Photochemically enhanced transduction of polymer-complexed adenovirus targeted to the epidermal growth factor receptor

microRNA-181a silencing by antisense oligonucleotides delivered by virus-like particles

Cowpea chlorotic mottle virus (CCMV) is a positive-sense RNA virus that can be repurposed for gene delivery applications. Understanding the self-assembly process of the virus enabled to remove its genome and replace it with desired nucleic acids, and we and others have previously reported using CCMV virus-like particle (VLP) to encapsulate siRNA, mRNA, as well as CpG oligodeoxynucleotides. In this study, the CCMV VLP was applied to encapsulate two different formats of anti-miR-181a oligonucleotides: naked RNA and chemically stabilized RNA to knockdown highly regulated miR-181a in ovarian cancer cells. miR-181a expression in ovarian tumors is associated with high aggressiveness, invasiveness, resistance to chemotherapy, and overall poor prognosis. Therefore, miR-181a is an important target for ovarian cancer therapy. qPCR data and cancer cell migration assays demonstrated higher knockdown efficacy when anti-miR-181a oligonucleotides were encapsulated and delivered using the VLPs resulting in reduced cancer cell invasiveness. Importantly, delivery of anti-miR-181a oligonucleotide into cells could be achieved without the aid of a transfection agent or surface modification. These results highlight the opportunity of plant-derived VLPs as nucleic acid carriers.

Spatially Defined Gene Delivery into Native Cells with the Red Light-Controlled OptoAAV Technology

The OptoAAV technology allows spatially defined delivery of transgenes into native target cells down to single-cell resolution by the illumination with cell-compatible and tissue-penetrating red light. The system is based on an adeno-associated viral (AAV) vector of serotype 2 with an engineered capsid (OptoAAV) and a photoreceptor-containing adapter protein mediating the interaction of the OptoAAV with the surface of the target cell in response to low doses of red and far-red light. In this article, we first provide detailed protocols for the production, purification, and analysis of the OptoAAV and the adapter protein. Afterward, we describe in detail the application of the OptoAAV system for the light-controlled transduction of human cells with global and patterned illumination. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Production, purification, and analysis of PhyB-DARPin_EGFR adapter protein Basic Protocol 2: Production, purification, and analysis of OptoAAV Basic Protocol 3: Red light-controlled viral transduction with the OptoAAV system Support Protocol: Spatially resolved transduction of two transgenes with the OptoAAV system.

Spatiotemporally confined red light-controlled gene delivery at single-cell resolution using adeno-associated viral vectors

Methodologies for the controlled delivery of genetic information into target cells are of utmost importance for genetic engineering in both fundamental and applied research. However, available methods for efficient gene transfer into user-selected or even single cells suffer from low throughput, the need for complicated equipment, high invasiveness, or side effects by off-target viral uptake. Here, we engineer an adeno-associated viral (AAV) vector system that transfers genetic information into native target cells upon illumination with cell-compatible red light. This OptoAAV system allows adjustable and spatially resolved gene transfer down to single-cell resolution and is compatible with different cell lines and primary cells. Moreover, the sequential application of multiple OptoAAVs enables spatially resolved transduction with different transgenes. The approach presented is likely extendable to other classes of viral vectors and is expected to foster advances in basic and applied genetic research.

Nonreplicating Adenoviral Vectors: Improving Tropism and Delivery of Cancer Gene Therapy

Recent preclinical and clinical studies have used viral vectors in gene therapy research, especially nonreplicating adenovirus encoding strategic therapeutic genes for cancer treatment. Adenoviruses were the first DNA viruses to go into therapeutic development, mainly due to well-known biological features: stability in vivo, ease of manufacture, and efficient gene delivery to dividing and nondividing cells. However, there are some limitations for gene therapy using adenoviral vectors, such as nonspecific transduction of normal cells and liver sequestration and neutralization by antibodies, especially when administered systemically. On the other hand, adenoviral vectors are amenable to strategies for the modification of their biological structures, including genetic manipulation of viral proteins, pseudotyping, and conjugation with polymers or biological membranes. Such modifications provide greater specificity to the target cell and better safety in systemic administration; thus, a reduction of antiviral host responses would favor the use of adenoviral vectors in cancer immunotherapy. In this review, we describe the structural and molecular features of nonreplicating adenoviral vectors, the current limitations to their use, and strategies to modify adenoviral tropism, highlighting the approaches that may allow for the systemic administration of gene therapy.

