Engineering Nanocarriers for siRNA Delivery

Multilamellar ceramide core-structured microvehicles with substantial skin barrier function recovery

This study introduces a multilamellar ceramide core-structured microvehicle platform for substantial skin barrier function recovery. Our approach essentially focused on fabricating bacterial cellulose nanofiber (BCNF)-enveloped ceramide-rich lipid microparticles (CerMPs) by solidifying BCNF-armored oil-in-water Pickering emulsions. The oil drops consisted of Ceramide NP (a phytosphingosine backbone N-acylated with a saturated stearic acid) and fatty alcohols (FAs) with a designated stoichiometry. The thin BCNF shell layer completely blocked the growth of ceramide molecular crystals from the CerMPs for a long time. The CerMP cores displayed a multilamellar structure wherein the interlayer distance and lateral packing could be manipulated using FAs with different alkyl chain lengths. The CerMPs remarkably lowered the trans-epidermal water loss while restoring the structural integrity of the epidermis in damaged skin. The results obtained herein highlight that the CerMP system provides a practical methodology for developing various types of skin-friendly formulations that can strengthen the skin barrier function.

Research Status and Prospect of Non-Viral Vectors Based on siRNA: A Review

Gene therapy has attracted much attention because of its unique mechanism of action, non-toxicity, and good tolerance, which can kill cancer cells without damaging healthy tissues. siRNA-based gene therapy can downregulate, enhance, or correct gene expression by introducing some nucleic acid into patient tissues. Routine treatment of hemophilia requires frequent intravenous injections of missing clotting protein. The high cost of combined therapy causes most patients to lack the best treatment resources. siRNA therapy has the potential of lasting treatment and even curing diseases. Compared with traditional surgery and chemotherapy, siRNA has fewer side effects and less damage to normal cells. The available therapies for degenerative diseases can only alleviate the symptoms of patients, while siRNA therapy drugs can upregulate gene expression, modify epigenetic changes, and stop the disease. In addition, siRNA also plays an important role in cardiovascular diseases, gastrointestinal diseases, and hepatitis B. However, free siRNA is easily degraded by nuclease and has a short half-life in the blood. Research has found that siRNA can be delivered to specific cells through appropriate vector selection and design to improve the therapeutic effect. The application of viral vectors is limited because of their high immunogenicity and low capacity, while non-viral vectors are widely used because of their low immunogenicity, low production cost, and high safety. This paper reviews the common non-viral vectors in recent years and introduces their advantages and disadvantages, as well as the latest application examples.

Reactive Oxygen Species─Responsive Lipid Nanoparticles for Effective RNAi and Corneal Neovascularization Therapy

Corneal neovascularization (CNV) is a common disease that affects the vision ability of more than 1 million people annually. Small interfering RNA (siRNA) delivery nanoparticle platforms are a promising therapeutic modality for CNV treatment. However, the efficient delivery of siRNA into cells and the effective release of siRNA from delivery vehicles in a particular cell type challenge effective RNAi clinical application for CNV suppression. This study reports the design of a novel reactive oxygen species (ROS)-responsive lipid nanoparticle for siRNA delivery into corneal lesions for enhanced RNAi as a potential CNV treatment. We demonstrated that lipid nanoparticles could efficiently deliver siRNA into human umbilical vein endothelial cells and release siRNA for enhanced gene silencing by using the upregulated ROS of CNV to promote lipid nanoparticle degradation. Moreover, the subconjunctival injection of siRNA nanocomplexes into corneal lesions effectively knocked down vascular endothelial growth factor expression and suppressed CNV formation in an alkali burn model. Thus, we believe that the strategy of using ROS-responsive lipid nanoparticles for enhanced RNAi in CNV could be further extended to a promising clinical therapeutic approach to attenuate CNV formation.

Surface-Functionalized Polymeric siRNA Nanoparticles for Tunable Targeting and Intracellular Delivery to Hematologic Cancer Cells

To date, the application of RNA therapeutics to hematologic malignancies has been challenging owing to the resistance of blood cancer cells against conventional transfection methods. Herein, triple-targeting moiety-functionalized polymeric small interfering RNA (siRNA) nanoparticles were systematically developed for efficient targeted delivery of RNA therapeutics to hematologic cancer cells. Polymeric siRNAs were synthesized using rolling circle transcription and were surface-functionalized with three types of targeting moieties─a natural ligand and two additional combinations of cell-specific antibodies─for tunable targetability. As a proof of concept, the optimization of the hyaluronic acid/antibody conjugation ratio was performed for selective intracellular delivery to various non-Hodgkin's lymphoma (NHL) cell lines (Daudi, Raji, Ramos, and Toledo cells) via receptor-mediated endocytosis. The engineered nanoparticles showed almost 10-fold enhanced NHL-specific intracellular delivery and induced significant in vitro anticancer effects. This multitargeted nanoparticle platform may effectively support the intracellular delivery of polymeric siRNA sequences, and thus promote therapeutic effects in hematopoietic malignancies.

