Intracellular organelle-targeted non-viral gene delivery systems

Enhanced oral bioavailability of cannabidiol by flexible zein nanoparticles: in vitro and pharmacokinetic studies

Introduction

Cannabidiol (CBD) has a variety of pharmacological effects including antiepileptic, antispasmodic, anxiolytic and anti-inflammatory among other pharmacological effects. However, since CBD is a terpene-phenolic compound, its clinical application is limited by its poor water solubility, low stability, and low bioavailability.

Methods

In this study, we used several strategies to address the above problems. Hydrochloric acid was used to modify zein to improve the molecular flexibility. Flexible zein nanoparticles (FZP-CBD) loaded with CBD was prepared to improve the stability and bioavailability of CBD. The parameters were evaluated in terms of morphology, particle size (PS), polydispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE%), loading capacity (LC%), and storage stability. Simulated gastrointestinal fluid release experiment and bioavailability assay were applied in the evaluation.

Results

The simulated gastrointestinal fluid experiment showed that the release rates of FZP-CBD and natural zein nanoparticles (NZP-CBD) loaded with CBD were 3.57% and 89.88%, respectively, after digestion with gastric fluid for 2 h, 92.12% and 92.56%, respectively, after intestinal fluid digestion for 2 h. Compared with NZP-CBD, the C max of FZP-CBD at 3 different doses of CBD was increased by 1.7, 1.3 and 1.5 times respectively, and AUC0-t was increased by 1.4, 1.1 and 1.7 times respectively, bioavailability (F) was increased by 135.9%, 114.9%, 169.6% respectively.

Discussion

The experimental results showed that FZP-CBD could protect most of the CBD from being released in the stomach, and then control its release in the intestines, promote the absorption of CBD in the small intestine, and increase the bioavailability of CBD. Therefore, FZP-CBD could improve the utilization value of CBD and provide a new idea for the application of CBD in medicine and pharmacy.

Design and application of DNA nanostructures for organelle-targeted delivery of anticancer drugs

INTRODUCTION

DNA nanostructures targeting organelles are of great significance for the early diagnosis and precise therapy of human cancers. This review is expected to promote the development of DNA nanostructure-based cancer treatment with organelle-level precision in the future.

AREAS COVERED

In this review, we introduce the different principles for targeting organelles, summarize the progresses in the development of organelle-targeting DNA nanostructures, highlight their advantages and applications in disease treatment, and discuss current challenges and future prospects.

EXPERT OPINION

Accurate targeting is a basic problem for effective cancer treatment. However, current DNA nanostructures cannot meet the actual needs. Targeting specific organelles is expected to further improve the therapeutic effect and overcome tumor cell resistance, thereby holding great practical significance for tumor treatment in the clinic. With the deepening of the research on the molecular mechanism of disease development, especially on tumorigenesis and tumor progression, and increasing understanding of the behavior of biological materials in living cells, more versatile DNA nanostructures will be constructed to target subcellular organelles for drug delivery, essentially promoting the early diagnosis of cancers, classification, precise therapy and the estimation of prognosis in the future.

Strategies for improving the safety and RNAi efficacy of noncovalent peptide/siRNA nanocomplexes

In the past decades, the striking development of cationic polypeptides and cell-penetrating peptides (CPPs) tailored for small interfering RNA (siRNA) delivery has been fuelled by the conception of nuclear acid therapy and precision medicine. Owing to their amino acid compositions, inherent secondary structures as well as diverse geometrical shapes, peptides or peptide-containing polymers exhibit good biodegradability, high flexibility, and bio-functional diversity as nonviral siRNA vectors. Also, a variety of noncovalent nanocomplexes could be built via self-assembling and electrostatic interactions between cationic peptides and siRNAs. Although the peptide/siRNA nanocomplex-based RNAi therapies, STP705 and MIR-19, are under clinical trials, a guideline addressing the current bottlenecks of peptide/siRNA nanocomplex delivery is in high demand for future research and development. In this review, we present strategies for improving the safety and RNAi efficacy of noncovalent peptide/siRNA nanocomplexes in the treatment of genetic disorders. Through thorough analysis of those RNAi formulations using different delivery strategies, we seek to shed light on the rationale of peptide design and modification in constructing robust siRNA delivery systems, including targeted and co-delivery systems. Based on this, we provide a timely and comprehensive understanding of how to engineer biocompatible and efficient peptide-based siRNA vectors.

