A role for peptides in overcoming endosomal entrapment in siRNA delivery - A focus on melittin

ZBTB46 coordinates angiogenesis and immunity to control tumor outcome

Tumor angiogenesis and immunity show an inverse correlation in cancer progression and outcome1. Here, we report that ZBTB46, a repressive transcription factor and a widely accepted marker for classical dendritic cells (DCs)2,3, controls both tumor angiogenesis and immunity. Zbtb46 was downregulated in both DCs and endothelial cells by tumor-derived factors to facilitate robust tumor growth. Zbtb46 downregulation led to a hallmark pro-tumor microenvironment (TME), including dysfunctional vasculature and immunosuppressive conditions. Analysis of human cancer data revealed a similar association of low ZBTB46 expression with an immunosuppressive TME and a worse prognosis. In contrast, enforced Zbtb46 expression led to TME changes to restrict tumor growth. Mechanistically, Zbtb46-deficient endothelial cells were highly angiogenic, and Zbtb46-deficient bone marrow progenitors upregulated Cebpb and diverted the DC program to immunosuppressive myeloid lineage output, potentially explaining the myeloid lineage skewing phenomenon in cancer4. Conversely, enforced Zbtb46 expression normalized tumor vessels and, by suppressing Cebpb, skewed bone marrow precursors toward immunostimulatory myeloid lineage output, leading to an immune-hot TME. Remarkably, Zbtb46 mRNA treatment synergized with anti-PD1 immunotherapy to improve tumor management in preclinical models. These findings identify ZBTB46 as a critical factor for angiogenesis and for myeloid lineage skewing in cancer and suggest that maintaining its expression could have therapeutic benefits.

Strategies and mechanisms for endosomal escape of therapeutic nucleic acids

Despite impressive recent establishment of therapeutic nucleic acids as drugs and vaccines, their broader medical use is impaired by modest performance in intracellular delivery. Inefficient endosomal escape presents a major limitation responsible for inadequate cytosolic cargo release. Depending on the carrier, this endosomal barrier can strongly limit or even abolish nucleic acid delivery. Different recent endosomal escape strategies and their hypothesized mechanisms are reviewed.

Functionalized extracellular nanovesicles as advanced CRISPR delivery systems

The clustered regularly interspaced short palindromic repeat (CRISPR) system, an emerging tool for genome editing, has garnered significant public interest for its potential in treating genetic diseases. Despite the rapid advancements in CRISPR technology, the progress in developing effective delivery strategies lags, impeding its clinical application. Extracellular nanovesicles (EVs), either in their endogenous forms or with engineered modifications, have emerged as a promising solution for CRISPR delivery. These EVs offer several advantages, including high biocompatibility, biological permeability, negligible immunogenicity, and straightforward production. Herein, we first summarize various types of functional EVs for CRISPR delivery, such as unmodified, modified, engineered virus-like particles (VLPs), and exosome-liposome hybrid vesicles, and examine their distinct intracellular pathways. Then, we outline the cutting-edge techniques for functionalizing extracellular vesicles, involving producer cell engineering, vesicle engineering, and virus-like particle engineering, emphasizing the diverse CRISPR delivery capabilities of these nanovesicles. Lastly, we address the current challenges and propose rational design strategies for their clinical translation, offering future perspectives on the development of functionalized EVs.

Achieving Endo/Lysosomal Escape Using Smart Nanosystems for Efficient Cellular Delivery

The delivery of therapeutic agents faces significant hurdles posed by the endo-lysosomal pathway, a bottleneck that hampers clinical effectiveness. This comprehensive review addresses the urgent need to enhance cellular delivery mechanisms to overcome these obstacles. It focuses on the potential of smart nanomaterials, delving into their unique characteristics and mechanisms in detail. Special attention is given to their ability to strategically evade endosomal entrapment, thereby enhancing therapeutic efficacy. The manuscript thoroughly examines assays crucial for understanding endosomal escape and cellular uptake dynamics. By analyzing various assessment methods, we offer nuanced insights into these investigative approaches' multifaceted aspects. We meticulously analyze the use of smart nanocarriers, exploring diverse mechanisms such as pore formation, proton sponge effects, membrane destabilization, photochemical disruption, and the strategic use of endosomal escape agents. Each mechanism's effectiveness and potential application in mitigating endosomal entrapment are scrutinized. This paper provides a critical overview of the current landscape, emphasizing the need for advanced delivery systems to navigate the complexities of cellular uptake. Importantly, it underscores the transformative role of smart nanomaterials in revolutionizing cellular delivery strategies, leading to a paradigm shift towards improved therapeutic outcomes.

Model-based meta-analysis to quantify the effects of short interfering RNA therapeutics on hepatitis B surface antigen turnover in hepatitis B-infected mice

The objective of this study was to compare the efficacy of short interfering RNA therapeutics (siRNAs) in reducing hepatitis B surface antigen (HBsAg) levels in hepatitis B-infected (HBV) mice across multiple siRNA therapeutic classes using model-based meta-analysis (MBMA) techniques. Literature data from 10 studies in HBV-infected mice were pooled, including 13 siRNAs, formulated as liposomal nanoparticles (LNPs) or conjugated to either cholesterol (chol) or N-acetylgalactosamine (GalNAc). Time course of the baseline- and placebo-corrected mean HBsAg profiles were modeled using kinetics of drug effect (KPD) model coupled to an indirect response model (IRM) within a longitudinal non-linear mixed-effects MBMA framework. Single and multiple dose simulations were performed exploring the role of dosing regimens across evaluated siRNA classes. The HBsAg degradation rate (0.72 day-1) was consistent across siRNAs but exhibited a large between-study variability of 31.4% (CV%). The siRNA biophase half-life was dependent on the siRNA class and was highest for GalNAc-siRNAs (21.06 days) and lowest for chol-siRNAs (2.89 days). ID50 estimates were compound-specific and were lowest for chol-siRNAs and highest for GalNAc-siRNAs. Multiple dose simulations suggest GalNAc-siRNAs may require between 4 and 7 times less frequent dosing at higher absolute dose levels compared to LNP-siRNAs and chol-siRNAs, respectively, to reach equipotent HBsAg-lowering effects in HBV mice. In conclusion, non-clinical HBsAg concentration-time data after siRNA administration can be described using the presented KPD-IRM MBMA framework. This framework allows to quantitatively compare the effects of siRNAs on the HBsAg time course and inform dose and regimen selection across siRNA classes. These results may support siRNA development, optimize preclinical study designs, and inform data analysis methodology of future anti-HBV siRNAs; and ultimately, support siRNA model-informed drug development (MIDD) strategies.

Design of pH-responsive antimicrobial peptide melittin analog-camptothecin conjugates for tumor therapy

Melittin, a classical antimicrobial peptide, is a highly potent antitumor agent. However, its significant toxicity seriously hampers its application in tumor therapy. In this study, we developed novel melittin analogs with pH-responsive, cell-penetrating and membrane-lytic activities by replacing arginine and lysine with histidine. After conjugation with camptothecin (CPT), CPT-AAM-1 and CPT-AAM-2 were capable of killing tumor cells by releasing CPT at low concentrations and disrupting cell membranes at high concentrations under acidic conditions. Notably, we found that the C-terminus of the melittin analogs was more suitable for drug conjugation than the N-terminus. CPT-AAM-1 significantly suppressed melanoma growth in vivo with relatively low toxicity. Collectively, the present study demonstrates that the development of antitumor drugs based on pH-responsive antimicrobial peptide-drug conjugates is a promising strategy.

