Effective cytoplasmic release of siRNA from liposomal carriers by controlling the electrostatic interaction of siRNA with a charge-invertible peptide, in response to cytoplasmic pH

Keeping up with the COVID's-Could siRNA-based antivirals be a part of the answer?

Coronavirus disease 2019 (COVID-19) is a highly contagious viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This deadly infection has resulted in more than 5.2 million deaths worldwide. The global rollout of COVID-19 vaccines has without doubt saved countless lives by reducing the severity of symptoms for patients. However, as the virus continues to evolve, there is a risk that the vaccines and antiviral designed to target the infection will no longer be therapeutically viable. Furthermore, there remain fears over both the short and long-term side effects of repeat exposure to currently available vaccines. In this review, we discuss the pros and cons of the vaccine rollout and promote the idea of a COVID medicinal toolbox made up of different antiviral treatment modalities, and present some of the latest therapeutic strategies that are being explored in this respect to try to combat the COVID-19 virus and other COVID viruses that are predicted to follow. Lastly, we review current literature on the use of siRNA therapeutics as a way to remain adaptable and in tune with the ever-evolving mutation rate of the COVID-19 virus.

Intraperitoneal administration of nanoparticles containing tocopheryl succinate prevents peritoneal dissemination

Intraperitoneal administration of anticancer nanoparticles is a rational strategy for preventing peritoneal dissemination of colon cancer owing to the prolonged retention of nanoparticles in the abdominal cavity. However, instability of nanoparticles in body fluids causes inefficient retention, reducing its anticancer effects. We have previously developed anticancer nanoparticles containing tocopheryl succinate, which showed high in vivo stability and multifunctional anticancer effects. In the present study, we have demonstrated that peritoneal dissemination derived from colon cancer was prevented by intraperitoneal administration of tocopheryl succinate nanoparticles. The biodistribution of tocopheryl succinate nanoparticles was evaluated by inductively coupled plasma mass spectroscopy and imaging analysis in mice administered quantum dot encapsulated tocopheryl succinate nanoparticles. Intraperitoneal administration of tocopheryl succinate nanoparticles showed longer retention in the abdominal cavity than by its intravenous administration. Moreover, due to effective biodistribution, tumor growth was prevented by intraperitoneal administration of tocopheryl succinate nanoparticles. Furthermore, the anticancer effect was attributed to the inhibition of cancer cell proliferation and improvement of the intraperitoneal microenvironment, such as decrease in the levels of vascular endothelial growth factor A, interleukin 10, and M2-like phenotype of tumor-associated macrophages. Collectively, intraperitoneal administration of tocopheryl succinate nanoparticles is expected to have multifaceted antitumor effects against colon cancer with peritoneal dissemination.

Biologics and their delivery systems: Trends in myocardial infarction

Cardiovascular disease is the leading cause of death around the world, in which myocardial infarction (MI) is a precipitating event. However, current therapies do not adequately address the multiple dysregulated systems following MI. Consequently, recent studies have developed novel biologic delivery systems to more effectively address these maladies. This review utilizes a scientometric summary of the recent literature to identify trends among biologic delivery systems designed to treat MI. Emphasis is placed on sustained or targeted release of biologics (e.g. growth factors, nucleic acids, stem cells, chemokines) from common delivery systems (e.g. microparticles, nanocarriers, injectable hydrogels, implantable patches). We also evaluate biologic delivery system trends in the entire regenerative medicine field to identify emerging approaches that may translate to the treatment of MI. Future developments include immune system targeting through soluble factor or chemokine delivery, and the development of advanced delivery systems that facilitate the synergistic delivery of biologics.

