Intracellular trafficking of nonviral vectors

Exploring the potential of nanomedicine for gene therapy across the physicochemical and cellular barriers

After COVID-19, a turning point in the way of pharmaceutical technology is gene therapy with beneficial potential to start a new medical era. However, commercialization of such pharmaceuticals would never be possible without the help of nanotechnology. Nanomedicine can fulfill the growing needs linked to safety, efficiency, and site-specific targeted delivery of Gene therapy-based pharmaceuticals. This review's goal is to investigate how nanomedicine may be used to transfer nucleic acids by getting beyond cellular and physicochemical barriers. Firstly, we provide a full description of types of gene therapy, their mechanism, translation, transcription, expression, type, and details of diseases with possible mechanisms that can only be treated with genes-based pharmaceuticals. Additionally, we also reviewed different types of physicochemical barriers, physiological and cellular barriers in nucleic acids (DNA/RNA) based drug delivery. Finally, we highlight the need and importance of cationic lipid-based nanomedicine/nanocarriers in gene-linked drug delivery and how nanotechnology can help to overcome the above-discussed barrier in gene therapy and their biomedical applications.

Design and synthesis of a shikimoyl-functionalized cationic di-block copolypeptide for cancer cell specific gene transfection

Targeted and efficient gene delivery systems hold tremendous potential for the improvement of cancer therapy by enabling appropriate modification of biological processes. Herein, we report the design and synthesis of a novel cationic di-block copolypeptide, incorporating homoarginine (HAG) and shikimoyl (LSA) functionalities (HDA-b-PHAGm-b-PLSAn), tailored for enhanced gene transfection specifically in cancer cells. The di-block copolypeptide was synthesized via sequential N-carboxyanhydride (NCA) ring-opening polymerization (ROP) techniques and its physicochemical properties were characterized, including molecular weight, dispersity, secondary conformation, size, morphology, and surface charge. In contrast to the cationic poly-L-homoarginine, we observed a significantly reduced cytotoxic effect of this di-block copolypeptide due to the inclusion of the shikimoyl glyco-polypeptide block, which also added selectivity in internalizing particular cells. This di-block copolypeptide was internalized via mannose-receptor-mediated endocytosis, which was investigated by competitive receptor blocking with mannan. We evaluated the transfection efficiency of the copolypeptide in HEK 293T (noncancerous cells), MDA-MB-231 (breast cancer cells), and RAW 264.7 (dendritic cells) and compared it with commonly employed transfection agents (Lipofectamine). Our findings demonstrate that the homoarginine and shikimoyl-functionalized cationic di-block copolypeptide exhibits potent gene transfection capabilities with minimal cytotoxic effects, particularly in cancer cells, while it is ineffective for normal cells, indicative of its potential as a promising platform for cancer cell-specific gene delivery systems. To evaluate this, we delivered an artificially designed miRNA-plasmid against Hsp90 (amiR-Hsp90) which upon successful transfection depleted the Hsp90 (a chaperone protein responsible for tumour growth) level specifically in cancerous cells and enforced apoptosis. This innovative approach offers a new avenue for the development of targeted therapeutics with an improved efficacy and safety profile in cancer treatment.

Multi-functional imidazolium dendrimers based on thiacalix[4]arenes: self-assembly, catalysis and DNA binding

For the first time, dendrimers based on thiacalix[4]arenes bearing imidazolium dendrons on one side and alkyl fragments on another side of the macrocyclic platform and symmetrical dendrimers with four dendrons on both sides were synthesized. Dendrons consist of gallic acid-based branches functionalized with imidazolium and triazolium groups. The physicochemical properties of the dendrimers such as micellar concentration (CMC), size, and solubilization capacity were measured. Novel dendrimers exhibit high binding efficiency with calf thymus DNA (ctDNA) as revealed by fluorescence quenching of the DNA-EtBr complex in the presence of macrocycles. Dendrimers have been used as supports for Pd nanoparticles, which show high catalytic activity for the reduction of nitroaromatic compounds.

Development of an Elastin-like Polypeptide-Based Nucleic Acid Delivery System Targeted to EGFR+ Bladder Cancer Cells Using a Layer-by-Layer Approach

Nucleic acid (NA)-based therapies are revolutionizing biomedical research through their ability to control cellular functions at the genetic level. This work demonstrates a versatile elastin-like polypeptide (ELP) carrier system using a layer-by-layer (LbL) formulation approach that delivers NA cargos ranging in size from siRNA to plasmids. The components of the system can be reconfigured to modulate the biochemical and biophysical characteristics of the carrier for engaging the unique features of the biological target. We show the physical characterization and biological performance of LbL ELP nucleic acid nanoparticles (LENNs) in murine and human bladder tumor cell lines. Targeting bladder tumors is difficult owing to the constant influx of urine into the bladder, leading to low contact times (typically <2 h) for therapeutic agents delivered via intravesical instillation. LENN complexes bind to bladder tumor cells within 30 min and become rapidly internalized to release their NA cargo within 60 min. Our data show that a readily adaptable NA-delivery system has been created that is flexible in its targeting ability, cargo size, and disassembly kinetics. This approach provides an alternative path to either lipid nanoparticle formulations that suffer from inefficiency and physicochemical instability or viral vectors that are plagued by manufacturing and immune rejection challenges. This agile ELP-based nanocarrier provides an alternative route for nucleic acid delivery using a biomanufacturable, biodegradable, biocompatible, and highly tunable vehicle capable of targeting cells via engagement with overexpressed cell surface receptors.

Interaction proteomics analysis to provide insight into TFAMoplex-mediated transfection

In an earlier investigation, our group introduced the TFAMoplex, a transfection agent based on the mitochondrial transcription factor A (TFAM) protein, which complexes DNA into nanoparticles. The original TFAMoplex further contained a bacterial phospholipase to achieve endosomal escape, and the vaccinia-related kinase 1 (VRK1), which significantly boosted the transfection efficiency of the system by an unknown mechanism. This study aims at replacing VRK1 within the TFAMoplex with dynein light chain proteins, specifically RP3, to directly tether the complexes to the dynein motor complex for enhanced cytosolic transport. To confirm the interaction between the dynein complex and the resulting fusion protein, we examined the binding kinetics of TFAM-RP3 to the dynein intermediate chains 1 and 2. Furthermore, we established a proteomics-based assay to compare cytosolic protein interactions of different TFAMoplex variants, including the RP3-modified version and the original VRK1-containing system. In the group of the VRK1-containing TFAMoplex, significant shifts of protein interactors were observed, especially for nucleolar proteins. Leveraging this knowledge, we incorporated one of these nuclear proteins, leucine-rich repeat-containing protein 59 (LRRC59), into the TFAMoplex, resulting in a significant improvement of transfection properties compared to the RP3-modified system and comparable levels versus the original, VRK1-containing version. This study not only advances our comprehension of the TFAMoplex system but also offers broader insights into the potential of protein engineering for designing effective gene delivery systems.