Three 'E' challenges for siRNA drug development

siRNA therapeutics have gained extensive attention, and to date six siRNAs are approved for clinical use. Despite being investigated for the treatment of metabolic, cardiovascular, infectious, and rare genetic diseases, cancer, and central nervous system (CNS) disorders, there exist several druggability challenges. Here, we provide insightful discussions concerning these challenges, comprising targeted accumulation and cellular uptake ('entry'), endolysosomal escape ('escape'), and in vivo pharmaceutical performance ('efficacy') - the three 'E' challenges - while also shedding light on siRNA drug development. Moreover, we propose several promising strategies that hold great potential in facilitating the clinical translation of siRNA therapeutics, including the exploration of diverse ligand-siRNA conjugates, expansion of potential disease targets, and excavation of novel modification geometries, as well as the development of combination therapies.

Extracellular vesicles as a potential delivery platform for CRISPR-Cas based therapy in epithelial ovarian cancer

Ovarian Cancer (OC) is the most common gynecological malignancy and the eighth most diagnosed cancer in females worldwide. Presently, it ranks as the fifth leading cause of cancer-related mortality among patients globally. Major factors contributing to the lethality of OC worldwide include delayed diagnosis, chemotherapy resistance, high metastatic rates, and the heterogeneity of subtypes. Despite continuous efforts to develop novel targeted therapies and chemotherapeutic agents, challenges persist in the form of OC resistance and recurrence. In the last decade, CRISPR-Cas-based genome editing has emerged as a powerful tool for modifying genetic and epigenetic mechanisms, holding potential for treating numerous diseases. However, a significant challenge for therapeutic applications of CRISPR-Cas technology is the absence of an optimal vehicle for delivering CRISPR molecular machinery into targeted cells or tissues. Recently, extracellular vesicles (EVs) have gained traction as potential delivery vehicles for various therapeutic agents. These heterogeneous, membrane-derived vesicles are released by nearly all cells into extracellular spaces. They carry a molecular cargo of proteins and nucleic acids within their intraluminal space, encased by a cholesterol-rich phospholipid bilayer membrane. EVs actively engage in cell-to-cell communication by delivering cargo to both neighboring and distant cells. Their inherent ability to shield molecular cargo from degradation and cross biological barriers positions them ideally for delivering CRISPR-Cas ribonucleoproteins (RNP) to target cells. Furthermore, they exhibit higher biocompatibility, lower immunogenicity, and reduced toxicity compared to classical delivery platforms such as adeno-associated virus, lentiviruses, and synthetic nanoparticles. This review explores the potential of employing different CRISPR-Cas systems to target specific genes in OC, while also discussing various methods for engineering EVs to load CRISPR components and enhance their targeting capabilities.

Polyethylenimine (PEI) in gene therapy: Current status and clinical applications

Polyethlyenimine (PEI) was introduced 1995 as a cationic polymer for nucleic acid delivery. PEI and its derivatives are extensively used in basic research and as reference formulations in the field of polymer-based gene delivery. Despite its widespread use, the number of clinical applications to date is limited. Thus, this review aims to consolidate the past applications of PEI in DNA delivery, elucidate the obstacles that hinder its transition to clinical use, and highlight potential prospects for novel iterations of PEI derivatives. The present review article is divided into three sections. The first section examines the mechanism of action employed by PEI, examining fundamental aspects of cellular delivery including uptake mechanisms, release from endosomes, and transport into the cell nucleus, along with potential strategies for enhancing these delivery phases. Moreover, an in-depth analysis is conducted concerning the mechanism underlying cellular toxicity, accompanied with approaches to overcome this major challenge. The second part is devoted to the in vivo performance of PEI and its application in various therapeutic indications. While systemic administration has proven to be challenging, alternative localized delivery routes hold promise, such as treatment of solid tumors, application as a vaccine, or serving as a therapeutic agent for pulmonary delivery. In the last section, the outcome of completed and ongoing clinical trials is summarized. Finally, an expert opinion is provided on the potential of PEI and its future applications. PEI-based formulations for nucleic acid delivery have a promising potential, it will be an important task for the years to come to introduce innovations that address PEI-associated shortcomings by introducing well-designed PEI formulations in combination with an appropriate route of administration.

Peptide-Based Nanoparticles for Systemic Extrahepatic Delivery of Therapeutic Nucleotides

Peptide-based nanoparticles (PBN) for nucleotide complexation and targeting of extrahepatic diseases are gaining recognition as potent pharmaceutical vehicles for fine-tuned control of protein production (up- and/or down-regulation) and for gene delivery. Herein, we review the principles and mechanisms underpinning self-assembled formation of PBN, cellular uptake, endosomal release, and delivery to extrahepatic disease sites after systemic administration. Selected examples of PBN that have demonstrated recent proof of concept in disease models in vivo are summarized to offer the reader a comparative view of the field and the possibilities for clinical application.

Endosomal escape of RNA therapeutics: How do we solve this rate-limiting problem?

With over 15 FDA approved drugs on the market and numerous ongoing clinical trials, RNA therapeutics, such as small interfering RNAs (siRNAs) and antisense oligonucleotides (ASOs), have shown great potential to treat human disease. Their mechanism of action is based entirely on the sequence of validated disease-causing genes without the prerequisite knowledge of protein structure, activity or cellular location. In contrast to small molecule therapeutics that passively diffuse across the cell membrane's lipid bilayer, RNA therapeutics are too large, too charged, and/or too hydrophilic to passively diffuse across the cellular membrane and instead are taken up into cells by endocytosis. However, endosomes are also composed of a lipid bilayer barrier that results in endosomal capture and retention of 99% of RNA therapeutics with 1% or less entering the cytoplasm. Although this very low level of endosomal escape has proven sufficient for liver and some CNS disorders, it is insufficient for the vast majority of extra-hepatic diseases. Unfortunately, there are currently no acceptable solutions to the endosomal escape problem. Consequently, before RNA therapeutics can be used to treat widespread human disease, the rate-limiting delivery problem of endosomal escape must be solved in a nontoxic manner.

Nanoparticle-Based Chimeric Antigen Receptor Therapy for Cancer Immunotherapy

Adoptive cell therapy with chimeric antigen receptor (CAR)-engineered T cells (CAR-Ts) has emerged as an innovative immunotherapy for hematological cancer treatment. However, the limited effect on solid tumors, complex processes, and excessive manufacturing costs remain as limitations of CAR-T therapy. Nanotechnology provides an alternative to the conventional CAR-T therapy. Owing to their unique physicochemical properties, nanoparticles can not only serve as a delivery platform for drugs but also target specific cells. Nanoparticle-based CAR therapy can be applied not only to T cells but also to CAR-natural killer and CAR-macrophage, compensating for some of their limitations. This review focuses on the introduction of nanoparticle-based advanced CAR immune cell therapy and future perspectives on immune cell reprogramming.