Recent Progress in Ionic Coassembly of Cationic Peptides and Anionic Species

Peptide assembly has been extensively exploited as a promising platform for the creation of hierarchical nanostructures and tailor-made bioactive materials. Ionic coassembly of cationic peptides and anionic species is paving the way to provide particularly important contribution to this topic. In this review, the recent progress of ionic coassembly soft materials derived from the electrostatic coupling between cationic peptides and anionic species in aqueous solution is systematically summarized. The presentation of this review starts from a brief background on the general importance and advantages of peptide-based ionic coassembly. After that, diverse combinations of cationic peptides with small anions, macro- and/or oligo-anions, anionic polymers, and inorganic polyoxometalates are described. Emphasis is placed on the hierarchical structures, value-added properties, and applications. The molecular design of cationic peptides and the general principles behind the ionic coassembled structures are discussed. It is summarized that the combination of interesting and unique characteristics that arise both from the chemical diversity of peptides and the wide range of anionic species may contribute in a variety of output, including drug delivery, tissue engineering, gene transfection, and antibacterial activity. The emergent new phenomena and findings are illustrated. Finally, the outlook for the peptide-based ionic coassembly systems is also presented.

Solvent-driven, self-assembled acid-responsive poly(ketalized serine)/siRNA complexes for RNA interference

Advances in bionanotechnology aim to develop smart nucleic acid delivery carriers with stimuli-responsive features to overcome challenges such as non-biodegradability, rapid clearance, immune response, and reaching intracellular targets. Peptide-based nanomaterials have become widely used in the field of gene and drug delivery due to their structural versatility and biomimetic properties. Particularly, polypeptide gene vectors that respond to biological stimuli, such as acidic intracellular environments, have promising applications in mediating efficient endosomal escape and drug release. Unfortunately, synthesis strategies for efficient polymerization of acid-labile peptides have been limited due to conditions that fail to preserve acid-degradable functional groups. Stable urethane derivatives of the acid-labile amino acid ketalized serine (kSer) were synthesized and polymerized to a high molecular weight under permissive conditions independent of elevated temperature, restrictive solvents, or an inert atmosphere. A new formulation strategy utilizing solvent-driven self-assembly of poly(kSer) peptides with small interfering RNA (siRNA) was developed, and the resulting poly(kSer)/siRNA complexes were further cross-linked for reinforced stability under physiological conditions. The complexes were highly monodisperse and precisely spherical in morphology, which has significant clinical implications in definitive biodistribution, cellular internalization, and intracellular trafficking patterns. Self-assembled, cross-linked poly(kSer)/siRNA complexes demonstrated efficient nucleic acid encapsulation, internalization, endosomal escape, and acid-triggered cargo release, tackling multiple hurdles in siRNA delivery. The acid-responsive polypeptides and solvent-driven self-assembly strategies demonstrated in this study could be applicable to developing other efficient and safe delivery systems for gene and drug delivery.

siRNA release kinetics from polymeric nanoparticles correlate with RNAi efficiency and inflammation therapy via oral delivery

Despite many efforts in the rational design of nanoparticles (NPs) to overcome the biological barriers to small interfering RNA (siRNA) delivery for improving gene silencing efficiency, little is known about the correlations between siRNA release kinetics and RNA interference (RNAi) efficiency and inflammation therapy via oral delivery. On the basis of mannose-modified trimethyl chitosan-cysteine (MTC) polymers, seven types of MTC NPs containing tumor necrosis factor (TNF)-α siRNA were prepared through ionic gelation. The siRNA release kinetics from MTC NPs were finely tuned by adjusting the kinds and amounts of the crosslinkers involved. These MTC NPs exhibited no disparities in siRNA protection against enzymatic degradation in physiological fluids and cellular uptake in macrophages; however, they showed distinct in vitro siRNA release profiles and intracellular unpacking kinetics. MTC NPs with relatively rapid and sustained siRNA release were responsible for efficient, prompt, and prolonged RNAi, contributing to desired therapeutic efficacy in acute and chronic inflammatory murine models following oral delivery. However, MTC NPs insufficiently releasing siRNA could not elicit effective RNAi. Collectively, the present investigation might provide broad insights into the optimization of siRNA nanocarriers with respect to their release kinetics for improving RNAi efficacies aiming at different types of inflammatory diseases. STATEMENT OF SIGNIFICANCE: siRNA release kinetics in the cytoplasm and pathological characteristics of diseases themselves determine the therapeutic efficacy of siRNA delivery. Herein, by adjusting the kinds and amounts of the crosslinkers involved, we developed seven types of MTC NPs containing TNF-α siRNA with distinct siRNA release kinetics. MTC NPs with relatively rapid and sustained siRNA release were responsible for prompt and prolonged RNAi, respectively, contributing to desired therapeutic efficacy in acute and chronic inflammation following oral delivery. These results might provide broad insights into the optimization of siRNA nanocarriers in respect to their release kinetics for improving therapeutic outcomes toward different clinical requirements.

