Intracellular trafficking of hybrid gene delivery vectors

Cationic liposomes overcome neutralizing antibodies and enhance reovirus efficacy in ovarian cancer

Reovirus (Reo) has shown promising potential in specifically killing tumor cells, and offering new possibilities for ovarian cancer (OC) treatment. However, neutralizing antibodies in the ascites from OC patients greatly limit the further application of Reo. In this study, we employed cationic liposomes (Lipo) to deliver Reo, significantly enhancing its ability to enter OC cells and its effectiveness in killing these cells under ascitic conditions. Pre-treatment with the MβCD inhibitor notably decreased Reo-mediated tumor cell death, indicating that Lipo primarily enables Reo's cellular uptake through caveolin-mediated endocytosis. Our results demonstrate that Lipo effectively facilitates the entry of Reo into the cytoplasm and triggers cell apoptosis. The above findings provide a new strategy to overcome the obstacle of neutralizing antibodies in the clinical application of Reo.

Intracellular Delivery of Glucose Oxidase for Enhanced Cytotoxicity toward PSMA-Expressing Prostate Cancer Cells

Reactive oxygen species (ROS) forming enzymes are of significant interest as anticancer agents due to their potent cytotoxicity. A key challenge in their clinical translation is attaining site-specific delivery and minimizing biodistribution to healthy tissues. Here, complexes composed of the ROS enzyme glucose oxidase (GOX), poly-l-lysine-grafted-polyethylene glycol (PLL-g-PEG), and anti-prostate specific membrane antigen (anti-PSMA) monoclonal antibody are synthesized for localized delivery and uptake in prostate cancer cells. Formation of anti-PSMA-PLL-g-PEG/GOX results in nanoscale complexes ≈30 nm in diameter with a ζ-potential of 6 mV. The anti-PSMA-PLL-g-PEG/GOX complexes show significant cytotoxicity (≈60% reduction in cell viability) against PSMA-expressing LNCaP cells compared to unmodified GOX. Importantly, cytotoxicity in LNCaP cells occurrs concurrently with anti-PSMA-PLL-g-PEG/GOX uptake and increases in intracellular generation of ROS. These results demonstrate that cytotoxicity of ROS inducing enzymes can be enhanced by intracellular delivery compared to equivalent concentrations of free enzyme, providing a novel means for cancer therapy.

Drug-free mannosylated liposomes inhibit tumor growth by promoting the polarization of tumor-associated macrophages

Background: Tumor-associated macrophages (TAMs) are critical in tumor progression and metastasis. Selective targeting of TAMs holds great potential to ameliorate the immunosuppressive tumor microenvironment and enhance the efficacy of antitumor therapy. Various liposomes have been developed to target TAMs via cell-specific surface receptors either to deplete or re-educate TAMs. Since immuno-stimulation often initiates with the interaction of nanocarriers with the innate immunity cells such as macrophages, the intrinsic impact of drug-free liposomes on macrophage activation and polarization via cell interaction is one of the most critical issues in nanomedicine for promoting effective immunotherapy.

Methods: In this study, conventional bare liposomes, PEGylated liposomes, and mannosylated liposomes were developed and the cytotoxicity, cellular internalization, immunostimulatory activity, targeting efficiency, antitumor efficacy, and mechanism were evaluated in vitro and in vivo.

Results: All liposomes displayed an ideal particle size, good biocompatibility, and controlled release behavior. Mannosylated liposomes exhibited superior in vitro cellular internalization and tumor spheroid penetration with the aid of the mannose receptor-mediated TAMs-targeting effects. In particular, mannosylated liposomes promoted the polarization of both M0 and M2 to the M1 phenotype by enhancing the expression ratio of CD86/CD206 in vitro. Of note, mannosylated liposomes could inhibit G422 glioma tumor growth, which may be attributed to the polarization of TAMs, as evidenced by the reduction in expression level of the TAMs surface marker.

Conclusion: These results indicate the potential value of mannosylated liposomes in the design of a rational delivery system to enhance the antitumor immune efficacy of immunomodulators by inducing a shift from the M2 to the M1 phenotype.

Non-viral Vector for Muscle-Mediated Gene Therapy

Non-viral gene delivery to skeletal muscle was one of the first applications of gene therapy that went into the clinic, mainly because skeletal muscle is an easily accessible tissue for local gene transfer and non-viral vectors have a relatively safe and low immunogenic track record. However, plasmid DNA, naked or complexed to the various chemistries, turn out to be moderately efficient in humans when injected locally and very inefficient (and very toxic in some cases) when injected systemically. A number of clinical applications have been initiated however, based on transgenes that were adapted to good local impact and/or to a wide physiological outcome (i.e., strong humoral and cellular immune responses following the introduction of DNA vaccines). Neuromuscular diseases seem more challenging for non-viral vectors. Nevertheless, the local production of therapeutic proteins that may act distantly from the injected site and/or the hydrodynamic perfusion of safe plasmids remains a viable basis for the non-viral gene therapy of muscle disorders, cachexia, as well as peripheral neuropathies.