Endosomal escape of nucleic acids from extracellular vesicles mediates functional therapeutic delivery

Extracellular vesicles hold great promise as a drug delivery platform for RNA-based therapeutics. However, there is a lack of experimental evidence for the intracellular trafficking of nucleic acid cargos, specifically, whether they are capable of escaping from the endolysosomal confinement in the recipient cells to be released into the cytosol and hence, interact with their cytoplasmic targets. Here, we demonstrated how red blood cell-derived extracellular vesicles (RBCEVs) release their therapeutic RNA/DNA cargos at specific intracellular compartments characteristic of late endosomes and lysosomes. The released cargos were functional and capable of knocking down genes of interest in recipient cells, resulting in tumor suppression in vitro and in an acute myeloid leukemia murine model without causing significant toxicity. Notably, surface functionalization of RBCEVs with an anti-human CXCR4 antibody facilitated their specific uptake by CXCR4⁺ leukemic cells, leading to enhanced gene silencing efficiency. Our results provide insights into the cellular uptake mechanisms and endosomal escape routes of nucleic acid cargos delivered by RBCEVs which have important implications for further improvements of the RBCEV-based delivery system.

The use of melittin to enhance transgene expression mediated by recombinant adeno-associated virus serotype 2 vectors both in vitro and in vivo

OBJECTIVE

Melittin, a cell-penetrating peptide, improves the efficiency of many non-viral gene delivery vectors, yet its application in viral vectors has not been well studied. The non-pathogenic recombinant adeno-associated virus (rAAV) vector is an ideal in vivo gene delivery vector. However, its full potential will only be achieved after improvement of its transduction efficiency. To improve the transduction efficiency of rAAV2 vectors, we attempted to develop a melittin-based rAAV2 vector delivery strategy.

METHODS

The melittin peptide was inserted into the rAAV2 capsid either in the loop VIII of all viral proteins (VPs) or at the N terminus of VP2. Various rAAV2-gfp or -fluc vectors were subjected to quantitative real-time polymerase chain reaction and Western blot assays to determine their titers and integrity of capsid proteins, respectively. Alternatively, the vectors based on wild-type capsid were pre-incubated with melittin, followed by transduction of cultured cells or tail vein administration of the mixture to C57BL/6 and BALB/c nude mice. In vivo bioluminescence imaging was performed to evaluate the transgene expression.

RESULTS

rAAV2 vectors with melittin peptide inserted in the loop VIII of VPs had low transduction efficiency, probably due to dramatically reduced ability to bind to the target cells. Fusing the melittin peptide at the N-terminus of VP2 produced vectors without the VP2 subunit. Interestingly, among the commonly used rAAV vectors, pre-incubation of rAAV2 and rAAV6 vectors with melittin significantly enhanced their transduction efficiency in HEK293 and Huh7 cells in vitro. Melittin also had the ability to increase the rAAV2-mediated transgene expression in mouse liver in vivo. Mechanistically, melittin did not change the vector-receptor interaction. Moreover, cell counting kit-8 assays of cultured cells and serum transaminase levels indicated melittin had little cytotoxicity.

CONCLUSION

Pre-incubation with melittin, but not insertion of melittin into the rAAV2 capsid, significantly enhanced rAAV2-mediated transgene expression. Although further in vivo evaluations are required, this research not only expands the pharmacological potential of melittin, but also provides a new strategy to improve gene therapy mediated by rAAV vectors.

Fusogenic peptide delivery of bioactive siRNAs targeting CSNK2A1 for treatment of ovarian cancer

Ovarian cancer has shown little improvement in survival among advanced-stage patients over the past decade. Current treatment strategies have been largely unsuccessful in treating advanced disease, with many patients experiencing systemic toxicity and drug-resistant metastatic cancer. This study evaluates novel fusogenic peptide carriers delivering short interfering RNA (siRNA) targeting casein kinase II, CSNK2A1, for reducing the aggressiveness of ovarian cancer. The peptides were designed to address two significant barriers to siRNA delivery: insufficient cellular uptake and endosomal entrapment. The three peptide variants developed, DIVA3, DIV3H, and DIV3W, were able to form monodisperse nanoparticle complexes with siRNA and protect siRNAs from serum and RNase degradation. Furthermore, DIV3W demonstrated optimal delivery of bioactive siRNAs into ovarian cancer cells with high cellular uptake efficiency and mediated up to 94% knockdown of CSNK2A1 mRNA compared with non-targeting siRNAs, resulting in decreased cell migration and recolonization in vitro. Intratumoral delivery of DIV3W-siCSNK2A1 complexes to subcutaneous ovarian tumors resulted in reduced CSNK2A1 mRNA and CK2α protein expression after 48 h and reduced tumor growth and migration in a 2-week multi-dosing regimen. These results demonstrate the potential of the DIV3W peptide to deliver bioactive siRNAs and confirms the role of CSNK2A1 in cell-cell communication and proliferation in ovarian cancer.

Delivery of RNA Therapeutics: The Great Endosomal Escape!

RNA therapeutics, including siRNAs, antisense oligonucleotides, and other oligonucleotides, have great potential to selectively treat a multitude of human diseases, from cancer to COVID to Parkinson's disease. RNA therapeutic activity is mechanistically driven by Watson-Crick base pairing to the target gene RNA without the requirement of prior knowledge of the protein structure, function, or cellular location. However, before widespread use of RNA therapeutics becomes a reality, we must overcome a billion years of evolutionary defenses designed to keep invading RNAs from entering cells. Unlike small-molecule therapeutics that are designed to passively diffuse across the cell membrane, macromolecular RNA therapeutics are too large, too charged, and/or too hydrophilic to passively diffuse across the cellular membrane and are instead taken up into cells by endocytosis. However, similar to the cell membrane, endosomes comprise a lipid bilayer that entraps 99% or more of RNA therapeutics, even in semipermissive tissues such as the liver, central nervous system, and muscle. Consequently, before RNA therapeutics can achieve their ultimate clinical potential to treat widespread human disease, the rate-limiting delivery problem of endosomal escape must be solved in a clinically acceptable manner.

mRNA nanomedicine: Design and recent applications

The rational design and application of mRNA-based medicine have recently yielded some key successes in the clinical management of human diseases. mRNA technology allows for the facile and direct production of proteins in vivo, thus circumventing the need for lengthy drug development cycles and complex production workflows. As such, mRNA formulations can significantly improve upon the biological therapies that have become commonplace in modern medicine. Despite its many advantages, mRNA is inherently fragile and has specific delivery requirements. Leveraging the engineering flexibility of nanobiotechnology, mRNA payloads can be incorporated into nanoformulations such that they do not invoke unwanted immune responses, are targeted to tissues of interest, and can be delivered to the cytosol, resulting in improved safety while enhancing bioactivity. With the rapidly evolving landscape of nanomedicine, novel technologies that are under development have the potential to further improve the clinical utility of mRNA medicine. This review covers the design principles relevant to engineering mRNA-based nanomedicine platforms. It also details the current research on mRNA nanoformulations for addressing viral infections, cancers, and genetic diseases. Given the trends in the field, future mRNA-based nanomedicines have the potential to change how many types of diseases are managed in the clinic.