Endolysosomal trapping of therapeutics and endosomal escape strategies

Internalizing therapeutic molecules or genes into cells and safely delivering them to the target tissue where they can perform the intended tasks is one of the key characteristics of the smart gene/drug delivery vector. Despite much research in this field, endosomal escape continues to be a significant obstacle to the development of effective gene/drug delivery systems. In this review, we discuss in depth the several types of endocytic pathways involved in the endolysosomal trapping of therapeutic agents. In addition, we describe numerous mechanisms involved in nanoparticle endosomal escape. Furthermore, many other techniques are employed to increase endosomal escape to minimize entrapment of therapeutic compounds within endolysosomes, which have been reviewed at length in this study.

In situ transient transfection of 3D cell cultures and tissues, a promising tool for tissue engineering and gene therapy

Various research fields use the transfection of mammalian cells with genetic material to induce the expression of a target transgene or gene silencing. It is a tool widely used in biological research, bioproduction, and therapy. Current transfection protocols are usually performed on 2D adherent cells or suspension cultures. The important rise of new gene therapies and regenerative medicine in the last decade raises the need for new tools to empower the in situ transfection of tissues and 3D cell cultures. This review will present novel in situ transfection methods based on a chemical or physical non-viral transfection of cells in tissues and 3D cultures, discuss the advantages and remaining gaps, and propose future developments and applications.

Case Report: A recurrent case of ALK-ALCL after autologous transplantation was successfully treated with BV + a modified CHEP chemotherapy containing mitoxantrone hydrochloride liposome with the addition of chidamide maintenance therapy

Background

ALK-negative anaplastic large cell lymphoma (ALK-ALCL) is a rare heterogeneous malignancy of T-cell origin.ALK- ALCL has a poor prognosis, with more patients experiencing relapses and refractory to treatment, and its treatment remains challenging. We report a case with bone involvement as the main clinical manifestation of recurrent, and the patient achieved significant partial remission after brentuximab vedotin(BV) combined with a modified CHEP chemotherapy containing mitoxantrone hydrochloride liposome (PLM60) with the addition of chidamide maintenance therapy and received regular follow-up, with a disease-free survival of 16 months to date. A literature review of the clinical presentation and treatment of ALCL was also conducted to identify strategies for its diagnosis and management.

Conclusions

ALK-ALCL with bone involvement as the main manifestation of recurrent is relatively rare. Here, BV combined a modified CHEP chemotherapy containing mitoxantrone hydrochloride liposome was applied for the first time in a patient with relapsed ALK-ALCL, inducing remission and extending survival. However, further prospective studies with many patients are needed to determine the biological characteristics of this rare type of ALK-ALCL and relevant treatment strategies.

pH-responsive polyzwitterion covered nanocarriers for DNA delivery

The success of gene therapy relies on gene nanocarriers to achieve therapeutic effects in vivo. Surface shielding of poly(ethylene glycol) (PEG), known as PEGylation, onto gene delivery carriers is a predominant strategy for extending blood circulation and improving therapeutic outcomes in vivo. Nevertheless, PEGylation frequently compromises the transfection efficiency by decreasing the interactions with the cellular membrane of the targeted cells, thereby preventing the cellular uptake and the subsequent endosomal escape. Herein, we developed a stepwise pH-responsive polyplex micelle for the plasmid DNA delivery with the surface covered by ethylenediamine-based polycarboxybetaines. This polyplex micelle switched its surface charge from neutral at pH 7.4 to positive at tumorous and endo-/lysosomal pH (i.e., pH 6.5 and 5.5, respectively), thus enhancing the cellular uptake and facilitating the endosomal escape toward efficient gene transfection. Additionally, the polyplex micelle demonstrated prolonged blood circulation as well as enhanced tumor accumulation, leading to highly effective tumor growth suppression by delivering an antiangiogenic gene. These results suggest the usefulness of a pH-responsive charge-switchable shell polymer on the surface of the polyplex micelle for the efficient nucleic acid delivery.

Biomedical applications of nanomaterials in the advancement of nucleic acid therapy: Mechanistic challenges, delivery strategies, and therapeutic applications

In the past few decades, substantial advancement has been made in nucleic acid (NA)-based therapies. Promising treatments include mRNA, siRNA, miRNA, and anti-sense DNA for treating various clinical disorders by modifying the expression of DNA or RNA. However, their effectiveness is limited due to their concentrated negative charge, instability, large size, and host barriers, which make widespread application difficult. The effective delivery of these medicines requires safe vectors that are efficient & selective while having non-pathogenic qualities; thus, nanomaterials have become an attractive option with promising possibilities despite some potential setbacks. Nanomaterials possess ideal characteristics, allowing them to be tuned into functional bio-entity capable of targeted delivery. In this review, current breakthroughs in the non-viral strategy of delivering NAs are discussed with the goal of overcoming challenges that would otherwise be experienced by therapeutics. It offers insight into a wide variety of existing NA-based therapeutic modalities and techniques. In addition to this, it provides a rationale for the use of non-viral vectors and a variety of nanomaterials to accomplish efficient gene therapy. Further, it discusses the potential for biomedical application of nanomaterials-based gene therapy in various conditions, such as cancer therapy, tissue engineering, neurological disorders, and infections.

CNS Delivery of Nucleic Acid Therapeutics: Beyond the Blood-Brain Barrier and Towards Specific Cellular Targeting

Nucleic acid-based therapeutic molecules including small interfering RNA (siRNA), microRNA(miRNA), antisense oligonucleotides (ASOs), messenger RNA (mRNA), and DNA-based gene therapy have tremendous potential for treating diseases in the central nervous system (CNS). However, achieving clinically meaningful delivery to the brain and particularly to target cells and sub-cellular compartments is typically very challenging. Mediating cell-specific delivery in the CNS would be a crucial advance that mitigates off-target effects and toxicities. In this review, we describe these challenges and provide contemporary evidence of advances in cellular and sub-cellular delivery using a variety of delivery mechanisms and alternative routes of administration, including the nose-to-brain approach. Strategies to achieve subcellular localization, endosomal escape, cytosolic bioavailability, and nuclear transfer are also discussed. Ultimately, there are still many challenges to translating these experimental strategies into effective and clinically viable approaches for treating patients.

Polymer- and lipid-based gene delivery technology for CAR T cell therapy

Chimeric antigen receptor T cell (CAR T cell) therapy is a revolutionary approach approved by the FDA and EMA to treat B cell malignancies and multiple myeloma. The production of these T cells has been done through viral vectors, which come with safety concerns, high cost and production challenges, and more recently also through electroporation, which can be extremely cytotoxic. In this context, nanosystems can constitute an alternative to overcome the challenges associated with current methods, resulting in a safe and cost-effective platform. However, the barriers associated with T cells transfection show that the design and engineering of novel approaches in this field are highly imperative. Here, we present an overview from CAR constitution to transfection technologies used in T cells, highlighting the lipid- and polymer-based nanoparticles as a potential delivery platform. Specifically, we provide examples, strengths and weaknesses of nanosystem formulations, and advances in nanoparticle design to improve transfection of T cells. This review will guide the researchers in the design and development of novel nanosystems for next-generation CAR T therapeutics.

