A Collaborative Assembly Strategy for Tumor-Targeted siRNA Delivery

Non-viral nanocarriers for intracellular delivery of microRNA therapeutics

MicroRNAs are small regulatory noncoding RNAs that regulate various biological processes. Herein, we will present the development of the strategies for intracellular miRNAs delivery, and specially focus on the rational designed routes, their mechanisms of action, as well as potential therapeutics used in the host cells orin vivostudies.

The development of tertiary amine cationic lipids for safe and efficient siRNA delivery

Tertiary amine-derived cationic lipid serves as the primary lipid of cationic liposomes, which can balance the effectiveness and safety of siRNA vectors.

Design of Tumor Microenvironment-Responsive Drug-Drug Micelle for Cancer Radiochemotherapy

Concomitant radiochemotherapy is a major therapeutic strategy for treating malignant tumors. However, the greatest challenge is how to improve the therapeutic effect of radiochemotherapy to achieve the proper synergetic chemo-/radiotherapy for the tumor. In this study, ferrocenium (antitumor effect) and nitroimidazole (hypoxic cell radiosensitization) conjugates were synthesized to form amphiphilic ferrocenium-hexane-nitroimidazole (Fe-NI), which can self-assemble in aqueous solution. The Fe-NI micelles successfully encapsulate the hydrophobic chemotherapy drug doxorubicin (DOX) and are modified with hyaluronic acid (HA) by electrostatic interactions to form HA-Fe-NIs-DOX micelles. HA-Fe-NIs-DOX micelles rapidly release DOX under tumor hypoxia and a high glutathione (GSH) environment and achieve a synergetic chemo-/radiotherapy for the tumor based on the properties of nitroimidazoles and ferrocenes. The biodistribution results obtained in vivo reveal an effective accumulation in the tumor. The HA-Fe-NIs-DOX micelles show a significant radiosensitizing effect on the tumors, and the combination of chemotherapy and radiotherapy is realized for the treatment of tumor in vitro and in vivo. These findings illustrate that HA-Fe-NIs micelles are a promising candidate, which enhances the antitumor effects as a DOX delivery system, owing to the synergistic mechanisms of antitumor agents and chemo-/radiotherapy.

Reversible Covalent Cross-Linked Polycations with Enhanced Stability and ATP-Responsive Behavior for Improved siRNA Delivery

Cationic polyplex as commonly used nucleic acid carriers faced several shortcomings, such as high cytotoxicity, low serum stability, and slow cargo release at the target site. The traditional solution is covering a negative charged layer (e.g., hyaluronic acid, HA) via electrostatic interaction. However, it was far from satisfactory for the deshielding by physiological anions in circulation (e.g., serum proteins, phosphate). In this study, we proposed a new strategy of reversible covalent cross-linking to enhance stability in circulation and enable stimuli-disassembly of polyplexes in tumor cells. Here, 25k polyethylenimine (PEI) was chosen as model polycations for veriying the hypothesis. HA-PEI conjugation was formed by the cross-linking of adenosine triphosphate grafted HA (HA-ATP) with phenylboronic acid grafted PEI (PEI-PBA) via the chemical reaction between PBA and ATP. Compared with noncovalent polyplex by electrostatic interaction (HA/PEI), HA-PEI exhibited much better colloidal stability and serum stability. The covered HA-ATP layer on PEI-PBA could maintain stable in the absence of physiological anions, while HA layer on PEI in HA/PEI group showed obvious detachment after anion's competition. More importantly, the covalent cross-linking polyplex could selectively release siRNA in the ATP rich environment of cytosol and significantly improve siRNA silence. Besides, the covalent cross-linking with HA-ATP could effectively reduce the cytotoxicity of cationic polyplex, improve the uptake by B61F10 cells and promote the endosomal escape. Consequently, this strategy of HA-PEI conjugation significantly enhanced the siRNA transfection in the absence or presence of FBS (fetal bovine serum) on B16F10 cells and CHO cells. Taken together, the reversible covalent cross-linking approach shows obvious superiority compared with the noncovalent absorption strategy. It held great potential to be developed to polish up the performance of cationic polyplex on reducing the toxicity, enhancing the serum tolerance and achieving controlled release of siRNA at target site.

Engineering Human Epidermal Growth Receptor 2-Targeting Hepatitis B Virus Core Nanoparticles for siRNA Delivery in Vitro and in Vivo