Photochemical Internalization for Intracellular Drug Delivery. From Basic Mechanisms to Clinical Research

Photochemical internalisation (PCI) is a unique intervention which involves the release of endocytosed macromolecules into the cytoplasmic matrix. PCI is based on the use of photosensitizers placed in endocytic vesicles that, following light activation, lead to rupture of the endocytic vesicles and the release of the macromolecules into the cytoplasmic matrix. This technology has been shown to improve the biological activity of a number of macromolecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins (RIPs), gene-encoding plasmids, adenovirus and oligonucleotides and certain chemotherapeutics, such as bleomycin. This new intervention has also been found appealing for intracellular delivery of drugs incorporated into nanocarriers and for cancer vaccination. PCI is currently being evaluated in clinical trials. Data from the first-in-human phase I clinical trial as well as an update on the development of the PCI technology towards clinical practice is presented here.

Methods for Modification of Therapeutic Viruses

The optimal clinical exploitation of viruses as gene therapy or oncolytic vectors will require them to be administered intravenously. Strategies must therefore be deployed to enable viruses to survive the harsh neutralizing environment of the bloodstream and achieve deposition within and throughout target tissues or tumor deposits. This chapter describes the genetic and chemical engineering approaches that are being developed to overcome these challenges.

Exploring the functions of polymers in adenovirus-mediated gene delivery: Evading immune response and redirecting tropism

Adenovirus (Ad) is a promising viral carrier in gene therapy because of its unique attribution. However, clinical applications of Ad vectors are currently restricted by their immunogenicity and broad native tropism. To address these obstacles, a variety of nonimmunogenic polymers are utilized to modify Ad vectors chemically or physically. In this review, we systemically discuss the functions of polymers in Ad-mediated gene delivery from two aspects: evading the host immune responses to Ads and redirecting Ad tropism. With polyethylene glycol (PEG) first in order, a variety of polymers have been developed to shield the surface of Ad vectors and well accomplished to evade the host immune response, block CAR-dependant cellular uptake, and reduce accumulation in the liver. In addition, shielding Ad vectors with targeted polymers (including targeting ligand-conjugated polymers and bio-responsive polymers) can also efficiently retarget Ad vectors to tumor tissues and reduce their distribution in nontargeted tissues. With its potential to evade the immune response and retarget Ad vectors, modification with polymers has been generally regarded as a promising strategy to facilitate the clinical applications of Ad vectors for virotherapy. STATEMENT OF SIGNIFICANCE: There is no doubt that Adenovirus (Ads) are attractive vectors for gene therapy, with high sophistication and effectiveness in overcoming both extra- and intracellular barriers, which cannot be exceeded by any other nonviral gene vectors. Unfortunately, their clinical applications are still restricted by some critical hurdles, including immunogenicity and native broad tropism. Therefore, a variety of elegant strategies have been developed from various angles to address these hurdles. Among these various strategies, coating Ads with nonimmunogenic polymers has attracted much attention. In this review, we systemically discuss the functions of polymers in Ad-mediated gene delivery from two aspects: evading the host immune responses to Ads and redirecting Ad tropism. In addition, the key factors in Ad modification with polymers have been highlighted and summarized to provide guiding theory for the design of more effective and safer polymer-Ad hybrid gene vectors.

