Rapid Optimization of Gene Delivery by Parallel End-modification of Poly(β-amino ester)s

A new era of targeting cystic fibrosis with non-viral delivery of genomic medicines

Cystic fibrosis (CF) is a complex genetic respiratory disorder that necessitates innovative gene delivery strategies to address the mutations in the gene. This review delves into the promises and challenges of non-viral gene delivery for CF therapy and explores strategies to overcome these hurdles. Several emerging technologies and nucleic acid cargos for CF gene therapy are discussed. Novel formulation approaches including lipid and polymeric nanoparticles promise enhanced delivery through the CF mucus barrier, augmenting the potential of non-viral strategies. Additionally, safety considerations and regulatory perspectives play a crucial role in navigating the path toward clinical translation of gene therapy.

Enhancing gene transfection of poly(β-amino ester)s through modulation of amphiphilicity and chain sequence

Poly(β-amino ester)s (PAEs) have emerged as a type of highly safe and efficient non-viral DNA delivery vectors. However, the influence of amphiphilicity and chain sequence on DNA transfection efficiency and safety profile remain largely unexplored. In this study, four PAEs with distinct amphiphilicity and chain sequences were synthesized. Results show that both amphiphilicity and chain sequence significantly affect the DNA binding and condensation ability of PAEs, as well as size, zeta potential and cellular uptake of PAE/DNA polyplexes. PAEs with different amphiphilicity and chain sequence exhibit cell type-dependent transfection capabilities: in human bladder transitional cell carcinoma (UM-UC-3), hydrophilic PAE (P-Philic) and amphiphilic PAE random copolymer (R-Amphilic) exhibit relatively higher gene transfection efficiency, while in human bladder epithelial immortalized cells (SV-HUC-1), hydrophobic PAE (P-Phobic), R-Amphilic, and amphiphilic PAE block copolymer (B-Amphilic) demonstrate higher transfection capability. Regardless of cell types, amphiphilic PAE block copolymer (B-Amphilic) always exhibits much lower gene transfection efficiency. In addition, in human colon cancer cells (HCT-116), P-Philic and R-Amphilic achieved superior gene transfection efficiency at high and low polymer/DNA weight ratios, respectively. Importantly, R-Amphilic can effectively deliver the gene encoding tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to human chondrosarcoma cells SW1353 to induce their apoptosis, highlighting its potential application in cancer gene therapy. This study not only establishes a new paradigm for enhancing the gene transfection efficiency of PAEs by modulating their amphiphilicity and chain sequence but also identifies R-Amphilic as a potential candidate for the effective delivery of TRAIL gene in cancer gene therapy.

Co-delivering irinotecan and imiquimod by pH-responsive micelle amplifies anti-tumor immunity against colorectal cancer

Irinotecan (IRT), a classic clinical chemotherapeutic agent for treating colorectal cancer, has been found to induce immunogenic cell death (ICD) while exerting cytotoxicity in tumor cells. This effect is likely to be amplified in combination with immune modulators. Unfortunately, free drugs without targeting capacity would receive poor outcomes and strong side effects. To address these issues, in this work, an acid-sensitive micelle based on an amphiphilic poly(β-amino ester) derivative was constructed to co-deliver IRT and the immune adjuvant imiquimod (IMQ), termed PII. PII kept stable under normal physiological conditions. After internalization by tumor cells, PII dissociated in acidic lysosomes and released IRT and IMQ rapidly. In the CT26 tumor mouse model, PII increased the intra-tumoral SN38 (the active metabolite of IRT) and IMQ concentrations by up to 9.39 and 3.44 times compared with the free drug solution. The tumor inhibition rate of PII achieved 87.29%. This might profit from that IRT induced ICD, which promoted dendritic cells (DCs) maturation and intra-tumoral infiltration of CD8+ T cells. In addition, IMQ enhanced the antigen presenting ability of DCs and stimulated tumor associated macrophages to secrete tumor-killing cytokines. PII provided an effective strategy to combat colorectal cancer by synergy of chemotherapy and immunoregulation.

Potent gene delivery from fluorinated poly(β-amino ester) in adhesive and suspension difficult-to-transfect cells for apoptosis and ferroptosis

Tremendous efforts have been made to improve polymeric property in gene delivery performances, especially when obstacle of transferring gene construct into difficult-to-transfect cells occurs. Innovations in the area of fluorination and fluorinated compounds with biomedical potential in medicinal chemistry are believed to assist in the development of new therapeutics. Fluorine modified polymers have shown to navigate the gene transfection cellular barriers and promoted the transfection outcomes. Gene transfer into some liver cancer cells and human leukemia cells has always been a challenge. Here, by facile incorporation of a fluorine containing amine monomer, 1H,1H-undecafluorohexylamine, fluorinated poly(β-amino ester) (FPAE) was synthesized to significantly improve the transfection performance, achieving high transfection efficiency of 87% and 55% in two representative difficult-to-transfect cells, HepG2 and Molt-4, which were cultured in adhesive and suspension condition, respectively. However, the potency of Lipofectamine 3000 was very limited. More importantly, functional studies revealed that FPAE can dramatically outperform Lipofectamine 3000 in delivering Bcl-xL and PKCβII to either provide the protection against apoptosis or promote the ferroptosis in HepG2 cells. This work facilitates gene therapies by overcoming biological barriers for targeting difficult-to-transfect cells and disease models when medically necessary.

mRNA-Based Nanomedicine: A New Strategy for Treating Infectious Diseases and Beyond

Messenger RNA (mRNA) has emerged as a new therapeutic agent for the prevention and treatment of a wide range of diseases. The recent achievement of the two lipid nanoparticle-mRNA vaccines developed by Moderna and Pfizer-BioNTech against coronavirus 2019 (COVID-19) disease in record time highlights the huge potential of mRNA technology and reshaping the landscape of vaccine development and the future of gene therapies. Challenges related to translational efficacy, mRNA stability, immunogenicity, and ensuring the quality of final products have been significantly improved by recent advancements in mRNA engineering and delivery. Thus, the present review aims to provide the latest innovations that incrementally overcome these issues and future directions in the context of ongoing clinical trials against infectious diseases and beyond.