A Novel Proteomic Method Reveals NLS Tagging of T-DM1 Contravenes Classical Nuclear Transport in a Model of HER2-Positive Breast Cancer

The next breakthrough for protein therapeutics is effective intracellular delivery and accumulation within target cells. Nuclear localization signal (NLS)-tagged therapeutics have been hindered by the lack of efficient nuclear localization due to endosome entrapment. Although development of strategies for tagging therapeutics with technologies capable of increased membrane penetration has resulted in proportional increased potency, nonspecific membrane penetration limits target specificity and, hence, widespread clinical success. There is a long-standing idea that nuclear localization of NLS-tagged agents occurs exclusively via classical nuclear transport. In the present study, we modified the antibody-drug conjugate trastuzumab-emtansine (T-DM1) with a classical NLS linked to cholic acid (cell accumulator [Accum]) that enables modified antibodies to escape endosome entrapment and increase nuclear localization efficiency without abrogating receptor targeting. In parallel, we developed a proteomics-based method to evaluate nuclear transport. Accum-modified T-DM1 significantly enhanced cytotoxic efficacy in the human epidermal growth factor receptor 2 (HER2)-positive SKBR3 breast cancer system. We discovered that efficacy was dependent on the nonclassical importin-7. Our evaluation reveals that when multiple classical NLS tagging occurs, cationic charge build-up as opposed to sequence dominates and becomes a substrate for importin-7. This study results in an effective target cell-specific NLS therapeutic and a general approach to guide future NLS-based development initiatives.

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.

Stepwise dual targeting and dual responsive polymer micelles for mitochondrion therapy

Methods to selectively destroy mitochondria of tumor cells and induce cell apoptosis with nanomedicine constitute challenges in cancer therapy. In the present study, we develop cell membrane/mitochondria dual targeting and pH/redox dual responsive nanoparticles for mitochondrion therapy. The nanoparticles are fabricated by the self-assembly of triphenylphosphonium (TPP) grafted poly(ethylene glycol)(PEG)-poly(d,l-lactide)(PLA) copolymers (TPP-PEG-ss-PLA) using disulfide bonds as the intermediate linkers. To shield the surface positive charge of the nanoparticles from TPP composition, chondroitin sulfate (CS) is employed to coat the nanoparticles, and this prolongs blood circulation while endowing an active targeting ability to the cell membrane. In acidic lyso-somes/endosomes, the negatively charged CS layer falls away to expose the TPP component. Subsequently, in the cyto-plasm, the nanoparticles can anchor to the mitochondrial outer membrane by TPP-mediated targeting, thereby inducing a decrease in the membrane potential and opening of the permeability transition pore. Thus, the overproduction of ROS in the mitochondria promotes cell apoptosis. The released DOX directly diffuse into the mitochondria, thereby resulting in mito-chondrial DNA damage. Therefore, the nanoparticles exhibit significant potential in terms of a new avenue for mitochondrion therapy in cancer treatment.

Ecotoxicological impact of selected polyethylenimines toward their potential application as nitrogen fertilizers with prolonged activity

Poly(2-oxazoline) polymers have found extensive application in the preparation of microcapsules for biomedical purposes. However, there is a scarcity of information related to their ecotoxicological assessment. Therefore, in this study, we focused on the ecotoxicity of selected polyethylenimines (PEIs) including poly(2-ethyl-2-oxazoline) (PEtOx) as an N-acyl-substituted PEI, linear polyethylenimine (LPEI) and branched polyethylenimine (BPEI). Oat (a monocotyledon) (Avena sativa) and radish (a dicotyledon) (Raphanus sativus) were selected as the representative plants, which are recommended by the Organization for Economic Cooperation and Development (OECD) 208 as the standard to test for plant growth. Shoot and root length, fresh and dry matter, level of total nitrogen in green parts of the plants, as well as total chlorophyll and carotenoids were determined. Phytotoxicity of all the tested parameters was dependent on the concentration of the examined polymers in the soil as well as on the time of their incubation in the soil. According to our results, the amount of nitrogen in green parts of the plants was increased compared to the control plants, which revealed the uptake of the plant-available form of nitrogen released from the tested PEIs. This was especially true for the plants treated with LPEI. Ecotoxicological impact of the incubated polymers in the soil against marine bacteria Allivibrio fischeri proved that, the all tested polyethylenimines may be classified as not harmful to aquatic microorganisms.

