Structural contributions of blocked or grafted poly(2-dimethylaminoethyl methacrylate) on PEGylated polycaprolactone nanoparticles in siRNA delivery

Poly(ε-caprolactone)-Based Graft Copolymers: Synthesis Methods and Applications in the Biomedical Field: A Review

Synthetic biopolymers are attractive alternatives to biobased polymers, especially because they rarely induce an immune response in a living organism. Poly ε-caprolactone (PCL) is a well-known synthetic aliphatic polyester universally used for many applications, including biomedical and environmental ones. Unlike poly lactic acid (PLA), PCL has no chiral atoms, and it is impossible to play with the stereochemistry to modify its properties. To expand the range of applications for PCL, researchers have investigated the possibility of grafting polymer chains onto the PCL backbone. As the PCL backbone is not functionalized, it must be first functionalized in order to be able to graft reactive groups onto the PCL chain. These reactive groups will then allow the grafting of new reagents and especially new polymer chains. Grafting of polymer chains is mainly carried out by "grafting from" or "grafting onto" methods. In this review we describe the main structures of the graft copolymers produced, their different synthesis methods, and their main characteristics and applications, mainly in the biomedical field.

Application of vinyl polymer-based materials as nucleic acids carriers in cancer therapy

Nucleic acid-based therapies have changed the paradigm of cancer treatment, where conventional treatment modalities still have several limitations in terms of efficacy and severe side effects. However, these biomolecules have a short half-life in vivo, requiring multiple administrations, resulting in severe suffering, discomfort, and poor patient compliance. In the early days of (nano)biotechnology, these problems caused concern in the medical community, but recently it has been recognized that these challenges can be overcome by developing innovative formulations. This review focuses on the use of vinyl polymer-based materials for the protection and delivery of nucleic acids in cancer. First, an overview of the properties of nucleic acids and their versatility as drugs is provided. Then, key information on the achievements to date, the most effective delivery methods, and the evaluation of functionalization approaches (stimulatory strategies) are critically discussed to highlight the importance of vinyl polymers in the new cancer treatment approaches. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

MiR-190 ameliorates glucotoxicity-induced dysfunction and apoptosis of pancreatic β-cells by inhibiting NOX2-mediated reactive oxygen species production

Glucotoxicity-induced pancreatic β-cell failure contributes to the development of type 2 diabetes mellitus (T2DM). Accumulating evidence reveals that miRNAs play a critical role in regulating pancreatic β-cell function and survival. In this study, we employed a self-assembled cell microarray (SAMcell)-based functional screening assay to identify miRNAs that are capable of regulating the dysfunction of β-cells induced by glucotoxicity. Among 62 conserved miRNAs we tested, miR-190 was identified as a candidate regulator that could effectively restore insulin expression in NIT-1 cells under high-glucose (HG) stimulation. Further analyses demonstrated that miR-190 was significantly down-regulated in HG-treated NIT-1 cells, as well as in the pancreas of diabetic mice. Mechanistic studies showed that Cybb is the direct target gene of miR-190, which encodes the gp91phox protein, a subunit of the NOX2 complex. Furthermore, both miR-190 overexpression and Cybb knockdown inhibited apoptosis and improved glucose-stimulated insulin secretion (GSIS) in HG-stimulated NIT-1 cells by attenuating the excessive production of reactive oxygen species (ROS). More importantly, a targeted delivery of mPEG-PCL-g-PDMAEMA nanoparticles/miR-190 complexes (PECgD NPs/miR-190) to the pancreas significantly ameliorated hyperglycemia, decreased fasting serum insulin levels, and improved glucose tolerance in diabetic mice. Taken together, our findings suggest that the miR-190/Cybb axis plays an important role in glucotoxicity-induced pancreatic β-cell failure. Restoring miR-190 expression levels may be a possible therapeutic strategy to protect β-cells in T2DM.

Aptamer-Enabled Nanomaterials for Therapeutics, Drug Targeting and Imaging

A wide variety of nanomaterials have emerged in recent years with advantageous properties for a plethora of therapeutic and diagnostic applications. Such applications include drug delivery, imaging, anti-cancer therapy and radiotherapy. There is a critical need for further components which can facilitate therapeutic targeting, augment their physicochemical properties, or broaden their theranostic applications. Aptamers are single-stranded nucleic acids which have been selected or evolved to bind specifically to molecules, surfaces, or cells. Aptamers can also act as direct biologic therapeutics, or in imaging and diagnostics. There is a rich field of discovery at the interdisciplinary interface between nanomaterials and aptamer science that has significant potential across biomedicine. Herein, we review recent progress in aptamer-enabled materials and discuss pending challenges for their future biomedical application.