An organotypic model of high-grade serous ovarian cancer to test the anti-metastatic potential of ROR2 targeted Polyion complex nanoparticles

High-grade serous ovarian cancer (HGSOC) is the most lethal gynaecological malignancy. Most patients are diagnosed at late stages when the tumour has metastasised throughout the peritoneal cavity. The Wnt receptor ROR2 has been identified as a promising therapeutic target in HGSOC, with limited targeting therapeutic options currently available. Small interfering RNA (siRNA)-based therapeutics hold great potential for inhibiting the function of specific biomarkers, however major challenges remain in efficient delivery and stability. The aim of this study was to investigate the ability of nanoparticles to deliver ROR2 siRNA into HGSOC cells, including platinum resistant models, and estimate the anti-metastatic effect via a 3D organotypic model for ovarian cancer. The nanoparticles were generated by conjugating poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA) of various chain length to bovine serum albumin (BSA), followed by the condensation of ROR2 siRNA into polyplexes, also termed polyion complex (PIC) nanoparticles. The toxicity and uptake of ROR2 siRNA PIC nanoparticles in two HGSOC cell lines, CaOV3 as well as its cisplatin resistant pair (CaOV3CisR), in addition to primary cells used for the 3D organotypic model were investigated. ROR2 knockdown at both transcriptional and translational levels were evaluated via real-time PCR and western blot analysis, respectively. Following 24 h incubation with the nanoparticles, functional assays were performed including proliferation (IncuCyte S3), transwell migration and 3D co-cultured transwell invasion assays. The PICs nanoparticles exhibited negligible toxicity in the paired CaOV3 cell lines or primary cells. Treating CaOV3 and CaOV3CisR cells with ROR2 siRNA containing PICs nanoparticles significantly inhibited migration and invasion ability. The biocompatible ROR2 siRNA conjugated PICs nanoparticles provide an innovative therapeutic option. ROR2 targeting therapy shows potential in treating HGSOC including platinum resistant forms.

Recent advances in functionalized upconversion nanoparticles for light-activated tumor therapy

Upconversion nanoparticles (UCNPs) are a class of optical nanocrystals doped with lanthanide ions that offer great promise for applications in controllable tumor therapy. In recent years, UCNPs have become an important tool for studying the treatment of various malignant and nonmalignant cutaneous diseases. UCNPs convert near-infrared (NIR) radiation into shorter-wavelength visible and ultraviolet (UV) radiation, which is much better than conventional UV activated tumor therapy as strong UV-light can be damaging to healthy surrounding tissue. Moreover, UV light generally does not penetrate deeply into the skin, an issue that UCNPs can now address. However, the current studies are still in the early stage of research, with a long way to go before clinical implementation. In this paper, we systematically analysed recent advances in light-activated tumor therapy using functionalized UCNPs. We summarized the purpose and mechanism of UCNP-based photodynamic therapy (PDT), gene therapy, immunotherapy, chemo-therapy and integrated therapy. We believe the creation of functional materials based on UCNPs will offer superior performance and enable innovative applications, increasing the scope and opportunities for cancer therapy in the future.

Selective transferrin coating as a facile strategy to fabricate BBB-permeable and targeted vesicles for potent RNAi therapy of brain metastatic breast cancer in vivo

Brain metastases are a most disturbing situation for breast cancer patients as there is basically no adequate treatment available. Any potential drug formulation has to be able to cross the blood-brain barrier (BBB) and specific to metastatic brain tumors without causing unacceptable adverse effects. Here, we developed transferrin-functionalized chimeric polymersomes carrying siRNA against polo-like kinase 1 (Tf@TBP-CPs-siPLK1) for treating brain metastatic MDA-MB 231 triple negative breast cancer (TNBC) xenografts in mice. To facilitate the loading of siPLK1, chimaeric polymersomes (CPs) were designed with spermine in the watery core and transferrin-binding peptide (TBP) at the surface, enabling attachment of transferrin after the siRNA loading step and thereby circumventing interference of transferrin with siRNA loading. Tf@TBP-CPs-siPLK1 encapsulating 3.8 wt% siRNA had a mean size of about 50 nm and a neutral zeta potential in phosphate buffer (PB). By virtue of the presence of transferrin, Tf@TBP-CPs demonstrated greatly (ca. 5-fold) enhanced internalization in MDA-MB 231 cells and transcytosis in the endothelial (bEnd.3) monolayer model in vitro as well as markedly improved accumulation in the orthotopically xenografted MDA-MB 231 tumor in the brain in vivo compared with control CPs lacking transferrin, supporting that transferrin mediates efficient BBB penetration and high specificity towards MDA-MB 231 cells. As a result, Tf@TBP-CPs-siPLK1 effectively inhibited tumor progression and prolonged the lifespan of the mice significantly. Selective transferrin coating appears to be a particularly facile strategy to fabricate BBB-permeable and targeted vesicles for potent RNAi therapy of brain metastatic breast cancer.

Nanomedicines for combating multidrug resistance of cancer

Chemotherapy typically involves the use of specific chemodrugs to inhibit the proliferation of cancer cells, but the frequent emergence of a variety of multidrug-resistant cancer cells poses a tremendous threat to our combat against cancer. The fundamental causes of multidrug resistance (MDR) have been studied for decades, and can be generally classified into two types: one is associated with the activation of diverse drug efflux pumps, which are responsible for translocating intracellular drug molecules out of the cells; the other is linked with some non-efflux pump-related mechanisms, such as antiapoptotic defense, enhanced DNA repair ability, and powerful antioxidant systems. To overcome MDR, intense efforts have been made to develop synergistic therapeutic strategies by introducing MDR inhibitors or combining chemotherapy with other therapeutic modalities, such as phototherapy, gene therapy, and gas therapy, in the hope that the drug-resistant cells can be sensitized toward chemotherapeutics. In particular, nanotechnology-based drug delivery platforms have shown the potential to integrate multiple therapeutic agents into one system. In this review, the focus was on the recent development of nanostrategies aiming to enhance the efficiency of chemotherapy and overcome the MDR of cancer in a synergistic manner. Different combinatorial strategies are introduced in detail and the advantages as well as underlying mechanisms of why these strategies can counteract MDR are discussed. This review is expected to shed new light on the design of advanced nanomedicines from the angle of materials and to deepen our understanding of MDR for the development of more effective anticancer strategies. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Fabricating nanoparticles co-loaded with survivin siRNA and Pt(IV) prodrug for the treatment of platinum-resistant lung cancer