The evolution of adenoviral vectors through genetic and chemical surface modifications

A long time has passed since the first clinical trial with adenoviral (Ad) vectors. Despite being very promising, Ad vectors soon revealed their limitations in human clinical trials. The pre-existing immunity, the marked liver tropism and the high toxicity of first generation Ad (FG-Ad) vectors have been the main challenges for the development of new approaches. Significant effort toward the development of genetically and chemically modified adenoviral vectors has enabled researchers to create more sophisticated vectors for gene therapy, with an improved safety profile and a higher transduction ability of different tissues. In this review, we will describe the latest findings in the high-speed, evolving field of genetic and chemical modifications of adenoviral vectors, a field in which different disciplines, such as biomaterial research, virology and immunology, co-operate synergistically to create better gene therapy tools for modern challenges.

Beyond Gene Delivery: Strategies to Engineer the Surfaces of Viral Vectors

Viral vectors have been extensively studied due to their great transduction efficiency compared to non-viral vectors. These vectors have been used extensively in gene therapy, enabling the comprehension of, not only the advantages of these vectors, but also the limitations, such as the activation of the immune system after vector administration. Moreover, the need to control the target of the vector has led to the development of chemical and non-chemical modifications of the vector surface, allowing researchers to modify the tropism and biodistribution profile of the vector, leading to the production of viral vectors able to target different tissues and organs. This review describes recent non-genetic modifications of the surfaces of viral vectors to decrease immune system activation and to control tissue targeting. The developments described herein provide opportunities for applications of gene therapy to treat acquired disorders and genetic diseases and to become useful tools in regenerative medicine.

Enhancing the therapeutic efficacy of adenovirus in combination with biomaterials

With the reason that systemically administered adenovirus (Ad) is rapidly extinguished by innate/adaptive immune responses and accumulation in liver, in vivo application of the Ad vector is strictly restricted. For achieving to develop successful Ad vector systems for cancer therapy, the chemical or physical modification of Ad vectors with polymers has been generally used as a promising strategy to overcome the obstacles. With polyethylene glycol (PEG) first in order, a variety of polymers have been developed to shield the surface of therapeutic Ad vectors and well accomplished to extend circulation time in blood and reduce liver toxicity. However, although polymer-coated Ads can successfully evacuate from a series of guarding systems in vivo and locate within tumors by enhanced permeability and retention (EPR) effect, the possibility to entering into the target cell is few and far between. To endow targeting moiety to polymer-coated Ad vectors, a diversity of ligands such as tumor-homing peptides, growth factors or antibodies, have been introduced with avoiding unwanted transduction and enhancing therapeutic efficacy. Here, we will describe and classify the characteristics of the published polymers with respect to Ad vectors. Furthermore, we will also compare the properties of variable targeting ligands, which are being utilized for addressing polymer-coated Ad vectors actively.

Current advances in adenovirus nanocomplexes: more specificity and less immunogenicity

An often overlooked issue in the field of adenovirus (Ad)-mediated cancer gene therapy is its limited capacity for effective systemic delivery. Although primary tumors can be treated effectively with intralesional injection of conventional Ad vectors, systemic metastasis is difficult to cure. Systemic administration of conventional naked Ads leads to acute accumulation of Ad particles in the liver, induction of neutralizing antibody, short blood circulation half-life, non-specific biodistribution in undesired organs, and low selective accumulation in the target disease site. Versatile strategies involving the modification of viral surfaces with polymers and nanomaterials have been designed for the purpose of maximizing Ad anti-tumor activity and specificity by systemic administration. Integration of viral and non-viral nanomaterials will substantially advance both fields, creating new concepts in gene therapeutics. This review focuses on current advances in the development of smart Ad hybrid nanocomplexes based on various design-based strategies for optimal Ad systemic administration.

Avidin-biotin technology in targeted therapy

IMPORTANCE OF THE FIELD

The goal of drug targeting is to increase the concentration of the drug in the vicinity of the cells responsible for disease without affecting healthy cells. Many approaches in cancer treatment are limited because of their broad range of unwanted side effects on healthy cells. Targeting can reduce side effects and increase efficacy of drugs in the patient.

AREAS COVERED IN THIS REVIEW

Avidin, originally isolated from chicken eggs, and its bacterial analogue, streptavidin, from Streptomyces avidinii, have extremely high affinity for biotin. This unique feature is the basis of avidin-biotin technology. This article reviews the current status of avidin-biotin systems and their use for pretargeted drug delivery and vector targeting.