Could artificial intelligence revolutionize the development of nanovectors for gene therapy and mRNA vaccines?

Gene therapy enables the introduction of nucleic acids like DNA and RNA into host cells, and is expected to revolutionize the treatment of a wide range of diseases. This growth has been further accelerated by the discovery of CRISPR/Cas technology, which allows accurate genomic editing in a broad range of cells and organisms in vitro and in vivo. Despite many advances in gene delivery and the development of various viral and non-viral gene delivery vectors, the lack of highly efficient non-viral systems with low cellular toxicity remains a challenge. The application of cutting-edge technologies such as artificial intelligence (AI) has great potential to find new paradigms to solve this issue. Herein, we review AI and its major subfields including machine learning (ML), neural networks (NNs), expert systems, deep learning (DL), computer vision and robotics. We discuss the potential of AI-based models and algorithms in the design of targeted gene delivery vehicles capable of crossing extracellular and intracellular barriers by viral mimicry strategies. We finally discuss the role of AI in improving the function of CRISPR/Cas systems, developing novel nanobots, and mRNA vaccine carriers.

Design of Smart Nanodiamonds: Introducing pH Sensitivity to Improve Nucleic Acid Carrier Efficiency of Diamoplexes

The mechanism of cellular uptake and intracellular fate of nanodiamond/nucleic acid complexes (diamoplexes) are major determinants of its performance as a gene carrier. Our group designed lysine-nanodiamonds (K-NDs) as vectors for nucleic acid delivery. In this work, we modified the surface of K-NDs with histidine to overcome endo-lysosomal entrapment diamoplexes, the major rate limiting step in gene transfer. Histidine is conjugated onto the NDs in two configurations: lysyl-histidine-NDs (HK-NDs) where histidine is loaded on 100% of the lysine moieties and lysine/lysyl-histidine-NDs (H50K50-NDs) where histidine is loaded on 50% of the lysine moieties. Both HK-NDs and H50K50-NDs maintained the optimum size distribution (i.e., <200 nm) and a cationic surface (zeta potential > 20 mV), similar to K-NDs. HK-NDs binds plasmid deoxyribonucleic acid (pDNA) and small interfering ribonucleic acid (siRNA) forming diamoplexes at mass ratios of 10:1 and 60:1, respectively. H50K50-NDs significantly improved nucleic acid binding, forming diamoplexes at a 2:1 mass ratio with pDNA and a 30:1 mass ratio with siRNA, which are at values similar to the K-NDs. The amount of histidine on the surface also impacted the interactions with mammalian cells. The HK-NDs reduced the cell viability by 30% at therapeutic concentrations, while H50K50-NDs maintained more than 90% cell viability, even at the highest concentrations. H50K50-NDs also showed highest cellular uptake within 24 h, followed by K-NDs and HK-NDs. Most functionalized NDs show cellular exit after 5 days, leaving less than 10% of cells with internalized diamonds. The addition of histidine to the ND resulted in higher transfection of anti-green fluorescent protein siRNA (anti-GFP siRNA) with the fraction of GFP knockdown being 0.8 vs. 0.6 for K-NDs at a mass ratio of 50:1. H50K50-NDs further improved transfection by achieving a similar fraction of GFP knockdown (0.8) at a lower mass ratio of 30:1. Overall, this study provides evidence that the addition of histidine, a pH-modulating entity in the functionalization design at an optimized ratio, renders high efficiency to the diamoplexes. Further studies will elucidate the uptake mechanism and intracellular fate to build the relationship between physicochemical characteristics and biological efficacy and create a platform for solid-core nanoparticle-based gene delivery.

Bacteriophage T4 as a nanovehicle for delivery of genes and therapeutics into human cells

The ability to deliver therapeutic genes and biomolecules into a human cell and restore a defective function has been the holy grail of medicine. Adeno-associated viruses and lentiviruses have been extensively used as delivery vehicles, but their capacity is limited to one (or two) gene(s). Bacteriophages are emerging as novel vehicles for gene therapy. The large 120 × 86-nm T4 capsid allows engineering of both its surface and its interior to incorporate combinations of DNAs, RNAs, proteins, and their complexes. In vitro assembly using purified components allows customization for various applications and for individualized therapies. Its large capacity, cell-targeting capability, safety, and inexpensive manufacturing could open unprecedented new possibilities for gene, cancer, and stem cell therapies. However, efficient entry into primary human cells and intracellular trafficking are significant barriers that must be overcome by gene engineering and evolution in order to translate phage-delivery technology from bench to bedside.

Effect of Methylation of the Hydrophilic Domain of Tocopheryl Ammonium-Based Lipids on their Nucleic Acid Delivery Properties

Lipid-enabled nucleic acid delivery has garnered tremendous attention in recent times. Tocopherol among the cationic lipids, 3b-[N-(N',N'-dimethylamino-ethane)carbamoyl]-cholesterol hydrochloride (DC-Chol) with a headgroup of dimethylammonium, and cholesterol as a hydrophobic moiety are found to be some of the most successful lipids and are being used in clinical trials. However, limited efficacy is a major limitation for their broader therapeutic application. In our prior studies, we demonstrated tocopherol to be a potential alternative hydrophobic moiety having additional antioxidant properties to develop efficient and safer liposomal formulations. Inspired by DC-Chol applications and taking cues from our own prior findings, herein, we report the design and synthesis of four alpha-tocopherol-based cationic derivatives with varying degrees of methylation, AC-Toc (no methylation), MC-Toc (monomethylation derivative), DC-Toc (dimethylation derivative), and TC-Toc (trimethylation derivative) and the evaluation of their gene delivery properties. The transfection studies showed that AC-Toc liposomes exhibited superior transfection compared to MC-Toc, DC-Toc, TC-Toc, and control DC-Chol, indicating that methylation in the hydrophilic moiety of Toc-lipids reduced their transfection properties. Cellular internalization studies in the presence of different endocytosis blockers revealed that all four tocopherol lipids were internalized through clathrin-mediated endocytosis, whereas control DC-Chol was found to be internalized through both macropinocytosis and clathrin-mediated endocytosis. These novel Toc-lipids exhibited higher antioxidant properties than DC-Chol by generating less reactive oxygen species, indicating lower cytotoxicity. Our present findings suggest that AC-Toc may be considered as an alternative to DC-Chol in liposomal transfections.