Assessing cellular internalization and endosomal escape abilities of novel BUFII-Graphene oxide nanobioconjugates

Cell-penetrating agents based on functionalized nanoplatforms have emerged as a promising approach for developing more efficient and multifunctional delivery vehicles for treating various complex diseases that require reaching different intracellular compartments. Our previous work has shown that achieving full cellular coverage and high endosomal escape rates is possible by interfacing magnetite nanoparticles with potent translocating peptides such as Buforin II (BUF-II). In this work, we extended such an approach to two graphene oxide (GO)-based nanoplatforms functionalized with different surface chemistries to which the peptide molecules were successfully conjugated. The developed nanobioconjugates were characterized via spectroscopic (FTIR, Raman), thermogravimetric, and microscopic (SEM, TEM, and AFM) techniques. Moreover, biocompatibility was assessed via standardized hemocompatibility and cytotoxicity assays in two cell lines. Finally, cell internalization and coverage and endosomal escape abilities were estimated with the aid of confocal microscopy analysis of colocalization of the nanobioconjugates with Lysotracker Green^®. Our findings showed coverage values that approached 100% for both cell lines, high biocompatibility, and endosomal escape levels ranging from 30 to 45% and 12–24% for Vero and THP-1 cell lines. This work provides the first routes toward developing the next-generation, carbon-based, cell-penetrating nanovehicles to deliver therapeutic agents. Further studies will be focused on elucidating the intracellular trafficking pathways of the nanobioconjugates to reach different cellular compartments.

Manipulating Offense and Defense Signaling to Fight Cold Tumors with Carrier-Free Nanoassembly of Fluorinated Prodrug and siRNA

Chemoimmunotherapy has shown great potential to activate an immune response, but the immunosuppressive microenvironment associated with T cell exhaustion remains a challenge in cancer therapy. The proper immune-modulatory strategy to provoke a robust immune response is to simultaneously regulate T-cell exhaustion and infiltration. Here, a new kind of carrier-free nanoparticle is developed to simultaneously deliver chemotherapeutic drug (doxorubicin, DOX), cytolytic peptide (melittin, MPI), and anti-TOX small interfering RNA (thymocyte selection-associated high mobility group box protein, TOX) using a fluorinated prodrug strategy. In this way, the enhanced immunogenic cell death (ICD) induced by the combination of DOX and MPI can act as "offense" signaling to increase CD8⁺ T-cell infiltration, while the decreased TOX expression interfered with siTOX can serve as "defense" signaling to mitigate CD8⁺ T-cell exhaustion. As a result, the integration of DOX, MPI, and siTOX in such a bifunctional system produced a potent antitumor immune response in liver cancer and metastasis, making it a promising delivery platform and effective strategy for converting "cold" tumors into "hot" ones.

The role of cell-penetrating peptides in potential anti-cancer therapy

Due to the complex physiological structure, microenvironment and multiple physiological barriers, traditional anti-cancer drugs are severely restricted from reaching the tumour site. Cell-penetrating peptides (CPPs) are typically made up of 5-30 amino acids, and can be utilised as molecular transporters to facilitate the passage of therapeutic drugs across physiological barriers. Up to now, CPPs have widely been used in many anti-cancer treatment strategies, serving as an excellent potential choice for oncology treatment. However, their drawbacks, such as the lack of cell specificity, short duration of action, poor stability in vivo, compatibility problems (i.e. immunogenicity), poor therapeutic efficacy and formation of unwanted metabolites, have limited their further application in cancer treatment. The cellular uptake mechanisms of CPPs involve mainly endocytosis and direct penetration, but still remain highly controversial in academia. The CPPs-based drug delivery strategy could be improved by clever design or chemical modifications to develop the next-generation CPPs with enhanced cell penetration capability, stability and selectivity. In addition, some recent advances in targeted cell penetration that involve CPPs provide some new ideas to optimise CPPs.

Engineered Cas9 extracellular vesicles as a novel gene editing tool

Extracellular vesicles (EVs) have shown promise as biological delivery vehicles, but therapeutic applications require efficient cargo loading. Here, we developed new methods for CRISPR/Cas9 loading into EVs through reversible heterodimerization of Cas9‐fusions with EV sorting partners. Cas9‐loaded EVs were collected from engineered Expi293F cells using standard methodology, characterized using nanoparticle tracking analysis, western blotting, and transmission electron microscopy and analysed for CRISPR/Cas9‐mediated functional gene editing in a Cre‐reporter cellular assay. Light‐induced dimerization using Cryptochrome 2 combined with CD9 or a Myristoylation‐Palmitoylation‐Palmitoylation lipid modification resulted in efficient loading with approximately 25 Cas9 molecules per EV and high functional delivery with 51% gene editing of the Cre reporter cassette in HEK293 and 25% in HepG2 cells, respectively. This approach was also effective for targeting knock‐down of the therapeutically relevant PCSK9 gene with 6% indel efficiency in HEK293. Cas9 transfer was detergent‐sensitive and associated with the EV fractions after size exclusion chromatography, indicative of EV‐mediated transfer. Considering the advantages of EVs over other delivery vectors we envision that this study will prove useful for a range of therapeutic applications, including CRISPR/Cas9 mediated genome editing.

Rationally designed DNA therapeutics can modulate human TH expression by controlling specific GQ formation in its promoter

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the catecholamine (CA) biosynthesis pathway, making TH a molecular target for controlling CA production, specifically dopamine. Dysregulation of dopamine is correlated with neurological diseases such as Parkinson's disease (PD) and post-traumatic stress disorder (PTSD), among others. Previously, we showed that a 49-nucleotide guanine (G)-rich sequence within the human TH promoter adopts two different sets of G-quadruplex (GQ) structures (5'GQ and 3'GQ), where the 5'GQ uses G-stretches I, II, IV, and VI in TH49, which enhances TH transcription, while the 3'GQ utilizes G-stretches II, IV, VI, and VII, which represses transcription. Herein, we demonstrated targeted switching of these GQs to their active state using rationally designed DNA GQ Clips (5'GQ and 3'GQ Clips) to modulate endogenous TH gene expression and dopamine production. As a translational approach, we synthesized a targeted nanoparticle delivery system to effectively deliver the 5'GQ Clip in vivo. We believe this strategy could potentially be an improved approach for controlling dopamine production in a multitude of neurological disorders, including PD.

