Delivery of nucleic acids for cancer gene therapy: overcoming extra- and intra-cellular barriers

Non-viral approaches in CAR-NK cell engineering: connecting natural killer cell biology and gene delivery

Natural Killer (NK) cells are exciting candidates for cancer immunotherapy with potent innate cytotoxicity and distinct advantages over T cells for Chimeric Antigen Receptor (CAR) therapy. Concerns regarding the safety, cost, and scalability of viral vectors has ignited research into non-viral alternatives for gene delivery. This review comprehensively analyses recent advancements and challenges with non-viral genetic modification of NK cells for allogeneic CAR-NK therapies. Non-viral alternatives including electroporation and multifunctional nanoparticles are interrogated with respect to CAR expression and translational responses. Crucially, the link between NK cell biology and design of drug delivery technologies are made, which is essential for development of future non-viral approaches. This review provides valuable insights into the current state of non-viral CAR-NK cell engineering, aimed at realising the full potential of NK cell-based immunotherapies.

Nanocarrier-based gene delivery for immune cell engineering

Clinical advances in genetically modified immune cell therapies, such as chimeric antigen receptor T cell therapies, have raised hope for cancer treatment. The majority of these biotechnologies are based on viral methods for ex vivo genetic modification of the immune cells, while the non-viral methods are still in the developmental phase. Nanocarriers have been emerging as materials of choice for gene delivery to immune cells. This is due to their versatile physicochemical properties such as large surface area and size that can be optimized to overcome several practical barriers to successful gene delivery. The in vivo nanocarrier-based gene delivery can revolutionize cell-based cancer immunotherapies by replacing the current expensive autologous cell manufacturing with an off-the-shelf biomaterial-based platform. The aim of this research is to review current advances and strategies to overcome the challenges in nanoparticle-based gene delivery and their impact on the efficiency, safety, and specificity of the process. The main focus is on polymeric and lipid-based nanocarriers, and their recent preclinical applications for cancer immunotherapy.

Development of a Spray-Dried Formulation of Peptide-DNA Nanoparticles into a Dry Powder for Pulmonary Delivery Using Factorial Design

BACKGROUND

Gene therapy via pulmonary delivery holds the potential to treat various lung pathologies. To date, spray drying has been the most promising method to produce inhalable powders. The present study determined the parameters required to spray dry nanoparticles (NPs) that contain the delivery peptide, termed RALA (N-WEARLARALARALARHLARALARALRACEA-C), complexed with plasmid DNA into a dry powder form designed for inhalation.

METHODS

The spray drying process was optimised using full factorial design with 19 randomly ordered experiments based on the combination of four parameters and three centre points per block. Specifically, mannitol concentration, inlet temperature, spray rate, and spray frequency were varied to observe their effects on process yield, moisture content, a median of particle size distribution, Z-average, zeta potential, encapsulation efficiency of DNA NPs, and DNA recovery. The impact of mannitol concentration was also examined on the spray-dried NPs and evaluated via biological functionality in vitro.

RESULTS

The results demonstrated that mannitol concentration was the strongest variable impacting all responses apart from encapsulation efficiency. All measured responses demonstrated a strong dependency on the experimental variables. Furthermore, spray drying with the optimal variables in combination with a low mannitol concentration (1% and 3%, w/v) produced functional RALA/pDNA NPs.

CONCLUSION

The optimal parameters have been determined to spray dry RALA/pDNA NPs into an dry powder with excellent biological functionality, which have the potential to be used for gene therapy applications via pulmonary delivery.

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.

Delivery of cancer therapies by synthetic and bio-inspired nanovectors

BACKGROUND

As a complement to the clinical development of new anticancer molecules, innovations in therapeutic vectorization aim at solving issues related to tumor specificity and associated toxicities. Nanomedicine is a rapidly evolving field that offers various solutions to increase clinical efficacy and safety. MAIN: Here are presented the recent advances for different types of nanovectors of chemical and biological nature, to identify the best suited for translational research projects. These nanovectors include different types of chemically engineered nanoparticles that now come in many different flavors of 'smart' drug delivery systems. Alternatives with enhanced biocompatibility and a better adaptability to new types of therapeutic molecules are the cell-derived extracellular vesicles and micro-organism-derived oncolytic viruses, virus-like particles and bacterial minicells. In the first part of the review, we describe their main physical, chemical and biological properties and their potential for personalized modifications. The second part focuses on presenting the recent literature on the use of the different families of nanovectors to deliver anticancer molecules for chemotherapy, radiotherapy, nucleic acid-based therapy, modulation of the tumor microenvironment and immunotherapy.