Nanoparticles for vaccine and gene therapy: Overcoming the barriers to nucleic acid delivery

Nucleic acid therapeutics can be used to control virtually every aspect of cell behavior and therefore have significant potential to treat genetic disorders, infectious diseases, and cancer. However, while clinically approved to treat a small number of diseases, the full potential of nucleic acid therapeutics is hampered by inefficient delivery. Nucleic acids are large, highly charged biomolecules that are sensitive to degradation and so the approaches to deliver these molecules differ significantly from traditional small molecule drugs. Current studies suggest less than 1% of the injected nucleic acid dose is delivered to the target cell in an active form. This inefficient delivery increases costs and limits their use to applications where a small amount of nucleic acid is sufficient. In this review, we focus on two of the major barriers to efficient nucleic acid delivery: (1) delivery to the target cell and (2) transport to the subcellular compartment where the nucleic acids are therapeutically active. We explore how nanoparticles can be modified with targeting ligands to increase accumulation in specific cells, and how the composition of the nanoparticle can be engineered to manipulate or disrupt cellular membranes and facilitate delivery to the optimal subcellular compartments. Finally, we highlight how with intelligent material design, nanoparticle delivery systems have been developed to deliver nucleic acids that silence aberrant genes, correct genetic mutations, and act as both therapeutic and prophylactic vaccines. This article is categorized under: Nanotechnology Approaches to Biology > Cells at the Nanoscale Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Biology-Inspired Nanomaterials > Lipid-Based Structures.

Gene- and RNAi-activated scaffolds for bone tissue engineering: Current progress and future directions

Large bone defects are usually managed by replacing lost bone with non-biological prostheses or with bone grafts that come from the patient or a donor. Bone tissue engineering, as a field, offers the potential to regenerate bone within these large defects without the need for grafts or prosthetics. Such therapies could provide improved long- and short-term outcomes in patients with critical-sized bone defects. Bone tissue engineering has long relied on the administration of growth factors in protein form to stimulate bone regeneration, though clinical applications have shown that using such proteins as therapeutics can lead to concerning off-target effects due to the large amounts required for prolonged therapeutic action. Gene-based therapies offer an alternative to protein-based therapeutics where the genetic material encoding the desired protein is used and thus loading large doses of protein into the scaffolds is avoided. Gene- and RNAi-activated scaffolds are tissue engineering devices loaded with nucleic acids aimed at promoting local tissue repair. A variety of different approaches to formulating gene- and RNAi-activated scaffolds for bone tissue engineering have been explored, and include the activation of scaffolds with plasmid DNA, viruses, RNA transcripts, or interfering RNAs. This review will discuss recent progress in the field of bone tissue engineering, with specific focus on the different approaches employed by researchers to implement gene-activated scaffolds as a means of facilitating bone tissue repair.

Engineered EV-Mimetic Nanoparticles as Therapeutic Delivery Vehicles for High-Grade Serous Ovarian Cancer

Simple Summary

In this review, we begin with the role of natural extracellular vesicles (EVs) in high-grade serous ovarian cancer (HGSOC). Then, we narrow our focus on the advantages of using EV-mimetic nanoparticles as a delivery vehicle for RNAi therapy and other chemotherapeutics. Furthermore, we discuss the challenges of the clinical translation of engineering EV mimetic drug delivery systems and the promising directions of further development.

Abstract

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy among women. Several obstacles impede the early diagnosis and effective treatment options for ovarian cancer (OC) patients, which most importantly include the development of platinum-drug-resistant strains. Currently, extensive efforts are being put into the development of strategies capable of effectively circumventing the physical and biological barriers present in the peritoneal cavity of metastatic OC patients, representing a late stage of gastrointestinal and gynecological cancer with an extremely poor prognosis. Naturally occurring extracellular vesicles (EVs) have been shown to play a pivotal role in progression of OC and are now being harnessed as a delivery vehicle for cancer chemotherapeutics. However, there are limitations to their clinical application due to current challenges in their preparation techniques. Intriguingly, there is a recent drive towards the use of engineered synthetic EVs for the delivery of chemotherapeutics and RNA interference therapy (RNAi), as they show the promise of overcoming the obstacles in the treatment of OC patients. This review discusses the therapeutic application of EVs in OC and elucidates the potential use of engineered EV-mimetic nanoparticles as a delivery vehicle for RNAi therapy and other chemotherapeutics, which would potentially improve clinical outcomes of OC patients.

Biopolymer-based Carriers for DNA Vaccine Design

Over the last 30 years, genetically engineered DNA has been tested as novel vaccination strategy against various diseases, including human immunodeficiency virus (HIV), hepatitis B, several parasites, and cancers. However, the clinical breakthrough of the technique is confined by the low transfection efficacy and immunogenicity of the employed vaccines. Therefore, carrier materials were designed to prevent the rapid degradation and systemic clearance of DNA in the body. In this context, biopolymers are a particularly promising DNA vaccine carrier platform due to their beneficial biochemical and physical characteristics, including biocompatibility, stability, and low toxicity. This article reviews the applications, fabrication, and modification of biopolymers as carrier medium for genetic vaccines.

Investigation of water-insoluble hydrophobic polyethylenimines as RNAi vehicles in chronic myeloid leukemia therapy

The discovery of RNA interference (RNAi) more than two decades ago opened avenues for avant-garde cancer treatments that possess the ability to evade issues hampering current chemotherapeutic strategies, owing to its specific gene sequence-driven mechanism of action. A potent short interfering RNA (siRNA) delivery vehicle designed to overcome physiological barriers is imperative for successful RNAi therapy. For this purpose, this study explored the characteristics and therapeutic efficacy of low-molecular weight (MW) polyethylenimine (PEI) with high cholesterol substitution, yielding water-insoluble polymers, in chronic myeloid leukemia (CML) K562 cells. A strong impact of cholesterol grafting on the physicochemical attributes of the resultant polymers and their corresponding complexes with siRNA was observed, with the siRNA binding capacity of polymers increasing and complex dissociation sensitivity decreasing with increase in cholesterol content of the polymers. The modified polymer complexes were significantly smaller in size and possessed higher cationic charge compared to the parent polymer. The interaction with anionic heparan sulfate preoteoglycans present on the cell surface was significant in cellular uptake of the complexes. The therapeutic efficacy of siRNA/polymer complexes was reflected in their ability to effectively silence the reporter green fluorescent protein gene and endogenous CML oncogene BCR-ABL as well as significantly inhibit colony formation by K562 cells post BCR-ABL silencing. The results of this study demonstrated beneficial effects of high levels of hydrophobic substitution on low MW PEI on their functional performance bestowing them the potential to be potent RNAi agents for CML therapy.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Antibody-Functionalized Gold Nanostar-Mediated On-Resonance Picosecond Laser Optoporation for Targeted Delivery of RNA Therapeutics

The rapid advances of genetic and genomic technology indicate promising therapeutic potential of genetic materials for regulating abnormal gene expressions causing diseases and disorders. However, targeted intracellular delivery of RNA therapeutics still remains a major challenge hindering the clinical translation. In this study, an elaborated plasmonic optoporation approach is proposed to efficiently and selectively transfect specific cells. The site-specific optoporation is obtained by tuning the spectral range of a supercontinuum pulsed picosecond laser in order for each individual cell binding gold nanostar with their unique resonance peak to magnify the local field strength in the near-infrared region and facilitate a selective delivery of small interfering RNA, messenger RNA, and Cas9-ribonucleoprotein into human retinal pigment epithelial cells. Numerical simulations indicate that optoporation is not due to a plasma-mediated process but rather due to a highly localized temperature rise both in time (few nanoseconds) and space (few nanometers). Taking advantage of the numerical simulation and fine-tuning of the optical strategy, the perforated lipid bilayer of targeted cells undergoes a membrane recovery process, important to retain their viability. The results signify the prospects of antibody functionalized nanostar-mediated optoporation as a simple and realistic gene delivery approach for future clinical practices.