Morphological Analysis of Trafficking and Processing of Anionic and Cationic Liposomes in Cultured Cells

Liposomes, artificial phospholipid vesicles, have been developed as a non-viral drug delivery system to allow contained agents to be efficiently delivered to target sites via systemic circulation. Liposomes have been used as a gene transfer tool with cultured cells; however, their precise trafficking and processing remain uncertain. Furthermore, liposomes with different surface charges are known to exhibit distinct properties. The purpose of the current study was to elucidate the intracellular trafficking and processing of liposomes with anionic and cationic surface charges from a morphological view point. We found that cationic liposomes (CLs) were more effectively taken by the cells than anionic liposomes (ALs). Confocal laser scanning microscopy and transmission electron microscopy demonstrated distinct intracellular localization and processing patterns of ALs and CLs. ALs and their contents were localized in lysosomes but not in cytosol, indicating that ALs are subjected to the endosome-lysosome system. In contrast, contents of CLs were distributed mainly in the cytosol. CLs appear to disturb the cell membrane and then collapse to release their contents into the cytosol. It is feasible that the contents of CLs enter the cytosol directly rather than via the endosome-lysosome system.

Nanoparticulate vaccine inhibits tumor growth via improved T cell recruitment into melanoma and huHER2 breast cancer

Nanoparticulate vaccines are promising tools to overcome cancer immune evasion. However, a deeper understanding on nanoparticle-immune cell interactions and treatments regime is required for optimal efficacy. We provide a comprehensive study of treatment schedules and mode of antigen-association to nanovaccines on the modulation of T cell immunity in vivo, under steady-state and tumor-bearing mice. The coordinated delivery of antigen and two adjuvants (Monophosphoryl lipid A, oligodeoxynucleotide cytosine-phosphate-guanine motifs (CpG)) by nanoparticles was crucial for dendritic cell activation. A single vaccination dictated a 3-fold increase on cytotoxic memory-T cells and raised antigen-specific immune responses against B16.M05 melanoma. It generated at least a 5-fold increase on IFN-γ cytokine production, and presented over 50% higher lymphocyte count in the tumor microenvironment, compared to the control. The number of lymphocytes at the tumor site doubled with triple immunization. This lymphocyte infiltration pattern was confirmed in mammary huHER2 carcinoma, with significant tumor reduction.

Core/Shell Gene Carriers with Different Lengths of PLGA Chains to Transfect Endothelial Cells

In order to improve the transfection efficiency and reduce the cytotoxicity of gene carriers, many strategies have been used to develop novel gene carriers. In this study, five complex micelles (MSP(2 k), MSP(4 k), MSP(6 k), MSP(8 k), and MSP(10 k)) were prepared from methoxy-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (mPEG-b-PLGA) and sorbitol-poly(d,l-lactide-co-glycolide)-graft-PEI (sorbitol-PLGA-g-PEI, where the designed molecular weights of PLGA chains were 2 kDa, 4 kDa, 6 kDa, 8 kDa, and 10 kDa, respectively) copolymers by a self-assembly method, and the mass ratio of mPEG-b-PLGA to sorbitol-PLGA-g-PEI was 1/3. These complex micelles and their gene complexes had appropriate sizes and zeta potentials, and pEGFP-ZNF580 (pDNA) could be efficiently internalized into EA.hy926 cells by their gene complexes (MSP(2 k)/pDNA, MSP(4 k)/pDNA, MSP(6 k)/pDNA, MSP(8 k)/pDNA, and MSP(10 k)/pDNA). The MTT assay results demonstrated that the gene complexes had low cytotoxicity in vitro. When the hydrophobic PLGA chain increased above 6 kDa, the gene complexes showed higher performance than that prepared from short hydrophobic chains. Moreover, the relative ZNF580 protein expression levels in MSP(6 k)/pDNA, MSP(8 k)/pDNA, and MSP(10 k)/pDNA) groups were 79.6%, 71.2%, and 73%, respectively. These gene complexes could promote the transfection of endothelial cells, while providing important information and insight for the design of new and effective gene carriers to promote the proliferation and migration of endothelial cells.