Natural steroid-based cationic copolymers cholesterol/diosgenin-r-PDMAEMAs and their pDNA nanoplexes: impact of steroid structures and hydrophobic/hydrophilic ratios on pDNA delivery

Using natural-based lipids to construct biocompatible, controllable and efficient nanocarriers and elucidating their structure-function relationships, was regarded as an important area for creating sustainable biomaterials. Herein, we utilized two natural steroids: cholesterol and diosgenin (bearing different hydrophobic tails) as the building blocks, to synthesize a series of natural steroid-based cationic random copolymers PMA6Chol-r-PDMAEMA and PMA6Dios-r-PDMAEMA via RAFT polymerization. The results demonstrated that the steroid-r-PDMAEMA copolymers could efficiently bind pDNA (N/P < 3.0) and then form near-spherical shape (142-449 nm) and positively-charged (+11.5 to +19.6 mV) nanoparticles. The in vitro cytotoxicity and gene transfection efficiency greatly depend on the steroid hydrophobic tail structures and steroid/PDMAEMA block ratios. Optimum transfection efficiency of the (Chol-P1/pDNA and Dios-P3/pDNA) nanoplexes could reach to 18.1-31.2% of the PEI-25K/pDNA complex. Moreover, all of the steroid-r-PDMAEMA/Cy3-pDNA nanoplexes have an obvious "lysosome localization" effect, indicating the steroid structures do not remarkably influence the intracellular localization behaviors of these nanoplexes.

Core Role of Hydrophobic Core of Polymeric Nanomicelle in Endosomal Escape of siRNA

Efficient endosomal escape is the most essential but challenging issue for siRNA drug development. Herein, a series of quaternary ammonium-based amphiphilic triblock polymers harnessing an elaborately tailored pH-sensitive hydrophobic core were synthesized and screened. Upon incubating in an endosomal pH environment (pH 6.5-6.8), mPEG₄₅-P(DPA₅₀-co-DMAEMA₅₆)-PT₅₃ (PDDT, the optimized polymer) nanomicelles (PDDT-Ms) and PDDT-Ms/siRNA polyplexes rapidly disassembled, leading to promoted cytosolic release of internalized siRNA and enhanced silencing activity evident from comprehensive analysis of the colocalization and gene silencing using a lysosomotropic agent (chloroquine) and an endosomal trafficking inhibitor (bafilomycin A1). In addition, PDDT-Ms/siPLK1 dramatically repressed tumor growth in both HepG2-xenograft and highly malignant patient-derived xenograft models. PDDT-Ms-armed siPD-L1 efficiently blocked the interaction of PD-L1 and PD-1 and restored immunological surveillance in CT-26-xenograft murine model. PDDT-Ms/siRNA exhibited ideal safety profiles in these assays. This study provides guidelines for rational design and optimization of block polymers for efficient endosomal escape of internalized siRNA and cancer therapy.

Combating drug-resistant bacterial infection using biodegradable nanoparticles assembled from comb-like polycarbonates grafted with amphiphilic polyquaternium

Bacterial infection is a serious clinical threat. The misuse of antibiotics has already resulted in the emergence of antibiotic-resistant strains of pathogenic bacteria. Efficient membrane-destructive antibacterial agents are considered as an alternative, promising solution against bacterial infection. Herein, we prepared a new type of comb-like cationic, polyethylene glycol (PEG) block polycarbonates with polyquaternium arms (G-CgQAs). The amphiphilic G-CgQAs could self-assemble into about 60 nm sized nanoparticles (NPs) with positive charges (20~30 mV). G-CgQA-3 NPs with an appropriate hydrophobic-hydrophilic balance in the polyquaternium arms showed antibacterial activity against Gram-negative, Gram-positive, and drug-resistant strains at low concentrations (MIC 64-128 μg mL-1) and low hemolysis (HC50 > 2000 μg mL-1). In vivo anti-infection tests indicated G-CgQA-3 NPs could highly inhibit the growth of vancomycin-resistant bacteria by spraying on wounds. Collectively, G-CgQA NPs hold great promise for the prevention of infection, serving as new antibacterial agents. This study also highlights the significance of a hydrophobic block in positive polyquaternium arms to facilitate the antibacterial activity of cationic, quaternized polymers. The design of comb-like amphiphilic cationic polycarbonates provides a new method for manufacturing antibacterial nano-agents.

ROS-Activatable siRNA-Engineered Polyplex for NIR-Triggered Synergistic Cancer Treatment

Small interfering RNA (siRNA) shows excellent pharmaceutical prospects in treating diverse life-threatening diseases. Photodynamic therapy (PDT) is a clinically employed noninvasive treatment method that can trigger selective damage toward targeted tissue and cells. However, insufficient delivery of siRNA and photosensitizer to cancer cells remarkably hindered the application of siRNA and PDT in the treatment of cancer. In this study, a unique reactive oxygen species (ROS)-activatable polyplex, which consists of the PEGylated cationic polymer, ROS-cleavable linker, photosensitizer Ce6, and RRM2-against siRNA, termed PPTC/siRNA, was engineered. Upon irradiation of near-infrared (NIR) light, the polyplex efficiently generated ROS, which triggered degradation of the ROS-sensitive linker, disassembling the complex, destabilization of the cell membrane, and significantly accelerated cellular entry and endosomal escape of siRNA. Besides achieving effective siRNA internalization and gene silence in cancer cells in vitro, PPTC/siRNA synergistically inhibited tumor growth in both cell line-derived xenograft and patient-derived xenograft hepatocellular carcinoma murine models by repressing the RRM2 expression (reducing cell proliferation) and triggering photodynamic killing (enhancing cell apoptosis). The proposed polyplex also showed ideal safety profiles both in cell line and in animal. It provides a novel strategy for NIR-triggered RNAi and PDT combinational cancer treatment.