Early chromosome condensation by XIST builds A-repeat RNA density that facilitates gene silencing

XIST RNA triggers chromosome-wide gene silencing and condenses an active chromosome into a Barr body. Here, we use inducible human XIST to examine early steps in the process, showing that XIST modifies cytoarchitecture before widespread gene silencing. In just 2-4 h, barely visible transcripts populate the large "sparse zone" surrounding the smaller "dense zone"; importantly, density zones exhibit different chromatin impacts. Sparse transcripts immediately trigger immunofluorescence for H2AK119ub and CIZ1, a matrix protein. H3K27me3 appears hours later in the dense zone, which enlarges with chromosome condensation. Genes examined are silenced after compaction of the RNA/DNA territory. Insights into this come from the findings that the A-repeat alone can silence genes and rapidly, but only where dense RNA supports sustained histone deacetylation. We propose that sparse XIST RNA quickly impacts architectural elements to condense the largely non-coding chromosome, coalescing RNA density that facilitates an unstable, A-repeat-dependent step required for gene silencing.

Advances in Functionalization of Bioresorbable Nanomembranes and Nanoparticles for Their Use in Biomedicine

Bioresorbable nanomembranes (NMs) and nanoparticles (NPs) are powerful polymeric materials playing an important role in biomedicine, as they can effectively reduce infections and inflammatory clinical patient conditions due to their high biocompatibility, ability to physically interact with biomolecules, large surface area, and low toxicity. In this review, the most common bioabsorbable materials such as those belonging to natural polymers and proteins for the manufacture of NMs and NPs are reviewed. In addition to biocompatibility and bioresorption, current methodology on surface functionalization is also revisited and the most recent applications are highlighted. Considering the most recent use in the field of biosensors, tethered lipid bilayers, drug delivery, wound dressing, skin regeneration, targeted chemotherapy and imaging/diagnostics, functionalized NMs and NPs have become one of the main pillars of modern biomedical applications.

Branch Unit Distribution Matters for Gene Delivery

As a key nonviral gene therapy vector, poly(β-amino ester) (PAE) has demonstrated great potential for clinical application after two decades of development. However, even after extensive efforts in structural optimizations, including screening chemical composition, molecular weight (MW), terminal groups, and topology, their DNA delivery efficiency still lags behind that of viral vectors. To break through this bottleneck, in this work, a thorough investigation of highly branched PAEs (HPAEs) was conducted to correlate their fundamental internal structure with their gene transfection performance. We show that an essential structural factor, branch unit distribution (BUD), plays an important role for HPAE transfection capability and that HPAEs with a more uniform distribution of branch units display better transfection efficacy. By optimizing BUD, a high-efficiency HPAE that surpasses well-known commercial reagents (e.g., Lipofectamine 3000 (Lipo3000), jetPEI, and Xfect) can be generated. This work opens an avenue for the structural control and molecular design of high-performance PAE gene delivery vectors.

Performance of nanoparticles for biomedical applications: The in vitro/in vivo discrepancy

Nanomedicine has a great potential to revolutionize the therapeutic landscape. However, up-to-date results obtained from in vitro experiments predict the in vivo performance of nanoparticles weakly or not at all. There is a need for in vitro experiments that better resemble the in vivo reality. As a result, animal experiments can be reduced, and potent in vivo candidates will not be missed. It is important to gain a deeper knowledge about nanoparticle characteristics in physiological environment. In this context, the protein corona plays a crucial role. Its formation process including driving forces, kinetics, and influencing factors has to be explored in more detail. There exist different methods for the investigation of the protein corona and its impact on physico-chemical and biological properties of nanoparticles, which are compiled and critically reflected in this review article. The obtained information about the protein corona can be exploited to optimize nanoparticles for in vivo application. Still the translation from in vitro to in vivo remains challenging. Functional in vitro screening under physiological conditions such as in full serum, in 3D multicellular spheroids/organoids, or under flow conditions is recommended. Innovative in vivo screening using barcoded nanoparticles can simultaneously test more than hundred samples regarding biodistribution and functional delivery within a single mouse.

Inflammation-modulating nanoparticles for pneumonia therapy

Pneumonia is a common but serious infectious disease, and is the sixth leading cause for death. The foreign pathogens such as viruses, fungi, and bacteria establish an inflammation response after interaction with lung, leading to the filling of bronchioles and alveoli with fluids. Although the pharmacotherapies have shown their great effectiveness to combat pathogens, advanced methods are under developing to treat complicated cases such as virus-infection and lung inflammation or acute lung injury (ALI). The inflammation modulation nanoparticles (NPs) can effectively suppress immune cells and inhibit inflammatory molecules in the lung site, and thereby alleviate pneumonia and ALI. In this review, the pathological inflammatory microenvironments in pneumonia, which are instructive for the design of biomaterials therapy, are summarized. The focus is then paid to the inflammation-modulating NPs that modulate the inflammatory cells, cytokines and chemokines, and microenvironments of pneumonia for better therapeutic effects. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease.

An intelligent responsive macrophage cell membrane-camouflaged mesoporous silicon nanorod drug delivery system for precise targeted therapy of tumors

Macrophage cell membrane-camouflaged nanocarriers can effectively reduce immune cell clearance and actively target tumors. In this study, a macrophage cell membrane-camouflaged mesoporous silica nanorod (MSNR)-based antitumor drug carrier equipped with a cationic polymer layer was developed. As drug carriers, these MSNRs were loaded with the thermosensitive phase change material L-menthol (LM), the chemotherapy drug doxorubicin (DOX) and the fluorescent molecule indocyanine green (ICG). The rod-like shape of the MSNRs was shown to enhance the penetration of the drug carriers to tumors. In the weakly acidic tumor microenvironment, the cationic polymer exhibited a proton sponge effect to trigger macrophage cell membrane coating detachment, promoting tumor cell uptake. Following nanocarrier uptake, ICG is heated by near-infrared (NIR) irradiation to make LM undergo a phase transition to release DOX and generate a synergistic effect of thermochemotherapy which kills tumor cells and inhibits tumor growth together with reactive oxygen species (ROS) produced by ICG. Overall, this nanohybrid drug delivery system demonstrates an intelligent cascade response, leads to tissue-cell specific targeting and improves drug release accuracy, thus proving to be an effective cancer therapy.

Highly branched poly(β-amino ester)s for gene delivery in hereditary skin diseases

Non-viral gene therapy for hereditary skin diseases is an attractive prospect. However, research efforts dedicated to this area are rare. Taking advantage of the branched structural possibilities of polymeric vectors, we have developed a gene delivery platform for the treatment of an incurable monogenic skin disease - recessive dystrophic epidermolysis bullosa (RDEB) - based on highly branched poly(β-amino ester)s (HPAEs). The screening of HPAEs and optimization of therapeutic gene constructs, together with evaluation of the combined system for gene transfection, were comprehensively reviewed. The successful restoration of type VII collagen (C7) expression both in vitro and in vivo highlights HPAEs as a promising generation of polymeric vectors for RDEB gene therapy into the clinic. Considering that the treatment of patients with genetic cutaneous disorders, such as other subtypes of epidermolysis bullosa, pachyonychia congenita, ichthyosis and Netherton syndrome, remains challenging, the success of HPAEs in RDEB treatment indicates that the development of viable polymeric gene delivery vectors could potentially expedite the translation of gene therapy for these diseases from bench to bedside.