Hepatitis B virus core (HBc) particles acquire the capacity to disassemble and reassemble in a controlled manner, allowing entrapment and delivery of drugs and macromolecules to cells. HBc particles are made of 180-240 copies of 21 kDa protein monomers, assembled into 30-34 nm diameter icosahedral particles. In this study, we aimed at formulating HBc particles for the delivery of siRNA for gene silencing in vitro and in vivo. We have previously reported recombinant HBc particles expressing Z_HER2 affibodies, specifically targeting human epidermal growth receptor 2 (HER2)-expressing cancer cells (Z_HER2-ΔHBc). siRNA was encapsulated within the Z_HER2-ΔHBc particles following disassembly and reassembly. The Z_HER2-ΔHBc-siRNA hybrids were able to secure the encapsulated siRNA from serum and nucleases in vitro. Enhanced siRNA uptake in HER2-expressing cancer cells treated with Z_HER2-ΔHBc-siRNA hybrids was observed compared to the nontargeted HBc-siRNA hybrids in a time- and dose-dependent manner. A successful in vitro polo-like kinase 1 (PLK1) gene knockdown was demonstrated in cancer cells treated with Z_HER2-ΔHBc-siPLK1 hybrids, to levels comparable to commercial transfecting reagents. Interestingly, Z_HER2-ΔHBc particles exhibit intrinsic capability of reducing the solid tumor mass, independent of siPLK1 therapy, in an intraperitoneal tumor model following intraperitoneal injection.

Hierarchical Nanoassemblies-Assisted Combinational Delivery of Cytotoxic Protein and Antibiotic for Cancer Treatment

Protein therapeutics hold increasing interest with the promise of revolutionizing the cancer treatment by virtue of a potent specific activity and reduced adverse effects. Nonetheless, the therapeutic efficacy of anticancer proteins is highly compromised by multiple successive physiological barriers to protein delivery. In addition, concurrent elimination of bulk tumor cells and highly tumorigenic cancer stem-like cells (CSCs) as a promising strategy has been evidenced to significantly improve cancer therapy. Here we show that a hierarchically assembled nanocomposite can self-adaptively transform its particulate property in response to endogenous tumor-associated signals to overcome the sequential barriers and achieve an enhanced antitumor efficacy by killing CSCs and bulk tumor cells synchronously. The nanoassemblies preferentially accumulate in tumors and dissociate under tumor microenvironmental acidity accompanied by the extracellular release of small-sized ribonuclease A (RNase A)-encapsulated nanocapsule (R-rNC) and small-molecule anti-CSC doxycycline (Doc), which exhibit increased tumor penetration and intracellular accumulation. The endocytosed R-rNC rapidly releases RNase A within both CSCs and tumor cells at intracellular reductive conditions, causing cell death by catalyzing RNA degradation, while Doc eradicates CSCs by inhibiting the mitochondrial biogenesis. The hierarchical assemblies show enhanced cytotoxicity on the CSC-enriched MDA-MB-231 mammospheres and an enhanced antitumor efficacy on the xenograft tumor mouse model.

Nanostructured Peptidotoxins as Natural Pro-Oxidants Induced Cancer Cell Death via Amplification of Oxidative Stress

Melittin (Mel), one of the host defense peptides derived from the venom of honeybees, demonstrates substantial anticancer properties, which is attributed to augmenting reactive oxygen species (ROS) generation. However, little has been reported on its pro-oxidation capacity in cancer oxidation therapy. In this study, an ROS amplifying nanodevice was fabricated through direct complexation of two natural pro-oxidants, Mel and condensed epigallocatechin gallate (pEGCG). The obtained nanocomplex (NC) was further covered with phenylboronic acid derivatized hyaluronic acid (pHA) through the ROS-responsive boronate ester coordination bond to produce pHA-NC. Upon undergoing receptor-mediated endocytosis into cancer cells, the inner cores of pHA-NC will be partially uncovered once pHA corona is degraded by hyaluronidase and will then escape from the lysosome by virtue of cytolytic Mel. The elevated ROS level in the tumor cytoplasm can disrupt the boronate ester bond to facilitate drug release. Both Mel and pEGCG could synergistically amplify oxidative stress and prolong ROS retention in cancer cells, leading to enhanced anticancer efficacy. This ROS cascade amplifier based on selective coordination bond and inherent pro-oxidation properties of natural ingredients could detect and elevate intracellular ROS signals, potentiating to move the tumor away from its homeostasis and make the tumor vulnerable. Compared to previously reported chemosynthetic pro-oxidants, the ROS self-sufficient system, fully composed of natural medicine, from this study provides a new insight in developing cancer oxidation therapy.

In situ dual-crosslinked nanoparticles for tumor targeting gene delivery

The instability of gene delivery systems and their "off-target" features are among the major hurdles in gene therapy. In this study, a facile fabrication platform is constructed to endow the gene delivery system with high stability in the circulation system and achieve targeted delivery of plasmid DNA (pDNA) into cancer cells. Aldehyde groups-bearing hyaluronic acid (HA-CHO) is initially synthesized through oxidation, and is then shielded on polyethylenimine/DNA (PEI/DNA) complex particles to form dual-crosslinked nanoparticles in situ. These nanoparticles simultaneously possess electrostatic and chemical crosslinks between outer layers and cores. The dual-crosslinking system further offers the following advantages when used for gene delivery. First, the two different in situ crosslinking routes strengthen nanoparticle stability. Second, targeting ligands on HA layers mediate specific recognition toward cancer cells. Cell and animal experiments demonstrate that the as-prepared complex particles exhibit enhanced stability in serum and excellent long circulation behavior in vivo. Third, the dual-crosslinked nanoparticles present good accumulation ability in tumors after intravenous injection into nude mice bearing HeLa tumors. Overall, the dual-crosslinking strategy is a promising solution for constructing an efficient gene delivery system.