Therapeutic siRNA: state of the art

RNA interference (RNAi) is an ancient biological mechanism used to defend against external invasion. It theoretically can silence any disease-related genes in a sequence-specific manner, making small interfering RNA (siRNA) a promising therapeutic modality. After a two-decade journey from its discovery, two approvals of siRNA therapeutics, ONPATTRO® (patisiran) and GIVLAARI™ (givosiran), have been achieved by Alnylam Pharmaceuticals. Reviewing the long-term pharmaceutical history of human beings, siRNA therapy currently has set up an extraordinary milestone, as it has already changed and will continue to change the treatment and management of human diseases. It can be administered quarterly, even twice-yearly, to achieve therapeutic effects, which is not the case for small molecules and antibodies. The drug development process was extremely hard, aiming to surmount complex obstacles, such as how to efficiently and safely deliver siRNAs to desired tissues and cells and how to enhance the performance of siRNAs with respect to their activity, stability, specificity and potential off-target effects. In this review, the evolution of siRNA chemical modifications and their biomedical performance are comprehensively reviewed. All clinically explored and commercialized siRNA delivery platforms, including the GalNAc (N-acetylgalactosamine)-siRNA conjugate, and their fundamental design principles are thoroughly discussed. The latest progress in siRNA therapeutic development is also summarized. This review provides a comprehensive view and roadmap for general readers working in the field.

The challenge and prospect of mRNA therapeutics landscape

Messenger RNA (mRNA)-based therapeutics hold the potential to cause a major revolution in the pharmaceutical industry because they can be used for precise and individualized therapy, and enable patients to produce therapeutic proteins in their own bodies without struggling with the comprehensive manufacturing issues associated with recombinant proteins. Compared with the current therapeutics, the production of mRNA is much cost-effective, faster and more flexible because it can be easily produced by in vitro transcription, and the process is independent of mRNA sequence. Moreover, mRNA vaccines allow people to develop personalized medications based on sequencing results and/or personalized conditions rapidly. Along with the great potential from bench to bedside, technical obstacles facing mRNA pharmaceuticals are also obvious. The stability, immunogenicity, translation efficiency, and delivery are all pivotal issues need to be addressed. In the recently published research results, these issues are gradually being overcome by state-of-the-art development technologies. In this review, we describe the structural properties and modification technologies of mRNA, summarize the latest advances in developing mRNA delivery systems, review the preclinical and clinical applications, and put forward our views on the prospect and challenges of developing mRNA into a new class of drug.

PAMAM-cRGD mediating efficient siRNA delivery to spermatogonial stem cells

Background

Spermatogonial stem cells (SSCs) are the cornerstone of sperm production and thus perpetual male fertility. In clinics, transplantation of patient’s own SSCs into testes is a promising technique to restore fertility when male germ cells have been depleted by gonadotoxic therapies. Auto-transplantation of genetically modified SSCs even has the potential to treat male infertility caused by genetic mutations. However, SSCs are refractory to transfection approaches. Poly(amidoamine) (PAMAM) dendrimers have the unique three-dimensional architecture, surface charge, and high density of surface groups that are suitable for ligand attachment, thereby facilitating target delivery. The goal of this study was to elucidate whether PAMAM dendrimers can efficiently deliver short interfering RNAs (siRNAs) to SSCs.

Methods and results

We introduced cyclic arginine-glycine-aspartic acid (cRGD) peptides to the fifth generation of PAMAM dendrimers (G5) to generate PAMAM-cRGD dendrimers (G5-cRGD). The characterization of G5-cRGD was detected by Fourier transform infrared spectroscope (FTIR), transmission electron microscope (TEM), and the Cell Counting Kit-8 (CCK-8) assay. Confocal microscopy and flow cytometry were used to evaluate the delivery efficiency of siRNA by G5-cRGD to SSCs. The results showed that G5-cRGD encompassing siRNA could self-assemble into spherical structures with nanoscale size and possess high transfection efficiency, excellent endosomal escape ability, and low cytotoxicity, superior to a commercial transfection reagent Lipofectamine® 2000. Moreover, we demonstrated that G5-cRGD efficiently delivered siRNAs and triggered gene silencing.

Conclusions

This study thus provides a promising nanovector for siRNA delivery in SSCs, facilitating the future clinical application of SSC auto-transplantation with genetically modified cells with a hope to cure male infertility that is caused by genetic disorders.