New approaches to moderate CRISPR-Cas9 activity: Addressing issues of cellular uptake and endosomal escape

CRISPR-Cas9 is rapidly entering molecular biology and biomedicine as a promising gene-editing tool. A unique feature of CRISPR-Cas9 is a single-guide RNA directing a Cas9 nuclease toward its genomic target. Herein, we highlight new approaches for improving cellular uptake and endosomal escape of CRISPR-Cas9. As opposed to other recently published works, this review is focused on non-viral carriers as a means to facilitate the cellular uptake of CRISPR-Cas9 through endocytosis. The majority of non-viral carriers, such as gold nanoparticles, polymer nanoparticles, lipid nanoparticles, and nanoscale zeolitic imidazole frameworks, is developed with a focus toward optimizing the endosomal escape of CRISPR-Cas9 by taking advantage of the acidic environment in the late endosomes. Among the most broadly used methods for in vitro and ex vivo ribonucleotide protein transfection are electroporation and microinjection. Thus, other delivery formats are warranted for in vivo delivery of CRISPR-Cas9. Herein, we specifically revise the use of peptide and nanoparticle-based systems as platforms for CRISPR-Cas9 delivery in vivo. Finally, we highlight future perspectives of the CRISPR-Cas9 gene-editing tool and the prospects of using non-viral vectors to improve its bioavailability and therapeutic potential.

Acylation of antimicrobial peptide-plasmid DNA vectors formulation for efficient gene delivery in cancer therapy

Antimicrobial peptides/DNA complexes were designed based on AMPs chensinin-1b and its corresponding lipo-chensinin-1b conjugated with an aliphatic acid with different chain lengths and therapeutic genes. The main goal of such a complex includes two aspects: first, antimicrobial peptides deliver therapeutic genes to cancer cells and genes expressed in targeted tissue for cancer gene therapy, and, second, the antimicrobial peptide kills cancer cells when used alone as an anticancer agent. This study presents a model composed of chensinin-1b and its lipo-chensinin-1b and eGFP plasmids, which were used as reporter genes, and the final peptide/eGFP plasmid complexes were analyzed by TEM and DLS. The gene transfection efficiency of the complex was evaluated by a microplate reader, FACS and CLSM. Compared with Lipo2000, the antimicrobial peptide showed specific selectivity for transfection against cancer cells and mammalian cells. The peptides chensinin-1b and lipo-chensinin-1b binding with the eGFP plasmid displayed optimal transfection efficiencies at a mass ratio of 8. In addition, PA-C1b can deliver p53-eGFP plasmids into MCF-7 cancer cells, and the proliferation of cells was inhibited and even caused cell death. Overall, PA-C1b was screened and found to have the highest transfection efficiency for gene delivery and good cellular uptake capability. The in vivo transfection ability of PA-C1b was investigated using a tumor-bearing mouse model, and the transfection efficiency reflected by the fluorescence of expressed GFP was determined by in vivo imaging. Conclusively, the antimicrobial peptide PA-C1b could be used as the nonviral vector with high efficiency for cancer gene therapy.

Peptide-Assisted Nucleic Acid Delivery Systems on the Rise

Concerns associated with nanocarriers' therapeutic efficacy and side effects have led to the development of strategies to advance them into targeted and responsive delivery systems. Owing to their bioactivity and biocompatibility, peptides play a key role in these strategies and, thus, have been extensively studied in nanomedicine. Peptide-based nanocarriers, in particular, have burgeoned with advances in purely peptidic structures and in combinations of peptides, both native and modified, with polymers, lipids, and inorganic nanoparticles. In this review, we summarize advances on peptides promoting gene delivery systems. The efficacy of nucleic acid therapies largely depends on cell internalization and the delivery to subcellular organelles. Hence, the review focuses on nanocarriers where peptides are pivotal in ferrying nucleic acids to their site of action, with a special emphasis on peptides that assist anionic, water-soluble nucleic acids in crossing the membrane barriers they encounter on their way to efficient function. In a second part, we address how peptides advance nanoassembly delivery tools, such that they navigate delivery barriers and release their nucleic acid cargo at specific sites in a controlled fashion.

Targeting NF-κB with Nanotherapy in a Mouse Model of Adult T-Cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive, clonal malignancy of mature T cells caused by human T-cell leukemia virus type 1. Although it is a rare tumor type, it serves as an excellent model of a virus driven process that transforms cells and engenders a highly malignant tumor that is extraordinarily difficult to treat. The viral transcriptional transactivator (Tax) in the HTLV-1 genome directly promotes tumorigenesis, and Tax-induced oncogenesis depends on its ability to constitutively activate NF-κB signaling. Accordingly, we developed and evaluated a nano-delivery system that simultaneously inhibits both canonical (p65) and noncanonical (p100) NF-κB signaling pathways locally in tumors after systemic administration. Our results demonstrate that siRNA is delivered rapidly to ATLL tumors after either i.p. or i.v. injection. The siRNA treatment significantly reduced both p65 and p100 mRNA and protein expression. Anti-NF-κB nanotherapy significantly inhibited tumor growth in two distinct tumor models in mice: a spontaneous Tax-driven tumor model, and a Tax tumor cell transplant model. Moreover, siRNA nanotherapy sensitized late-stage ATLL tumors to the conventional chemotherapeutic agent etoposide, indicating a pleiotropic benefit for localized siRNA nanotherapeutics.

Melittin inhibits lung metastasis of human osteosarcoma: Evidence of wnt/β-catenin signaling pathway participation

Melittin is a major active peptide component of bee venom that has been demonstrated to show anti-tumor effects. Osteosarcoma is a type of bone tumor with a high degree of malignancy, and metastasis is the main challenge of osteosarcoma therapy. This study aimed to investigate the role of melittin in the lung metastasis of osteosarcoma. 143 B cells were treated with different concentrations of melittin in vitro. Wound-healing and transwell assays were performed to determine the cell migration and invasion potential. Quantitative real-time PCR and Western blot experiments were performed to evaluate the expression levels of Wnt/β-catenin signaling pathway-related factors after treatment with melittin. The orthotopic implantation model and hematoxylin-eosin staining were used to investigate the effect of melittin treatment on tumor formation and lung metastasis. Immunohistochemical staining and Western blot experiments were performed to indicate the melittin-mediated expression changes in Wnt/β-catenin signaling pathway-related factors. The cell migration and invasion potential were observed to be inhibited in a dose-dependent manner upon treatment with melittin. Treatment with medium and high concentrations of melittin attenuated the mRNA and protein expression of LRP5, β-catenin, MMP-2, cyclin D, c-Myc, survivin, MMP-9, and VEGF genes in vitro. Melittin significantly inhibited the growth of tibia xenografts in nude mice and decreased the number of lung metastatic nodules. Consistent with the results observed in vitro, treatment with melittin at medium and high concentrations attenuated the expression of Wnt/β-catenin signaling pathway-related factors in vivo. In vitro, Wnt/β-catenin signaling pathway was involved in Melittin-mediated -migration and invasion potential of 143 B cells. Similarly, as observed in the in vivo experiments, Wnt/β-catenin signaling pathway was also associated with the role of melittin on lung metastasis of osteosarcomas.

Nanoscopy for endosomal escape quantification

The successful cytosolic delivery of nanoparticles is hampered by their endosomal entrapment and degradation. To push forward the smart development of nanoparticles we must reliably detect and quantify their endosomal escape process. However, the current methods employed are not quantitative enough at the nanoscale to achieve this. Nanoscopy is a rapidly evolving field that has developed a diverse set of powerful techniques in the last two decades, opening the door to explore nanomedicine with an unprecedented resolution and specificity. The understanding of key steps in the drug delivery process - such as endosomal escape - would benefit greatly from the implementation of the most recent advances in microscopy. In this review, we provide the latest insights into endosomal escape of nanoparticles obtained by nanoscopy, and we discuss the features that would allow these techniques to make a great impact in the field.