Resistance to platinum agents is a crucial challenge in the treatment of cancer using platinum drugs. To overcome the resistance of cells, the survivin protein is supposed to be decreased, since it has previously been found to be overexpressed in drug-resistant cancer cells in anti-apoptosis pathways, while the intracellular effective platinum accumulation should be increased. In the present work, a protamine/hyaluronic acid nanocarrier was used to load survivin siRNA with Pt(IV) loaded outside the coated polyglutamic acid (PGA) by chemical conjugation. The siRNA was released from the co-loaded nanoparticle prior to Pt(IV), in this way, the expression of survivin protein was effectively reduced, which, in turn, could avoid the anti-apoptosis of drug resistant cells. Here, Pt(IV) displayed a sustained release effect and gradually reduced to the toxic Pt(II) species, which reduced drug efflux and enhance apoptosis of the cancer cells. In vitro studies demonstrated that co-loaded nanoparticles resulted in similar cell killing performance in A549/DDP cells (cisplatin resistant) compared with non-siRNA loaded nanoparticles in A549 cells (cisplatin sensitive). NP-siRNA/Pt(IV) exhibited a greatly improved therapeutic effect (TIR, 82.46%) in a nude mice A549/DDP tumor model, with no serious adverse effects observed. Thus, co-loading of Pt(IV) and survivin siRNA nanoparticles could reverse cisplatin resistance and therefore has promising prospects for efficient cancer chemotherapy.

Dual-targeting RNA nanoparticles for efficient delivery of polymeric siRNA to cancer cells

A new dual-targeting polymeric siRNA nanoparticle (Dual-PSNP) was developed via multiple processes: rolling circle transcription, condensation, electrostatic deposition, and click chemistry. The Dual-PSNP showed significantly improved cancer-specific intracellular delivery, gene knockdown efficacy, and apoptosis-mediated cytotoxicity through additive receptor-mediated interactions of the two ligands.

Biodegradable calcium phosphate nanoparticles for cancer therapy

Calcium phosphate is the inorganic mineral of hard tissues such as bone and teeth. Due to their similarities to the natural bone, calcium phosphates are highly biocompatible and biodegradable materials that have found numerous applications in dental and orthopedic implants and bone tissue engineering. In the form of nanoparticles, calcium phosphate nanoparticles (CaP's) can also be used as effective delivery vehicles to transfer therapeutic agents such as nucleic acids, drugs, proteins and enzymes into tumor cells. In addition, facile preparation and functionalization of CaP's, together with their inherent properties such as pH-dependent solubility provide advantages in delivery and release of these bioactive agents using CaP's as nanocarriers. In this review, the challenges and achievements in the intracellular delivery of these agents to tumor cells are discussed. Also, the most important issues in the design and potential applications of CaP-based biominerals are addressed with more focus on their biodegradability in tumor microenvironment.

Brain Targeted Gold Liposomes Improve RNAi Delivery for Glioblastoma

INTRODUCTION

Glioblastoma (GBM) is the most common and lethal of the central nervous system (CNS) malignancies. The initiation, progression, and infiltration ability of GBMs are attributed in part to the dysregulation of microRNAs (miRNAs). Thus, targeting dysregulated miRNAs with RNA oligonucleotides (RNA interference, RNAi) has been proposed for GBM treatment. Despite promising results in the laboratory, RNA oligonucleotides have clinical limitations that include poor RNA stability and off-target effects. RNAi therapies against GBM confront an additional obstacle, as they need to cross the blood-brain barrier (BBB).

METHODS

Here, we developed gold-liposome nanoparticles conjugated with the brain targeting peptides apolipoprotein E (ApoE) and rabies virus glycoprotein (RVG). First, we functionalized gold nanoparticles with oligonucleotide miRNA inhibitors (OMIs), creating spherical nucleic acids (SNAs). Next, we encapsulated SNAs into ApoE, or RVG-conjugated liposomes, to obtain SNA-Liposome-ApoE and SNA-Liposome-RVG, respectively. We characterized each nanoparticle in terms of their size, charge, encapsulation efficiency, and delivery efficiency into U87 GBM cells in vitro. Then, they were administered intravenously (iv) in GBM syngeneic mice to evaluate their delivery efficiency to brain tumor tissue.

RESULTS

SNA-Liposomes of about 30-50 nm in diameter internalized U87 GBM cells and inhibited the expression of miRNA-92b, an aberrantly overexpressed miRNA in GBM cell lines and GBM tumors. Conjugating SNA-Liposomes with ApoE or RVG peptides increased their systemic delivery to the brain tumors of GBM syngeneic mice. SNA-Liposome-ApoE demonstrated to accumulate at higher extension in brain tumor tissues, when compared with non-treated controls, SNA-Liposomes, or SNA-Liposome-RVG.

DISCUSSION

SNA-Liposome-ApoE has the potential to advance the translation of miRNA-based therapies for GBM as well as other CNS disorders.

siRNA Conjugated Nanoparticles-A Next Generation Strategy to Treat Lung Cancer

Despite major progress in both therapeutic and diagnostic techniques, lung cancer is still considered the leading cause of cancer mortality in the world due to the ineffectiveness of the classical treatments used nowadays. Luckily, the discovery of small interfering RNA (siRNA) planted hope in the hearts of scientists and patients worldwide as a new breakthrough in the world of oncology and a robust tool for finally curing cancer. However, the valuable siRNA must be protected and preserved to ensure the effectiveness of this gene therapy, thus nanoparticles are gaining more attention than previous years as the optimal carriers for this fragile molecule. siRNA-loaded nanoparticles are being extensively investigated to find the appropriate formulation, combination, and delivery route with one objective in mind—successfully overcoming all possible limitations shown in clinical studies and making full use of this novel technique to become the next generation treatment to wipe out many chronic diseases, including cancer. In this review, the benefits of using siRNA and nanoparticles in lung cancer treatment will be globally reviewed before discussing why and how nanoparticles and siRNA can be combined to achieve an efficient treatment of lung cancer for prospective clinical applications.