RNAi therapeutic and its innovative biotechnological evolution

Recently, United States Food and Drug Administration (FDA) and European Commission (EC) approved Alnylam Pharmaceuticals' RNA interference (RNAi) therapeutic, ONPATTRO™ (Patisiran), for the treatment of the polyneuropathy of hereditary transthyretin-mediated (hATTR) amyloidosis in adults. This is the first RNAi therapeutic all over the world, as well as the first FDA-approved treatment for this indication. As a milestone event in RNAi pharmaceutical industry, it means, for the first time, people have broken through all development processes for RNAi drugs from research to clinic. With this achievement, RNAi approval may soar in the coming years. In this paper, we introduce the basic information of ONPATTRO and the properties of RNAi and nucleic acid therapeutics, update the clinical and preclinical development activities, review its complicated development history, summarize the key technologies of RNAi at early stage, and discuss the latest advances in delivery and modification technologies. It provides a comprehensive view and biotechnological insights of RNAi therapy for the broader audiences.

Structural exploration of hydrophobic core in polycationic micelles for improving siRNA delivery efficiency and cell viability

Improving siRNA delivery efficiency often encounters a dilemma with poor or decreased biocompatibility for polycationic micelles.

Statistical versus block fluoropolymers in gene delivery

A statistical fluorocopolymer shows dramatically higher transfection efficiency in gene delivery than a block one.

Core/Shell Gene Carriers with Different Lengths of PLGA Chains to Transfect Endothelial Cells

In order to improve the transfection efficiency and reduce the cytotoxicity of gene carriers, many strategies have been used to develop novel gene carriers. In this study, five complex micelles (MSP(2 k), MSP(4 k), MSP(6 k), MSP(8 k), and MSP(10 k)) were prepared from methoxy-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (mPEG-b-PLGA) and sorbitol-poly(d,l-lactide-co-glycolide)-graft-PEI (sorbitol-PLGA-g-PEI, where the designed molecular weights of PLGA chains were 2 kDa, 4 kDa, 6 kDa, 8 kDa, and 10 kDa, respectively) copolymers by a self-assembly method, and the mass ratio of mPEG-b-PLGA to sorbitol-PLGA-g-PEI was 1/3. These complex micelles and their gene complexes had appropriate sizes and zeta potentials, and pEGFP-ZNF580 (pDNA) could be efficiently internalized into EA.hy926 cells by their gene complexes (MSP(2 k)/pDNA, MSP(4 k)/pDNA, MSP(6 k)/pDNA, MSP(8 k)/pDNA, and MSP(10 k)/pDNA). The MTT assay results demonstrated that the gene complexes had low cytotoxicity in vitro. When the hydrophobic PLGA chain increased above 6 kDa, the gene complexes showed higher performance than that prepared from short hydrophobic chains. Moreover, the relative ZNF580 protein expression levels in MSP(6 k)/pDNA, MSP(8 k)/pDNA, and MSP(10 k)/pDNA) groups were 79.6%, 71.2%, and 73%, respectively. These gene complexes could promote the transfection of endothelial cells, while providing important information and insight for the design of new and effective gene carriers to promote the proliferation and migration of endothelial cells.

Temperature-Sensitive Gold Nanoparticle-Coated Pluronic-PLL Nanoparticles for Drug Delivery and Chemo-Photothermal Therapy

Gold nanoparticle-coated Pluronic-b-poly(L-lysine) nanoparticles (Pluronic-PLL@Au NPs) were synthesized via an easy one-step method and employed as carriers for the delivery of paclitaxel (PTX) in chemo-photothermal therapy, in which Pluronic-PLL acts as the reductant for the formation of AuNPs without the need for an additional reducing agent.

METHODS

The deposition of AuNPs on the surface of Pluronic-PLL micelles and the thermal response of the system were followed via ultraviolet-visible spectroscopy and dynamic light scattering. Calcein-AM and MTT assays were used to study the cell viability of MDA-MB-231 cells treated with PTX-loaded Pluronic-PLL@Au NPs, and we then irradiated the cells with NIR light.

RESULTS

An obvious temperature response was observed for the Pluronic-PLL@Au NPs. Blood compatibility and in vitro cytotoxicity assays confirmed that the Pluronic-PLL@Au NPs have excellent biocompatibility. Compared to Taxol, the PTX-loaded Pluronic-PLL@Au NPs exhibited higher cytotoxicity in MDA-MB-231 cells. All of these results and confocal laser scanning microscopy analysis results suggest that Pluronic-PLL@Au NPs greatly enhance the cellular uptake efficiency of the drug.

CONCLUSION

As confirmed by in vitro and in vivo studies, the combination of chemotherapy and photothermal therapy can cause more damage than chemo- or photothermal therapy did alone, demonstrating the synergistic effect of chemo-photothermal treatment. Thus, the as-prepared Pluronic-PLL@Au NPs are promising for chemo-photothermal therapy.