Investigating the pharmacodynamic durability of GalNAc-siRNA conjugates

One hallmark of trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNAs is the remarkable durability of silencing that can persist for months in preclinical species and humans. Here, we investigated the underlying biology supporting this extended duration of pharmacological activity. We found that siRNA accumulation and stability in acidic intracellular compartments is critical for long-term activity. We show that functional siRNA can be liberated from these compartments and loaded into newly generated Argonaute 2 protein complexes weeks after dosing, enabling continuous RNAi activity over time. Identical siRNAs delivered in lipid nanoparticles or as GalNAc conjugates were dose-adjusted to achieve similar knockdown, but only GalNAc–siRNAs supported an extended duration of activity, illustrating the importance of receptor-mediated siRNA trafficking in the process. Taken together, we provide several lines of evidence that acidic intracellular compartments serve as a long-term depot for GalNAc–siRNA conjugates and are the major contributor to the extended duration of activity observed in vivo.

Gene Editing by Extracellular Vesicles

CRISPR/Cas technologies have advanced dramatically in recent years. Many different systems with new properties have been characterized and a plethora of hybrid CRISPR/Cas systems able to modify the epigenome, regulate transcription, and correct mutations in DNA and RNA have been devised. However, practical application of CRISPR/Cas systems is severely limited by the lack of effective delivery tools. In this review, recent advances in developing vehicles for the delivery of CRISPR/Cas in the form of ribonucleoprotein complexes are outlined. Most importantly, we emphasize the use of extracellular vesicles (EVs) for CRISPR/Cas delivery and describe their unique properties: biocompatibility, safety, capacity for rational design, and ability to cross biological barriers. Available molecular tools that enable loading of desired protein and/or RNA cargo into the vesicles in a controllable manner and shape the surface of EVs for targeted delivery into specific tissues (e.g., using targeting ligands, peptides, or nanobodies) are discussed. Opportunities for both endogenous (intracellular production of CRISPR/Cas) and exogenous (post-production) loading of EVs are presented.

Antimicrobial peptide AR-23 derivatives with high endosomal disrupting ability enhance poly(l-lysine)-mediated gene transfer

Background

pH‐sensitive peptides are a relatively new strategy for conquering the poor endosomal release of cationic polymer‐mediated transfection. Modification of antimicrobial peptides by exchanging positively‐charged residues with negatively‐charged glutamic acid residues (Glu) greatly improves its lytic activity at the endosomal pH, which could improve cationic polymer‐mediated transfection.

Methods

In the present study, we investigated the effect of the number of Glu substituted for positively‐charged residues on the endosomal escape activity of AR‐23 and the ability of mutated AR‐23 with respect to enhancing cationic polymer‐mediated transfection. Three analogs were synthesized by replacing the positively‐charged residues in the AR‐23 sequence with Glu one‐by‐one.

Results

The pH‐sensitive lysis ability of the peptides, the effect of peptides on the physicochemical characteristics, the intracellular trafficking, the transfection efficiency and the cytotoxicity of the polyplexes were determined. Increased lytic activity of peptides was observed with the increased number of Glu replacement in the AR‐23 sequence at acidic pH. The number of Glu substituted for positively‐charged residues of AR‐23 dramatically affects its lysis ability at neutral pH. Triple‐Glu substitution in the AR‐23 sequence greatly improved poly(l‐lysine)‐mediated gene transfection efficiency at the same time as maintaining low cytotoxicity.

Conclusions

The results indicate that replacement of positively‐charged residues with sufficient Glu residues may be considered as a method for designing pH‐sensitive peptides, which could be applied as potential enhancers for improving cationic polymer‐mediated transfection.

Prospects for the potential of RNA interference in the treatment of autoimmune diseases: Small interfering RNAs in the spotlight

The identification of RNA interference (RNAi) has caused a growing interest in harnessing its potential in the treatment of different diseases. Modulation of dysregulated genes through targeting by RNAi represents a potential approach with which to alter the biological pathways at a post-transcriptional level, especially as it pertains to autoimmunity and malignancy. Short hairpin RNAs (shRNA), short interfering RNAs (siRNA), and microRNAs (miRNA) are mainly involved as effector mechanisms in the targeting of RNAi biological pathways. The manipulation and delivery of these molecules in an efficient way promotes the specificity and stability of RNAi-based systems, while minimizing the unwanted adverse reactions by the immune system and reducing cytotoxicity and off-target effects. Advances made to date in identifying the etiopathogenesis of autoimmune diseases has prompted the utilization of RNAi-based systems in vitro and in vivo. Future investigations aimed at deciphering the molecular basis of RNAi and optimizing the delivery of RNAi-based targeting systems will hopefully promote the applicability of such regulatory mechanisms and, ultimately, transfer the acquired knowledge from bench-to-bedside to ameliorate human diseases. In this review, we seek to clarify the potential of RNAi, with a focus on siRNAs, in designing therapeutics for potential treatment of human autoimmune disorders.

Acylation of the antimicrobial peptide CAMEL for cancer gene therapy

Obtaining ideal gene delivery vectors is still a major goal in cancer gene therapy. CAMEL, a short hybrid antimicrobial peptide, can kill cancer cells by membrane lysis. In this study, we constructed a series of non-viral vectors by attaching fatty acids with different chain lengths to the N-terminus of CAMEL. Our results showed that the cellular uptake and transfection efficiency of acyl-CAMEL started to significantly increase from a chain length of 12 carbons. C18-CAMEL was screened for gene delivery because it had the highest transfection efficiency. Surprisingly, C18-CAMEL/plasmid complexes displayed strong endosomal escape activity after entering cells via endocytosis. Importantly, C18-CAMEL could deliver p53 plasmids to cancer cells and significantly inhibited cell proliferation by the expression of p53. In addition, the C18-CAMEL/p53 plasmid complexes and the MDM2 inhibitor nutlin-3a showed significantly synergistic anticancer activity against MCF-7 cells expressing wild-type p53. Conclusively, our study demonstrated that conjugation of stearic acid to antimicrobial peptides is a simple and successful approach for constructing efficient and economical non-viral vectors for cancer gene therapy.

Role of Lipid-Based and Polymer-Based Non-Viral Vectors in Nucleic Acid Delivery for Next-Generation Gene Therapy

The field of gene therapy has experienced an insurgence of attention for its widespread ability to regulate gene expression by targeting genomic DNA, messenger RNA, microRNA, and short-interfering RNA for treating malignant and non-malignant disorders. Numerous nucleic acid analogs have been developed to target coding or non-coding sequences of the human genome for gene regulation. However, broader clinical applications of nucleic acid analogs have been limited due to their poor cell or organ-specific delivery. To resolve these issues, non-viral vectors based on nanoparticles, liposomes, and polyplexes have been developed to date. This review is centered on non-viral vectors mainly comprising of cationic lipids and polymers for nucleic acid-based delivery for numerous gene therapy-based applications.