Designing siRNA-conjugated plant oil-based nanoparticles for gene silencing and cancer therapy

In this study, the anticancer activities of two siRNA carriers were compared using a human lung adenocarcinoma epithelial cell line (A549). Firstly, poly(styrene)-graft-poly(linoleic acid) (PS-g-PLina) and poly(styrene)-graft-poly(linoleic acid)-graft-poly(ethylene glycol) (PS-g-PLina-g-PEG) graft copolymers were synthesized by free-radical polymerization. PS-PLina and PS-PLina-PEG nanoparticles (NPs) were prepared by solvent evaporation method and were then characterized. The size was found as 150 ± 10 nm for PS-PLina and 184 ± 6 nm for PS-PLina-PEG NPs. The NPs were functionalized with poly(l-lysine) (PLL) for c-myc siRNA conjugation. siRNA entrapment efficiencies were found in the range of 4-63% for PS-PLina-PLL and 6-42% for PS-PLina-PEG-PLL NPs. The short-term stability test was realised for 1 month. siRNA release profiles were also investigated. In vitro anticancer activity of siRNA-NPs was determined by MTT, flow cytometry, and fluorescence microscopy analyses. Obtained findings showed that both NPs systems were promising as siRNA delivery tool for lung cancer therapy.

Metallo-Cubosomes: Zinc-Functionalized Cubic Nanoparticles for Therapeutic Nucleotide Delivery

Development of an effective and potent RNA delivery system remains a challenge for the clinical application of RNA therapeutics. Herein, we describe the development of an RNA delivery platform derived from self-assembled bicontinuous cubic lyotropic liquid crystalline phases, functionalized with zinc coordinated lipids. These metallo-cubosomes were prepared from a series of novel lipidic zinc(II)-bis(dipicolylamine) (Zn₂BDPA)) complexes admixed with glycerol monooleate (GMO). The zinc metallo-cubosomes showed the high affinity to siRNA through interaction between Zn₂BDPA and the phosphate groups of RNA molecules. Using a combination of dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM), we demonstrated that a variety of Zn₂BDPA lipid derivatives can be loaded into GMO cubosomes and the introduction of Zn₂BDPA lipids effected an internal cubic phase transition of the resulting metallo-cubosomes. The findings of this study lay the foundations for the development of a new class of noncationic lipid-based encapsulation systems, metallo-cubosomes for RNA therapeutic delivery.

Overcoming multidrug resistance through inhalable siRNA nanoparticles-decorated porous microparticles based on supercritical fluid technology

BACKGROUND

In recent times, the co-delivery therapeutics have garnered enormous interest from researchers in the treatment of cancers with multidrug resistance (MDR) due to their efficient delivery of multiple agents, which result in synergistic effects and capable of overcoming all the obstacles of MDR in cancer. However, an efficient delivery platform is required for the conveyance of diverse agents that can successfully devastate MDR in cancer.

METHODS

Initially, short-interfering RNA-loaded chitosan (siRNA-CS) nanoparticles were synthesized using the ionic gelation method. Further, the siRNA-CS nanoparticles and doxorubicin hydrochloride (DOX) were co-loaded in poly-L-lactide porous microparticles (PLLA PMs) (nano-embedded porous microparticles, [NEPMs]) by the supercritical anti-solvent (SAS) process.

RESULTS AND DISCUSSION

The NEPM formulation exhibited an excellent aerodynamic performance and sustained release of DOX, which displayed higher anticancer efficacy in drug-resistant cells (human small cell lung cancer, H69AR cell line) than those treated with either free DOX and DOX-PLLA PMs due to the siRNA from CS nanoparticles silenced the MDR gene to DOX therapy.

CONCLUSION

This eco-friendly process provides a convenient way to fabricate such innovative NEPMs co-loaded with a chemotherapeutic agent and a gene, which can devastate MDR in cancer through the co-delivery system.

Simultaneous Delivery of Electrostatically Complexed Multiple Gene-Targeting siRNAs and an Anticancer Drug for Synergistically Enhanced Treatment of Prostate Cancer

Simultaneous silencing of multiple apoptosis-related genes is an attractive approach to treat cancer. In this article, we present a multiple gene-targeting siRNA/drug delivery system for prostate cancer treatment with a high efficiency. Bcl-2, survivin, and androgen receptor genes involved in the cell apoptosis pathways were chosen as silencing targets with three different siRNAs. The colloidal nanocomplex delivery system (<10 nm in size) was formulated electrostatically between anionic siRNAs and a cationic drug (BZT), followed by encapsulation with the Pluronic F-68 polymer. The formulated nanocomplex system exhibited sufficient stability against nuclease-induced degradation, leading to successful intracellular delivery for the desired therapeutic performance. Silencing of targeted genes and apoptosis induction were evaluated in vitro on human prostate LNCaP-LN3 cancer cells by using various biological analysis tools (e.g., real-time PCR, MTT cell viability test, and flow cytometry). It was demonstrated that when the total loaded siRNA amounts were kept the same in the nanocomplexes, the simultaneous silencing of triple genes with co-loaded siRNAs (i.e., Bcl-2, survivin, and AR-targeting siRNAs) enhanced BZT-induced apoptosis of cancer cells more efficiently than the silencing of each single gene alone, offering a novel way of improving the efficacy of gene therapeutics including anticancer drug.