Non-viral Gene Delivery

Although viral vectors comprise the majority of gene delivery vectors, their various safety, production, and other practical concerns have left a research gap to be addressed. The non-viral vector space encompasses a growing variety of physical and chemical methods capable of gene delivery into the nuclei of target cells. Major physical methods described in this chapter are microinjection, electroporation, and ballistic injection, magnetofection, sonoporation, optical transfection, and localized hyperthermia. Major chemical methods described in this chapter are lipofection, polyfection, gold complexation, and carbon-based methods. Combination approaches to improve transfection efficiency or reduce immunological response have shown great promise in expanding the scope of non-viral gene delivery.

Endocytosis and intracellular traffic of cholesterol-PDMAEMA liposome complexes in human epithelial-like cells

Liposomes are generally used as delivery systems, as they are capable of encapsulating a wide variety of molecules (i.e. plasmids, recombinant proteins, therapeutic drugs). However, liposomal drug delivery have to fulfill different requirements, such as the effective internalization by the target cells and avoidance of the degradative activity of the intracellular compartments. The use of polymer lipid complexes (PLCs), by including different polymers in the liposome formulation, could improve internalization and intracellular release of drugs. The aim of the present work is to study the mechanisms of cellular uptaking and the intracellular trafficking of PLCs formed with cholesterol-poly(2-(dimethylamino)ethyl methacrylate) CHO-PDMAEMA and lecithin (LC CHO-PD). Calcein-loaded liposomes were used to determine cellular uptake and intracellular localization by flow cytometry and confocal microscopy. Incorporation of CHO-PDMAEMA to lecithin liposomes enhanced the internalization capacity of PLCs. Internalization of PLCs by human epithelial-like cells (HEK-293) diminished at 4°C, suggesting uptake by endocytosis. PLCs showed no co-localization with acidic compartments after internalization. Experiments with endocytosis inhibitors and co-localization of liposomes and albumin, suggested the caveolae endocytic pathway as the most probable route for intracellular trafficking of PLCs. In this work, we demonstrated an efficient uptake of LC CHO-PDs by human epithelial-like cells (HEK-293) through the non-degradative caveolae endocytic pathway. The mode of internalization and the intracellular fate of liposomes under study, suggest a promising use of LC CHO-PDs as drug delivery systems.

Phospholipid-chitosan hybrid nanoliposomes promoting cell entry for drug delivery against cervical cancer

This study emphasizes the development of a novel surface modified liposome as an anticancer drug nanocarrier. Quaternized N,O-oleoyl chitosan (QCS) was synthesized and incorporated into liposome vesicles, generating QCS-liposomes (Lip-QCS). The Lip-QCS liposomes were spherical in shape (average size diameter 171.5±0.8nm), with a narrow size distribution (PDI 0.1±0.0) and zeta potential of 11.7±0.7mV. In vitro mucoadhesive tests indicated that Lip-QCS possesses a mucoadhesive property. Moreover, the presence of QCS was able to induce the cationic charge on the surface of liposome. Cellular internalization of Lip-QCS was monitored over time, with the results revealing that the cell entry level of Lip-QCS was elevated at 24h. Following this, Lip-QCS were then employed to load cisplatin, a common platinum-containing anti-cancer drug, with a loading efficiency of 27.45±0.78% being obtained. The therapeutic potency of the loaded Lip-QCS was investigated using a 3D spheroid cervical cancer model (SiHa) which highlighted their cytotoxicity and apoptosis effect, and suitability as a controllable system for sustained drug release. This approach has the potential to assist in development of an effective drug delivery system against cervical cancer.

Polymeric Nanohybrids as a New Class of Therapeutic Biotransporters

A possible solution to enhance existing drug and gene therapies is to develop hybrid nanocarriers capable of delivering therapeutic agents in a controlled and targeted manner. This goal can be achieved by designing nanohybrid systems, which combine organic or inorganic nanomaterials with biomacromolecules into a single composite. The unique combination of properties along with their facile fabrication enables the design of smart carriers for both drug and gene delivery. These hybrids can be further modified with cell targeting motifs to enhance their biological interactivity. In this Talents and Trends article, an overview of emerging nanohybrid-based technologies will be provided to highlight their potential use as innovative platforms for improved cancer therapies and new strategies in regenerative medicine. The clinical relevance of these systems will be reviewed to define the current challenges which still need to be addressed to allow these therapies to move from bench to bedside.

Protein cages and synthetic polymers: a fruitful symbiosis for drug delivery applications, bionanotechnology and materials science

Protein cages have become essential tools in bionanotechnology due to their well-defined, monodisperse, capsule-like structure. Combining them with synthetic polymers greatly expands their application, giving rise to novel nanomaterials fore.g.drug-delivery, sensing, electronic devices and for uses as nanoreactors.