STATEMENT OF SIGNIFICANCE

This manuscript focused on the in situ dual-crosslinked nanoparticles for tumor targeting pDNA delivery. The novel system is prepared by in situ shielding HA-CHO on PEI/DNA complexes. The electrostatic crosslink formed between carboxyl groups on HA-CHO and amine groups on PEI as well as the reaction between aldehyde groups on HA-CHO and amine groups on PEI contributes to the chemical crosslink. By introduction of HA-CHO on PEI/DNA complexes, they show promoting colloidal stability, enhanced cellular uptake and tumor targeting ability. The in vivo experiments further confirm the excellent ability of long circulation and tumor accumulation. Accordingly, HA-CHO2/PEI/DNA has great potential for tumor targeting antitumor therapy.

Size-dependent uptake of electrically neutral amphipathic polymeric nanoparticles by cell-sized liposomes and an insight into their internalization mechanism in living cells

The size-dependent uptake of amphipathic uncharged-nanoparticles in cell-sized liposomes is emerging as a new insight into their internalization mechanism in living cells.

A modular assembly pH-sensitive charge reversal siRNA delivery system

Cationic lipids and polymers are the most common non-viral vectors for siRNA delivery; however, their intense positively charged character may give rise to serum-triggered aggregation, immune activation, inflammation stimulation and grievous toxicity.

Facile dynamic one-step modular assembly based on boronic acid-diol for construction of a micellar drug delivery system

This study reports a facile and dynamic one-step modular assembly strategy based on boronic acid-diol for constructing focus-responsive micellar drug delivery systems.

Reactive oxygen species (ROS)-responsive nanomedicine for RNAi-based cancer therapy

Although much effort has been dedicated to the development of efficient siRNA delivery for cancer therapy, delivery nanomaterials that can particularly respond to reactive oxygen species (ROS), which are overproduced in the tissue and mitochondria of cancer cells, are still rare for the clinical translation of RNA interference (RNAi)-based therapy. To this end, we developed a ROS-responsive boronic vehicle with a lipid envelope for systemic vascular endothelial growth factor (VEGF) siRNA delivery so as to improve RNAi cancer therapy. We found that the efficiency of siRNA delivery largely relied on the ROS responsiveness of the carrier we have developed to mediate timely siRNA release, the PEG-functionalized lipid layer to shield the surface charge of polyplexes as well as the ability of the phenylboronic moiety to stabilize siRNA. The unique carrier nanostructure provides the efficient systemic transportation of siRNA to the tumor site for effective knockdown of the VEGF, which resulted in a significant antiangiogenesis effect and the effective inhibition of tumor growth in vivo. The current study defines a new systemic delivery strategy for siRNA by cooperatively integrating multifunctional lipid coatings with the ROS-responsive boronic polymer, which may potentially benefit RNAi-based therapy in the dawning era of precision nanomedicine for cancer therapy.

MMP-2-Sensitive HA End-Conjugated Poly(amidoamine) Dendrimers via Click Reaction To Enhance Drug Penetration into Solid Tumor

Currently, the limited penetration of nanoparticles remains a major challenge for antitumor nanomedicine to penetrate into the tumor tissues. Herein, we propose a size-shrinkable drug delivery system based on a polysaccharide-modified dendrimer with tumor microenvironment responsiveness for the first time to our knowledge, which was formed by conjugating the terminal glucose of hyaluronic acid (HA) to the superficial amidogen of poly(amidoamine) (PAMAM), using a matrix metalloproteinase-2 (MMP-2)-cleavable peptide (PLGLAG) via click reaction. These nanoparticles had an initial size of ∼200 nm, but once deposited in the presence of MMP-2, they experienced a dramatic and fast size change and dissociated into their dendrimer building blocks (∼10 nm in diameter) because of cleavage of PLGLAG. This rapid size-shrinking characteristic not only promoted nanoparticle extravasation and accumulation in tumors benefited from the enhanced permeability and retention effect but also achieved faster nanoparticle diffusion and penetration. We have further conducted comparative studies of MMP-2-sensitive macromolecules (HA-pep-PAMAM) and MMP-2-insensitive macromolecules (HA-PAMAM) synthesized with a similar particle size, surface charge, and chemical composition and evaluated in both monolayer cells and multicellular spheroids. The results confirmed that the enzyme-responsive size shrink is an implementable strategy to enhance drug penetration and to improve therapeutic efficacy. Meanwhile, macromolecule-based nanoparticles with size-variable characteristics not only promote drug penetration, but they can also be used as gene delivery systems, suggesting great potential as nano-delivery systems.

