 57.3±1.9% for chitosan and chitosan:siRNA (10:1 w/w) nanoparticles respectively. The stability of chitosan-encapsulated siRNA was maintained after nebulisation. Cell viability was high (>85%) at the highest chitosan concentration (83 μg/ml).

CONCLUSION

The results suggest that crosslinked chitosan nanoparticles have potential for siRNA delivery to the lungs using a jet nebuliser.

Chitosan combined with poly-L-arginine as efficient, safe, and serum-insensitive vehicle with RNase protection ability for siRNA delivery

Chitosan (CS) combined with poly-L-arginine (PLA) was formulated and evaluated for its performance to deliver siRNA to HeLa cells expressing enhanced green fluorescent protein (EGFP). Compared with the formulations using single polymer in which the polyplexes were completely formed at the weight ratio of >20 : 1 for CS/siRNA or 1 : 1 for PLA/siRNA, the combination of CS and PLA could reduce the amounts of the polymers required for the complete complexation with siRNA, thereby forming positively charged, nanosized polyplex at the weight ratio of CS/PLA/siRNA of 5 : 0.5: 1. In addition, while the transfection efficiency of CS/siRNA and PLA/siRNA was very low at physiological pH (7.4), CS/PLA/siRNA at the optimal weight ratio of 5 : 0.5 : 1 satisfactorily silenced the endogenous EGFP gene at pH 7.4 as well as at pH 6.4 without the deterrent effect from serum. The combined polymers could protect siRNA from RNase degradation over a period of at least 6 h. Furthermore, MTT assay results demonstrated that CS/PLA/siRNA complexes showed acceptably low cytotoxicity with 75% cell viability. Therefore, CS combined with PLA is easy to prepare, safe, and promising for use as an efficient siRNA delivery vehicle.

Recent developments in nanoparticle-based siRNA delivery for cancer therapy

RNA interference (RNAi) is a gene regulation mechanism initiated by RNA molecules that enables sequence-specific gene silencing by promoting degradation of specific mRNAs. Molecular therapy using small interfering RNA (siRNA) has shown great therapeutic potential for diseases caused by abnormal gene overexpression or mutation. The major challenges to application of siRNA therapeutics include the stability and effective delivery of siRNA in vivo. Important progress in nanotechnology has led to the development of efficient siRNA delivery systems. In this review, the authors discuss recent advances in nanoparticle-mediated siRNA delivery and the application of siRNA in clinical trials for cancer therapy. This review will also offer perspectives on future applications of siRNA therapeutics.

Development and characterization of chitosan-PEG-TAT nanoparticles for the intracellular delivery of siRNA

Recently, cell-penetrating peptides have been proposed to translocate antibodies, proteins, and other molecules in targeted drug delivery. The proposed study presents the synthesis and characterization of a peptide-based chitosan nanoparticle for small interfering RNA (siRNA) delivery, in-vitro. Specifically, the synthesis included polyethylene glycol (PEG), a hydrophilic polymer, and trans-activated transcription (TAT) peptide, which were chemically conjugated on the chitosan polymer. The conjugation was achieved using N-Hydroxysuccinimide-PEG-maleimide (heterobifunctional PEG) as a cross-linker, with the bifunctional PEG facilitating the amidation reaction through its N-Hydroxysuccinimide group and reacting with the amines on chitosan. At the other end of PEG, the maleimide group was chemically conjugated with the cysteine-modified TAT peptide. The degree of substitution on chitosan with PEG and on PEG with TAT was confirmed using colorimetric assays. The resultant polymer was used to form nanoparticles complexing siRNA, which were then characterized for particle size, morphology, cellular uptake, and cytotoxicity. The nanoparticles were tested in-vitro on mouse neuroblastoma cells (Neuro2a). Particle size and surface charge were characterized and an optimal pH condition and PEG molecular weight were determined to form sterically stable nanoparticles. Results indicate 7.5% of the amines in chitosan polymer were conjugated to the PEG and complete conjugation of TAT peptide was observed on the synthesized PEGylated chitosan polymer. Compared with unmodified chitosan nanoparticles, the nanoparticles formed at pH 6 were monodispersed and of <100 nm in size, exhibiting maximum cell transfection ability and very low cytotoxicity. Thus, this research may be of significance in translocating biotherapeutic molecules for intracellular delivery applications.