High-throughput screening of nanoparticles in drug delivery

The use of pharmacologically active compounds to manage and treat diseases is of utmost relevance in clinical practice. It is well recognized that spatial-temporal control over the delivery of these biomolecules will greatly impact their pharmacokinetic profile and ultimately their therapeutic effect. Nanoparticles (NPs) prepared from different materials have been tested successfully in the clinic for the delivery of several biomolecules including non-coding RNAs (siRNA and miRNA) and mRNAs. Indeed, the recent success of mRNA vaccines is in part due to progress in the delivery systems (NP based) that have been developed for many years. In most cases, the identification of the best formulation was done by testing a small number of novel formulations or by modification of pre-existing ones. Unfortunately, this is a low throughput and time-consuming process that hinders the identification of formulations with the highest potential. Alternatively, high-throughput combinatorial design of NP libraries may allow the rapid identification of formulations with the required release and cell/tissue targeting profile for a given application. Combinatorial approaches offer several advantages over conventional methods since they allow the incorporation of multiple components with varied chemical properties into materials, such as polymers or lipid-like materials, that will subsequently form NPs by self-assembly or chemical conjugation processes. The current review highlights the impact of high-throughput in the development of more efficient drug delivery systems with enhanced targeting and release kinetics. It also describes the current challenges in this research area as well as future directions.

Systemic delivery of mRNA and DNA to the lung using polymer-lipid nanoparticles

Non-viral vectors offer the potential to deliver nucleic acids including mRNA and DNA into cells in vivo. However, designing materials that effectively deliver to target organs and then to desired compartments within the cell remains a challenge. Here we develop polymeric materials that can be optimized for either DNA transcription in the nucleus or mRNA translation in the cytosol. We synthesized poly(beta amino ester) terpolymers (PBAEs) with modular changes to monomer chemistry to investigate influence on nucleic acid delivery. We identified two PBAEs with a single monomer change as being effective for either DNA (D-90-C12-103) or mRNA (DD-90-C12-103) delivery to lung endothelium following intravenous injection in mice. Physical properties such as particle size or charge did not account for the difference in transfection efficacy. However, endosome co-localization studies revealed that D-90-C12-103 nanoparticles resided in late endosomes to a greater extent than DD-90-C12-103. We compared luciferase expression in vivo and observed that, even with nucleic acid optimized vectors, peak luminescence using mRNA was two orders of magnitude greater than pDNA in the lungs of mice following systemic delivery. This study indicates that different nucleic acids require tailored delivery vectors, and further support the potential of PBAEs as intracellular delivery materials.

Polyplex-Loaded Hydrogels for Local Gene Delivery to Human Dermal Fibroblasts

Impaired cutaneous healing leading to chronic wounds affects between 2 and 6% of the total population in most developed countries and it places a substantial burden on healthcare budgets. Current treatments involving antibiotic dressings and mechanical debridement are often not effective, causing severe pain, emotional distress, and social isolation in patients for years or even decades, ultimately resulting in limb amputation. Alternatively, gene therapy (such as mRNA therapies) has emerged as a viable option to promote wound healing through modulation of gene expression. However, protecting the genetic cargo from degradation and efficient transfection into primary cells remain significant challenges in the push to clinical translation. Another limiting aspect of current therapies is the lack of sustained release of drugs to match the therapeutic window. Herein, we have developed an injectable, biodegradable and cytocompatible hydrogel-based wound dressing that delivers poly(β-amino ester)s (pBAEs) nanoparticles in a sustained manner over a range of therapeutic windows. We also demonstrate that pBAE nanoparticles, successfully used in previous in vivo studies, protect the mRNA load and efficiently transfect human dermal fibroblasts upon sustained release from the hydrogel wound dressing. This prototype wound dressing technology can enable the development of novel gene therapies for the treatment of chronic wounds.

Nanoparticles as Adjuvants and Nanodelivery Systems for mRNA-Based Vaccines

Messenger RNA (mRNA)-based vaccines have shown promise against infectious diseases and several types of cancer in the last two decades. Their promise can be attributed to their safety profiles, high potency, and ability to be rapidly and affordably manufactured. Now, many RNA-based vaccines are being evaluated in clinical trials as prophylactic and therapeutic vaccines. However, until recently, their development has been limited by their instability and inefficient in vivo transfection. The nanodelivery system plays a dual function in RNA-based vaccination by acting as a carrier system and as an adjuvant. That is due to its similarity to microorganisms structurally and size-wise; the nanodelivery system can augment the response by the immune system via simulating the natural infection process. Nanodelivery systems allow non-invasive mucosal administration, targeted immune cell delivery, and controlled delivery, reducing the need for multiple administrations. They also allow co-encapsulating with immunostimulators to improve the overall adjuvant capacity. The aim of this review is to discuss the recent developments and applications of biodegradable nanodelivery systems that improve RNA-based vaccine delivery and enhance the immunological response against targeted diseases.

Poly(beta-amino ester)s as gene delivery vehicles: challenges and opportunities

INTRODUCTION

Gene delivery technologies are being developed for an increasing number of biomedical applications, with delivery vehicles including viruses and non-viral materials. Among biomaterials used for non-viral gene delivery, poly(beta-amino ester)s (PBAEs), a class of synthetic, biodegradable polymers, have risen as a leading gene delivery vehicle that has been used for multiple applications in vitro and in vivo.

AREAS COVERED

This review summarizes the key properties of PBAEs and their development, including a discussion of the advantages and disadvantages of PBAEs for gene delivery applications. The use of PBAEs to improve the properties of other drug delivery vehicles is also summarized.