Versatile Chemical Derivatizations to Design Glycol Chitosan-Based Drug Carriers

Glycol chitosan (GC) and its derivatives have been extensively investigated as safe and effective drug delivery carriers because of their unique physiochemical and biological properties. The reactive functional groups such as the amine and hydroxyl groups on the GC backbone allow for easy chemical modification with various chemical compounds (e.g., hydrophobic molecules, crosslinkers, and acid-sensitive and labile molecules), and the versatility in chemical modifications enables production of a wide range of GC-based drug carriers. This review summarizes the versatile chemical modification methods that can be used to design GC-based drug carriers and describes their recent applications in disease therapy.

Engineering the Surface of Smart Nanocarriers Using a pH-/Thermal-/GSH-Responsive Polymer Zipper for Precise Tumor Targeting Therapy In Vivo

Nanocarrier surface chemistry plays a vital role in mediating cell internalization and enhancing delivery efficiency during in vivo chemotherapy. Inspired by the ability of proteins to alter their conformation to mediate functions, a pH-/thermal-/glutathione-responsive polymer zipper consisting of cell-penetrating poly(disulfide)s and thermosensitive polymers bearing guanidinium/phosphate (Gu⁺ /pY^- ) motifs to spatiotemporally tune the surface composition of nanocarriers for precise tumor targeting and efficient drug delivery is developed. Surface engineering allows the nanocarriers to remain undetected during blood circulation and favors passive accumulation at tumor sites, where the acidic microenvironment and photothermal heating break the pY^- /Gu⁺ binding and rupture the zipper, thereby exposing the penetrating shell and causing enhanced cellular uptake via counterion-/thiol-/receptor-mediated endocytosis. The in vivo study demonstrates that by manipulating the surface states on command, the nanocarriers show longer blood circulation time, minimized uptake and drug leakage in normal organs, and enhanced accumulation and efficient drug release at tumor sites, greatly inhibiting tumor growth with only slight damage to normal tissues. If integrated with a photothermal dye approved by the U.S. Food and Drug Administration (FDA), polymer zipper would provide a versatile protocol for engineering nanomedicines with high selectivity and efficiency for clinical cancer treatment.

Stimuli-responsive liposomes for drug delivery

The ultimate goal of drug delivery is to increase the bioavailability and reduce the toxic side effects of the active pharmaceutical ingredient (API) by releasing them at a specific site of action. In the case of antitumor therapy, association of the therapeutic agent with a carrier system can minimize damage to healthy, nontarget tissues, while limit systemic release and promoting long circulation to enhance uptake at the cancerous site due to the enhanced permeation and retention effect (EPR). Stimuli-responsive systems have become a promising way to deliver and release payloads in a site-selective manner. Potential carrier systems have been derived from a wide variety of materials, including inorganic nanoparticles, lipids, and polymers that have been imbued with stimuli-sensitive properties to accomplish triggered release based on an environmental cue. The unique features in the tumor microenvironment can serve as an endogenous stimulus (pH, redox potential, or unique enzymatic activity) or the locus of an applied external stimulus (heat or light) to trigger the controlled release of API. In liposomal carrier systems triggered release is generally based on the principle of membrane destabilization from local defects within bilayer membranes to effect release of liposome-entrapped drugs. This review focuses on the literature appearing between November 2008-February 2016 that reports new developments in stimuli-sensitive liposomal drug delivery strategies using pH change, enzyme transformation, redox reactions, and photochemical mechanisms of activation. WIREs Nanomed Nanobiotechnol 2017, 9:e1450. doi: 10.1002/wnan.1450 For further resources related to this article, please visit the WIREs website.

Co-delivery of paclitaxel and anti-survivin siRNA via redox-sensitive oligopeptide liposomes for the synergistic treatment of breast cancer and metastasis

The overexpression of survivin in breast cancer cells is an important factor of paclitaxel (PTX) resistance in breast cancer. To overcome PTX resistance and improve the antitumor effect of PTX, we developed a novel liposome-based nanosystem (PTX/siRNA/SS-L), composed of a redox-sensitive cationic oligopeptide lipid (LHSSG2C₁₄) with a proton sponge effect, natural soybean phosphatidylcholine (SPC), and cholesterol for co-delivery of PTX and anti-survivin siRNA, which could specifically downregulate survivin overexpression. PTX/siRNA/SS-L exhibited high encapsulation efficiency and rapid redox-responsive release of both PTX and siRNA. Moreover, in vitro studies on the 4T1 breast cancer cells revealed that PTX/siRNA/SS-L offered significant advantages over other experimental groups, such as higher cellular uptake, successful endolysosomal escape, reduced survivin expression, the lowest cell viability and wound healing rate, as well as the highest apoptosis rate. In particular, in vivo evaluation of 4T1 tumor-bearing mice showed that PTX/siRNA/SS-L had lower toxicity and induced a synergistic inhibitory effect on tumor growth and pulmonary metastasis. Collectively, the collaboration of anti-survivin siRNA and PTX via redox-sensitive oligopeptide liposomes provides a promising strategy for the treatment of breast cancer and metastasis.