CONCLUSION

This review will help the readers to better appreciate the complexity of available nanovectors and to identify the most fitting "type" for efficient and specific delivery of diverse anticancer therapies.

Metformin-conjugated micellar system with intratumoral pH responsive de-shielding for co-delivery of doxorubicin and nucleic acid

A novel PMet-P(cdmPEG_2K) polymeric micellar carrier was developed for tumor-targeted co-delivery of DOX and nucleic acids (NA), based on polymetformin and a structure designed to lose the PEG shell in response to the acidic extracellular tumor environment. NA/DOX co-loaded micelleplexes exhibited enhanced inhibition of cell proliferation compared to DOX-loaded micelles, and displayed a higher level of cytotoxicity at an acidic pH (6.8) which mimicks the tumor microenvironment. The PMet-P(cdmPEG_2K) micelles achieved significantly improved transfection with either a reporter plasmid or Cy3-siRNA, and enhanced DOX intracellular uptake in 4T1.2 cells at pH 6.8. Importantly, PMet-P(cdmPEG_2K) micelles showed excellent pEGFP (EGFP expression plasmid) transfection in an aggressive murine breast cancer (4T1.2) model. By using a plasmid encoding IL-12 (pIL-12), we investigated the combined effect of chemotherapy and gene therapy. PMet-P(cdmPEG_2K) micelles co-loaded with DOX and pIL-12 were more effective at inhibiting tumor growth compared to micelles loaded with DOX or pIL-12 alone. In addition, this micellar system was effective in co-delivery of siRNA and DOX into tumor cells. Our results suggest that PMet-P(cdmPEG_2K) has the potential for chemo and nucleic acid combined cancer therapy.

Dramatic influence of the hydroxy functionality of azasugar moiety in the head group region of tocopherol-based cationic lipids on in vitro gene transfection efficacies

Cationic lipids have been effectively used as nonviral vectors for the delivery of polynucleic acids into the cytosol.

Delivery across the blood-brain barrier: nanomedicine for glioblastoma multiforme

The malignant brain cancer, glioblastoma multiforme (GBM), is heterogeneous, infiltrative, and associated with chemo- and radioresistance. Despite pharmacological advances, prognosis is poor. Delivery into the brain is hampered by the blood-brain barrier (BBB), which limits the efficacy of both conventional and novel therapies at the target site. Current treatments for GBM remain palliative rather than curative; therefore, innovative delivery strategies are required and nanoparticles (NPs) are at the forefront of future solutions. Since the FDA approval of Doxil® (1995) and Abraxane (2005), the first generation of nanomedicines, development of nano-based therapies as anti-cancer treatments has escalated. A new generation of NPs has been investigated to efficiently deliver therapeutic agents to the brain, overcoming the restrictive properties of the BBB. This review discusses obstacles encountered with systemic administration along with integration of NPs incorporated with conventional and emerging treatments. Barriers to brain drug delivery, NP transport mechanisms across the BBB, effect of opsonisation on NPs administered systemically, and peptides as NP systems are addressed.

Progress in arginine-based gene delivery systems

Arginine based gene delivery systems with enhanced membrane penetration and lower cytotoxicity greatly enrich the gene vectors library and outline a new development direction of gene delivery.

Cyclodextrin-based delivery systems for cancer treatment

Cyclodextrins, one of safe excipients, are able to form host-guest complexes with fitted molecules given the unique nature imparted by their structure in result of a number of pharmaceutical applications. On the other hand, targeted or responsive materials are appealing therapeutic platforms for the development of next-generation precision medications. Meanwhile, cyclodextrin-based polymers or assemblies can condense DNA and RNA in result to be used as genetic therapeutic agents. Armed with a better understanding of various pharmaceutical mechanisms, especially for cancer treatment, researchers have made lots of works about cyclodextrin-based drug delivery systems in materials chemistry and pharmaceutical science. This Review highlights recent advances in cyclodextrin-based delivery systems for cancer treatment capable of targeting or responding to the physiological environment. Key design principles, challenges and future directions, including clinical translation, of cyclodextrin-based delivery systems are also discussed.