A hybrid siRNA delivery complex for enhanced brain penetration and precise amyloid plaque targeting in Alzheimer's disease mice

To realize the therapeutic potential of gene drugs for Alzheimer's disease (AD), non-invasive, tissue-specific and efficient delivery technologies must be developed. Here, a hybrid system for amyloid plaques targeted siRNA delivery was formed by PEGylated Poly(2-(N,N-dimethylamino) ethyl methacrylate) (PEG-PDMAEMA) conjugated with two d-peptides, a CGN for brain penetration and a QSH for β-amyloid binding. The hybrid complex CQ/siRNA, composed of 25% MPEG-PDMAEMA, 50% CGN-PEG-PDMAEMA and 25% QSH-PEG-PDMAEMA, showed negligible cytotoxicity and could protect siRNA from enzyme degradation. Being taken up by neuron cells, the complexes could escape from lysosomes, release siRNA in the cytoplasm and thus producing effective gene silence (down-regulated protein level to 18.5%). After intravenous injection, CQ/siRNA penetrated into the brain in an intact form and located around the plaques in transgenic AD mice. The precisely amyloid plaques delivery resulted in increased therapeutic activities, which was demonstrated by the strong mRNA (36.4%) knockdown of BACE1 (a therapeutic target of AD), the less yield of enzyme-digested products sAPPβ (-42.6%), as well as the better neurons protection than the single component complexes. In conclusion, the hybrid complex could efficiently and precisely deliver an siRNA to the AD lesion and might be a potential candidate for gene therapy for AD.

STATEMENT OF SIGNIFICANCE

The gene delivery system achieving high brain penetration and lesion region accumulation was first applied to treat AD, and the preparation exhibited a significantly better neuroprotective effect than that modified with a single ligand. The intracellular process of which the complexes escape from lysosomes and release the siRNA in cytoplasm was revealed. The brain targeting and amyloid plaque binding ability of the complex were systemic evaluated, and the in vivo co-location experiments provided a direct evidence of the precise delivery of the siRNA to the amyloid plaques. One of the targeting ligands, CGN, which was a retro-inverso modified peptide to achieve better affinity to the BBB, was first applied to the brain targeting system.

Branched polyesters: Preparative strategies and applications

In the last 20years, the availability of precision chemical tools (e.g. controlled/living polymerizations, 'click' reactions) has determined a step change in the complexity of both the macromolecular architecture and the chemical functionality of biodegradable polyesters. A major part in this evolution has been played by the possibilities that controlled macromolecular branching offers in terms of tailored physical/biological performance. This review paper aims to provide an updated overview of preparative techniques that derive hyperbranched, dendritic, comb, grafted polyesters through polycondensation or ring-opening polymerization mechanisms.

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.

Pharmacokinetic Behaviors of Intravenously Administered siRNA in Glandular Tissues

The pharmacokinetics of small interfering RNAs (siRNAs) is a pivotal issue for siRNA-based drug development. In this study, we comprehensively investigated the behavior of siRNAs in vivo in various tissues and demonstrated that intravenously-injected naked siRNA accumulated remarkably in the submandibular gland, bulbourethral gland, and pancreas, with a respective half-life of ~22.7, ~45.6, and ~30.3 h. This was further confirmed by gel separation of tissue homogenates and/or supernatants. In vivo imaging and cryosectioning suggested that delivery carriers significantly influence the distribution and elimination profiles of siRNA. Gene-silencing assays revealed that neither naked nor liposome-formulated siRNA resulted in gene knockdown in the submandibular and bulbourethral glands after systemic administration, suggesting that these glands function as drug reservoirs that enable slow siRNA release into the circulation. But robust gene-silencing was achieved by local injection of liposome-encapsulated siRNA into the submandibular gland. Our results enhance understanding of the pharmacokinetic properties of siRNAs and we believe that they will facilitate the development of siRNA therapy, especially for the submandibular gland.

Antibody h-R3-dendrimer mediated siRNA has excellent endosomal escape and tumor targeted delivery ability, and represents efficient siPLK1 silencing and inhibition of cell proliferation, migration and invasion

The major obstacle to developing siRNA delivery is their extracellular and intracellular barriers. Herein, a humanized anti-EGFR monoclonal antibody h-R3 was developed to modify the self-assembled binary complexes (dendriplexes) of PAMAM and siRNA via electrostatic interactions, and two common ligands HSA and EGF were used as a control. Compared to dendriplexes, h-R3/EGF/HSA-dendriplexes showed increased particle size, decreased zeta potentials and lower cytotoxicity. Moreover, h-R3-dendriplexes presented greater cellular uptake and excellent endosomal escape ability in HepG2 cells. Ex vivo fluorescence imaging revealed that h-R3-dendriplexes showed higher targeted delivery and gene expression in the tumors than dendriplexes, HSA-dendriplexes and EGF-dendriplexes, which was in agreement with confocal results of cryosections. Furthermore, h-R3-dendriplexes for siPLK1 delivery indicated efficient gene silencing, potentiated cell growth inhibition and cell apoptosis, and suppressed cellular migration/invasion. These results indicate that h-R3-dendriplexes represent a great potential to be used as efficient targeted siRNA delivery carriers.