Nonviral cancer gene therapy: Delivery cascade and vector nanoproperty integration

Gene therapy represents a promising cancer treatment featuring high efficacy and limited side effects, but it is stymied by a lack of safe and efficient gene-delivery vectors. Cationic polymers and lipid-based nonviral gene vectors have many advantages and have been extensively explored for cancer gene delivery, but their low gene-expression efficiencies relative to viral vectors limit their clinical translations. Great efforts have thus been devoted to developing new carrier materials and fabricating functional vectors aimed at improving gene expression, but the overall efficiencies are still more or less at the same level. This review analyzes the cancer gene-delivery cascade and the barriers, the needed nanoproperties and the current strategies for overcoming these barriers, and outlines PEGylation, surface-charge, size, and stability dilemmas in vector nanoproperties to efficiently accomplish the cancer gene-delivery cascade. Stability, surface, and size transitions (3S Transitions) are proposed to resolve those dilemmas and strategies to realize these transitions are comprehensively summarized. The review concludes with a discussion of the future research directions to design high-performance nonviral gene vectors.

Towards Hypoxia-responsive Drug-eluting Embolization Beads

Drug release from chemoembolization microspheres stimulated by the presence of a chemically reducing environment may provide benefits for targeting drug resistant and metastatic hypoxic tumours. A water-soluble disulfide-based bifunctional cross-linker bis(acryloyl)-(l)-cystine (BALC) was synthesised, characterised and incorporated into a modified poly(vinyl) alcohol (PVA) hydrogel beads at varying concentrations using reverse suspension polymerisation. The beads were characterised to confirm the amount of cross-linker within each formulation and its effects on the bead properties. Elemental and UV/visible spectroscopic analysis confirmed the incorporation of BALC within the beads and sizing studies showed that in the presence of a reducing agent, all bead formulations increased in mean diameter. The BALC beads could be loaded with doxorubicin hydrochloride and amounts in excess of 300mg of drug per mL of hydrated beads could be achieved but required conversion of the carboxylic acid groups of the BALC to their sodium carboxylate salt forms. Elution of doxorubicin from the beads demonstrated a controlled release via ionic exchange. Some formulations exhibited an increase in size and release of drug in the presence of a reducing agent, and therefore demonstrated the ability to respond to an in vitro reducing environment.

Multifunctional Nucleus-targeting Nanoparticles with Ultra-high Gene Transfection Efficiency for In Vivo Gene Therapy

Cancer stem cell-like cells (CSCL) are responsible for tumor recurrence associated with conventional therapy (e.g. surgery, radiation, and chemotherapy). Here, we developed a novel multifunctional nucleus-targeting nanoparticle-based gene delivery system which is capable of targeting and eradicating CSCL. These nanoparticles can facilitate efficient endosomal escape and spontaneously penetrate into nucleus without additional nuclear localization signal. They also induced extremely high gene transfection efficiency (>95%) even in culture medium containing 30% serum, which significantly surpassed that of some commercial transfection reagents, such as Lipofectamine 2000 and Lipofectamine 3000 etc. Especially, when loaded with the TRAIL gene, this system mediated remarkable depletion of CSCL. Upon systemic administration, the nanoparticles accumulated in tumor sites while sparing the non-cancer tissues and significantly inhibited the growth of tumors with no evident systemic toxicity. Taken together, our results suggest that these novel multifunctional, nucleus-targeting nanoparticles are a very promising in vivo gene delivery system capable of targeting CSCL and represent a new treatment candidate for improving the survival of cancer patients.

Combining Fluorination and Bioreducibility for Improved siRNA Polyplex Delivery

Polycations are promising vectors for the delivery of siRNA therapeutics but they often suffer from toxicity and low in vivo delivery efficacy. This study tests the hypothesis that combining fluorination and bioreducibility of polycations will overcome problems with both the toxicity and delivery efficacy. To test the hypothesis, we synthesized bioreducible (RHB) and nonreducible (NHB) poly(amido amine)s. The RHB were additionally fluorinated using reaction with heptafluorobutyric anhydride to obtain F-RHB. We found that both RHB and F-RHB showed significantly reduced cytotoxicity compared with NHB, which allowed their safe use in a wider range of doses than NHB. All three synthesized polycations formed polyplexes with siRNA. F-RHB achieved the best siRNA silencing efficacy in multiple cell lines in vitro, which was at least in part because of fluorination-induced enhancement of cellular uptake and improved endosomal escape. Lastly, F-RHB showed greatly improved Luc silencing efficacy in tumors in vivo when compared with polyplexes based on RHB, NHB, as well as control poly(ethylenimine) (PEI). This study suggests that combining fluorination with bioreducibility of polycations is a promising strategy to the design of siRNA delivery vectors with improved toxicity and in vivo activity profiles.