Recent advances in peptide-targeted micelleplexes: Current developments and future perspectives

The decoding of the human genome revolutionized the understanding of how genetics influence the interplay between health and disease, in a multidisciplinary perspective. Thus, the development of exogenous nucleic acids-based therapies has increased to overcome hereditary or acquired genetic-associated diseases. Gene drug delivery using non-viral systems, for instance micelleplexes, have been recognized as promising options for gene-target therapies. Micelleplexes are core-shell structures, at a nanometric scale, designed using amphiphilic block copolymers. These can self-assemble in an aqueous medium, leading to the formation of a hydrophilic and positively charged corona - that can transport nucleic acids, - and a hydrophobic core - which can transport poor water-soluble drugs. However, the performance of these types of carriers usually is hindered by several in vivo barriers. Fortunately, due to a significant amount of research, strategies to overcome these shortcomings emerged. With a wide range of structural features, good stability against proteolytic degradation, affordable characteristic, easy synthesis, low immunogenicity, among other advantages, peptides have increasingly gained popularity as target ligands for non-viral carriers. Hence, this review addresses the use of peptides with micelleplexes illustrating, through the analysis of in vitro and in vivo studies, the potential and future perspectives of this combination.

Rapidly Transducing and Spatially Localized Magnetofection Using Peptide-Mediated Non-Viral Gene Delivery Based on Iron Oxide Nanoparticles

Non-viral delivery systems are generally of low efficiency, which limits their use in gene therapy and editing applications. We previously developed a technology termed glycosaminoglycan (GAG)-binding enhanced transduction (GET) to efficiently deliver a variety of cargos intracellularly; our system employs GAG-binding peptides, which promote cell targeting, and cell penetrating peptides (CPPs), which enhance endocytotic cell internalization. Herein, we describe a further modification by combining gene delivery and magnetic targeting with the GET technology. We associated GET peptides, plasmid (p)DNA, and iron oxide superparamagnetic nanoparticles (MNPs), allowing rapid and targeted GET-mediated uptake by application of static magnetic fields in NIH3T3 cells. This produced effective transfection levels (significantly higher than the control) with seconds to minutes of exposure and localized gene delivery two orders of magnitude higher in targeted over non-targeted cell monolayers using magnetic fields (in 15 min exposure delivering GFP reporter pDNA). More importantly, high cell membrane targeting by GET-DNA and MNP co-complexes and magnetic fields allowed further enhancement to endocytotic uptake, meaning that the nucleic acid cargo was rapidly internalized beyond that of GET complexes alone (GET-DNA). Magnetofection by MNPs combined with GET-mediated delivery allows magnetic field-guided local transfection in vitro and could facilitate focused gene delivery for future regenerative and disease-targeted therapies in vivo.

A novel strategy of selective gene delivery by using a uniform magnetic field

The application of a magnetic field to enhance the transfection efficiency has been reported to be mainly dependent on the magnetic force generated by a magnetic field gradient to attract paramagnetic bead-conjugated carrier and polynucleotide complexes. This strategy has the advantage of targeting a point or an area on the culture vessel. However, it is difficult to target deeply placed tissues in vivo. Uniform magnetic field-correlated effect is applicable to such a purpose. Here, we attempted to establish a novel procedure for uniform magnetic field-dependent enhancement of transfection efficiency. We examined the effect of a 1.5 mT uniform magnetic field on cellular reactive oxygen species (ROS) level and transfection efficiency mediated by a ROS-sensitive transfection carrier. Our experimental results revealed that a 1.5 mT uniform magnetic field transiently decreased cellular ROS levels and strongly enhanced transfection efficiency mediated by polyethylenimine (PEI). The uniform magnetic field-dependent enhancement of PEI-mediated in vivo transfection was confirmed in the livers of mice. Local intensification of a uniform magnetic field in a culture dish resulted in selective gene delivery into cells on the target area. Although further examination and improvement are necessary for this procedure, our findings provide a novel option for spatial control of gene delivery.

Stabilization of Poly (β-Amino Ester) Nanoparticles for the Efficient Intracellular Delivery of PiggyBac Transposon

The administration of gene-editing tools has been proposed as a promising therapeutic approach for correcting mutations that cause diseases. Gene-editing tools, composed of relatively large plasmid DNA constructs that often need to be co-delivered with a guiding protein, are unable to spontaneously penetrate mammalian cells. Although viral vectors facilitate DNA delivery, they are restricted by the size of the plasmid to carry. In this work, we describe a strategy for the stable encapsulation of the gene-editing tool piggyBac transposon into Poly (β-amino ester) nanoparticles (NPs). We propose a non-covalent and a covalent strategy for stabilization of the nanoformulation to slow down release kinetics and enhance intracellular delivery. We found that the formulation prepared by covalently crosslinking Poly (β-amino ester) NPs are capable to translocate into the cytoplasm and nuclei of human glioblastoma (U87MG) cells within 1 h of co-culturing, without the need of a targeting moiety. Once internalized, the nanoformulation dissociates, delivering the plasmid presumably as a response to the intracellular acidic pH. Transfection efficiency is confirmed by green fluorescence protein (GFP) expression in U87MG cells. Covalently stabilized Poly (β-amino ester) NPs are able to transfect ~55% of cells causing non-cytotoxic effects. The strategy described in this work may serve for the efficient non-viral delivery of other gene-editing tools.

Osteogenic differentiation cues of the bone morphogenetic protein-9 (BMP-9) and its recent advances in bone tissue regeneration

Bone regeneration using bioactive molecules and biocompatible materials is growing steadily with the advent of the new findings in cellular signaling. Bone Morphogenetic Protein (BMP)-9 is a considerably recent discovery from the BMP family that delivers numerous benefits in osteogenesis. The Smad cellular signaling pathway triggered by BMPs is often inhibited by Noggin. However, BMP-9 is resistant to Noggin, thus, facilitating a more robust cellular differentiation of osteoprogenitor cells into preosteoblasts and osteoblasts. This review encompasses a general understanding of the Smad signaling pathway activated by the BMP-9 ligand molecule with its specific receptors. The robust osteogenic cellular differentiation cue provided by BMP-9 has been reviewed from a bone regeneration perspective with several in vitro as well as in vivo studies reporting promising results for future research. The effect of the biomaterial, chosen in such studies as the scaffold or carrier matrix, on the activity of BMP-9 and subsequent bone regeneration has been highlighted in this review. The non-viral delivery technique for BMP-9 induced bone regeneration is a safer alternative to its viral counterpart. The recent advances in non-viral BMP-9 delivery have also highlighted the efficacy of the protein molecule at a low dosage. This opens a new horizon as a more efficient and safer alternative to BMP-2, which was prevalent among clinical trials; however, BMP-2 applications have reported its downsides during bone defect healing such as cystic bone formation.