EXPERT OPINION

PBAEs are designed to have multiple characteristics that are ideal for gene delivery, including their reversible positive charge, which promotes binding to nucleic acids as well as imparting high buffering capacity, and their rapid degradability under mild conditions. Simultaneously, some of their properties also lead to nanoparticle instability and low transfection efficiency in physiological environments. The ease with which PBAEs can be chemically modified as well as non-covalently blended with other materials, however, allows them to be customized specifically to overcome delivery barriers for varied applications.

mRNA Vaccine Era-Mechanisms, Drug Platform and Clinical Prospection

Messenger ribonucleic acid (mRNA)-based drugs, notably mRNA vaccines, have been widely proven as a promising treatment strategy in immune therapeutics. The extraordinary advantages associated with mRNA vaccines, including their high efficacy, a relatively low severity of side effects, and low attainment costs, have enabled them to become prevalent in pre-clinical and clinical trials against various infectious diseases and cancers. Recent technological advancements have alleviated some issues that hinder mRNA vaccine development, such as low efficiency that exist in both gene translation and in vivo deliveries. mRNA immunogenicity can also be greatly adjusted as a result of upgraded technologies. In this review, we have summarized details regarding the optimization of mRNA vaccines, and the underlying biological mechanisms of this form of vaccines. Applications of mRNA vaccines in some infectious diseases and cancers are introduced. It also includes our prospections for mRNA vaccine applications in diseases caused by bacterial pathogens, such as tuberculosis. At the same time, some suggestions for future mRNA vaccine development about storage methods, safety concerns, and personalized vaccine synthesis can be found in the context.

The Multifaceted Histidine-Based Carriers for Nucleic Acid Delivery: Advances and Challenges

Histidines incorporated into carriers of nucleic acids may enhance the extracellular stability of the nanoparticle, yet aid in the intracellular disruption of the nanoparticle, enabling the release of the nucleic acid. Moreover, protonation of histidines in the endosomes may result in endosomal swelling with subsequent lysis. These properties of histidine are based on its five-member imidazole ring in which the two nitrogen atoms may form hydrogen bonds or act as a base in acidic environments. A wide variety of carriers have integrated histidines or histidine-rich domains, which include peptides, polyethylenimine, polysaccharides, platform delivery systems, viral phages, mesoporous silica particles, and liposomes. Histidine-rich carriers have played key roles in our understanding of the stability of nanocarriers and the escape of the nucleic acids from endosomes. These carriers show great promise and offer marked potential in delivering plasmids, siRNA, and mRNA to their intracellular targets.

A combinatorial library of biodegradable polyesters enables non-viral gene delivery to post-mitotic human stem cell-derived polarized RPE monolayers

Safe and effective delivery of DNA to post-mitotic cells, especially highly differentiated cells, remains a challenge despite significant progress in the development of gene delivery tools. Biodegradable polymeric nanoparticles (NPs) offer an array of advantages for gene delivery over viral vectors due to improved safety, carrying capacity, ease of manufacture, and cell-type specificity. Here we demonstrate the use of a high-throughput screening (HTS) platform to synthesize and screen a library of 148 biodegradable polymeric nanoparticles, successfully identifying structures that enable efficient transfection of human pluripotent stem cell differentiated human retinal pigment epithelial (RPE) cells with minimal toxicity. These NPs can deliver plasmid DNA (pDNA) to RPE monolayers more efficiently than leading commercially available transfection reagents. Novel synthetic polymers are described that enable high efficacy non-viral gene delivery to hard-to-transfect polarized human RPE monolayers, enabling gene loss- and gain-of-function studies of cell signaling, developmental, and disease-related pathways. One new synthetic polymer in particular, 3,3'-iminobis(N,N-dimethylpropylamine)-end terminated poly(1,5-pentanediol diacrylate-co-3 amino-1-propanol) (5-3-J12), was found to form self-assembled nanoparticles when mixed with plasmid DNA that transfect a majority of these human post-mitotic cells with minimal cytotoxicity. The platform described here can be utilized as an enabling technology for gene transfer to human primary and stem cell-derived cells, which are often fragile and resistant to conventional gene transfer approaches.

Nanoparticles for nucleic acid delivery: Applications in cancer immunotherapy

Immunotherapy has recently emerged as a powerful tool for cancer treatment. Early clinical successes from cancer immunotherapy have led to a growing list of FDA approvals, and many new therapies are in clinical and preclinical development. Nucleic acid therapeutics, including DNA, mRNA, and genome editing systems, hold significant potential as a form of immunotherapy due to its robust use in cancer vaccination, adoptive T-cell therapy, and gene regulation. However, these therapeutics must overcome numerous delivery obstacles to be successful, including rapid in vivo degradation, poor uptake into target cells, required nuclear entry, and potential in vivo toxicity in healthy cells and tissues. Nanoparticle delivery systems have been engineered to overcome several of these barriers as a means to safely and effectively deliver nucleic acid therapeutics to immune cells. In this Review, we discuss the applications of nucleic acid therapeutics in cancer immunotherapy, and we detail how nanoparticle platforms have been designed to deliver mRNA, DNA, and genome editing systems to enhance the potency and safety of these therapeutics.

Delivering the Messenger: Advances in Technologies for Therapeutic mRNA Delivery

mRNA has broad potential as a therapeutic. Current clinical efforts are focused on vaccination, protein replacement therapies, and treatment of genetic diseases. The clinical translation of mRNA therapeutics has been made possible through advances in the design of mRNA manufacturing and intracellular delivery methods. However, broad application of mRNA is still limited by the need for improved delivery systems. In this review, we discuss the challenges for clinical translation of mRNA-based therapeutics, with an emphasis on recent advances in biomaterials and delivery strategies, and we present an overview of the applications of mRNA-based delivery for protein therapy, gene editing, and vaccination.

Inhaled Nanoformulated mRNA Polyplexes for Protein Production in Lung Epithelium

Noninvasive aerosol inhalation is an established method of drug delivery to the lung, and remains a desirable route for nucleic-acid-based therapeutics. In vitro transcribed (IVT) mRNA has broad therapeutic applicability as it permits temporal and dose-dependent control of encoded protein expression. Inhaled delivery of IVT-mRNA has not yet been demonstrated and requires development of safe and effective materials. To meet this need, hyperbranched poly(beta amino esters) (hPBAEs) are synthesized to enable nanoformulation of stable and concentrated polyplexes suitable for inhalation. This strategy achieves uniform distribution of luciferase mRNA throughout all five lobes of the lung and produces 101.2 ng g-1 of luciferase protein 24 h after inhalation of hPBAE polyplexes. Importantly, delivery is localized to the lung, and no luminescence is observed in other tissues. Furthermore, using an Ai14 reporter mouse model it is identified that 24.6% of the total lung epithelial cell population is transfected after a single dose. Repeat dosing of inhaled hPBAE-mRNA generates consistent protein production in the lung, without local or systemic toxicity. The results indicate that nebulized delivery of IVT-mRNA facilitated by hPBAE vectors may provide a clinically relevant delivery system to lung epithelium.