Cell surface-engineering to embed targeting ligands or tracking agents on the cell membrane

The key challenge to improve the efficacy of cell therapy is how to efficiently modify cells with a specific molecule or compound that can guide the cells to the target tissue. To address this, we have developed a cell surface engineering technology to non-invasively modify the cell surface. This technology can embed a wide variety of bioactive molecules on any cell surface and allow for the targeting of a wide range of tissues in a variety of disease states. Using our cell surface engineering technology, mesenchymal stem cells (MSC)s were modified with: 1) a homing peptide or a recombinant protein to facilitate the migration of the cells toward a specific molecular target; or 2) magnetic resonance imaging (MRI) contrast agents to allow for in vivo tracking of the cells. The incorporation of a homing peptide or a targeting ligand on MSCs facilitated the migration of the cells toward their molecular target. MRI contrast agents were successfully embedded on the cell surfaces without adverse effects to the cells and the contrast agent-labeled cells were detectable by MRI. Our technology is a promising method of cell surface engineering that is applicable to a broad range of cell therapies.

Direct Cytoplasmic Delivery and Nuclear Targeting Delivery of HPMA-MT Conjugates in a Microtubules Dependent Fashion

As the hearts of tumor cells, the nucleus is the ultimate target of many chemotherapeutic agents and genes. However, nuclear drug delivery is always hampered by multiple intracellular obstacles, such as low efficiency of lysosome escape and insufficient nuclear trafficking. Herein, an N-(2-hydroxypropyl) methacrylamide (HPMA) polymer-based drug delivery system was designed, which could achieve direct cytoplasmic delivery by a nonendocytic pathway and transport into the nucleus in a microtubules dependent fashion. A special targeting peptide (MT), derived from an endogenic parathyroid hormone-related protein, was conjugated to the polymer backbone, which could accumulate into the nucleus a by microtubule-mediated pathway. The in vitro studies found that low temperature and NaN3 could not influence the cell internalization of the conjugates. Besides, no obvious overlay of the conjugates with lysosome demonstrated that the polymer conjugates could enter the tumor cell cytoplasm by a nonendocytic pathway, thus avoiding the drug degradation in the lysosome. Furthermore, after suppression of the microtubule dynamics with microtubule stabilizing docetaxel (DTX) and destabilizing nocodazole (Noc), the nuclear accumulation of polymeric conjugates was significantly inhibited. Living cells fluorescence recovery after photobleaching study found that the nuclear import rate of conjugates was 2-fold faster compared with the DTX and Noc treated groups. These results demonstrated that the conjugates transported into the nucleus in a microtubules dependent way. Therefore, in addition to direct cytoplasmic delivery, our peptide conjugated polymeric platform could simultaneously mediate nuclear drug accumulation, which may open a new path for further intracellular genes/peptides delivery.

Reducible Poly(Oligo-D-Arginine) as an Efficient Carrier of the Thymidine Kinase Gene in the Intracranial Glioblastoma Animal Model