Niosomal virosome derived by vesicular stomatitis virus glycoprotein as a new gene carrier

Virosomes as membranous vesicles with viral fusion protein in their membrane are versatile vehicles for cargo delivery. The vesicular stomatitis virus glycoprotein (VSV-G) is a common fusogenic protein used in virosome preparation. This glycoprotein has been used in liposomal systems so far, but in this study, we have tried to use the niosomal form instead of liposome for. Niosomes are vesicular systems composed of non-ionic surfactants. Niosomes were constructed by the thin-film hydration method. VSV-G gene in pMD2.G plasmid was expressed in the HEK293T cell line and then was reconstituted in the niosome bilayer. The formation of niosomal virosomes was confirmed with different methods such as SDS-PAGE gel, western blotting, and transmission electron microscopy (TEM). The efficiency of niosomal virosome was investigated with the pmCherry reporter gene. SDS-PAGE and western blotting proved the expression and successful insertion of protein into the bilayer. The TEM images showed the spike projection of VSV-G on the surface of niosomes. The transfection results showed high efficiency of niosomal virosomes as a novel carrier. This report has verified that niosome could be used as an efficient bilayer instead of liposome to construct virosomes.

Polyethylenimine-based nanovector grafted with mannitol moieties to achieve effective gene delivery and transfection

Polyethylenimine (PEI), a kind of cationic non-viral gene delivery vector, is capable of stable and efficient transgene expression for gene delivery. However, low transfection efficiency in vivo along with high toxicity limited the further application of gene therapy in the clinic. To enhance gene transfection performance and reduce cytotoxicity of polyethylenimine, branched polyethylenimine-derived cationic polymers BPEI25 k-man-S/L/M/H with different grafting degree with mannitol moieties were prepared and the transfection efficiency was evaluated. Among them, BPEI25 k-man-L showed the best transfection efficiency, lower toxicity, and significantly enhanced long-term systemic transgene expression for 96 h in vivo even at a single-dose administration. The results of cellular uptake mechanism and western-blot experiments revealed that the mannitol modification of BPEI25 k induced and up-regulated the phosphorylation of caveolin-1 and thus enhanced the caveolae-mediated cellular uptake. This class of gene delivery system highlights a paradigmatic approach for the development of novel and safe non-viral vectors for gene therapy.

Polymer nanocarriers for MicroRNA delivery

Abnormal expression of microRNAs (miRNAs), which are highlyconserved noncoding RNAs that regulate the expression of various genes post transcriptionally to control cellular functions, has been associated with the development of many diseases. In some cases, disease-promoting miRNAs are upregulated, while in other instances disease-suppressive miRNAs are downregulated. To alleviate this imbalanced miRNA expression, either antagomiRs or miRNA mimics can be delivered to cells to inhibit or promote miRNA expression, respectively. Unfortunately, the clinical translation of bare antagomiRs and miRNA mimics has been challenging because nucleic acids are susceptible to nuclease degradation, display unfavorable pharmacokinetics, and cannot passively enter cells. This review emphasizes the challenges associated with miRNA mimic delivery and then discusses the design and implementation of polymer nanocarriers to overcome these challenges. Preclinical efforts are summarized, and a forward-looking perspective on the future clinical translation of polymer nanomaterials as miRNA delivery vehicles is provided.

Biodegradable calcium phosphate nanoparticles for cancer therapy

Calcium phosphate is the inorganic mineral of hard tissues such as bone and teeth. Due to their similarities to the natural bone, calcium phosphates are highly biocompatible and biodegradable materials that have found numerous applications in dental and orthopedic implants and bone tissue engineering. In the form of nanoparticles, calcium phosphate nanoparticles (CaP's) can also be used as effective delivery vehicles to transfer therapeutic agents such as nucleic acids, drugs, proteins and enzymes into tumor cells. In addition, facile preparation and functionalization of CaP's, together with their inherent properties such as pH-dependent solubility provide advantages in delivery and release of these bioactive agents using CaP's as nanocarriers. In this review, the challenges and achievements in the intracellular delivery of these agents to tumor cells are discussed. Also, the most important issues in the design and potential applications of CaP-based biominerals are addressed with more focus on their biodegradability in tumor microenvironment.

Phospholipid-Coated Guanosine Diphosphate Auxiliary CaP Active Nanoparticles Can Systematically Improve the Efficiency of Gene Therapy for Cancer Disease

Endogenous active substance guanosine diphosphate (GDP) is involved in the physiological process of DNA transfection and expression in the cytoplasm by binding to Ran proteins. To substantially improve the gene delivery efficiency of nanoparticles, phospholipid-coated Ca(P-GDP)/pDNA/NLS hybrid nanoparticles were prepared using GDP as a common biophosphorus source based on the biological process of exogenous gene expression in the cells. This nanoparticle has a relative uniform particle size distribution and in vitro stability. The addition of GDP in nanoparticles significantly enhanced the gene expression efficiency with good biocompatibility. Moreover, an in vivo study further verified that hybrid nanoparticles were more effective in increasing the p53 gene expression, thus significantly inhibiting the tumor growth in the heterotopic tumor model of nude mice. These results demonstrated that phospholipid-coated Ca(P-GDP) nanoparticles were a potential nonviral gene vector to promote gene expression. The experimental results confirmed the feasibility of designing a delivery system based on active substances and provided a new solution to improve the transfection efficiency of gene drugs.

Gastrin-releasing peptide receptor-targeted hybrid peptide/phospholipid pDNA/siRNA delivery systems

Aim: To develop a peptide/phospholipid hybrid system for gastrin-releasing peptide receptor (GRPR)-targeted delivery of pDNA or siRNA. Materials & methods: A multifunctional GRPR-targeted peptide R₉-K(GALA)-BBN(6-14) was combined with a phospholipid oligonucleotide delivery system (1:1 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine and 1,2-dioleoyl-3-trimethylammonium-propane) and evaluated for pDNA and siRNA delivery in terms of complex size, toxicity, receptor-targeted delivery and gene expression or knockdown efficiency. Results: By combining peptide and phospholipid delivery systems, synergistic improvements in gene expression and knockdown were observed when compared with either system alone. The optimized formulation demonstrated high levels of EGFP expression and EGFP knockdown, GRPR-targeted delivery, enhanced endosomal release and minimal toxicity. Conclusion: The peptide/phospholipid hybrid system provides efficient GRPR-targeted DNA/siRNA delivery.

Genome Editing with mRNA Encoding ZFN, TALEN, and Cas9

Genome-editing technologies based on programmable nucleases have significantly broadened our ability to make precise and direct changes in the genomic DNA of various species, including human cells. Delivery of programmable nucleases into the target tissue or cell is one of the pressing challenges in transforming the technology into medicine. In vitro-transcribed (IVT) mRNA-mediated delivery of nucleases has several advantages, such as transient expression with efficient in vivo and in vitro delivery, no genomic integration, a potentially low off-target rate, and high editing efficiency. This review focuses on key barriers related to IVT mRNA delivery, on developed modes of delivery, and on the application and future prospects of mRNA encoding nuclease-mediated genome editing in research and clinical trials.