A theranostic micelleplex co-delivering SN-38 and VEGF siRNA for colorectal cancer therapy

The development of an efficient colorectal cancer therapy is currently a public health priority. In the present work, we proposed a multifunctional theranostic micellar drug delivery system utilizing cationic PDMA-block-poly(ε-caprolactone) (PDMA-b-PCL) micelles as nanocarriers of SN-38 (7-ethyl-10-hydroxycamptothecin), ultra-small superparamagnetic iron oxide nanoparticles (USPIO), and small interfering RNA (siRNA) that targets human vascular endothelial growth factor (VEGF). The VEGF siRNA was conjugated to polyethylene glycol (PEG) (siRNA-PEG) before complexation with the micelles in order to improve the siRNA's stability and to prolong its retention time in the blood circulation. To further improve the in vivo biosafety, we prepared mixed micelles using mPEG-PCL together with PDMA-b-PCL copolymer. The SN-38/USPIO-loaded siRNA-PEG mixed micelleplexes passively targeted to tumor regions and synergistically facilitated VEGF silencing and chemotherapy, thus efficiently suppressing tumor growth via a multi-dose therapy regimen. Additionally, the SN-38/USPIO-loaded siRNA-PEG mixed micelleplexes acted as a negative magnetic resonance imaging (MRI) contrast agent in T2-weighted imaging, resulting in a powerful tool for the diagnosis and for tracking of the therapeutic outcomes. In summary, we established a theranostic micellar drug and gene delivery system that not only synergistically combined gene silencing and chemotherapy but also served as a negative MRI contrast agent, which reveal its potential as a novel colorectal cancer therapy.

The Promising Nanocarrier for Doxorubicin and siRNA Co-delivery by PDMAEMA-based Amphiphilic Nanomicelles

Synergistic effects of anticancer drug and siRNA have displayed superior advantages for cancer therapy. Herein, we deeply analyzed the feasibility that whether doxorubicin (DOX) and siRNA could be co-delivered by mPEG-PCL-graft-PDMAEMA (PECD) micelles, which mediated excellent DNA/siRNA delivery in vitro and in vivo reported in our previous work. DOX-loaded NPs (PECD-D) were developed by nanoprecipitation technology and exhibited high drug loading content (DLC, 9.5%). In vitro cytotoxicity study in MDA-MB-231 cells, PECD-D treated groups had lower IC50 compared to free DOX groups (F-DOX) at different transfection time (24, 48, and 72h), which maybe attribute to its high cellular uptake and endosomal escape properties. The speculation was confirmed with the results of drug release profile in acidic media, flow cytometry analysis and confocal images. Futhermore, Cy5 labeled siRNA was introduced in PECD-D micelles (PECD-D/siRNA) to track the behavior of dual-loaded nanodrug in vitro and in vivo. Flow cytometry analysis presented that DOX and siRNA were successfully co-delivered into cells, the positive cells ratio were 94.6 and 99.5%, respectively. Confocal images showed that not only DOX and siRNA existed in cytoplasm, but DOX traversed endosome/lysosome and entered into cell nucleus. For in vivo tumor-targeting evaluation in BALB/c nude mice, both DOX and Cy5-siRNA could be detected in tumor sites after intravenous injection with PECD-D/siRNA formulation. Therefore, we believed that PECD micelles have a potential ability as DOX and siRNA co-delivery carrier for cancer therapy.

Cationic Micelles Based on Polyhedral Oligomeric Silsesquioxanes for Enhanced Gene Transfection

The synthesis and gene transfection efficiency of a series of amphiphilic copolymers, poly(2-(dimethylamino)ethyl methacrylate)-poly (methacrylate isobutyl polyhedral oligomeric silsesquioxane) (PDMAEMA-POSS) copolymers are reported. The hydrophobic POSS interior allows a cell-sensitizing drug such as paclitaxel to be incorporated, whereas the cationic and hydrophilic PDMAEMA corona allows the complexation of anionic DNA to form a nano-sized polyplex. These drug-encapsulated copolymers display excellent gene transfection efficiency compared with polyethylenimine or PDMAEMA homopolymers.