Gene therapy has been considered as an alternative treatment for glioblastoma therapy. In this study, a glioblastoma-specific suicide gene, pEpo-NI2-SV-TK, was delivered into the intracranial glioblastoma model using reducible poly(oligo-d-arginines) (rPOA). pEpo-NI2-SV-TK has the erythropoietin (Epo) enhancer and the nestin intron 2 (NI2) for glioblastoma specific gene expression. The in vitro studies showed that the rPOA formed stable complexes with pEpo-NI2-SV-TK. In the MTT and TUNEL assays, rPOA showed lower cytotoxicity than polyethylenimine (25 kDa, PEI25k). In addition, the rPOA/pEpo-NI2-SV-TK complex induced higher glioblastoma cell death under hypoxic condition than normoxic condition, suggesting that pEpo-NI2-SV-TK induced gene expression in the hypoxic tumor tissue. For in vivo therapeutic efficacy evaluation, the rPOA/pEpo-NI2-SV-TK complex was injected into the brains of an intracranial glioblastoma rat model. The rPOA/pEpo-NI2-SV-TK injected group had a significantly reduced tumor size, compared with the control and the PEI25k/pEpo-NI2-SV-TK injected group. The TUNEL assay showed that the rPOA-pEpo-NI2-SV-TK complex had more apoptotic cells than the control and PEI25k/pEpo-NI2-SV-TK injected groups. These results suggest that the rPOA is an efficient carrier for pEpo-NI2-SV-TK and increased the therapeutic efficacy in the intracranial glioblastoma models. Therefore, the rPOA/pEpo-NI2-SV-TK complex may be useful for glioblastoma specific gene therapy.

Gene therapy for bone engineering

Bone has an intrinsic healing capacity that may be exceeded when the fracture gap is too big or unstable. In that moment, osteogenic measures need to be taken by physicians. It is important to combine cells, scaffolds and growth factors, and the correct mechanical conditions. Growth factors are clinically administered as recombinant proteins. They are, however, expensive and needed in high supraphysiological doses. Moreover, their half-life is short when administered to the fracture. Therefore, gene therapy may be an alternative. Cells can constantly produce the protein of interest in the correct folding, with the physiological glycosylation and in the needed amounts. Genes can be delivered in vivo or ex vivo by viral or non-viral methods. Adenovirus is mostly used. For the non-viral methods, hydrogels and recently sonoporation seem to be promising means. This review will give an overview of recent advancements in gene therapy approaches for bone regeneration strategies.

Monitoring the intracellular transformation process of surface-cleavable PLGA particles containing disulfide bonds by fluorescence resonance energy transfer

The FRET technique was used to quantify the surface cleavage kinetics of PLGA particles containing disulfide bonds in cells.

Non viral vectors in gene therapy- an overview

Non-viral vectors are simple in theory but complex in practice. Apart from intra cellular and extracellular barriers, number of other challenges also needs to be overcome in order to increase the effectiveness of non-viral gene transfer. These barriers are categorized as production, formulation and storage. No one-size-fits-all solution to gene delivery, which is why in spite of various developments in liposome, polymer formulation and optimization, new compounds are constantly being proposed and investigated. In this review, we will see in detail about various types of non-viral vectors highlighting promising development and recent advances that had improved the non-viral gene transfer efficiency of translating from "Bench to bedside".

Applications of nanomaterials as vaccine adjuvants

Vaccine adjuvants are applied to amplify the recipient's specific immune responses against pathogen infection or malignancy. A new generation of adjuvants is being developed to meet the demands for more potent antigen-specific responses, specific types of immune responses, and a high margin of safety. Nanotechnology provides a multifunctional stage for the integration of desired adjuvant activities performed by the building blocks of tailor-designed nanoparticles. Using nanomaterials for antigen delivery can provide high bioavailability, sustained and controlled release profiles, and targeting and imaging properties resulting from manipulation of the nanomaterials' physicochemical properties. Moreover, the inherent immune-regulating activity of particular nanomaterials can further promote and shape the cellular and humoral immune responses toward desired types. The combination of both the delivery function and immunomodulatory effect of nanomaterials as adjuvants is thought to largely benefit the immune outcomes of vaccination. In this review, we will address the current achievements of nanotechnology in the development of novel adjuvants. The potential mechanisms by which nanomaterials impact the immune responses to a vaccine and how physicochemical properties, including size, surface charge and surface modification, impact their resulting immunological outcomes will be discussed. This review aims to provide concentrated information to promote new insights for the development of novel vaccine adjuvants.