Myeloid-specific Asxl2 deletion limits diet-induced obesity by regulating energy expenditure

We previously established that global deletion of the enhancer of trithorax and polycomb (ETP) gene, Asxl2, prevents weight gain. Because proinflammatory macrophages recruited to adipose tissue are central to the metabolic complications of obesity, we explored the role of ASXL2 in myeloid lineage cells. Unexpectedly, mice without Asxl2 only in myeloid cells (Asxl2ΔLysM) were completely resistant to diet-induced weight gain and metabolically normal despite increased food intake, comparable activity, and equivalent fecal fat. Asxl2ΔLysM mice resisted HFD-induced adipose tissue macrophage infiltration and inflammatory cytokine gene expression. Energy expenditure and brown adipose tissue metabolism in Asxl2ΔLysM mice were protected from the suppressive effects of HFD, a phenomenon associated with relatively increased catecholamines likely due to their suppressed degradation by macrophages. White adipose tissue of HFD-fed Asxl2ΔLysM mice also exhibited none of the pathological remodeling extant in their control counterparts. Suppression of macrophage Asxl2 expression, via nanoparticle-based siRNA delivery, prevented HFD-induced obesity. Thus, ASXL2 controlled the response of macrophages to dietary factors to regulate metabolic homeostasis, suggesting modulation of the cells' inflammatory phenotype may impact obesity and its complications.

Applications of RNA interference in the treatment of arthritis

RNA interference (RNAi) is a cellular mechanism for post-transcriptional gene regulation mediated by small interfering RNA (siRNA) and microRNA. siRNA-based therapy holds significant promise for the treatment of a wide-range of arthritic diseases. siRNA selectively suppresses the expression of a gene product and can thus achieve the specificity that is lacking in small molecule inhibitors. The potential use of siRNA-based therapy in arthritis, however, has not progressed to clinical trials despite ample evidence for efficacy in preclinical studies. One of the main challenges to clinical translation is the lack of a suitable delivery vehicle to efficiently and safely access diverse pathologies. Moreover, the ideal targets in treatment of arthritides remain elusive given the complexity and heterogeneity of these disease pathogeneses. Herein, we review recent preclinical studies that use RNAi-based drug delivery systems to mitigate inflammation in models of rheumatoid arthritis and osteoarthritis. We discuss a self-assembling peptide-based nanostructure that demonstrates the potential of overcoming many of the critical barriers preventing the translation of this technology to the clinic.

The current state and future directions of RNAi-based therapeutics

The RNA interference (RNAi) pathway regulates mRNA stability and translation in nearly all human cells. Small double-stranded RNA molecules can efficiently trigger RNAi silencing of specific genes, but their therapeutic use has faced numerous challenges involving safety and potency. However, August 2018 marked a new era for the field, with the US Food and Drug Administration approving patisiran, the first RNAi-based drug. In this Review, we discuss key advances in the design and development of RNAi drugs leading up to this landmark achievement, the state of the current clinical pipeline and prospects for future advances, including novel RNAi pathway agents utilizing mechanisms beyond post-translational RNAi silencing.

Lipid nanocarriers for microRNA delivery

Non-coding RNAs (ncRNAs) like microRNAs (miRNAs) or small interference RNAs (siRNAs) with their power to selectively silence any gene of interest enable the targeting of so far 'undruggable' proteins and diseases. Such RNA molecules have gained much attention from biotech and pharmaceutical companies, which led to the first Food and Drug Administration (FDA) approved ncRNA therapeutic in 2018. However, the main barrier in clinical practice of ncRNAs is the lack of an effective delivery system that can protect the RNA molecules from nuclease degradation, deliver them to specific tissues and cell types, and release them into the cytoplasm of the targeted cells, all without inducing adverse effects. For that reason, drug delivery approaches, formulations, technologies and systems for transporting pharmacological ncRNA compounds to achieve a diagnostic or therapeutic effect in the human body are in demand. Here, we review the development of therapeutic lipid-based nanoparticles for delivery of miRNAs, one class of endogenous ncRNAs with specific regulatory functions. We outline challenges and opportunities for advanced miRNA-based therapies, and discuss the complexity associated with the delivery of functional miRNAs. Novel strategies are addressed how to deal with the most critical points in miRNA delivery, such as toxicity, specific targeting of disease sites, proper cellular uptake and endosomal escape of miRNAs. Current fields of application and various preclinical settings involving miRNA therapeutics are discussed, providing an outlook to future clinical approaches. Following the current trends and technological developments in nanomedicine exciting new delivery systems for ncRNA-based therapeutics can be expected in upcoming years.

Effective In Vivo Topical Delivery of siRNA and Gene Silencing in Intact Corneal Epithelium Using a Modified Cell-Penetrating Peptide

Autosomal dominantly inherited genetic disorders such as corneal dystrophies are amenable to allele-specific gene silencing with small interfering RNA (siRNA). siRNA delivered to the cornea by injection, although effective, is not suitable for a frequent long-term treatment regimen, whereas topical delivery of siRNA to the cornea is hampered by the eye surface's protective mechanisms. Herein we describe an attractive and innovative alternative for topical application using cell-penetrating peptide derivatives capable of complexing siRNA non-covalently and delivering them into the cornea. Through a rational design approach, we modified derivatives of a cell-penetrating peptide, peptide for ocular delivery (POD), already proved to diffuse into the corneal layers. These POD derivatives were able to form siRNA-peptide complexes (polyplexes) of size and ζ-potential similar to those reported able to undergo cellular internalization. Successful cytoplasmic release and gene silencing in vitro was obtained when an endosomal disruptor, chloroquine, was added. A palmitoylated-POD, displaying the best delivery properties, was covalently functionalized with trifluoromethylquinoline, an analog of chloroquine. This modified POD, named trifluoromethylquinoline-palmitoyl-POD (QN-Palm-POD), when complexed with siRNA and topically applied to the eye in vivo, resulted in up to 30% knockdown of luciferase reporter gene expression in the corneal epithelium. The methods developed within represent a valid standardized approach that is ideal for screening of a range of delivery formulations.

Anti-Tumor Effects of Melittin and Its Potential Applications in Clinic

Melittin, a major component of bee venom, is a water-soluble toxic peptide of which a various biological effects have been identified to be useful in anti-tumor therapy. In addition, Melittin also has anti-parasitic, anti-bacterial, anti-viral, and anti-inflammatory activities. Therefore, it is a very attractive therapeutic candidate for human diseases. However, melittin induces extensive hemolysis, a severe side effect that dampens its future development and clinical application. Thus, studies of melittin derivatives and new drug delivery systems have been conducted to explore approaches for optimizing the efficacy of this compound, while reducing its toxicity. A number of reviews have focused on each side, respectively. In this review, we summarize the research progress on the anti-tumor effects of melittin and its derivatives, and discuss its future potential clinical applications.