Gal8 Visualization of Endosome Disruption Predicts Carrier-Mediated Biologic Drug Intracellular Bioavailability

Endolysosome entrapment is one of the key barriers to the therapeutic use of biologic drugs that act intracellularly. The screening of prospective nanoscale endosome-disrupting delivery technologies is currently limited by methods that are indirect and cumbersome. Here, we statistically validate Galectin 8 (Gal8) intracellular tracking as a superior approach that is direct, quantitative, and predictive of therapeutic cargo intracellular bioactivity through in vitro high-throughput screening and in vivo validation. Gal8 is a cytosolically dispersed protein that, when endosomes are disrupted, redistributes by binding to glycosylation moieties selectively located on the inner face of endosomal membranes. The quantitative redistribution of a Gal8 fluorescent fusion protein from the cytosol into endosomes is demonstrated as a real-time, live-cell assessment of endosomal integrity that does not require labeling or modification of either the carrier or the biologic drug and that allows quantitative distinction between closely related, endosome-disruptive drug carriers. Through screening two families of siRNA polymeric carrier compositions at varying dosages, we show that Gal8 endosomal recruitment correlates strongly ( r = 0.95 and p < 10-4) with intracellular siRNA bioactivity. Through this screen, we gathered insights into how composition and molecular weight affect endosome disruption activity of poly[(ethylene glycol)- b-[(2-(dimethylamino)ethyl methacrylate)- co-(butyl methacrylate)]] [PEG-(DMAEMA- co-BMA)] siRNA delivery systems. Additional studies showed that Gal8 recruitment predicts intracellular bioactivity better than current standard methods such as Lysotracker colocalization ( r = 0.35, not significant), pH-dependent hemolysis (not significant), or cellular uptake ( r = 0.73 and p < 10-3). Importantly, the Gal8 recruitment method is also amenable to fully objective high-throughput screening using automated image acquisition and quantitative image analysis, with a robust estimated Z' of 0.6 (whereas assays with Z' > 0 have high-throughput screening utility). Finally, we also provide measurements of in vivo endosomal disruption based on Gal8 visualization ( p < 0.03) of a nanocarrier formulation confirmed to produce significant cytosolic delivery and bioactivity of siRNA within tumors ( p < 0.02). In sum, this report establishes the utility of Gal8 subcellular tracking for the rapid optimization and high-throughput screening of the endosome disruption potency of intracellular delivery technologies.

Biomaterial substrate modifications that influence cell-material interactions to prime cellular responses to nonviral gene delivery

IMPACT STATEMENT

This review summarizes how biomaterial substrate modifications (e.g. chemical modifications like natural coatings, ligands, or functional side groups, and/or physical modifications such as topography or stiffness) can prime the cellular response to nonviral gene delivery (e.g. affecting integrin binding and focal adhesion formation, cytoskeletal remodeling, endocytic mechanisms, and intracellular trafficking), to aid in improving gene delivery for applications where a cell-material interface might exist (e.g. tissue engineering scaffolds, medical implants and devices, sensors and diagnostics, wound dressings).

Super-resolution Imaging of Proton Sponge-Triggered Rupture of Endosomes and Cytosolic Release of Small Interfering RNA

The intracellular delivery of nucleic acids and proteins remains a key challenge in the development of biological therapeutics. In gene therapy, the inefficient delivery of small interfering RNA (siRNA) to the cytosol by lipoplexes or polyplexes is often ascribed to the entrapment and degradation of siRNA payload in the endosomal compartments. A possible mechanism by which polyplexes rupture the endosomal membrane and release their nucleic acid cargo is commonly defined as the "proton sponge effect". This is an osmosis-driven process triggered by the proton buffering capacity of polyplexes. Herein, we investigate the molecular basis of the "proton sponge effect" through direct visualization of the siRNA trafficking process, including analysis of individual polyplexes and endosomes, using stochastic optical reconstruction microscopy. We probe the sequential siRNA trafficking steps through single molecule super-resolution analysis of subcellular structures, polyplexes, and silencing RNA molecules. Specifically, individual intact polyplexes released in the cytosol upon rupture of the endosomes, the damaged endosomal vesicles, and the disassembly of the polyplexes in the cytosol are examined. We find that the architecture of the polyplex and the rigidity of the cationic polymer chains are crucial parameters that control the mechanism of endosomal escape driven by the proton sponge effect. We provide evidence that in highly branched and rigid cationic polymers, such as glycogen or polyethylenimine, immobilized on silica nanoparticles, the proton sponge effect is effective in inducing osmotic swelling and rupture of endosomes.

Development of double strand RNA mPEI nanoparticles and application in treating invasive breast cancer

dsRNA mPEI nanoparticles entered cytoplasm and lysosomal escape occurred. dsRNA was released to form a dsRNA–RISC complex. Then, remaining sense strand bound to mRNA, forming a new structure. Thus, mRNA was cleared and translation was inhibited.

Delivery of docetaxel using pH-sensitive liposomes based on D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate: Comparison with PEGylated liposomes

This study aimed to investigate the ability of the novel materials D-α-tocopheryl poly(2-ethyl-2-oxazoline) succinate (TPOS) to construct pH-sensitive liposomes. TPOS was initially synthesized and characterized by TLC, FTIR, and ¹H-NMR. The buffering capacity of polyethylene glycol- distearoyl phosphatidylethanolamine (PEG-DSPE) and TPOS was determined by acid-base titration, and TPOS displayed a slower downtrend and gentler slope of titration curve than PEG-DSPE within pH 7.4–5.0. Studies on the in vitro drug release demonstrated that TPOS modified docetaxel (DOC) liposomes (TPOS-DOC-L) had a slower drug-release rate at pH 7.4 similar to PEGylated-DOC liposomes (PEG-DOC-L), whereas the release rate reached approximately 86.92% ± 1.69% at pH 6.4. In vitro cellular uptake assays by microplate reader, and flow cytometry revealed that TPOS modified coumarin 6 liposomes (TPOS-C6-L) had stronger cellular uptake at pH 6.4 than that at pH 7.4 (P < 0.01). Conversely, for PEGylated C6 liposomes (PEG-C6-L) and conventional C6 liposomes (C6-L), very similar cellular uptakes were exhibited at different pH values. Confocal laser scanning microscopy images showed that PEG-C6-L and C6-L were mainly located in lysosomes. By contrast, TPOS-C6-L showed broader cytoplasmic release and distribution at 4 h. MTT assay showed that the cytotoxicity of TPOS-DOC-L was similar to that of PEG-DOC-L and conventional DOC liposomes (DOC-L) at the same DOC concentration and at pH 7.4, but was much lower than those at pH 6.4 after 48 h of incubation. The apoptosis of PEG-DOC-L and DOC-L had no remarkable improvement with decreased pH from 7.4 to 6.4. Meanwhile, TPOS-DOC-L significantly induced the apoptosis of HeLa cells with decreased pH. Therefore, TPOS can be a biomaterial for the construction of a pH-sensitive drug delivery system.