Self-Amplifying Replicon RNA Vaccine Delivery to Dendritic Cells by Synthetic Nanoparticles

Dendritic cells (DC) play essential roles determining efficacy of vaccine delivery with respect to immune defence development and regulation. This renders DCs important targets for vaccine delivery, particularly RNA vaccines. While delivery of interfering RNA oligonucleotides to the appropriate intracellular sites for RNA-interference has proven successful, the methodologies are identical for RNA vaccines, which require delivery to RNA translation sites. Delivery of mRNA has benefitted from application of cationic entities; these offer value following endocytosis of RNA, when cationic or amphipathic properties can promote endocytic vesicle membrane perturbation to facilitate cytosolic translocation. The present review presents how such advances are being applied to the delivery of a new form of RNA vaccine, replicons (RepRNA) carrying inserted foreign genes of interest encoding vaccine antigens. Approaches have been developed for delivery to DCs, leading to the translation of the RepRNA and encoded vaccine antigens both in vitro and in vivo. Potential mechanisms favouring efficient delivery leading to translation are discussed with respect to the DC endocytic machinery, showing the importance of cytosolic translocation from acidifying endocytic structures. The review relates the DC endocytic pathways to immune response induction, and the potential advantages for these self-replicating RNA vaccines in the near future.

A highly sensitive ratiometric fluorescent probe for the detection of cytoplasmic and nuclear hydrogen peroxide

As a marker for oxidative stress and a second messenger in signal transduction, hydrogen peroxide (H2O2) plays an important role in living systems. It is thus critical to monitor the changes in H2O2 in cells and tissues. Here, we developed a highly sensitive and versatile ratiometric H2O2 fluorescent probe (NP1) based on 1,8-naphthalimide and boric acid ester. In response to H2O2, the ratio of its fluorescent intensities at 555 and 403 nm changed 1020-fold within 200 min. The detecting limit of NP1 toward H2O2 is estimated as 0.17 μM. It was capable of imaging endogenous H2O2 generated in live RAW 264.7 macrophages as a cellular inflammation response, and especially, it was able to detect H2O2 produced as a signaling molecule in A431 human epidermoid carcinoma cells through stimulation by epidermal growth factor. This probe contains an azide group and thus has the potential to be linked to various molecules via the click reaction. After binding to a Nuclear Localization Signal peptide, the peptide-based combination probe (pep-NP1) was successfully targeted to nuclei and was capable of ratiometrically detecting nuclear H2O2 in living cells. These results indicated that NP1 was a highly sensitive ratiometric H2O2 dye with promising biological applications.

Functional polymers of gene delivery for treatment of myocardial infarct

Ischemic heart disease is rapidly growing as the common cause of death in the world. It is a disease that occurs as a result of coronary artery stenosis and is caused by the lack of oxygen within cardiac muscles due to an imbalance between oxygen supply and demand. The conventional medical therapy is focused on the use of drug eluting stents, coronary-artery bypass graft surgery and anti-thrombosis. Gene therapy provides great opportunities for treatment of cardiovascular disease. In order for gene therapy to be successful, the development of proper gene delivery systems and hypoxia-regulated gene expression vectors is the most important factors. Several non-viral gene transfer methods have been developed to overcome the safety problems of viral transduction. Some of which include plasmids that regulate gene expression that is controlled by environment specific promoters in the transcriptional or the translational level. This review explores polymeric gene carriers that target the myocardium and hypoxia-inducible vectors, which regulate gene expression in response to hypoxia, and their application in animal myocardial infarction models.

Cell penetrating peptides: efficient vectors for delivery of nanoparticles, nanocarriers, therapeutic and diagnostic molecules

Efficient delivery of therapeutic and diagnostic molecules to the cells and tissues is a difficult challenge. The cellular membrane is very effective in its role as a selectively permeable barrier. While it is essential for cell survival and function, also presents a major barrier for intracellular delivery of cargo such as therapeutic and diagnostic agents. In recent years, cell-penetrating peptides (CPPs), that are relatively short cationic and/or amphipathic peptides, received great attention as efficient cellular delivery vectors due to their intrinsic ability to enter cells and mediate uptake of a wide range of macromolecular cargo such as plasmid DNA (pDNA), small interfering RNA (siRNAs), drugs, and nanoparticulate pharmaceutical carriers. This review discusses the various uptake mechanisms of these peptides. Furthermore, we discuss recent advances in the use of CPP for the efficient delivery of nanoparticles, nanocarriers, DNA, siRNA, and anticancer drugs to the cells. In addition, we have been highlighting new results for improving endosomal escape of CPP-cargo molecules. Finally, pH-responsive and activable CPPs for tumor-targeting therapy have been described.