Optimization of a Degradable Polymer-Lipid Nanoparticle for Potent Systemic Delivery of mRNA to the Lung Endothelium and Immune Cells

mRNA therapeutics hold great potential for treating a variety of diseases through protein-replacement, immunomodulation, and gene editing. However, much like siRNA therapy the majority of progress in mRNA delivery has been confined to the liver. Previously, we demonstrated that poly(β-amino esters), a class of degradable polymers, are capable of systemic mRNA delivery to the lungs in mice when formulated into nanoparticles with poly(ethylene glycol)-lipid conjugates. Using experimental design, a statistical approach to optimization that reduces experimental burden, we demonstrate herein that these degradable polymer-lipid nanoparticles can be optimized in terms of polymer synthesis and nanoparticle formulation to achieve a multiple order-of-magnitude increase in potency. Furthermore, using genetically engineered Cre reporter mice, we demonstrate that mRNA is functionally delivered to both the lung endothelium and pulmonary immune cells, expanding the potential utility of these nanoparticles.

Poly(β-amino ester)-co-poly(caprolactone) Terpolymers as Nonviral Vectors for mRNA Delivery In Vitro and In Vivo

The production of new proteins with messenger RNA (mRNA) has gained a broad interest due to its potential for addressing a wide range of diseases. Here, the design and characterization of novel ionizable poly(β-amino ester)-co-poly(caprolactone) terpolymers, synthesized via the combination of the ring opening polymerization and the Michael step-growth polymerization, are reported. The versatility of this method is demonstrated by varying the number of caprolactone units attached to each poly(β-amino ester) (PBAE) terpolymer. The ability of the novel poly-caprolactone (PCL)-based PBAE materials to deliver mRNA is shown to depend on the physiochemical characteristics of the material, such as lipophilicity, as well as the formulation method used to complex the polymer with the oligonucleotide. This latter variable represents a previously unstudied aspect of PBAE library screens that can play an important role in identifying true top candidates for nucleic acid delivery. The most stable terpolymer is injected intravenously (IV) in mice and shows a transfection efficacy several times higher than the polyethylenimine (PEI) which is focused in the spleen, opening the possibility to use these biodegradable carriers in the intravenous delivery of antigen-encoding mRNA for cancer immunotherapy and vaccination.

Biodegradable brain-penetrating DNA nanocomplexes and their use to treat malignant brain tumors

The discovery of powerful genetic targets has spurred clinical development of gene therapy approaches to treat patients with malignant brain tumors. However, lack of success in the clinic has been attributed to the inability of conventional gene vectors to achieve gene transfer throughout highly disseminated primary brain tumors. Here, we demonstrate ex vivo that small nanocomplexes composed of DNA condensed by a blend of biodegradable polymer, poly(β-amino ester) (PBAE), with PBAE conjugated with 5kDa polyethylene glycol (PEG) molecules (PBAE-PEG) rapidly penetrate healthy brain parenchyma and orthotopic brain tumor tissues in rats. Rapid diffusion of these DNA-loaded nanocomplexes observed in fresh tissues ex vivo demonstrated that they avoided adhesive trapping in the brain owing to their dense PEG coating, which was critical to achieving widespread transgene expression throughout orthotopic rat brain tumors in vivo following administration by convection enhanced delivery. Transgene expression with the PBAE/PBAE-PEG blended nanocomplexes (DNA-loaded brain-penetrating nanocomplexes, or DNA-BPN) was uniform throughout the tumor core compared to nanocomplexes composed of DNA with PBAE only (DNA-loaded conventional nanocomplexes, or DNA-CN), and transgene expression reached beyond the tumor edge, where infiltrative cancer cells are found, only for the DNA-BPN formulation. Finally, DNA-BPN loaded with anti-cancer plasmid DNA provided significantly enhanced survival compared to the same plasmid DNA loaded in DNA-CN in two aggressive orthotopic brain tumor models in rats. These findings underscore the importance of achieving widespread delivery of therapeutic nucleic acids within brain tumors and provide a promising new delivery platform for localized gene therapy in the brain.

Polymer-Lipid Nanoparticles for Systemic Delivery of mRNA to the Lungs

Therapeutic nucleic acids hold great promise for the treatment of disease but require vectors for safe and effective delivery. Synthetic nanoparticle vectors composed of poly(β-amino esters) (PBAEs) and nucleic acids have previously demonstrated potential utility for local delivery applications. To expand this potential utility to include systemic delivery of mRNA, hybrid polymer-lipid nanoformulations for systemic delivery to the lungs were developed. Through coformulation of PBAEs with lipid-polyethylene glycol (PEG), mRNA formulations were developed with increased serum stability and increased in vitro potency. The formulations were capable of functional delivery of mRNA to the lungs after intravenous administration in mice. To our knowledge, this is the first report of the systemic administration of mRNA for delivery to the lungs using degradable polymer-lipid nanoparticles.

Biodegradable DNA Nanoparticles that Provide Widespread Gene Delivery in the Brain

Successful gene therapy of neurological disorders is predicated on achieving widespread and uniform transgene expression throughout the affected disease area in the brain. However, conventional gene vectors preferentially travel through low-resistance perivascular spaces and/or are confined to the administration site even with the aid of a pressure-driven flow provided by convection-enhanced delivery. Biodegradable DNA nanoparticles offer a safe gene delivery platform devoid of adverse effects associated with virus-based or synthetic nonbiodegradable systems. Using a state-of-the-art biodegradable polymer, poly(β-amino ester), colloidally stable sub-100 nm DNA nanoparticles are engineered with a nonadhesive polyethylene glycol corona that are able to avoid the adhesive and steric hindrances imposed by the extracellular matrix. Following convection enhanced delivery, these brain-penetrating nanoparticles are able to homogeneously distribute throughout the rodent striatum and mediate widespread and high-level transgene expression. These nanoparticles provide a biodegradable DNA nanoparticle platform enabling uniform transgene expression patterns in vivo and hold promise for the treatment of neurological diseases.

Novel Disulfide-Containing Poly(β-amino ester)-Functionalised Magnetic Nanoparticles for Efficient Gene Delivery

Poly(β-amino ester)s (PBAEs) have been proved to effectively transfer DNA to various cell types. However, PBAEs with high molecular weights also show considerable toxicities, partly resulting from inadequate degradation of their polyester backbone. In this study, we created novel poly(β-amino ester)s (SF-1, 2, 3, and 4; notation SFs refers to all the four polymers) which were characterised by the cleavable disulfide bonds. Moreover, a new technique, termed magnetofection that uses magnetic nanoparticles to enhance gene expression, has recently been well developed. The negatively charged magnetic nanoparticles (MNPs) with good biocompatibility in vitro were prepared here to subsequently combine with SFs and DNA via electrostatic interaction, leading to the formation of the magnetic gene complexes MNP/SFs/DNA. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and transfection experiments were performed in A549 cells to investigate all the resulting complexes. Studies indicated that the synthesised PBAEs exhibited good biodegradation and regulated release of DNA as a result of the reductive cleavage of the disulfide bonds, giving higher transfection efficiency along with much lower cytotoxicity compared with commercially available transfection agent polyethylenimine (Mw 25 kDa). Furthermore, when MNP was involved at a MNP/DNA weight ratio of 0.5, the magnetic gene complexes MNP/SFs/DNA showed enhanced levels of gene expression while maintaining low cytotoxicity.