Structural mediation on polycation nanoparticles by sulfadiazine to enhance DNA transfection efficiency and reduce toxicity

Reducing the toxicity while maintaining high transfection efficiency is an important issue for cationic polymers as gene carriers in clinical application. In this paper, a new zwitterionic copolymer, polycaprolactone-g-poly(dimethylaminoethyl methyacrylate-co-sulfadiazine methacrylate) (PC-SDZ) with unique pH-sensitivity, was designed and prepared. The incorporation of sulfadiazine into poly(dimethylaminoethyl methacrylate) (PDMAEMA) chains successfully mediates the surface properties including compacter shell structure, lower density of positive charges, stronger proton buffer capability, and enhanced hydrophobicity, which lead to reduction in toxicity and enhancements in stability, cellular uptake, endosome escape, and transfection efficiency for the PC-SDZ2 nanoparticles (NPs)/DNA complexes. Excellent transfection efficiency at the optimal N/P ratio of 10 was observed for PC-SDZ2 NPs/DNA complexes, which was higher than that of the commercial reagent-branched polyethylenimine (PEI). The cytotoxicity was evaluated by CCK8 measurement, and the results showed significant reduction in cytotoxicity even at high concentration of complexes after sulfadiazine modification. Therefore, this work may demonstrate a new way of structural mediation of cationic polymer carriers for gene delivery with high efficiency and low toxicity.

Effects of hydrophobic core components in amphiphilic PDMAEMA nanoparticles on siRNA delivery

Due to their biodegradable character, polyesters such as polycaprolactone (PCL), poly(D,L-lactide) (PDLLA), and polylactic-co-glycolic acid (PLGA) were widely used as the hydrophobic cores of amphiphilic cationic nanoparticles (NPs) for siRNA delivery. However, fewer researches focused on facilitating siRNA delivery by adjusting the polyester composition of these nanoparticles. Herein, we investigated the contribution of polyester segments in siRNA delivery in vitro by introducing different ratio of DLLA moieties in PCL segments of mPEG-block-PCL-graft-poly(dimethylamino ethyl methacrylate)(PEG-b-PCL-g-PDMAEMA). It was noticed that compared with the other ratios of DLLA moieties, a certain molar ratio (about 70%) of the NPs, named mPEG45-P(CL21-co-DLLA48)-g-(PDMAEMA29)2 (PECLD-70), showed the highest gene knockdown efficiency but poorest cellular uptake ability in vitro. Further research revealed that NPs with various compositions of the polyester cores showed different physicochemical properties including particle size, zeta potential and stiffness, leading to different endocytosis mechanisms thus influencing the cellular uptake efficiency. Subsequently, we observed that the cells treated by PECLD-70 NPs/Cy5 siRNA complexes exhibited more diffuse Cy5 signal distribution than other NPs by confocal laser scanning microscope, which suggested that siRNA delivered by PECLD-70 NPs/Cy5 siRNA complexes possessed of stronger capabilities in escaping from endosome/lysosome, entering the RNA-induced silencing complex (RISC) and cutting the target mRNA efficiently. The different siRNA release profile was dominated by the degradation rate of polyester segments. Therefore, it could be concluded that the adjustment of hydrophobic core of cationic nanoparticles could significantly affect their transfection behavior and appropriate polyester composition should be concerned in designing of analogous siRNA vectors.

A shape memory copolymer based on 2-(dimethylamino)ethyl methacrylate and methyl allyl polyethenoxy ether for potential biological applications

This study reports a novel shape memory copolymer synthesized with 2-(dimethylamino)-ethyl-methacrylate (DMAEMA) and methyl-allyl-polyethenoxy-ether (TPEG) for potential biological applications.

Design and fabrication of functional polycaprolactone

Functional polycaprolactone (PCL) has great potential for applications in biomedical areas. This review summarizes the recent progress in the chemical synthesis of functional PCL. The functional PCL can be synthesized by (a) homopolymerization or copolymerization of functional ε-caprolactone (ε-CL), (b) copolymerization of 2-methylene-1-3-dioxepane with functional vinyl monomers, or (c) copolymerization of ε-CL with functional carbonate monomers. This review presents the recent trends in the synthesis of functional PCL and its biomedical applications.

The synergistic regulation of VEGF-mediated angiogenesis through miR-190 and target genes

VEGF is a major contributor to angiogenesis, a vital process in normal growth and development and tumor transition. However, the current clinical efficacy of VEGF inhibitors is limited, and the molecular mechanism underlying VEGF regulation remains to be elucidated. Here we show that miR-190 directly targets a group of angiogenic effectors besides VEGF per se. Noted, these effectors can transcriptionally regulate VEGF expression in an intracellular or intercellular manner, thus demonstrating that miR-190 modulates the VEGF-mediated tumor angiogenesis at three levels. The synergistic effect of miR-190 and its target genes demonstrates a complex but apparently more stable system, allowing for the tight control of the level of VEGF. Finally, we showed that miR-190 significantly suppresses tumor metastasis, especially angiogenesis. Together, these results indicate that miR-190 is a promising antitumor target in clinical applications.