WHAT THE READER WILL GAIN

The reader will gain an understanding of the following approaches using the avidin-biotin system: i) targeting antibodies and therapeutic molecules are administered separately leading to a reduction of drug dose in normal tissues compared with conventional (radio)immunotherapies; ii) introducing avidin gene into specific tissues by local gene transfer, which subsequently can sequester and concentrate considerable amounts of therapeutic ligands; and iii) enabling transductional targeting of gene therapy vectors.

TAKE HOME MESSAGE

Avidin and biotin technology has proved to be an extremely versatile tool with broad applications, such as pretargeting, delivering avidin gene into cells enabling targeting of biotinylated compounds and targeting of viral vectors.

Chitosan modification of adenovirus to modify transfection efficiency in bovine corneal epithelial cells

Background

The purpose of this study is to modulate the transfection efficiency of adenovirus (Ad) on the cornea by the covalent attachment of chitosan on adenoviral capsids via a thioether linkage between chitosan modified with 2-iminothiolane and Ad cross-linked with N-[γ-maleimidobutyryloxy]succinimide ester (GMBS).

Methodology/Principal Findings

Modified Ad was obtained by reaction with the heterobifunctional crosslinking reagent, GMBS, producing maleimide-modified Ad (Ad-GMBS). Then, the chitosan-SH was conjugated to Ad-GMBS via a thioether bond at different ratios of Ad to GMBS to chitosan-SH. The sizes and zeta potentials of unmodified Ad and chitosan-modified Ads were measured, and the morphologies of the virus particles were observed under transmission electron microscope. Primary cultures of bovine corneal epithelial cells were transfected with Ads and chitosan-modified Ads in the absence or presence of anti-adenovirus antibodies. Chitosan modification did not significantly change the particle size of Ad, but the surface charge of Ad increased significantly from −24.3 mV to nearly neutral. Furthermore, primary cultures of bovine corneal epithelial cells were transfected with Ad or chitosan-modified Ad in the absence or presence of anti-Ad antibodies. The transfection efficiency was attenuated gradually with increasing amounts of GMBS. However, incorporation of chitosan partly restored transfection activity and rendered the modified antibody resistant to antibody neutralization.

Conclusions/Significance

Chitosan can provide a platform for chemical modification of Ad, which offers potential for further in vivo applications.

Photochemical internalization: a new tool for gene and oligonucleotide delivery

Photochemical internalization (PCI) is a novel technology for release of endocytosed macromolecules into the cytosol. The technology is based on the use of photosensitizers located in endocytic vesicles. Upon activation by light such photosensitizers induce a release of macromolecules from their compartmentalization in endocytic vesicles. PCI has been shown to increase the biological activity of a large variety of macromolecules and other molecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins, immunotoxins, plasmids, adenovirus, various oligonucleotides, dendrimer-based delivery of chemotherapeutica and unconjugated chemotherapeutica such as bleomycin and doxorubicin. This review will present the basis for the PCI concept and the most recent significant developments.

Strategies to overcome host immunity to adenovirus vectors in vaccine development

The first clinical evaluations of adenovirus (Ad)-based vectors for gene therapy were initiated in the mid-1990s and led to great anticipation for future utility. However, excitement surrounding gene therapy, particularly Ad-based therapy, was diminished upon the death of Jesse Gelsinger, and recent discouraging results from the HIV vaccine STEP trial have brought efficacy and safety issues to the forefront again. Even so, Ad vectors are still considered among the safest and most effective vaccine vectors. Innate and pre-existing immunity to Ad mediate much of the acute toxicities and reduced therapeutic efficacies observed following vaccination with this vector. Thus, innovative strategies must continue to be developed to reduce Ad-specific antigenicity and immune recognition. This review provides an overview and critique of the most promising strategies, including results from preclinical trials in mice and nonhuman primates, which aim to revive the future of Ad-based vaccines.