Novel Oligo-Guanidyl-PEG Carrier Forming Rod-Shaped Polyplexes

A novel unconventional supramolecular oligo-cationic structure (Agm₆-M-PEG-OCH₃) has been synthesized to yield high efficiency therapeutic oligonucleotide (ON) delivery. Agm₆-M-PEG-OCH₃ was obtained by a multistep protocol that included the conjugation of agmatine (Agm) moieties to maltotriose (M), which was further derivatized with one poly(ethylene glycol) (PEG) chain. Gel electrophoresis analysis showed that the 19 base pairs dsDNA model ON completely associates with Agm₆-M-PEG-OCH₃ at 3 N/P molar ratio, which is in agreement with the in silico molecular predictions. Isothermal titration calorimetry (ITC) analyses showed that the Agm₆-M-PEG-OCH₃/ON association occurs through a combination of mechanisms depending on the N/P ratios resulting in different nanostructures. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed that the Agm₆-M-PEG-OCH₃/ON polyplexes have rod-shape structure with a mean diameter of 50-75 nm and aspect ratio depending on the N/P ratio. The polyplexes were stable over time in buffer, while a slight size increase was observed in the presence of serum proteins. Cell culture studies showed that neither Agm₆-M-PEG-OCH₃ nor polyplexes displayed cytotoxic effects. Cellular uptake depended on the cell line and polyplex composition: cellular internalization was higher in the case of MCF-7 and KB cells compared to MC3T3-E1 cells and polyplexes with smaller aspect ratio were taken-up by cells more efficiently than polyplexes with higher aspect ratio. Finally, preliminary studies showed that our novel carrier efficiently delivered ONs into cells providing gene silencing.

Ratiometric co-encapsulation and co-delivery of doxorubicin and paclitaxel by tumor-targeted lipodisks for combination therapy of breast cancer

Combination therapy is a promising treatment for certain advanced drug-resistant cancers. Although effective inhibition of various tumor cells was reported in vitro, combination treatment requires improvement in vivo due to uncontrolled ratiometric delivery. In this study, a tumor-targeting lipodisk nanoparticle formulation was developed for ratiometric loading and the transportation of two hydrophobic model drugs, doxorubicin (DOX) and paclitaxel (PTX), in one single platform. Furthermore, a slightly acidic pH-sensitive peptide (SAPSP) incorporated into lipodisks effectively enhanced the tumor-targeting and cell internalization. The obtained co-loaded lipodisks were approximately 30 nm with a pH-sensitive property. The ratiometric co-delivery of two drugs via lipodisks was confirmed in both the drug-resistant MCF-7/ADR cell line and its parental MCF-7 cell line in vitro, as well as in a tumor-bearing mouse model in vivo compared with a cocktail solution of free drugs. Co-loaded lipodisks exerted improved cytotoxicity to tumor cells in culture, particularly to drug-resistant tumor cells at synergistic drug ratios. In an in vivo xenograft mouse model, the anti-tumor ability of co-loaded lipodisks was evidenced by the remarkable inhibitory effect on tumor growth of either MCF-7 or MCF-7/ADR tumors, which may be attributed to the increased and ratiometric accumulation of both drugs in the tumor tissues. Therefore, tumor-specific lipodisks were crucial for the combination treatment of DOX and PTX to completely exert a synergistic anti-cancer effect. It is concluded that for co-loaded lipodisks, cytotoxicity data in vitro could be used to predict their inhibitory activity in vivo, potentially enhancing the clinical outcome of synergistic therapy.