Application of cationized magnetoferritin for magnetic field-assisted delivery of short interfering RNA in vitro

Cationized magnetoferritin is used for development of a simple, efficient, and fast delivery of short interference RNA into cells using combination of magnetophoresis for pre-concentration of siRNA-magnetoferritin complex on the surface of plated cells with subsequent application of nanosecond laser pulses producing stress waves in transfection chamber, which permeabilize cell membrane for the facilitated delivery of siRNA into the cell interior. As has been quantified using siRNA inducing cell death assay, by combination of these two physical factors we have obtained high efficiency for tested three different human carcinoma cells. Proposed method of gene silencing based on cationized magnetoferritin is a versatile and easily accessible platform with many possible applications in gene therapy.

Poly(glycoamidoamine) brush nanomaterials for systemic siRNA delivery in vivo

Delivery is the key challenge for siRNA based therapeutics. Here, we report the development of new poly(glycoamidoamine) brush nanomaterials for efficient siRNA delivery. GluN4C10 polymer brush nanoparticles, a lead material, demonstrated significantly improved delivery efficiency for siRNA against factor VII (FVII) in mice compared to poly(glycoamidoamine) brush nanomaterials reported previously.

RNA interference for glioblastoma therapy: Innovation ladder from the bench to clinical trials

Glioblastoma multiforme (GBM) is the most common and deadliest type of primary brain tumor with a prognosis of 14months after diagnosis. Current treatment for GBM patients includes "total" tumor resection, temozolomide-based chemotherapy, radiotherapy or a combination of these options. Although, several targeted therapies, gene therapy, and immunotherapy are currently in the clinic and/or in clinical trials, the overall survival of GBM patients has hardly improved over the last two decades. Therefore, novel multitarget modalities are urgently needed. Recently, RNA interference (RNAi) has emerged as a novel strategy for the treatment of most cancers, including GBM. RNAi-based therapies consist of using small RNA oligonucleotides to regulate protein expression at the post-transcriptional level. Despite the therapeutic potential of RNAi molecules, systemic limitations including short circulatory stability and low release into the tumor tissue have halted their progress to the clinic. The effective delivery of RNAi molecules through the blood-brain barrier (BBB) represents an additional challenge. This review focuses on connecting the translational process of RNAi-based therapies from in vitro evidence to pre-clinical studies. We delineate the effect of RNAi in GBM cell lines, describe their effectiveness in glioma mouse models, and compare the proposed drug carriers for the effective transport of RNAi molecules through the BBB to reach the tumor in the brain. Furthermore, we summarize the most important obstacles to overcome before RNAi-based therapy becomes a reality for GBM treatment.

siRNA delivery using polyelectrolyte-gold nanoassemblies in neuronal cells for BACE1 gene silencing

Small interfering RNA (siRNA) mediated RNA interference is a versatile therapeutic tool for many intractable genetic disorders. Various nanoassemblies specifically designed to deliver the siRNAs could be utilized for efficient siRNA delivery which is one of the major concern for the success of this therapeutic. Thus, in the present study, polyelectrolyte-gold nanoassemblies (PE-Gold NAs) were selected for siRNA delivery of an in vitro verified siRNA. Three different polyelectrolytes (polyethyleneimine, citraconic anhydride modified poly (allylamine) hydrochloride and poly l-arginine) were used to formulate the PE-Gold NAs using the layer-by-layer technique. Successful physico-chemical characterizations of these PE-Gold NAs were performed using UV-Visible, FTIR, ¹H-NMR spectroscopies, XRD, TEM, DLS and Zeta potential measurements. In vitro studies for the cytotoxicity, the uptake of these nanoassemblies and the gene silencing were carried out using these PE-Gold NAs in N2a and NB4 1A3 (murine neuronal) cell lines. The three selected PE-Gold NAs showed significant BACE1 (β-site APP cleaving enzyme 1) gene silencing (50-60%). This work demonstrates the potential of PE-Gold NAs to deliver siRNA targeting BACE1 in neuronal cells. Finally, it was concluded that different polyelectrolytes used in the PE-Gold NAs achieve different gene silencing due to the variation in their delivery efficiencies.

Facial Layer-by-Layer Engineering of Upconversion Nanoparticles for Gene Delivery: Near-Infrared-Initiated Fluorescence Resonance Energy Transfer Tracking and Overcoming Drug Resistance in Ovarian Cancer

Development of multidrug resistance (MDR) contributes to the majority of treatment failures in clinical chemotherapy. We report facial layer-by-layer engineered upconversion nanoparticles (UCNPs) for near-infrared (NIR)-initiated tracking and delivery of small interfering RNA (siRNA) to enhance chemotherapy efficacy by silencing the MDR1 gene and resensitizing resistant ovarian cancer cells to drug. Layer-by-layer engineered UCNPs were loaded with MDR1 gene-silencing siRNA (MDR1-siRNA) by electrostatic interaction. The delivery vehicle enhances MDR1-siRNA cellular uptake, protects MDR1-siRNA from nuclease degradation, and promotes endosomal escape for silencing the MDR gene. The intrinsic photon upconversion of UCNPs provides an unprecedented opportunity for monitoring intracellular attachment and release of MDR1-siRNA by NIR-initiated fluorescence resonance energy transfer occurs between donor UCNPs and acceptor fluorescence dye-labeled MDR1-siRNA. Enhanced chemotherapeutic efficacy in vitro was demonstrated by cell viability assay. The developed delivery vehicle holds great potential in delivery and imaging-guided tracking of therapeutic gene targets for effective treatment of drug-resistant cancers.