Photochemical enhancement of DNA delivery by EGF receptor targeted polyplexes

Photochemical internalization (PCI) is a physico-chemical targeting method that enables light directed delivery of nucleic acids into cells. The technology is based on photosensitizers that localize in the membranes of endocytic vesicles. A light activation of the photosensitizers induces photochemical reactions that lead to rupture of the vesicular membranes. This results in the release of endocytosed compounds (e.g., nucleic acids) into the cell cytosol. Physico-chemical and biological targeting techniques can be combined to promote efficient and specific gene delivery to target cells. The present protocol describes PCI of epidermal growth factor receptor (EGFR)-targeted DNA polyplexes. The DNA polyplexes made are small (50-100 nm in diameter), and they contain polyethylenimine (PEI) conjugated with the EGF protein as a cell-binding ligand for EGFR-mediated endocytosis and polyethylene glycol (PEG) for masking the polyplex surface charge. PCI of such targeted PEG-PEI/DNA polyplexes enables high and EGFR-specific gene transfer activity in cells. Although describing in detail PCI of DNA polyplexes, the methodology presented in this protocol is also applicable for PCI of other gene therapy vectors (e.g. viral vectors), peptide nucleic acids (PNA), small interfering RNA (siRNA), and for vectors targeted to alternate cell surface receptors. Generally, PCI can be applied whenever 100% survival of the treated cell population is not required.

Synthesis and characterization of polyrotaxanes consisting of cationic alpha-cyclodextrins threaded on poly[(ethylene oxide)-ran-(propylene oxide)] as gene carriers

Cationic polymers have been receiving growing attention as gene delivery carriers. Herein, a series of novel cationic supramolecular polyrotaxanes with multiple cationic alpha-cyclodextrin (alpha-CD) rings threaded and blocked on a poly[(ethylene oxide)-ran-(propylene oxide)] (P(EO-r-PO)) random copolymer chain were synthesized and investigated for gene delivery. In the cationic polyrotaxanes, approximately 12 cationic alpha-CD rings were threaded on the P(EO-r-PO) copolymer with a molecular weight of 2370 Da and an EO/PO molar ratio of 4:1, while the cationic alpha-CD rings were grafted with linear or branched oligoethylenimine (OEI) of various chain lengths and molecular weights up to 600 Da. The OEI-grafted alpha-CD rings were only located selectively on EO segments of the P(EO-r-PO) chain, while PO segments were free of complexation. This increased the mobility of the cationic alpha-CD rings and the flexibility of the polyrotaxanes, which enhanced the interaction of the cationic alpha-CD rings with DNA and/or the cellular membrane. All cationic polyrotaxanes synthesized in this work could efficiently condense plasmid DNA to form nanoparticles that were suitable for delivery of the gene. Cytotoxicity studies showed that the cationic polyrotaxanes with all linear OEI chains of molecular weights up to 423 Da exhibited much less cytotoxicity than high-molecular-weight branched polyethylenimine (PEI) (25 kDa) in both HEK293 and COS7 cell lines. The cationic polyrotaxanes displayed high gene transfection efficiencies in a variety of cell lines including HEK293, COS7, BHK-21, SKOV-3, and MES-SA. Particularly, the gene delivery capability of the cationic polyrotaxanes in HEK293 cells was much higher than that of high-molecular-weight branched PEI (25 k).

Advances in preclinical investigation of prostate cancer gene therapy

Treating recurrent prostate cancer poses a great challenge to clinicians. Research efforts in the last decade have shown that adenoviral vector-based gene therapy is a promising approach that could expand the arsenal against prostate cancer. This maturing field is at the stage of being able to translate many preclinical discoveries into clinical practices. At this juncture, it is important to highlight the promising strategies including prostate-targeted gene expression, the use of oncolytic vectors, therapy coupled to reporter gene imaging, and combined treatment modalities. In fact, the early stages of clinical investigation employing combined, multimodal gene therapy focused on loco-regional tumor eradication and showed promising results. Clinicians and scientists should seize the momentum of progress to push forward to improve the therapeutic outcome for the patients.