α1-Acid Glycoprotein Has the Potential to Serve as a Biomimetic Drug Delivery Carrier for Anticancer Agents

Nanosize plasma proteins could be used as a biomimetic drug delivery system (DDS) for cancer treatment when loaded with anticancer drugs based on the fact that plasma proteins can serve as a source of nutrients for cancer cells. This prompted us to investigate the potential of α₁-acid glycoprotein (AGP) for this role because it is a nanosize plasma protein and binds a variety of anticancer agents. Pharmacokinetic analyses indicated that AGP is distributed more extensively in tumor tissue than human serum albumin, which was already established as a cancer DDS carrier. AGP is possibly being incorporated into tumor cells via endocytosis pathways. Moreover, a synthetic AGP-derived peptide which possesses a high ability to form an α-helix, as deduced from the primary structure of AGP, was also taken up by the tumor cells. AGP loaded with anticancer agents, such as paclitaxel or nitric oxide, efficiently induced tumor cell death. These results suggest that AGP has the potential to be a novel DDS carrier for anticancer agents.

Coming in and Finding Out: Blending Receptor-Targeted Delivery and Efficient Endosomal Escape in a Novel Bio-Responsive siRNA Delivery System for Gene Knockdown in Pulmonary T Cells

RNA interference (RNAi) offers the potential to selectively silence disease-related genes in defined cell subsets. Translation into the clinical routine is, however, still hampered by the lack of efficient carrier systems for therapeutic siRNA, endosomal entrapment presenting a major hurdle. A promising siRNA delivery system has previously been developed on the base of polyethylenimine (PEI) and the targeting ligand transferrin (Tf) to specifically reach activated T cells in the lung. In the present work, the focus is on optimizing Tf-PEI polyplexes for gene knockdown in primary activated T cells by improving their endosomal escape properties. Blending of the conjugate with membrane lytic melittin significantly enhanced endosomal release and thereby cytoplasmic delivery, while maintaining selective T cell targeting abilities and overall cell tolerability. The gathered data furthermore demonstrate that melittin addition also distinctly improves several other essential particle characteristics, such as siRNA encapsulation efficiency and stability in lung lining fluids. In conclusion, this results in a novel upgraded siRNA delivery system that is not only able to specifically deliver its payload to the desired target cells via receptor-mediated endocytosis, but also shows enhanced release from endosomal vesicles in order to initiate RNAi in the cytoplasm.

Overcoming Endosomal Entrapment in Drug Delivery

Intracellular delivery of biological agents such as peptides, proteins, and nucleic acids generally rely on the endocytic pathway as the major uptake mechanism, resulting in their entrapment inside the endosome and lysosome. The recent discovery of cell-penetrating molecules of exceptionally high endosomal escape and cytosolic delivery efficiencies and elucidation of their mechanism of action represent major breakthroughs in this field. In this Topical Review, we provide an overview of the recent progress in understanding and enhancing the endosomal escape process and the new opportunities opened up by these recent findings.

Peptide-based gene delivery vectors

Gene therapy as a strategy for disease treatment requires safe and efficient gene delivery systems that encapsulate nucleic acids and deliver them to effective sites in the cell.

Development of an antibacterial surface with a self-defensive and pH-responsive function

In this work, a charge conversion mechanism was introduced to build a bacteria responsive antibacterial surface.

pH-Sensitive Polymers as Dynamic Mediators of Barriers to Nucleic Acid Delivery

The nonviral delivery of exogenous nucleic acids (NA) into cells for therapeutic purposes has rapidly matured into tangible clinical impact. Synthetic polymers are particularly attractive vectors for NA delivery due to their relatively inexpensive production compared to viral alternatives and their highly tailorable chemical properties; indeed, many preclinical investigations have revealed the primary biological barriers to nonviral NA delivery by systematically varying polymeric material properties. This review focuses on applications of pH-sensitive chemistries that enable polymeric vectors to serially address multiple biological barriers to NA delivery. In particular, we focus on recent innovations with in vivo evaluation that dynamically enable colloidal stability, cellular uptake, endosomal escape, and nucleic acid release. We conclude with a summary of successes to date and projected areas for impactful future research.

Codelivery of a cytotoxin and photosensitiser via a liposomal nanocarrier: a novel strategy for light-triggered cytosolic release

Endosomal entrapment is a key issue for the intracellular delivery of many nano-sized biotherapeutics to their cytosolic or nuclear targets. Photochemical internalisation (PCI) is a novel light-based solution that can be used to trigger the endosomal escape of a range of bioactive agents into the cytosol leading to improved efficacy in pre-clinical and clinical studies. PCI typically depends upon the endolysosomal colocalisation of the bioactive agent with a suitable photosensitiser that is administered separately. In this study we demonstrate that both these components may be combined for codelivery via a novel multifunctional liposomal nanocarrier, with a corresponding increase in the biological efficacy of the encapsulated agent. As proof of concept, we show here that the cytotoxicity of the 30 kDa protein toxin, saporin, in MC28 fibrosarcoma cells is significantly enhanced when delivered via a cell penetrating peptide (CPP)-modified liposome, with the CPP additionally functionalised with a photosensitiser that is targeted to endolysosomal membranes. This innovation opens the way for the efficient delivery of a range of biotherapeutics by the PCI approach, incorporating a clinically proven liposome delivery platform and using bioorthogonal ligation chemistries to append photosensitisers and peptides of choice.

Anti-JNK2 peptide-siRNA nanostructures improve plaque endothelium and reduce thrombotic risk in atherosclerotic mice

BACKGROUND

A direct and independent role of inflammation in atherothrombosis was recently highlighted by the Canakinumab Antiinflammatory Thrombosis Outcome Study (CANTOS) trial, showing the benefit of inhibiting signaling molecules, eg, interleukins. Accordingly, we sought to devise a flexible platform for preventing the inflammatory drivers at their source to preserve plaque endothelium and mitigate procoagulant risk.

METHODS

p5RHH-siRNA nanoparticles were formulated through self-assembly processes. The therapeutic efficacy of p5RHH-JNK2 siRNA nanoparticles was evaluated both in vitro and in vivo.

RESULTS

Because JNK2 is critical to macrophage uptake of oxidized lipids through scavenger receptors that engender expression of myriad inflammatory molecules, we designed an RNA-silencing approach based on peptide-siRNA nanoparticles (p5RHH-siRNA) that localize to atherosclerotic plaques exhibiting disrupted endothelial barriers to achieve control of JNK2 expression by macrophages. After seven doses of p5RHH-JNK2 siRNA nanoparticles over 3.5 weeks in ApoE-/- mice on a Western diet, both JNK2 mRNA and protein levels were significantly decreased by 26% (P=0.044) and 42% (P=0.042), respectively. Plaque-macrophage populations were markedly depleted and NFκB and STAT3-signaling pathways inhibited by 47% (P<0.001) and 46% (P=0.004), respectively. Endothelial barrier integrity was restored (2.6-fold reduced permeability to circulating 200 nm nanoparticles in vivo, P=0.003) and thrombotic risk attenuated (200% increased clotting times to carotid artery injury, P=0.02), despite blood-cholesterol levels persistently exceeding 1,000 mg/dL. No adaptive or innate immunoresponses toward the nanoparticles were observed, and blood tests after the completion of treatment confirmed the largely nontoxic nature of this approach.

CONCLUSION

The ability to formulate these nanostructures rapidly and easily interchange or multiplex their oligonucleotide content represents a promising approach for controlling deleterious signaling events locally in advanced atherosclerosis.