Enhanced nanoparticle delivery exploiting tumour-responsive formulations

Nanoparticles can be used as drug carriers, contrast agents and radiosensitisers for the treatment of cancer. Nanoparticles can either passively accumulate within tumour sites, or be conjugated with targeting ligands to actively enable tumour deposition. With respect to passive accumulation, particles < 150 nm accumulate with higher efficiency within the tumour microenvironment, a consequence of the enhanced permeability and retention effect. Despite these favourable properties, clinical translation of nano-therapeutics is inhibited due to poor in vivo stability, biodistribution and target cell internalisation. Nano-therapeutics can be modified to exploit features of the tumour microenvironment such as elevated hypoxia, increased pH and a compromised extracellular matrix. This is in contrast to cytotoxic chemotherapies which generally do not exploit the characteristic pathological features of the tumour microenvironment, and as such are prone to debilitating systemic toxicities. This review examines strategies for tumour microenvironment targeting to improve nanoparticle delivery, with particular focus on the delivery of nucleic acids and gold nanoparticles. Evidence for key research areas and future technologies are presented and critically evaluated. Among the most promising technologies are the development of next-generation cell penetrating peptides and the incorporation of micro-environment responsive stealth molecules.

M3RNA Drives Targeted Gene Delivery in Acute Myocardial Infarction

IMPACT STATEMENT

The M³RNA (microencapsulated modified messenger RNA) platform is an approach to deliver messenger RNA (mRNA) in vivo, achieving a nonintegrating and viral-free approach to gene therapy. This technology was, in this study, tested for its utility in the myocardium, providing a unique avenue for targeted gene delivery into the freshly infarcted myocardial tissue. This study provides the evidentiary basis for the use of M³RNA in the heart through depiction of its performance in cultured cells, healthy rodent myocardium, and acutely injured porcine hearts. By testing the technology in large animal models of infarction, compatibility of M³RNA with current coronary intervention procedures was verified.

Systemic tumor-targeted sodium iodide symporter (NIS) gene therapy of hepatocellular carcinoma mediated by B6 peptide polyplexes

BACKGROUND

Nonviral polymer-based gene transfer represents an adaptable system for tumor-targeted gene therapy because various design strategies of shuttle systems, together with the mechanistic concept of active tumor targeting, lead to improved gene delivery vectors resulting in higher tumor specificity, efficacy and safety.

METHODS

Using the sodium iodide symporter (NIS) as a theranostic gene, nonviral gene delivery vehicles based on linear polyethylenimine (LPEI), polyethylene glycol (PEG) and coupled to the synthetic peptide B6 (LPEI-PEG-B6), which specifically binds to tumor cells, were investigated in a hepatocellular carcinoma xenograft model for tumor selectivity and transduction efficiency.

RESULTS

In vitro incubation of three different tumor cell lines with LPEI-PEG-B6/NIS resulted in significant increase in iodide uptake activity compared to untargeted and empty vectors. After establishment of subcutaneous HuH7 tumors, NIS-conjugated nanoparticles were injected intravenously followed by analysis of radioiodide biodistribution using ¹²³ I-scintigraphy showing significant perchlorate-sensitive iodide accumulation in tumors of LPEI-PEG-B6/NIS-treated mice (8.0 ± 1.5% ID/g ¹²³ I; biological half-life of 4 h). After four cycles of repetitive polyplex/¹³¹ I applications, a significant delay of tumor growth was observed, which was associated with markedly improved survival in the therapy group.

CONCLUSIONS

These results clearly demonstrate that systemic in vivo NIS gene transfer using nanoparticle vectors coupled to B6 tumor targeting ligand is capable of inducing tumor-specific radioiodide uptake. This promising gene therapy approach opens the exciting prospect of NIS-mediated radionuclide therapy in metastatic cancer, together with the possibility of combining several targeting ligands to enhance selective therapeutic efficacy in a broad field of cancer types with various receptor expression profiles.

