A bridge to silencing: Co-assembling anionic nanoparticles of siRNA and hyaluronan sulfate via calcium ion bridges

Response of cardiovascular environment to sulfonated hyaluronic acid with higher sulfur content

Sulfonated hyaluronic acid (S-HA) has been shown to promote endothelialization in the treatment of cardiovascular diseases according to amounts of investigations. In this study, two kinds of S-HA with higher sulfur content were obtained successfully. Through a series of cell experiments, it was found that the S-HA with higher sulfur content not only possessed stronger ability of promoting the growth and migration of endothelial cells, regulating the phenotype of smooth muscle cells, but also had stronger anti-inflammatory function. Furthermore, all the S-HA molecules are very compatible with blood.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Ca2+ participating self-assembly of an apoferritin nanostructure for nucleic acid drug delivery

One of the most encountered obstacles for utilizing nano-sized vehicles to implement the in vivo delivery of nucleic acid drugs (NADs) is the possible steric hindrance caused by their intrinsic size and charge. In this work, we added Ca2+ for the pH triggered self-assembly process of H-apoferritin (HFn), to neutralize negative charges and help siRNA condense during complexation and particle formation. As expected, the internalization efficiency of siRNA in HFn particle formation could be enhanced 1.65-fold, compared with that without incorporated Ca2+. Furthermore, the calcification that occurred within the cavity of HFn particles endows them with endosomal escape capability, which could explain their contribution to the demonstrated in vitro and in vivo gene silencing effect achieved by the internalized siRNA. Thus, this Ca2+ participating self-assembly process of a protein nanostructure would lead to advanced internalization efficiency for NAD therapy.

Natural Polysaccharides for siRNA Delivery: Nanocarriers Based on Chitosan, Hyaluronic Acid, and Their Derivatives

Natural polysaccharides are frequently used in the design of drug delivery systems due to their biocompatibility, biodegradability, and low toxicity. Moreover, they are diverse in structure, size, and charge, and their chemical functional groups can be easily modified to match the needs of the final application and mode of administration. This review focuses on polysaccharidic nanocarriers based on chitosan and hyaluronic acid for small interfering RNA (siRNA) delivery, which are highly positively and negatively charged, respectively. The key properties, strengths, and drawbacks of each polysaccharide are discussed. In addition, their use as efficient nanodelivery systems for gene silencing applications is put into context using the most recent examples from the literature. The latest advances in this field illustrate effectively how chitosan and hyaluronic acid can be modified or associated with other molecules in order to overcome their limitations to produce optimized siRNA delivery systems with promising in vitro and in vivo results.

Co-assembled Ca2+ Alginate-Sulfate Nanoparticles for Intracellular Plasmid DNA Delivery

Successful gene therapy requires the development of suitable carriers for the selective and efficient delivery of genes to specific target cells, with minimal toxicity. In this work, we present a non-viral vector for gene delivery composed of biocompatible materials, CaCl2, plasmid DNA and the semi-synthetic anionic biopolymer alginate sulfate (AlgS), which spontaneously co-assembled to form nanoparticles (NPs). The NPs were characterized with a slightly anionic surface charge (Zeta potential [ζ] = -14 mV), an average size of 270 nm, and their suspension was stable for several days with no aggregation. X-ray photoelectron spectroscopy (XPS) validated their ternary composition, and it elucidated the molecular interactions among Ca2+, the plasmid DNA, and the AlgS. Efficient cellular uptake (>80%), associated with potent GFP gene expression (22%-35%), was observed across multiple cell types: primary rat neonatal cardiac fibroblasts, human breast cancer cell line, and human hepatocellular carcinoma cells. The uptake mechanism of the NPs was studied using imaging flow cytometry and shown to be via active, clathrin-mediated endocytosis, as chemical inhibition of this pathway significantly reduced EGFP expression. The NPs were cytocompatible and did not activate the T lymphocytes in human peripheral blood mononuclear cells. Proof of concept for the efficacy of these NPs as a carrier in cancer gene therapy was demonstrated for Diphtheria Toxin Fragment A (DT-A), resulting in abrogation of protein synthesis and cell death in the human breast cancer cell line. Collectively, our results show that the developed AlgS-Ca2+-plasmid DNA (pDNA) NPs may be used as an effective non-viral carrier for pDNA.

Hyaluronan-based delivery of therapeutic oligonucleotides for treatment of human diseases

INTRODUCTION

Oligonucleotide therapeutics such as antisense oligonucleotides and siRNA requires chemical modifications and nano-sized carriers to circumvent stability problems in vivo, to reach target tissues, and to overcome tissue and cellular barriers. Hyaluronic acid (HA), already utilized in drug delivery and tissue engineering, possess properties that are useful to solve these problems and achieve full potential of oligonucleotide therapeutics.

AREAS COVERED

Complexes of oligonucleotide therapeutics with HA are discussed in terms of interactions providing the complexes formation and genes targeted by the therapeutics to cure diseases such as cancer, atherosclerosis, liver cirrhosis, and inflammation. The achieved therapeutic effects are rationalized as consequences of biodistribution, cell internalization and endosomal escape provided by HA.