RNAi-based therapeutics for lung cancer: biomarkers, microRNAs, and nanocarriers

INTRODUCTION

Despite the current advances in the discovery of the lung cancer biomarkers and, consequently, in the diagnosis, this pathology continues to be the primary cause of cancer-related death worldwide. In most cases, the illness is diagnosed in an advanced stage, which limits the current treatment options available and reduces the survival rate. Therefore, RNAi-based therapy arises as a promising option to treat lung cancer.

AREAS COVERED

This review provides an overview on the exploitation of lung cancer biology to develop RNAi-based therapeutics to be applied in the treatment of lung cancer. Furthermore, the review analyzes the main nanocarriers designed to deliver RNAi molecules and induce antitumoral effects in lung cancer, and provides updated information about current RNAi-based therapeutics for lung cancer in clinical trials.

EXPERT OPINION

RNAi-based therapy uses nanocarriers to perform a targeted and efficient delivery of therapeutic genes into lung cancer cells, by taking advantage of the known biomarkers in lung cancer. These therapeutic genes are key regulatory molecules of crucial cellular pathways involved in cell proliferation, migration, and apoptosis. Thereby, the characteristics and functionalization of the nanocarrier and the knowledge of lung cancer biology have direct influence in improving the therapeutic effect of this therapy.

A reduction-responsive liposomal nanocarrier with self-reporting ability for efficient gene delivery

In the past few decades, although various reduction-responsive nanocarriers have been designed and explored for gene delivery, it is difficult to directly detect or monitor the reduction capability of these carriers, especially under intracellular conditions. Taking advantage of the generated fluorescence signal in the reduction process of the naphthalimide-sulfonamide (NS) group, we developed a novel liposomal nanocarrier, FNSL, which showed reduction-sensitive property and self-reporting character. As a new reduction-responsive site in a gene delivery system, the NS group in FNSL is capable of responding to glutathione (GSH) and simultaneously emitting green fluorescence at 500 nm in both extra- and intracellular circumstances. Hence, it will be very convenient to assess the reducibility of this carrier and monitor the stimuli-responsive gene release via fluorescence signal. FNSL has high affinity for DNA and can condense it into nanoparticles with a proper nano-size and zeta potential. Compared with the non-reducible FNAL, FNSL showed enhanced gene release capability, higher transfection efficiency (TE), and lower cytotoxicity. Furthermore, treatment of FNSL-mediated transfection with slightly exogenous GSH greatly improved the TE of FNSL in HepG2 cells, and its TE was even higher than that of Lipofectamine 2000. These results demonstrate that FNSL possesses great potential for efficient and low-toxicity gene delivery, and this study on a bioreducible liposome with self-reporting ability would be a guide for further research on the development of biodegradable gene carriers.

Cationic switchable lipids: pH-triggered molecular switch for siRNA delivery

A pH-sensitive molecular switch able to change its conformation upon protonation at endosomal pH values is embedded into the structure of cationic lipidoid materials, thus conferring endosomal escape properties. Involvement of the conformational switch in the endosomal escape process was confirmed and leading material identified was able to induce efficient gene knockdown both in vitro and in vivo. The lipid nanoparticles reported here are promising for therapeutic applications and this work could serve as a template for future design of stimulus-responsive (ionic, redox, light) molecular switch for drug and gene delivery.

Delivery of siRNA Using Lipid Nanoparticles Modified with Cell Penetrating Peptide

Clinical development of siRNA has been hindered by the lack of an effective delivery system. Here, we report the construction of a novel siRNA delivery system, sTOLP, which is based on cell penetrating peptide oleoyl-octaarginine (OA-R8) modified multifunctional lipid nanoparticles. sTOLP nanoparticles are composed of a protamine complexed siRNA core, OA-R8, cationic and PEGylated lipids, and transferrin as a targeting ligand. sTOLP formulation was optimized and characterized in vitro and showed excellent gene silencing activity. In vivo, siRNA encapsulated in sTOLP exhibited potent tumor inhibition (61.7%) and was preferentially taken up by hepatocytes and tumor cells in HepG2-bearing nude mice without inducing immunogenicity or hepatic or renal toxicity. Furthermore, sTOLP-loaded siRNA had stability in circulation greater than that of free siRNA. These data demonstrated potential utility of sTOLP-mediated siRNA delivery in cancer therapy.