Artificial Virus Delivers CRISPR-Cas9 System for Genome Editing of Cells in Mice

CRISPR-Cas9 has emerged as a versatile genome-editing platform. However, due to the large size of the commonly used CRISPR-Cas9 system, its effective delivery has been a challenge and limits its utility for basic research and therapeutic applications. Herein, a multifunctional nucleus-targeting "core-shell" artificial virus (RRPHC) was constructed for the delivery of CRISPR-Cas9 system. The artificial virus could efficiently load with the CRISPR-Cas9 system, accelerate the endosomal escape, and promote the penetration into the nucleus without additional nuclear-localization signal, thus enabling targeted gene disruption. Notably, the artificial virus is more efficient than SuperFect, Lipofectamine 2000, and Lipofectamine 3000. When loaded with a CRISPR-Cas9 plasmid, it induced higher targeted gene disruption efficacy than that of Lipofectamine 3000. Furthermore, the artificial virus effectively targets the ovarian cancer via dual-receptor-mediated endocytosis and had minimum side effects. When loaded with the Cas9-hMTH1 system targeting MTH1 gene, RRPHC showed effective disruption of MTH1 in vivo. This strategy could be adapted for delivering CRISPR-Cas9 plasmid or other functional nucleic acids in vivo.

Cationic lipids with a cyclen headgroup: synthesis and structure–activity relationship studies as non-viral gene vectors

The structure–activity relationships of cyclen-based cationic lipids as non-viral gene delivery vectors were studied and clarified.

pH-Sensitive Nanomicelles for High-Efficiency siRNA Delivery in Vitro and in Vivo: An Insight into the Design of Polycations with Robust Cytosolic Release

The extremely low efficient cytosolic release of the internalized siRNA has emerged recently as a central issue for siRNA delivery, while there is a lack of guidelines to facilitate the cytosolic release of internalized siRNA. To address these concerns, we studied the contribution of the pH-sensitive inner core on handling the cytosolic release of siRNA delivered by a series of PG-P(DPAx-co-DMAEMAy)-PCB amphiphilic polycation nanomicelles (GDDC-Ms) with extremely low internalization (<1/4 of lipofactamine 2000 (Lipo2000)). Significantly, just by varying the mole ratio of DPA and DMAEMA to adjust the initial disassembly pH (pH_dis) of the core near to 6.8, GDDC₄-Ms/siRNA could get nearly 98.8% silencing efficiency at w/w = 12 with 50 nM siRNA and ∼78% silencing efficiency at w/w = 30 with a very low dose of 5 nM siRNA in HepG-2 cell lines, while Lipo2000 only got 65.7% with 50 nM siRNA. Furthermore, ∼98.4% silencing efficiency was also realized in the hard-to-transfect human acute monoblastic leukemia cell line U937 by GDDC₄-Ms/siRNA (at w/w = 15, 50 nM siRNA), in the inefficient case for Lipo2000. Additionally, the high silencing efficiency (∼80%) in skin tissue in vivo was discovered. Undoubtedly, the robust potential of GDDC₄-Ms in handling the cytosolic release paves a simple but efficient new way for the design of the nonviral siRNA vector.

Multifunctional "core-shell" nanoparticles-based gene delivery for treatment of aggressive melanoma

Gene therapy may be a promising and powerful strategy for cancer treatment, but efficient targeted gene delivery in vivo has so far remained challenging. Here, we developed a well-tailored and versatile "core-shell" ternary system (RRPHC) of systemic gene delivery for treatment of aggressive melanoma. The capsid-like "shell" of this system was engineered to mediate depth penetration to tissues, simultaneously target the CD44 receptors and integrin α_vβ₃ receptors overexpressed on neovasculature and most malignant tumor cells, while the "core" was responsible for nucleus-targeting and effective transfection. The RRPHC ternary complexes enhanced cellular uptake via dual receptor-mediated endocytosis, improved the endosomal escape and significantly promoted the plasmid penetration into the nucleus. Notably, RRPHC ternary complexes exhibited ultra-high gene transfection efficiency (∼100% in B16F10 cells), which surpassed that of commercial transfection agents, PEI 25K, Lipofectamine 2000 and even Lipofectamine 3000. Especially, RRPHC ternary complexes showed excellent serum resistance and remained high gene transfection efficacy (∼100%) even in medium containing 30% serum. In vivo biodistribution imaging demonstrated RRPHC ternary complexes possessed much more accumulation and extensive distribution throughout tumor regions while minimal location in other organs. Furthermore, systemic delivery of the pro-apoptotic mTRAIL gene to tumor xenografts by RRPHC ternary complexes resulted in remarkable inhibition of melanoma, with no systemic toxicity. These results demonstrated that the designed novel RRPHC ternary complexes might be a promising gene delivery system for targeted cancer therapy in vivo.