EXPERT OPINION

Design of electrostatic, coordination, and hydrophobic interactions as well as covalent conjugation between oligonucleotide drugs, HA macromolecules and intermediate ligands are crucial for carrier-cargo association and dissociation under different conditions to impart oligonucleotides stability in vivo, their accumulation in diseased organs, cellular uptake, and dissociation in cytoplasm intact. These are the delivery factors that provides eventual complex formation of oligonucleotide therapeutics with their mRNA, microRNA, or protein targets. Elucidation of the impact of structural parameters of oligonucleotide/HA complexes on their therapeutic effect in vivo is important for the future rational design of the delivery agents.

Signal Transducer and Activator of Transcription (STATs) Proteins in Cancer and Inflammation: Functions and Therapeutic Implication

Signal Transducer and Activator of Transcription (STAT) pathway is connected upstream with Janus kinases (JAK) family protein and capable of integrating inputs from different signaling pathways. Each family member plays unique functions in signal transduction and crucial in mediating cellular responses to different kind of cytokines. STAT family members notably STAT3 and STAT5 have been involved in cancer progression whereas STAT1 plays opposite role by suppressing tumor growth. Persistent STAT3/5 activation is known to promote chronic inflammation, which increases susceptibility of healthy cells to carcinogenesis. Here, we review the role of STATs in cancers and inflammation while discussing current therapeutic implications in different cancers and test models, especially the delivery of STAT3/5 targeting siRNA using nanoparticulate delivery system.

Nanoparticle Delivery of miRNA-21 Mimic to Cardiac Macrophages Improves Myocardial Remodeling after Myocardial Infarction

MicroRNA-based therapy that targets cardiac macrophages holds great potential for treatment of myocardial infarction (MI). Here, we explored whether boosting the miRNA-21 transcript level in macrophage-enriched areas of the infarcted heart could switch their phenotype from pro-inflammatory to reparative, thus promoting resolution of inflammation and improving cardiac healing. We employed laser capture microdissection (LCM) to spatially monitor the response to this treatment in the macrophage-enriched zones. MiRNA-21 mimic was delivered to cardiac macrophages post MI by nanoparticles (NPs), spontaneously assembled due to the complexation of hyaluronan-sulfate with the nucleic acid mediated by calcium ion bridges, yielding slightly anionic NPs with a mean diameter of 130 nm. Following intravenous administration, the miRNA-21 NPs were targeted to cardiac macrophages at the infarct zone, elicited their phenotype switch from pro-inflammatory to reparative, promoted angiogenesis, and reduced hypertrophy, fibrosis and cell apoptosis in the remote myocardium. Our work thus presents a new therapeutic strategy to manipulate macrophage phenotype using nanoparticle delivery of miRNA-21 with a potential for use to attenuate post-MI remodeling and heart failure.

Surface Analysis of Nanocomplexes by X-ray Photoelectron Spectroscopy (XPS)

Self-assembled nanocomplexes composed of individual molecules that spontaneously connect via noncovalent interactions have recently emerged as versatile alternatives to conventional controlled drug delivery systems because of their unique bioinspired properties (responsiveness, dynamics, etc.). Characterization of such nanocomplexes typically includes their size distribution, surface charge, morphology, drug entrapment efficiency, and verification of the coexistence of labeled components within the nanocomplexes using a colocalization study. Less common is the direct examination of the molecular interactions between the different components in the coassembled nanocomplex, especially in nanocomplexes composed of hygroscopic components, because convenient methods are still lacking. Here, we present a detailed experimental protocol for determining the surface composition and the chemical bonds by X-ray photoelectron spectroscopy (XPS) after drying the deposit hygroscopic sample overnight under UHV. We applied this method to investigate the surface chemistry of binary Ca²⁺-siRNA nanocomplexes and ternary nanocomplexes of hyaluronan-sulfate (HAS)-Ca²⁺-siRNA, deposited on a wafer. Notably, we showed that the protocol can be implemented to study the surface composition and interactions of the deposited nanocomplexes with a traditional XPS instrument, and it requires only a relatively small amount of the nanocomplex suspension.

Bioreducible Cross-Linked Hyaluronic Acid/Calcium Phosphate Hybrid Nanoparticles for Specific Delivery of siRNA in Melanoma Tumor Therapy

This study introduces a novel cross-linking strategy capable of successfully stabilizing CaP nanoparticles and stimuli-responsive small interfering RNA (siRNA) release. We synthesized a polysaccharide derivative thiolated hyaluronic acid (HA-SH), which was slightly modified but multifunctional and developed a smart redox-responsive delivery system. siRNA was efficaciously condensed by calcium phosphate (CaP) via electrostatic interaction to form a positively charged inner "core". Disulfide cross-linked HA (HA-ss-HA) was formed and played a role as an anionic outer "shell" to stabilize the CaP core. We demonstrated that the nanoparticles were stable both in the storage milieu and systemic circulation, thus overcoming the most serious disadvantage of CaP nanoparticles for gene delivery. Meanwhile, this smart system could selectively release siRNA into the cytosol by both a GSH-triggered disassembly and successful endosomal escape. Therefore, the hybrid delivery system achieved an 80% gene-silencing efficiency in vitro for both luciferase and Bcl2. Silencing of Bcl2 resulted in dramatic apoptosis of B16F10 cells. Besides, equipped with the tumor-targeting component HA, the nanoparticles significantly suppressed the growth of B16F10 xenograft tumor in mice. The anionic HA-ss-HA-equipped nanoparticles showed no apparent toxicity in vitro or in vivo, as well as showed a high transfection efficiency. Taken together, this redox-responsive, tumor-targeting smart anionic nanoparticle holds great promise for exploitation in functionalized siRNA delivery and tumor therapy.