Doxorubicin conjugate of poly(ethylene glycol)-block-polyphosphoester for cancer therapy

Polyphosphoesters with repeating phosphoester linkages in the backbone can be easily functionalized, are biodegradable and potentially biocompatible, and may be potential candidates as polymer carriers of drug conjugates. Here, the efficacy of a polyphosphoester drug conjugate as an anticancer agent in vivo is assessed for the first time. With controlled synthesis, doxorubicin conjugated to poly(ethylene glycol)-block-polyphosphoester (PPEH-DOX) via labile hydrazone bonds form spherical nanoparticles in aqueous solution with an average diameter of ≈60 nm. These nanoparticles are effectively internalized by MDA-MB-231 breast cancer cells and release the conjugated doxorubicin in response to the intracellular pH of endosomes and lysosomes, resulting in significant antiproliferative activity in cancer cells. Compared with free doxorubicin injection, PPEH-DOX injection exhibits much longer circulation behavior in the plasma of mice and leads to enhanced drug accumulation in tumor cells. In an MDA-MB-231 xenograft murine model, inhibition of tumor growth with systemic delivery of PPEH-DOX nanoparticles is more pronounced compared with free doxorubicin injection, suggesting the potential of polyphosphoesters as carriers of drug conjugates in cancer therapy.

Polycation-detachable nanoparticles self-assembled from mPEG-PCL-g-SS-PDMAEMA for in vitro and in vivo siRNA delivery

Long circulation, cell internalization, endosomal escape and small interfering RNA (siRNA) release to the cytoplasm are the prerequisite considerations for siRNA delivery vectors. Herein, a kind of sheddable nanoparticles (NPs) with micelle architecture for siRNA delivery were fabricated by using an intracellular-activated polycation-detachable copolymer (PECssD), which was prepared by introducing highly reducing environment-responsive disulfide linkages between PEGylated polycaprolactone (PCL) and the grafted polycation, poly(2-dimethylaminoethyl methacrylate) (PDMAEMA). The architecture of PECssD self-assembled NPs includes a biodegradable hydrophobic PCL core, a PEG shield and a detachable comb-like polycation surface. The stable nanosized complexes of PECssD NPs with siRNA, termed PECssD/siRNA micelleplexes, were formed, which could prolong circulation, improve accumulation and retention in tumor tissue, and be favorable for internalization. In particular, the cleavage of the disulfide linkages in the intracellular microenvironment and the subsequent dissociation of the PDMAEMA/siRNA polyplexes from the PEGylated PCL cores of PECssD/siRNA micelleplexes were also confirmed, which facilitated the endosomal escape and the efficient release of siRNA. As a result, the distribution of siRNA in cytoplasm was enhanced and subsequently promoted the efficiency of siRNA in gene silencing. Furthermore, systemic administration of the NPs carrying siPlk1 (polo-like kinase 1 specific siRNA) induced a tumor-suppressing effect in the HeLa-Luc xenograft murine model. Therefore, the devised strategy of the polycation-detachable copolymer PECssD NPs could address the requirements of the multistep systemic delivery process of siRNA. The hydrophobic core of the PECssD/siRNA micelleplexes is expected to entrap antitumor drugs or other therapeutic agents for combined therapies.

Intracellular cleavable poly(2-dimethylaminoethyl methacrylate) functionalized mesoporous silica nanoparticles for efficient siRNA delivery in vitro and in vivo

A low cytotoxicity and high efficiency delivery system with the advantages of low cost and facile fabrication is needed for the application of small interfering RNA (siRNA) delivery both in vitro and in vivo. For these prerequisites, cationic polymer-mesoporous silica nanoparticles (ssCP-MSNs) were prepared by surface functionalized mesoporous silica nanoparticles with disulfide bond cross-linked poly(2-dimethylaminoethyl methacrylate) (PDMAEMA). In vitro and in vivo evaluations were performed. The synthesized ssCP-MSNs are 100-150 nm in diameter with a pore size of 10 nm and a positively charged surface with a high zeta potential of 27 mV. Consequently, the ssCP-MSNs showed an excellent binding capacity for siRNA, and an enhancement in the cell uptake and cytosolic availability of siRNA. Furthermore, the intracellular reducing cleavage of the disulfide bonds cross-linking the PDMAEMA segments led to intracellular cleavage of PDMAEMA from ssCP-MSNs, which facilitated the intracellular triggered release of siRNA. Therefore, promoted RNA interference was observed in HeLa-Luc cells, which was equal to that of Lipofectamine 2000. Significantly, compared to Lipofectamine 2000, the ssCP-MSNs were more biocompatible, with low cytotoxicity (even non-cytotoxicity) and promotion of cell proliferation to HeLa-Luc cells. The in vivo systemic distribution studies certified that ssCP-MSNs/siRNA could prolong the duration of siRNA in vivo, and that they accumulated in the adrenal gland, liver, lung, spleen, kidney, heart and thymus after intravenous injection. Encouragingly, with the ability to deliver siRNA to a tumor, ssCP-MSNs/siRNA showed a tumor suppression effect in the HeLa-Luc xenograft murine model after intravenous injection. Therefore, the ssCP-MSNs cationic polymer-mesoporous silica nanoparticles with low cytotoxicity are promising for siRNA delivery.