Codelivery of anticancer drugs and siRNA by mesoporous silica nanoparticles

The most common method for cancer treatment is chemotherapy. Multidrug resistance (MDR) is one of the major obstacles in chemotherapeutic treatment of many human cancers. One strategy to overcome this challenge is the delivery of anticancer drugs and siRNA simultaneously using nanoparticles. Mesoporous silica nanoparticles are one of the most popular nanoparticles for cargo delivery because of their intrinsic porosity. This paper highlights recent advances in codelivery of chemotherapeutic and siRNA with mesoporous silica nanoparticles for cancer therapy. In addition, synthesis and functionalization approaches of these nanoparticles are summarized. This review presents insight into the utilization of nanoparticles and combination therapy to achieve more promising results in chemotherapy.

Conjugates of small targeting molecules to non-viral vectors for the mediation of siRNA

To use siRNA (small interfering RNA) for gene therapy, a gene delivery system is often necessary to overcome several challenging requirements including rapid excretion, low stability in blood serum, non-specific accumulation in tissues, poor cellular uptake and inefficient intracellular release. Active and/or passive targeting should help the delivery system to reach the desired tissue or cell, to be internalized, and to deliver siRNA to the cytoplasm so that siRNA can inhibit protein synthesis. This review covers conjugates of small targeting molecules and non-viral delivery systems for the mediation of siRNA, with a focus on their transfection properties in order to help the development of new and efficient siRNA delivery systems, as the therapeutic solutions of tomorrow.

STATEMENT OF SIGNIFICANCE

The delivery of siRNA into cells or tissues remains to be a challenge for its applications, an alternative strategy for siRNA delivery systems is direct conjugation of non-viral vectors with targeting moieties for cellular delivery. In comparison to macromolecules, small targeting molecules have attracted great attention due to their many potential advantages including significant simplicity and ease of production, good repeatability and biodegradability. This review will focus on the most recent advances in the delivery of siRNA using conjugates of small targeting molecules and non-viral delivery systems. Based the editor's suggestions, we hope the revised manuscript could provide more profound understanding to the conjugates of targeting molecules to vectors for mediation of siRNA.

Near-infrared light activated delivery platform for cancer therapy

Cancer treatment using conventional drug delivery platforms may lead to fatal damage to normal cells. Among various intelligent delivery platforms, photoresponsive delivery platforms are becoming popular, as light can be easily focused and tuned in terms of power intensity, wavelength, and irradiation time, allowing remote and precise control over therapeutic payload release both spatially and temporally. This unprecedented controlled delivery manner is important to improve therapeutic efficacy while minimizing side effects. However, most of the existing photoactive delivery platforms require UV/visible excitation to initiate their function, which suffers from phototoxicity and low level of tissue penetration limiting their practical applications in biomedicine. With the advanced optical property of converting near infrared (NIR) excitation to localized UV/visible emission, upconversion nanoparticles (UCNPs) have emerged as a promising photoactive delivery platform that provides practical applications for remote spatially and temporally controlled release of therapeutic payload molecules using low phototoxic and high tissue penetration NIR light as the excitation source. This article reviews the state-of-the-art design, synthesis and therapeutic molecular payload encapsulation strategies of UCNP-based photoactive delivery platforms for cancer therapy. Challenges and promises for engineering of advanced delivery platforms are also highlighted.

Amylose-Based Cationic Star Polymers for siRNA Delivery

A new siRNA delivery system using a cationic glyco-star polymer is described. Spermine-modified 8-arm amylose star polymer (with a degree of polymerization of approximately 60 per arm) was synthesized by chemoenzymatic methods. The cationic star polymer effectively bound to siRNA and formed spherical complexes with an average hydrodynamic diameter of 230 nm. The cationic 8-arm star polymer complexes showed superior cellular uptake characteristics and higher gene silencing effects than a cationic 1-arm polymer. These results suggest that amylose-based star polymers are a promising nanoplatform for glycobiomaterials.

Enhanced Immunostimulating Activity of Lactobacilli-Mimicking Materials by Controlling Size

The design and synthesis of materials capable of activating the immune system in a safe manner is of great interest in immunology and related fields. Lactobacilli activate the innate immune system of a host when acting as probiotics. Here, we constructed lactobacilli-mimicking materials in which polysaccharide-peptidoglycan complexes (PS-PGs) derived from lactobacilli were covalently conjugated to the surfaces of polymeric microparticles with a wide variety of sizes, ranging from 200 nm to 3 μm. The artificial lactobacilli successfully stimulated macrophages without cytotoxicity. Importantly, we found that the size of artificial lactobacilli strongly influenced their immunostimulating activities, and that artificial lactobacilli of 1 μm exhibited 10-fold higher activity than natural lactobacilli. One major advantage of the artificial lactobacilli is facile control of size, which cannot be changed in natural lactobacilli. These findings provide new insights into the design of materials for immunology as well as the molecular biology of lactobacillus.