Materials for non-viral intracellular delivery of messenger RNA therapeutics

Though therapeutics based on messenger RNA (mRNA) have broad potential in applications such as protein replacement therapy, cancer immunotherapy, and genomic engineering, their effective intracellular delivery remains a challenge. A chemically diverse suite of delivery materials with origins as materials for cellular transfection of DNA and small interfering RNAs (siRNAs) has recently been reported to have promise as non-viral delivery agents for mRNA. These materials include covalent conjugates, protamine complexes, nanoparticles based on lipids or polymers, and hybrid formulations. This review will highlight the use of delivery materials for mRNA, with a specific focus on their mechanisms of action, routes of administration, and dosages. Additionally, strategies in which these materials can be adapted and optimized to address challenges specific to mRNA delivery are also discussed. The technologies included have shown varying promise for therapeutic use, specifically having been used to deliver mRNA in vivo or exhibiting characteristics that could make in vivo use a possibility. In so doing, it is the intention of this review to provide a comprehensive look at the progress and possibilities in applying nucleic acid delivery technology specifically toward the emerging area of mRNA therapeutics.

Complexation and release of DNA in polyplexes formed with reducible linear poly(β-amino esters)

Designing nanocarriers for gene delivery is a multidisciplinary challenge that involves not only DNA condensation with biocompatible polymers, but also DNA-release processes. Once the genetic material is introduced into the cell, the rupture of degradable bonds permits the unpacking and release of the load. In this work, a dual-degradable polycation - composed by a linear poly(β-amino ester) chain in which ester and disulfide bonds coexist - has been used to condense a DNA plasmid. The goal was to reinforce the spontaneous hydrolysis of the ester groups with the intracellular break-up of the disulfide bonds, since these reducible bonds are degraded in the reductive intracellular environment. For a comparative study, two poly(β-amino ester) molecules differing only in the presence (or absence) of some SS bonds have been tested. DNA condensation, physico-chemical characterization of the polyplexes formed, and degradation studies have been carried out at pH 5 and pH 7. The acidic conditions gave the best nanoparticles, due to a better solubilization of both polymers and to a higher stability of the ester bonds. Despite the synthesis and storage of polyplexes were much more appropriate at pH 5, transfection efficiency in HeLa cells was similar irrespective the original pH used. Only in those polyplexes formed at low polymer:DNA ratios (i.e. 5 and 10 (w/w)) was transfection more effective when the plasmid was condensed at an acidic pH. With regard to the DNA-release efficiency in the intracellular medium, degradation of the polymers was practically governed by the rapid hydrolysis of the ester groups, this spontaneous and rapid process masking, unfortunately, any potential contribution associated with the breakup of the disulfide bonds.

Highly compacted biodegradable DNA nanoparticles capable of overcoming the mucus barrier for inhaled lung gene therapy

Gene therapy has emerged as an alternative for the treatment of diseases refractory to conventional therapeutics. Synthetic nanoparticle-based gene delivery systems offer highly tunable platforms for the delivery of therapeutic genes. However, the inability to achieve sustained, high-level transgene expression in vivo presents a significant hurdle. The respiratory system, although readily accessible, remains a challenging target, as effective gene therapy mandates colloidal stability in physiological fluids and the ability to overcome biological barriers found in the lung. We formulated highly stable DNA nanoparticles based on state-of-the-art biodegradable polymers, poly(β-amino esters) (PBAEs), possessing a dense corona of polyethylene glycol. We found that these nanoparticles efficiently penetrated the nanoporous and highly adhesive human mucus gel layer that constitutes a primary barrier to reaching the underlying epithelium. We also discovered that these PBAE-based mucus-penetrating DNA nanoparticles (PBAE-MPPs) provided uniform and high-level transgene expression throughout the mouse lungs, superior to several gold standard gene delivery systems. PBAE-MPPs achieved robust transgene expression over at least 4 mo following a single administration, and their transfection efficiency was not attenuated by repeated administrations, underscoring their clinical relevance. Importantly, PBAE-MPPs demonstrated a favorable safety profile with no signs of toxicity following intratracheal administration.

Surface charge tunability as a powerful strategy to control electrostatic interaction for high efficiency silencing, using tailored oligopeptide-modified poly(beta-amino ester)s (PBAEs)

Here we present an extended family of pBAEs that incorporate terminal oligopeptide moieties synthesized from both positive and negative amino acids. Polymer formulations of mixtures of negative and positive oligopeptide-modified pBAEs are capable of condensing siRNA into discrete nanoparticles. We have demonstrated that efficient delivery of nucleic acids in a cell-type dependent manner can be achieved by careful control of the pBAE formulation. In addition, our approach of adding differently charged oligopeptides to the termini of poly(β-amino ester)s is of great interest for the design of tailored complexes having specific features, such as tuneable zeta potential. We anticipate that this surface charge tunability may be a powerful strategy to control unwanted electrostatic interactions, while preserving high silencing efficiency and reduced toxicity.

Miniaturization of gene transfection assays in 384- and 1536-well microplates

The miniaturization of gene transfer assays to either 384- or 1536-well plates greatly economizes the expense and allows much higher throughput when transfecting immortalized and primary cells compared with more conventional 96-well assays. To validate the approach, luciferase and green fluorescent protein (GFP) reporter gene transfer assays were developed to determine the influence of cell seeding number, transfection reagent to DNA ratios, transfection time, DNA dose, and luciferin dose on linearity and sensitivity. HepG2, CHO, and NIH 3T3 cells were transfected with polyethylenimine (PEI)-DNA in both 384- and 1536-well plates. The results established optimal transfection parameters in 384-well plates in a total assay volume of 35μl and in 1536-well plates in a total assay volume of 8μl. A luciferase assay performed in 384-well plates produced a Z' score of 0.53, making it acceptable for high-throughput screening. Primary hepatocytes were harvested from mouse liver and transfected with PEI DNA and calcium phosphate DNA nanoparticles in 384-well plates. Optimal transfection of primary hepatocytes was achieved on as few as 250cellsperwell in 384-well plates, with CaPO4 proving to be 10-fold more potent than PEI.