Recent developments in the use of adenoviruses and immunotoxins in cancer gene therapy

Despite setbacks in the past and apparent hurdles ahead, gene therapy is advancing toward reality. The past several years have witnessed this new field of biomedicine developing rapidly both in breadth and depth, especially for the treatment of cancer, thanks largely to the better understanding of molecular and genetic basis of oncogenesis and the development of new and improved vectors and technologies for gene delivery and targeting. This article is intended to provide a brief review of recent advances in cancer gene therapy using adenoviruses, both as vectors and as oncolytic agents, and some of the recent progress in the development of immunotoxins for use in cancer gene therapy.

Photochemical internalization of therapeutic macromolecular agents: a novel strategy to kill multidrug-resistant cancer cells

Drug resistance is a major problem for chemotherapy. Entrapment of anticancer drugs in endolysosomal compartments or active extrusions by plasma membrane proteins of the ATP-binding cassette (ABC) superfamily are important resistance mechanisms. This study evaluated photochemical internalization (PCI) of membrane-impermeable macromolecules that are not the target of ABC drug pumps for treating multidrug-resistant (MDR) cancer cells. We used the drug-sensitive uterine fibrosarcoma cell line MES-SA and its MDR, P-glycoprotein (P-gp)-overexpressing derivative MES-SA/Dx5 with the photosensitizer disulfonated meso-tetraphenylporphine (TPPS(2a)) and broad spectrum illumination. The PCI of doxorubicin, the ribosome-inactivating protein gelonin and adenoviral transduction were assessed in both cell lines, together with the uptake and excretion of TPPS(2a) and of two fluid phase markers easily detectable by fluorescence [lucifer yellow (LY) and fluorescein isothiocyanate (FITC)-dextran], as a model of gelonin uptake. Both cell lines were resistant to PCI of doxorubicin, but equally sensitive to PCI of gelonin, even though the endocytosis rates of LY and FITC-dextran were significantly lower in the MDR cells. In control studies, MES-SA/Dx5 cells were more resistant to photodynamic therapy (TPPS(2a) + light only). This was not mediated by P-gp, as there were no differences in the uptake and efflux of TPPS(2a) between the cell lines. After adenoviral infection, PCI enhanced gene delivery in both cell lines. In conclusion, PCI of macromolecular therapeutic agents that are not targets of P-gp is a novel therapeutic strategy to kill MDR cancer cells.

Photochemically enhanced adenoviral transduction in a multicellular environment

Photochemical internalization (PCI) enhances adenovirus (Ad) transgene expression in a variety of cell lines in vitro. However, measurements of the photochemical effect on transduction in multicellular environments are lacking. In this study, spheroids of DU 145 prostate cancer cells were used as a model to evaluate Ad serotype 5 (Ad5) transduction in a multicellular environment in response to PCI treatment. Furthermore, the Ad5 was coated with poly(2-methyl-acrylic acid 2-[(2-(dimethylamino)-ethyl)-methyl-amino]-ethyl ester) (pDAMA) to evaluate whether physicochemical properties such as charge and size of viral vectors affect transduction of photochemically treated spheroids. Spheroids incubated with photosensitizer TPPS(2a) (1 microg ml(-1)) and infected with adenovirus contained 3-fold higher percentage of reporter gene expressing cells after exposure to blue light (0.42 J cm(-2)) compared to no light, as analysed by flow cytometry of dissociated spheroids two days after treatment. The cells within the infected spheroids were further divided into three sections corresponding to the interior, intermediate and peripheral layers of the spheroids. This was performed by staining the spheroids with a diffusion-limited dye prior to dissociation. Transduction of cells within photochemically treated and untreated spheroids was heterogeneous, with a radial reduction of transgene expression towards the inner section of the spheroid. The coating of Ad with pDAMA induced up to 2-fold decrease in transduction of cells in the interior section of spheroids compared to uncomplexed Ad, while transduction of the peripheral section remained unchanged. The decrease in transduction could be related to reduced diffusion due to the size of the Ad-pDAMA complexes.