Co-delivery of chemosensitizing siRNA and an anticancer agent via multiple monocomplexation-induced hydrophobic association

Synergistic combination of gene targeting and chemotherapy by co-delivering siRNA and anticancer drugs has widely been investigated to develop siRNA-based therapeutics for cancer treatment. Despite clinical potential of this approach, big challenges still remain such as delivery efficiency or stability/biocompatibility of the siRNA delivery system. Here we report a simple and biocompatible co-delivering formulation based on a unique complexation method, i.e., multiple monocomplexation-induced hydrophobic association between Bcl-2 targeting siRNA and a monocationic anticancer agent (benzethonium chloride, BZT). A colloidal formulation of the hydrophobically associated multiple monocomplex (HMplex) composed of siRNA, BZT and Pluronic F-68 was spontaneously constructed by physical mixing of the ternary constituents. In vitro and in vivo studies revealed that the ternary HMplex with a low charge ratio (N/P=4) possesses a tightly complexed stable nanostructure with Pluronic surface and small colloidal size less than 10nm, which allowed for 1) suitable protection of siRNA in serum-rich physiological environment, 2) efficient intracellular transfection into the cytoplasm, and 3) successful peritumoral co-delivery into the tumor tissue with dense interstitial matrix. Compared to non-targeting HMplexes between scrambled siRNA and BZT, Bcl-2 targeting HMplexes enhanced significantly both mRNA down-regulation by siRNA and apoptosis induction by BZT, and thus greatly suppressed the tumor volume when administered to highly aggressive and resistant human breast cancer xenografts (MDA-MB-231) in mice. These results elucidate that the co-complexed siRNA and BZT were liberated by intracellular decomplexation to trigger a synergistically combined therapeutic action. The successful siRNA/chemodrug co-delivery in vivo via peritumoral route and the greatly promoted therapeutic efficacy thereby represent the clinical potential of HMplexes for adjuvant locoregional cancer treatment by gene-targeted combination therapy.

Live cell imaging of duplex siRNA intracellular trafficking

Intracellular distribution of siRNA after in vitro transfection typically depends on lipopolyplexes, which must release the siRNA into the cytosol. Here, the fate of siRNAs was monitored by FRET-based live cell imaging. Subsequent to in situ observation of uptake and release processes, this approach allowed the observation of a number of hitherto uncharacterized intracellular distribution and degradation processes, commencing with a burst of endosomal releases, followed, in some cases, by fast siRNA influx into the nucleus. The continued observation of intact siRNA against a background of free fluorophores resulting from advanced degradation was possible by a specifically developed imaging algorithm, which identified populations of intact siRNA in pixels based on FRET. This proved to be essential in the end point definition of siRNA distribution, which typically featured partially degraded siRNA pools in perinuclear structures. Our results depict the initial 4 h as a critical time window, characterized by fast initial burst release into the cytosol, which lay the foundations for subsequent intracellular distribution of siRNA. Combination with a subsequent slower, but sustained release from endosomal reservoirs may contribute to the efficiency and duration of RNAi, and explain the success of lipopolyplexes in RNAi experiments in cell culture.

Promoting siRNA delivery via enhanced cellular uptake using an arginine-decorated amphiphilic dendrimer

RNA interference (RNAi) with small interfering RNA (siRNA) is expected to offer an attractive means to specifically and efficiently silence disease-associated genes for treating various diseases provided that safe and efficient delivery systems are available. In this study, we have established an arginine-decorated amphiphilic dendrimer composed of a hydrophobic alkyl chain and a hydrophilic PAMAM dendron bearing arginine terminals as nonviral vector for siRNA delivery. Indeed, this dendrimer proved to be very effective at delivering siRNAs in human prostate cancer PC-3 cells and in human hematopoietic CD34+ stem cells, leading to improved gene silencing compared to the corresponding nonarginine decorated dendrimer. Further investigation confirmed that this dendrimer was granted with the capacity to form stable nanoparticles with siRNA and significantly enhance cellular uptake of siRNA. In addition, this dendrimer revealed no discernible cytotoxicity. All these findings demonstrate that decoration of the dendrimer surface with arginine residues is indeed a useful strategy to improve the delivery ability of dendrimers.

Synthesis and immunestimulating activity of lactobacilli-originated polysaccharide-polymeric microparticle conjugates

The design and synthesis of biomaterials capable of activating the immune system are of interest in immunology-related fields because of their ability to tune up the immune defenses of the host. Lactobacilli are a major constituent of normal human indigenous flora, and some specific strains are known to activate the immune system of the host as probiotics. In this study, we first fabricated novel biohybrid materials in which lactobacilli (L. casei strain Shirota, LcS)-originated polysaccharide-peptidoglycan complexes (PS-PGs) are conjugated with polymeric microparticles (MPs). PS-PGs conjugated onto polymeric MPs surfaces bound its specific antibody, suggesting that PS-PGs kept their original molecular recognition ability. The PS-PGs-based hybrid MPs with an appropriate density of conjugated PS-PGs effectively induced high levels of IL-12 production from macrophages without cytotoxicity. These results suggest that LcS-originated PS-PGs could be available bio-originated materials for developing novel biomaterials capable of activating the immune system in a safe manner.

Amphiphilic gold nanoparticles displaying flexible bifurcated ligands as a carrier for siRNA delivery into the cell cytosol

The nanoparticle-based delivery of siRNA with a noncationic outermost surface at a low particle concentration is greatly desired. We newly synthesized a bifurcated ligand (BL) possessing hydrophobic and hydrophilic arms as a surface ligand for gold nanoparticles (AuNPs) to allow siRNA delivery. The concept underlying the design of this ligand is that amphiphilic property should allow AuNPs to permeate the cell cytosol thorough the endosomal membrane. BLs and quaternary cationic ligands were codisplayed on 40 nm AuNPs, which were subsequently coated with siRNA via electrostatic interaction. The number of siRNAs immobilized on a single nanoparticle was 26, and the conjugate showed a negative zeta potential due to siRNAs on the outermost surface of the AuNPs. Apparent gene silencing of luciferase expression in HeLa cells was achieved at an AuNP concentration as low as 60 pM. Almost no gene silencing was observed for AuNPs not displaying BLs. To reveal the effect of the BL, we compared the number of AuNPs internalized into HeLa cells and the localization in the cytosol between AuNPs displaying and those not displaying BLs. These analyses indicated that the role of BLs is not only the simple promotion of cellular uptake but also involves the enhancement of AuNPs permeation into the cytosol from the endosomes, leading to effective gene silencing.