Oral Nanostructured Lipid Carriers Loaded with Near-Infrared Dye for Image-Guided Photothermal Therapy

Photothermal therapy exerts its anticancer effect by converting laser radiation energy into hyperthermia using a suitable photosensitizer. This study reports development of nanostructured lipid carriers (NLCs) suitable for noninvasive oral delivery of a near-infrared photosensitizer dye IR780. The carrier encapsulating the dye (IR780@NLCs) was stable in simulated gastric and intestinal conditions and showed greatly enhanced oral absorption of IR780 when compared with the free dye. As a result of increased oral bioavailability, enhanced accumulation of the dye in subcutaneous mouse colon tumors (CT-26 cells) was observed following oral gavage of IR780@NLCs. Photothermal antitumor activity of orally administered IR780@NLCs was evaluated following local laser irradiation of the CT-26 tumors. We observed significant effect of the photothermal IR780@NLCs treatment on the rate of the tumor growth and no toxicity associated with the oral administration of IR780@NLCs. Overall, orally administered IR780@NLCs represents a safe and noninvasive method to achieve systemic tumor delivery of a photosensitizing dye for applications in photothermal anticancer therapies.

Recent progress in development of siRNA delivery vehicles for cancer therapy

Recent progress in RNA biology has broadened the scope of therapeutic targets of RNA drugs for cancer therapy. However, RNA drugs, typically small interfering RNAs (siRNAs), are rapidly degraded by RNases and filtrated in the kidney, thereby requiring a delivery vehicle for efficient transport to the target cells. To date, various delivery formulations have been developed from cationic lipids, polymers, and/or inorganic nanoparticles for systemic delivery of siRNA to solid tumors. This review describes the current status of clinical trials related to siRNA-based cancer therapy, as well as the remaining issues that need to be overcome to establish a successful therapy. It, then introduces various promising design strategies of delivery vehicles for stable and targeted siRNA delivery, including the prospects for future design.

Targeting cancer with hyaluronic acid-based nanocarriers: recent advances and translational perspectives

Hyaluronic acid is a natural polysaccharide that has been widely explored for the development of anticancer therapies due to its ability to target cancer cells. Moreover, advances made in the last decade have revealed the versatility of this biomaterial in the design of multifunctional carriers, intended for the delivery of a variety of bioactive molecules, including polynucleotides, immunomodulatory drugs and imaging agents. In this review, we aim to provide an overview of the major recent achievements in this field, highlighting the application of the newly developed nanostructures in combination therapies, immunomodulation and theranostics. Finally, we will discuss the main challenges and technological advances that will allow these carriers to be considered as candidates for clinical development.

Transcutaneous iontophoretic delivery of STAT3 siRNA using layer-by-layer chitosan coated gold nanoparticles to treat melanoma

Overexpression of signal transducer and activator of transcription 3 (STAT3) protein prevents apoptosis and enhances proliferation of melanocytes. The aim of this study was to investigate the feasibility of using layer-by-layer assembled gold nanoparticles (LbL-AuNP) as a carrier for iontophoretic delivery of STAT3 siRNA to treat melanoma. Chitosan coated AuNP (AuNP-CS) were prepared by direct reduction of HAuCl4 in the presence of chitosan. The AuNP-CS were then sequentially layered with siRNA and chitosan to form AuNP-CS/siRNA/CS. STAT3 siRNA replaced with scrambled siRNA or sodium alginate were used as controls. The average particle size and zeta-potential of the prepared LbL-AuNP were 150±10nm (PDI: 0.41±0.06) and 35±6mV, respectively. In vitro studies in B16F10 murine melanoma cells showed that AuNP-CS/siRNA/CS inhibited the cell growth by 49.0±0.6% and 66.0±0.2% at 0.25nM and 0.5nM STAT3 siRNA concentration, respectively. Fluorescence microscopy and flow cytometry studies showed a time dependent cell uptake of the LbL-AuNP up to 120min. Clathrin mediated endocytosis was found to be the predominant cell uptake mechanism for LbL-AuNP. STAT3 siRNA loaded LbL-AuNP reduced the STAT3 protein expression by 47.3% in B16F10 cells. Similarly, apoptosis assay showed 29% and 44% of early and late apoptotic events, respectively after treatment with STAT3 siRNA loaded LbL-AuNP. Confocal microscope and skin cryosections showed that application of 0.47mA/cm(2) of anodal iontophoresis enhanced the skin penetration of LbL-AuNP to reach viable epidermis. In conclusion, layer-by-layer chitosan coated AuNP can be developed as a carrier for iontophoretic delivery of STAT3 siRNA to treat melanoma.

Hyaluronic acid reagent functional chitosan-PEI conjugate with AQP2-siRNA suppressed endometriotic lesion formation

To identify a new drug candidate for treating endometriosis which has fewer side effects, a new polymeric nanoparticle gene delivery system consisting of polyethylenimine-grafted chitosan oligosaccharide (CSO-PEI) with hyaluronic acid (HA) and small interfering RNA (siRNA) was designed. There was no obvious difference in sizes observed between (CSO-PEI/siRNA)HA and CSO-PEI/siRNA, but the fluorescence accumulation in the endometriotic lesion was more significant for (CSO-PEI/siRNA)HA compared with CSO-PEI/siRNA due to the specific binding of HA to CD44. In addition, the (CSO-PEI/siRNA)HA nanoparticle gene therapy significantly decreased the endometriotic lesion sizes with atrophy and degeneration of the ectopic endometrium. The epithelial cells of ectopic endometrium from rat models of endometriosis showed a significantly lower CD44 expression than control after treatment with (CSO-PEI/siRNA)HA. Furthermore, observation under an electron microscope showed no obvious toxic effect on the reproductive organs. Therefore, (CSO-PEI/siRNA)HA gene delivery system can be used as an effective method for the treatment of endometriosis.