Deciphering the role of substrate stiffness in enhancing the internalization efficiency of plasmid DNA in stem cells using lipid-based nanocarriers

This study investigates the role of substrate stiffness in the non-viral transfection of human adipose-derived stem cells (hASCs) with the aim to maximize the hASC expression of vascular endothelial growth factor (VEGF). The results confirm the direct effect of substrate stiffness in regulating cytoskeletal remodeling and corresponding plasmid internalization.

Increasing the anticancer performance of bufalin (BUF) by introducing an endosome-escaping polymer and tumor-targeting peptide in the design of a polymeric prodrug

A well-defined multifunctional brush-type polymeric prodrug covalently linked with an anticancer drug (bufalin, BUF), a tumor-targeting peptide (RGD), and an endosome-escaping polymer, poly(N,N-diethylaminoethyl methacrylate-co-butyl methacrylate (P(DEA-co-BMA)), was developed. Its anticancer performance against colon cancer was investigated in vitro and in vivo. Reversible addition-fragmentation transfer (RAFT) polymerization of oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), 2-((3-(tert-butoxy)-3-oxopropyl)thio)ethyl methacrylate (BSTMA), and 2-(2-bromoisobutyryloxy)ethylmethacrylate (BIEM) afforded the multifunctional random copolymer, P(OEGMA-co-BSTMA-co-BIEM), in which hydrophilic POEGMA can stabilize nanoparticles in water, PBSTMA can be converted into carboxyl groups, and PBIEM can be employed as a macromolecular atom radical transfer polymerization (ATRP) initiator. The ATRP of DEA and BMA using P(OEGMA-co-BSTMA-co-BIEM) as a macromolecular ATRP initiator led to the formation of the pH-responsive brush-type copolymer, P(OEGMA-co-BSTMA)-g-P(DEA-co- BMA). After hydrolysis by trifluoroacetic acid and post-functionalization the final polymeric prodrug, P(OEGMA-co-BUF-co-RGD)-g-P(DEA-co-BMA), was obtained with a drug content of ∼7.8 wt%. P(OEGMA-co-BUF-co-RGD)-g-P(DEA-co-BMA) can be assembled into nanoparticles (BUF- NP-RGD) in aqueous solution with a diameter of 148.4 ± 0.7 nm and a zeta potential of -7.6 ± 0.4 mV. BUF-NP-RGD exhibited controlled drug release in the presence of esterase. Additionally, P(OEGMA-co- BSMA)-g-P(DEA-co-BMA) showed a significant hemolysis effect at a pH comparable to that of endosomes/lysosomes. Cell viability and a tumor-bearing nude mouse model were employed to evaluate the anticancer efficacy of BUF-NP-RGD. It was revealed that BUF-NP-RGD showed improved anticancer performance compared with that of free BUF both in vitro and in vivo. Histological and immunochemical analysis further demonstrated that BUF-NP-RGD exhibited improved cell apoptosis, angiogenesis inhibition, and an anti-proliferation effect.

Structure optimisation to improve the delivery efficiency and cell selectivity of a tumour-targeting cell-penetrating peptide

Cell-penetrating peptide (CPP) is used for the delivery of biomacromolecules across the cell membrane and is limited in cancer therapy due to the lack of cell selectivity. Epidermal growth factor receptor (EGFR) has been widely used in clinical targeted therapy for tumours. Here, we reported a novel tumour targeting cell-penetrating peptide (TCPP), EHB (ELBD-C6H) with 20-fold and 3000-fold greater transmembrane ability and tumour cell selectivity than our previously reported S3-HBD and classic CPP TAT, respectively. In this new TCPP, a specific alpha helix structure was inserted into a repeated amino acid (AA) sequence formed by tandem multiple selected key AA residues of vaccinia growth factor (VGF), and this sequence was then fused to a tailored heparin binding domain sequence (C6H) derived from heparin-binding epidermal growth factor-like growth factor to intensify its targeting delivery ability. EHB could carry anticancer proteins such as MAP30 (Momordica Antiviral Protein 30 kDa) into EGFR-overexpressing cancer cell and inhibit cell growth, but it had a greatly reduced interaction with normal cells. These results indicated that EHB, as a novel efficient TCPP for the selective delivery of drug molecules into cancer cells, would help to improve the efficacy and safety of anti-tumour drugs.

PEGylation for enhancing nanoparticle diffusion in mucus

The viscoelastic mucus secretions coating exposed organs such as the lung airways and the female reproductive tract can trap and quickly eliminate not only foreign pathogens and ultrafine particles but also particle-based drug delivery systems, thus limiting sustained and targeted drug delivery at mucosal surfaces. To improve particle distribution across the mucosa and enhance delivery to the underlying epithelium, many investigators have sought to develop nanoparticles capable of readily traversing mucus. The first synthetic nanoparticles shown capable of rapidly penetrating physiological mucus secretions utilized a dense coating of polyethylene glycol (PEG) covalently grafted onto the surface of preformed polymeric nanoparticles. In the decade since, PEG has become the gold standard in engineering mucus-penetrating drug carriers for sustained and targeted drug delivery to the lungs, gastrointestinal tract, eyes, and female reproductive tract. This review summarizes the history of the development of various PEG-based mucus-penetrating particles, and highlights the key physicochemical properties of PEG coatings and PEGylation strategies to achieve muco-inert PEG coatings on nanoparticle drug carriers for improved drug and gene delivery at mucosal surfaces.

Efficient and non-toxic gene delivery by anionic lipoplexes based on polyprenyl ammonium salts and their effects on cell physiology

BACKGROUND

One of the major challenges limiting the development of gene therapy is an absence of efficient and safe gene carriers. Among the nonviral gene delivery methods, lipofection is considered as one of the most promising. In the present study, a set of cationic polyprenyl derivatives [trimethylpolyprenylammonium iodides (PTAI)] with different lengths of polyprenyl chains (from 7, 8 and 11 to 15 isoprene units) was suggested as a component of efficient DNA vehicles.

METHODS

Optimization studies were conducted for PTAI in combination with co-lipid dioleoylphosphatidylethanolamine on DU145 human prostate cancer cells using: size and zeta potential measurements, confocal microscopy, the fluorescein diacetate/ethidium bromide test, cell counting, time-lapse monitoring of cell movement, gap junctional intercellular coupling analysis, antimicrobial activity assay and a red blood cell hemolysis test.

RESULTS

The results obtained show that the lipofecting activity of PTAI allows effective transfection of plasmid DNA complexed in negatively-charged lipoplexes of 200-500 nm size into cells without significant side effects on cell physiology (viability, proliferation, morphology, migration and gap junctional intercellular coupling). Moreover, PTAI-based vehicles exhibit a potent bactericidal activity against Staphylococcus aureus and Escherichia coli. The developed anionic lipoplexes are safe towards human red blood cell membranes, which are not disrupted in their presence.

CONCLUSIONS

The developed carriers constitute a group of promising lipofecting agents of a new type that can be utilized as effective lipofecting agents in vitro and they are also an encouraging basis for in vivo applications.