Therapeutic targeting of non-coding RNAs in cancer

The majority of the human genome encodes RNAs that do not code for proteins. These non-coding RNAs (ncRNAs) affect normal expression of the genes, including oncogenes and tumour suppressive genes, which make them a new class of targets for drug development in cancer. Although microRNAs (miRNAs) are the most studied regulatory ncRNAs to date, and miRNA-targeted therapeutics have already reached clinical development, including the mimics of the tumour suppressive miRNAs miR-34 and miR-16, which reached phase I clinical trials for the treatment of liver cancer and mesothelioma, the importance of long non-coding RNAs (lncRNAs) is increasingly being recognised. Here, we describe obstacles and advances in the development of ncRNA therapeutics and provide the comprehensive overview of the ncRNA chemistry and delivery technologies. Furthermore, we summarise recent knowledge on the biological functions of miRNAs and their involvement in carcinogenesis, and discuss the strategies of their therapeutic manipulation in cancer. We review also the emerging insights into the role of lncRNAs and their potential as targets for novel treatment paradigms. Finally, we provide the up-to-date summary of clinical trials involving miRNAs and future directions in the development of ncRNA therapeutics.

The Potential of Zebrafish as a Model Organism for Improving the Translation of Genetic Anticancer Nanomedicines

In the last few decades, the field of nanomedicine applied to cancer has revolutionized cancer treatment: several nanoformulations have already reached the market and are routinely being used in the clinical practice. In the case of genetic nanomedicines, i.e., designed to deliver gene therapies to cancer cells for therapeutic purposes, advances have been less impressive. This is because of the many barriers that limit the access of the therapeutic nucleic acids to their target site, and the lack of models that would allow for an improvement in the understanding of how nanocarriers can be tailored to overcome them. Zebrafish has important advantages as a model species for the study of anticancer therapies, and have a lot to offer regarding the rational development of efficient delivery of genetic nanomedicines, and hence increasing the chances of their successful translation. This review aims to provide an overview of the recent advances in the development of genetic anticancer nanomedicines, and of the zebrafish models that stand as promising tools to shed light on their mechanisms of action and overall potential in oncology.

Preparation, characterization, and transfection efficiency of low molecular weight polyethylenimine-based nanoparticles for delivery of the plasmid encoding CD200 gene

Various strategies have been utilized to improve both gene transfer efficiency and cell-induced toxicity of polyethylenimine (PEI), the most extensively investigated cationic polymeric vector. In this study, we sought to enhance transfection efficiency of low molecular weight PEI (LMW PEI) while maintaining its low toxicity by cross-linking LMW PEI via succinic acid linker. These modifications were designed to improve the hydrophilic–hydrophobic balance of the polymer, by enhancing the buffering capacity and maintaining low cytotoxic effects of the final conjugate. Decreased expression of CD200 in the central nervous system has been considered as one of the proposed mechanisms associated with neuroinflammation in multiple sclerosis; therefore, we selected plasmid-encoding CD200 gene for transfection using the modified PEI derivatives. Dynamic light scattering experiments demonstrated that the modified PEIs were able to condense plasmid DNA and form polyplexes with a size of approximately 130 nm. The highest level of CD200 expression was achieved at a carrier to plasmid ratio of 8, where the expression level was increased by 1.5 fold in the SH-SY5Y cell line, an in vitro model of neurodegenerative disorders. Furthermore, the results of in vivo imaging of the LMW PEI-based nanoparticles in the mouse model of multiple sclerosis revealed that fluorescently labeled plasmid encoding CD200 was distributed from the injection site to various tissues and organs including lymph nodes, liver, brain, and finally, kidneys. The nanoparticles also showed the ability to cross the blood–brain barrier and enter the periventricular area.

Self-assembled core–shell-corona multifunctional non-viral vector with AIE property for efficient hepatocyte-targeting gene delivery

Core–shell-corona multifunctional nanoparticles were prepared and used for cell imaging and cell-targeting delivery of genes toward hepatocytes.