Programmed Nanococktail for Intracellular Cascade Reaction Regulating Self-Synergistic Tumor Targeting Therapy

In this work, a ZnO based nanococktail with programmed functions is designed and synthesized for self-synergistic tumor targeting therapy. The nanococktail can actively target tumors via specific interaction of hyaluronic acid (HA) with CD44 receptors and respond to HAase-rich tumor microenvironment to induce intracellular cascade reaction for controlled therapy. The exposed cell-penetrating peptide (R8) potentiates the cellular uptake of therapeutic nanoparticles into targeted tumor cells. Then ZnO cocktail will readily degrade in acidic endo/lysosomes and induce the production of desired reactive oxygen species (ROS) in situ. The destructive ROS not only leads to serious cell damage but also triggers the on-demand drug release for precise chemotherapy, thus achieving enhanced antitumor efficiency synergistically. After tail vein injection of ZnO cocktail, a favorable tumor apoptosis rate (71.2 ± 8.2%) is detected, which is significantly superior to that of free drug, doxorubicin (12.9 ± 5.2%). Both in vitro and in vivo studies demonstrate that the tailor-made ZnO cocktail with favorable biocompatibility, promising tumor specificity, and self-synergistically therapeutic capacity opens new avenues for cancer therapy.

A novel type of self-assembled nanoparticles as targeted gene carriers: an application for plasmid DNA and antimicroRNA oligonucleotide delivery

In this study, a new type of amphiphilic cetylated polyethyleneimine (PEI) was synthesized, and then polylactic-co-glycolic acid (PLGA)/cetylated PEI/hyaluronic acid nanoparticles (PCPH NPs) were developed by self-assembly as a novel type of gene-delivering vehicle. The PCPH NPs showed good DNA-condensation ability by forming polyplexes with small particle size and positive zeta potential. The transfection efficiency and cytotoxicity of PCPH NPs were evaluated as plasmid DNA vectors to transfect HepG2 in vitro. PCPH NPs exhibited much lower cytotoxicity and higher gene-transfection efficiency than PEI (25,000) and commercial transfection reagents. Furthermore, PCPH NPs were used as an anti-miR-221 vector for transfecting HepG2 cells, and anti-miR-221 was effectively transfected into cells and produced a greater inhibitory effect on cancer-cell growth by PCPH NPs. These results demonstrate that PCPH NPs can be a promising nonviral vector for gene-delivery systems.

A novel multifunctional biomimetic Au@BSA nanocarrier as a potential siRNA theranostic nanoplatform

A novel siRNA nanocarrier based on biomimetic Au@BSA nanoflowers is fabricated which could serve as a potential theranostic nanoplatform.

Reversal of multidrug resistance by co-delivery of paclitaxel and lonidamine using a TPGS and hyaluronic acid dual-functionalized liposome for cancer treatment

Multidrug resistance (MDR) remains the primary issue in cancer therapy, which is characterized by the overexpressed P-glycoprotein (P-gp)-included efflux pump or the upregulated anti-apoptotic proteins. In this study, a D-alpha-tocopheryl poly (ethylene glycol 1000) succinate (TPGS) and hyaluronic acid (HA) dual-functionalized cationic liposome containing a synthetic cationic lipid, 1,5-dioctadecyl-N-histidyl-L-glutamate (HG2C18) was developed for co-delivery of a small-molecule chemotherapeutic drug, paclitaxel (PTX) with a chemosensitizing agent, lonidamine (LND) to treat the MDR cancer. It was demonstrated that the HG2C18 lipid contributes to the endo-lysosomal escape of the liposome following internalization for efficient intracellular delivery. The TPGS component was confirmed able to elevate the intracellular accumulation of PTX by inhibiting the P-gp efflux, and to facilitate the mitochondrial-targeting of the liposome. The intracellularly released LND suppressed the intracellular ATP production by interfering with the mitochondrial function for enhanced P-gp inhibition, and additionally, sensitized the MDR breast cancer (MCF-7/MDR) cells to PTX for promoted induction of apoptosis through a synergistic effect. Functionalized with the outer HA shell, the liposome preferentially accumulated at the tumor site and showed a superior antitumor efficacy in the xenograft MCF-7/MDR tumor mice models. These findings suggest that this dual-functional liposome for co-delivery of a cytotoxic drug and an MDR modulator provides a promising strategy for reversal of MDR in cancer treatment.