Cationic Charged Polymer Vesicles from Amphiphilic PEI-g-PSSA-g-PEI as Potential Gene Delivery Vehicles

Polymer vesicles have attracted extensive interest for a variety of biomedical applications. Herein, novel polymer vesicles are prepared by the self-assembly of amphiphilic polyethyleneimine-g-poly(disulfide amine)-g-polyethyleneimine (PEI-g-PSSA-g-PEI) for gene delivery. To investigate the effect of hydrophobicity on transfection efficiency, a small series of PEI-g-PSSA-g-PEI were prepared under uniform conditions containing PEI fragments of the same molecular weight. The hydrophobicity of PEI-g-PSSA-g-PEI was adjusted by varying the hydrophobic content in the poly(disulfide amine) backbone and by choosing hydrophobic monomers ranging in length from C12 to C16. The hydrophobicity of polymers was also related to DNA binding affinity. Polymer vesicles obtained from the water-insoluble polymers condensed with DNA into polyplexes with sizes below 200 nm and surface charge ranging from +10 to +35 mV that were suitable for cell endocytosis. DNA polyplexes exhibited an inverted hexagonal structure, observed by transmission electron microscopy. The results of in vitro transfection demonstrate that the hydrophobic–hydrophilic balance of copolymers greatly affects their transfection properties. The top-performing polymer, II-70 %, showed improved transfection efficiency and significantly lower cytotoxicity on COS-7 cells when compared with commercial reagents polyethyleneimine (PEI 25K) and Lipofectamine 2000. These results indicate that cationic polymer vesicles with tunable hydrophobicity are promising materials for gene delivery.

MUC1 Promoter-Driven DTA as a Targeted Therapeutic Strategy against Pancreatic Cancer

Mucin1 (MUC1) is overexpressed in pancreatic ductal adenocarcinoma (PDA) and is associated with tumor aggressiveness, suggesting that MUC1 is a promising therapeutic target for promoter-driven diphtheria toxin A (DTA). Endogenous MUC1 transcript levels were analyzed by quantitative PCR (qPCR) in multiple PDA cells (Capan1, HPAFII, Su.86.86, Capan2, Hs766T, MiaPaCa2, and Panc1). Expression levels were correlated with luciferase activity and cell death after transfection with MUC1 promoter-driven luciferase and DTA constructs. MUC1-positive (+) cells had significantly elevated MUC1 mRNA expression compared with MUC1-negative (-) cells. Luciferase activity was significantly higher in MUC1(+) cells when transfected with MUC1 promoter-driven luciferase and MUC1(+) cells underwent enhanced cell death after transfection with a single dose of MUC1 promoter-driven DTA. IFNγ pretreatment enhanced MUC1 expression in MUC1(-) cells and induced sensitivity to MUC1-DTA therapy. Matched primary and metastatic tumor lesions from clinical specimens revealed similar MUC1 IHC labeling patterns, and a tissue microarray of human PDA biopsies revealed increased immunolabeling with a combination of MUC1 and mesothelin (MSLN) antibodies, compared with either antibody alone. Combining MUC1 with MSLN-targeted DTA enhanced drug efficacy in an in vitro model of heterogeneous PDA. These data demonstrate that MUC1 promoter-driven DTA preferentially kills MUC1-expressing PDA cells and drugs that enhance MUC1 expression sensitize PDA cells with low MUC1 expression.

IMPLICATIONS

MUC1 expression in primary and metastatic lesions provides a rationale for the development of a systemic MUC1 promoter-driven DTA therapy that may be further enhanced by combination with other promoter-driven DTA constructs.

Hybrid biosynthetic gene therapy vector development and dual engineering capacity

Genetic vaccines offer a treatment opportunity based upon successful gene delivery to specific immune cell modulators. Driving the process is the vector chosen for gene cargo packaging and subsequent delivery to antigen-presenting cells (APCs) capable of triggering an immune cascade. As such, the delivery process must successfully navigate a series of requirements and obstacles associated with the chosen vector and target cell. In this work, we present the development and assessment of a hybrid gene delivery vector containing biological and biomaterial components. Each component was chosen to design and engineer gene delivery separately in a complimentary and fundamentally distinct fashion. A bacterial (Escherichia coli) inner core and a biomaterial [poly(beta-amino ester)]-coated outer surface allowed the simultaneous application of molecular biology and polymer chemistry to address barriers associated with APC gene delivery, which include cellular uptake and internalization, phagosomal escape, and intracellular cargo concentration. The approach combined and synergized normally disparate vector properties and tools, resulting in increased in vitro gene delivery beyond individual vector components or commercially available transfection agents. Furthermore, the hybrid device demonstrated a strong, efficient, and safe in vivo humoral immune response compared with traditional forms of antigen delivery. In summary, the flexibility, diversity, and potential of the hybrid design were developed and featured in this work as a platform for multivariate engineering at the vector and cellular scales for new applications in gene delivery immunotherapy.

Niemann-Pick C1 affects the gene delivery efficacy of degradable polymeric nanoparticles

Despite intensive research effort, the rational design of improved nanoparticulate drug carriers remains challenging, in part due to a limited understanding of the determinants of nanoparticle entry and transport in target cells. Recent studies have shown that Niemann-Pick C1 (NPC1), the lysosome membrane protein that mediates trafficking of cholesterol in cells, is involved in the endosomal escape and subsequent infection caused by filoviruses, and that its absence promotes the retention and efficacy of lipid nanoparticles encapsulating siRNA. Here, we report that NPC1 deficiency results in dramatic reduction in internalization and transfection efficiency mediated by degradable cationic gene delivery polymers, poly(β-amino ester)s (PBAEs). PBAEs utilized cholesterol and dynamin-dependent endocytosis pathways, and these were found to be heavily compromised in NPC1-deficient cells. In contrast, the absence of NPC1 had minor effects on DNA uptake mediated by polyethylenimine or Lipofectamine 2000. Strikingly, stable overexpression of human NPC1 in chinese hamster ovary cells was associated with enhanced gene uptake (3-fold) and transfection (10-fold) by PBAEs. These findings reveal a role of NPC1 in the regulation of endocytic mechanisms affecting nanoparticle trafficking. We hypothesize that in-depth understanding sites of entry and endosomal escape may lead to highly efficient nanotechnologies for drug delivery.