Nanovector-based prolyl hydroxylase domain 2 silencing system enhances the efficiency of stem cell transplantation for infarcted myocardium repair

Mesenchymal stem cell (MSC) transplantation has attracted much attention in myocardial infarction therapy. One of the limitations is the poor survival of grafted cells in the ischemic microenvironment. Small interfering RNA-mediated prolyl hydroxylase domain protein 2 (PHD2) silencing in MSCs holds tremendous potential to enhance their survival and paracrine effect after transplantation. However, an efficient and biocompatible PHD2 silencing system for clinical application is lacking. Herein, we developed a novel PHD2 silencing system based on arginine-terminated generation 4 poly(amidoamine) (Arg-G4) nanoparticles. The system exhibited effective and biocompatible small interfering RNA delivery and PHD2 silencing in MSCs in vitro. After genetically modified MSC transplantation in myocardial infarction models, MSC survival and paracrine function of IGF-1 were enhanced significantly in vivo. As a result, we observed decreased cardiomyocyte apoptosis, scar size, and interstitial fibrosis, and increased angiogenesis in the diseased myocardium, which ultimately attenuated ventricular remodeling and improved heart function. This work demonstrated that an Arg-G4 nanovector-based PHD2 silencing system could enhance the efficiency of MSC transplantation for infarcted myocardium repair.

Functional nanostructures for effective delivery of small interfering RNA therapeutics

Small interfering RNA (siRNA) has proved to be a powerful tool for target-specific gene silencing via RNA interference (RNAi). Its ability to control targeted gene expression gives new hope to gene therapy as a treatment for cancers and genetic diseases. However, siRNA shows poor pharmacological properties, such as low serum stability, off-targeting, and innate immune responses, which present a significant challenge for clinical applications. In addition, siRNA cannot cross the cell membrane for RNAi activity because of its anionic property and stiff structure. Therefore, the development of a safe, stable, and efficient system for the delivery of siRNA therapeutics into the cytoplasm of targeted cells is crucial. Several nanoparticle platforms for siRNA delivery have been developed to overcome the major hurdles facing the therapeutic uses of siRNA. This review covers a broad spectrum of non-viral siRNA delivery systems developed for enhanced cellular uptake and targeted gene silencing in vitro and in vivo and discusses their characteristics and opportunities for clinical applications of therapeutic siRNA.

Enhancing endosomal escape for nanoparticle mediated siRNA delivery

Gene therapy with siRNA is a promising biotechnology to treat cancer and other diseases. To realize siRNA-based gene therapy, a safe and efficient delivery method is essential. Nanoparticle mediated siRNA delivery is of great importance to overcome biological barriers for systemic delivery in vivo. Based on recent discoveries, endosomal escape is a critical biological barrier to be overcome for siRNA delivery. This feature article focuses on endosomal escape strategies used for nanoparticle mediated siRNA delivery, including cationic polymers, pH sensitive polymers, calcium phosphate, and cell penetrating peptides. Work has been done to develop different endosomal escape strategies based on nanoparticle types, administration routes, and target organ/cell types. Also, enhancement of endosomal escape has been considered along with other aspects of siRNA delivery to ensure target specific accumulation, high cell uptake, and low toxicity. By enhancing endosomal escape and overcoming other biological barriers, great progress has been achieved in nanoparticle mediated siRNA delivery.

Layer-by-layer nanoparticles as an efficient siRNA delivery vehicle for SPARC silencing

Efficient and safe delivery systems for siRNA therapeutics remain a challenge. Elevated secreted protein, acidic, and rich in cysteine (SPARC) protein expression is associated with tissue scarring and fibrosis. Here we investigate the feasibility of encapsulating SPARC-siRNA in the bilayers of layer-by-layer (LbL) nanoparticles (NPs) with poly(L-arginine) (ARG) and dextran (DXS) as polyelectrolytes. Cellular binding and uptake of LbL NPs as well as siRNA delivery were studied in FibroGRO cells. siGLO-siRNA and SPARC-siRNA were efficiently coated onto hydroxyapatite nanoparticles. The multilayered NPs were characterized with regard to particle size, zeta potential and surface morphology using dynamic light scattering and transmission electron microscopy. The SPARC-gene silencing and mRNA levels were analyzed using ChemiDOC western blot technique and RT-PCR. The multilayer SPARC-siRNA incorporated nanoparticles are about 200 nm in diameter and are efficiently internalized into FibroGRO cells. Their intracellular fate was also followed by tagging with suitable reporter siRNA as well as with lysotracker dye; confocal microscopy clearly indicates endosomal escape of the particles. Significant (60%) SPARC-gene knock down was achieved by using 0.4 pmole siRNA/μg of LbL NPs in FibroGRO cells and the relative expression of SPARC mRNA reduced significantly (60%) against untreated cells. The cytotoxicity as evaluated by xCelligence real-time cell proliferation and MTT cell assay, indicated that the SPARC-siRNA-loaded LbL NPs are non-toxic. In conclusion, the LbL NP system described provides a promising, safe and efficient delivery platform as a non-viral vector for siRNA delivery that uses biopolymers to enhance the gene knock down efficiency for the development of siRNA therapeutics.