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.

Localization of exogenous DNA to mitochondria in skeletal muscle following hydrodynamic limb vein injection

Mitochondrial genetic disorders are a major cause of mitochondrial diseases. It is therefore likely that mitochondrial gene therapy will be useful for the treatment of such diseases. Here, we report on the possibility of mitochondrial gene delivery in skeletal muscle using hydrodynamic limb vein (HLV) injection. The HLV injection procedure, a useful method for transgene expression in skeletal muscle, involves the rapid injection of a large volume of naked plasmid DNA (pDNA) into the distal vein of a limb. We hypothesized that the technique could be used to deliver pDNA not only to nuclei but also to mitochondria, since cytosolic pDNA that is internalized by the method may be able to overcome mitochondrial membrane. We determined if pDNA could be delivered to myofibrillar mitochondria by HLV injection by PCR analysis. Mitochondrial toxicity assays showed that the HLV injection had no influence on mitochondrial function. These findings indicate that HLV injection promises to be a useful technique for in vivo mitochondrial gene delivery.

Nuclear location signal peptide–modified poly (ethyleneimine)/DNA complexes: An efficient gene delivery vector in vitro and in vivo

The low transfection efficiency of nonviral gene delivery systems limits their applications. In this study, we demonstrated a simple method to modify poly(ethyleneimine)/DNA complexes with a nuclear location signal peptide via bis(succinimidyl) penta(ethylene glycol) coupling. The amount of grafted nuclear location signal peptide was controlled within a range of 0–9 µg for poly(ethyleneimine)/DNA complexes containing 10 µg DNA and 100 µg poly(ethyleneimine) by adjusting the grafting agent and peptide feeds. The particle size and surface zeta-potential of the complexes were largely retained after nuclear location signal immobilization. Based on the results of the flow cytometry measurements, the nuclear location signal–modified poly(ethyleneimine)/DNA complexes were internalized into at bone marrow stem cells at a significantly faster rate and a higher amount than the unmodified complexes. In vitro transfection experiments, using plasmid DNA encoding bone morphogenetic protein 2, indicated that the nuclear location signal peptide–modified poly(ethyleneimine)/DNA complexes have significantly higher gene transfection ability toward bone marrow stem cells than unmodified complexes. The porous collagen scaffolds loaded with nuclear location signal–modified poly(ethyleneimine)/plasmid DNA encoding bone morphogenetic protein 2 complexes successfully transfected tissue cells and induced the human bone morphogenetic protein 2 expression in a rat. The modification of the poly(ethyleneimine)/DNA complexes with nuclear location signal peptide was effective in enhancing gene transfection of complexes in vitro and in vivo, thus indicating potential applications for bioactive scaffolds with enhanced tissue regeneration performance.

Physicochemical properties determine nanomaterial cellular uptake, transport, and fate

Although a growing number of innovations have emerged in the fields of nanobiotechnology and nanomedicine, new engineered nanomaterials (ENMs) with novel physicochemical properties are posing novel challenges to understand the full spectrum of interactions at the nano-bio interface. Because these could include potentially hazardous interactions, researchers need a comprehensive understanding of toxicological properties of nanomaterials and their safer design. In depth research is needed to understand how nanomaterial properties influence bioavailability, transport, fate, cellular uptake, and catalysis of injurious biological responses. Toxicity of ENMs differ with their size and surface properties, and those connections hold true across a spectrum of in vitro to in vivo nano-bio interfaces. In addition, the in vitro results provide a basis for modeling the biokinetics and in vivo behavior of ENMs. Nonetheless, we must use caution in interpreting in vitro toxicity results too literally because of dosimetry differences between in vitro and in vivo systems as well the increased complexity of an in vivo environment. In this Account, we describe the impact of ENM physicochemical properties on cellular bioprocessing based on the research performed in our groups. Organic, inorganic, and hybrid ENMs can be produced in various sizes, shapes and surface modifications and a range of tunable compositions that can be dynamically modified under different biological and environmental conditions. Accordingly, we cover how ENM chemical properties such as hydrophobicity and hydrophilicity, material composition, surface functionalization and charge, dispersal state, and adsorption of proteins on the surface determine ENM cellular uptake, intracellular biotransformation, and bioelimination versus bioaccumulation. We review how physical properties such as size, aspect ratio, and surface area of ENMs influence the interactions of these materials with biological systems, thereby affecting their hazard potential. We discuss our actual experimental findings and show how these properties can be tuned to control the uptake, biotransformation, fate, and hazard of ENMs. This Account provides specific information about ENM biological behavior and safety issues. This research also assists the development of safer nanotherapeutics and guides the design of new materials that can execute novel functions at the nano-bio interface.