Activation of the STING adaptor attenuates experimental autoimmune encephalitis

Cytosolic DNA sensing activates the stimulator of IFN genes (STING) adaptor to induce IFN type I (IFN-αβ) production. Constitutive DNA sensing to induce sustained STING activation incites tolerance breakdown, leading to autoimmunity. In this study, we show that systemic treatments with DNA nanoparticles (DNPs) induced potent immune regulatory responses via STING signaling that suppressed experimental autoimmune encephalitis (EAE) when administered to mice after immunization with myelin oligodendrocyte glycoprotein (MOG), at EAE onset, or at peak disease severity. DNP treatments attenuated infiltration of effector T cells into the CNS and suppressed innate and adaptive immune responses to myelin oligodendrocyte glycoprotein immunization in spleen. Therapeutic responses were not observed in mice treated with cargo DNA or cationic polymers alone, indicating that DNP uptake and cargo DNA sensing by cells with regulatory functions was essential for therapeutic responses to manifest. Intact STING and IFN-αβ receptor genes, but not IFN-γ receptor genes, were essential for therapeutic responses to DNPs to manifest. Treatments with cyclic diguanylate monophosphate to activate STING also delayed EAE onset and reduced disease severity. Therapeutic responses to DNPs were critically dependent on IDO enzyme activity in hematopoietic cells. Thus, DNPs and cyclic diguanylate monophosphate attenuate EAE by inducing dominant T cell regulatory responses via the STING/IFN-αβ/IDO pathway that suppress CNS-specific autoimmunity. These findings reveal dichotomous roles for the STING/IFN-αβ pathway in either stimulating or suppressing autoimmunity and identify STING-activating reagents as a novel class of immune modulatory drugs.

Co-delivery of doxorubicin and RNA using pH-sensitive poly (β-amino ester) nanoparticles for reversal of multidrug resistance of breast cancer

An appropriate co-delivery system for chemotherapeutic agents and nucleic acid drugs will provide a more efficacious approach for the treatment of breast cancer by reversing multidrug resistance (MDR). In this work, a new amphiphilic poly (β-amino ester), poly[(1,4-butanediol)-diacrylate-β-5-polyethylenimine]-block-poly[(1,4-butanediol)-diacrylate-β-5-hydroxy amylamine] (PDP-PDHA) was synthesized, and the doxorubicin (DOX) and survivin-targeting shRNA (shSur) co-loading nanoparticle (PDNs) were prepared. The pH-sensitive poly[(1,4-butanediol) diacrylate-β-5-hydroxy amylamine] (PDHA) endowed PDNs both pH-triggered drug release characteristics and enhanced endo/lysosomal escape ability, thus improving the cytotoxicity of DOX and the transfection efficiency. PDNs also increased the DOX accumulation, down-regulated 57.7% survivin expression, induced 80.8% cell apoptosis and changed the cell cycle in MCF-7/ADR cells. In the MCF-7/ADR tumor-bearing mice models, after administrated intravenously, PDNs raised the accumulation of DOX and shSur in the tumor tissue by 10.4 and 20.2 folds, respectively, resulting in obvious inhibition of the tumor growth with tumor inhibiting rate of 95.9%. The combination of DOX and RNA interference showed synergistic effect on overcoming MDR. Therefore, PDNs could be a promising co-delivery vector for effective therapy of drug resistant breast cancer.

Oligopeptide-terminated poly(β-amino ester)s for highly efficient gene delivery and intracellular localization

The main limitation of gene therapy towards clinics is the lack of robust, safe and efficient gene delivery vectors. This paper describes new polycations for gene delivery based on poly(β-amino ester)s (pBAE) containing terminal oligopeptides. The authors developed oligopeptide-modified pBAE-pDNA nanoparticles that achieve better cellular viability and higher transfection efficacy than other end-modified pBAE and commercial transfection agents. Gene expression in highly permissive cell lines was remarkably high, but transfection efficiency in less-permissive cell lines was highly dependent on oligopeptide composition and nanoparticle formulation. Moreover, the use of selected oligopeptides in the pBAE formulation led to preferential intracellular localization of the particles. Particle analysis of highly efficient pBAE formulations revealed different particle sizes and charge features, which indicates chemical pseudotyping of the particle surface, related to the oligopeptide chemical nature. In conclusion, chemical modification at the termini of pBAE with amine-rich oligopeptides is a powerful strategy for developing delivery systems for future gene therapy applications.

Molecular-genetic imaging of cancer

Molecular-genetic imaging of cancer using nonviral delivery systems has great potential for clinical application as a safe, efficient, noninvasive tool for visualization of various cellular processes including detection of cancer, and its attendant metastases. In recent years, significant effort has been expended in overcoming technical hurdles to enable clinical adoption of molecular-genetic imaging. This chapter will provide an introduction to the components of molecular-genetic imaging and recent advances on each component leading to safe, efficient clinical applications for detecting cancer. Combination with therapy, namely, generating molecular-genetic theranostic constructs, will provide further impetus for clinical translation of this promising technology.

Serum-resistant complex nanoparticles functionalized with imidazole-rich polypeptide for gene delivery to pulmonary metastatic melanoma

To enhance serum-resistance and overcome the lysosomal barrier are effective and feasible strategies to increase the transfection efficiency of non-viral gene delivery system. For the systemic delivery of therapeutic gene, we previously developed self-assemble carboxymethyl poly(l-histidine) (CM-PLH)/poly(β-amino ester) (PbAE)/pDNA ternary complex nanoparticles based on electrostatic coating as an effective pDNA carrier. Recharging cationic PbAE/pDNA polyplexes with CM-PLH was a promising method to reduce the cytotoxicity and enhance the stability in vivo of positive charged polyplexes. In the present study, the transfection activities of ternary complex nanoparticles were further evaluated in vitro and in vivo. The transfection efficiency of ternary complex nanoparticles showed significant serum-resistance (CM-PLH-containing (51.9±4.35)% in 50% FBS>CM-PLH-free (14.7±5.66)% in 50% FBS), cell line dependent (HEK293>MCF-7>COS7>B16F10>A549>Hela>SPC-A1>CHO>SKOV3) and incubation period dependent (24 h, 20 h, 16 h>12 h>8 h>4 h>2 h>1 h>0.5 h). After transfected with ternary complex nanoparticles loading pGV240-MDA-7/IL-24, the B16F10 cells exhibited significant apoptosis and proliferation inhibition due to the expression of IL-24. Moreover, in the pulmonary metastatic melanoma model, ternary complex nanoparticles loading pGV240-MDA-7/IL-24 showed significant antitumor therapeutic efficacy in vivo. These results suggested that CM-PLH/PbAE/pDNA ternary complex nanoparticles were promising and challenging gene vector for practical application.