Preparation, characterization, and in vitro and in vivo investigation of chitosan-coated poly (d,l-lactide-co-glycolide) nanoparticles for intestinal delivery of exendin-4

Background

Exendin-4 is an incretin mimetic agent approved for type 2 diabetes treatment. However, the required frequent injections restrict its clinical application. Here, the potential use of chitosan-coated poly (d,l-lactide-co-glycolide) (CS-PLGA) nanoparticles was investigated for intestinal delivery of exendin-4.

Methods and results

Nanoparticles were prepared using a modified water–oil–water (w/o/w) emulsion solvent-evaporation method, followed by coating with chitosan. The physical properties, particle size, and cell toxicity of the nanoparticles were examined. The cellular uptake mechanism and transmembrane permeability were performed in Madin-Darby canine kidney-cell monolayers. Furthermore, in vivo intraduodenal administration of exendin-4-loaded nanoparticles was carried out in rats. The PLGA nanoparticle coating with chitosan led to a significant change in zeta potential, from negative to positive, accompanied by an increase in particle size of ~30 nm. Increases in both the molecular weight and degree of deacetylation of chitosan resulted in an observable increase in zeta potential but no apparent change in the particle size of ~300 nm. Both unmodified PLGA and chitosan-coated nanoparticles showed only slight cytotoxicity. Use of different temperatures and energy depletion suggested that the cellular uptake of both types of nanoparticles was energy-dependent. Further investigation revealed that the uptake of PLGA nanoparticles occurred via caveolin-mediated endocytosis and that of CS-PLGA nanoparticles involved both macropinocytosis and clathrin-mediated endocytosis, as evidenced by using endocytic inhibitors. However, under all conditions, CS-PLGA nanoparticles showed a greater potential to be transported into cells, as shown by flow cytometry and confocal microscopy. Transmembrane permeability analysis showed that unmodified and modified PLGA nanoparticles could improve the transport of exendin-4 by up to 8.9- and 16.5-fold, respectively, consistent with the evaluation in rats.

Conclusion

The chitosan-coated nanoparticles have a higher transport potential over both free drug and unmodified particles, providing support for their potential development as a candidate oral delivery agent for exendin-4.

Targeted gene delivery to ischemic myocardium by homing peptide-guided polymeric carrier

Myocardial ischemia needs an alternative treatment such as gene therapy for the direct protection of cardiomyocytes against necrosis or apoptosis and to prevent the development of myocardial fibrosis and cardiac dysfunction. Despite the utility of gene therapy, its therapeutic use is limited due to inadequate transfection in cardiomyocytes and difficulty in directing to ischemic myocardium. Here, we present a polymeric gene carrier that is capable of targeting ischemic myocardium, resulting in high localization within the ischemic zone of the left ventricle (LV) of an ischemia/reperfusion (I/R) rat model upon systemic administration. Cystamine bisacrylamide-diamino hexane (CD) polymer was modified with the ischemic myocardium-targeted peptide (IMTP) and D-9-arginine (9R) for dual effects of the homing to ischemic myocardium and enhanced transfection efficiency with minimized polymer use. Conjugation of IMTP and 9R to CD led to an increase in transfection under hypoxia and significantly reduced the amount of polymer required for high transfection. Finally, we confirmed targeting of IMTP-CD-9R/DNA polyplex to ischemic myocardium and enhanced gene expression in LV of the I/R rat after tail vein injection. This study provides a clue that gene therapy for the treatment of myocardial ischemia can be achieved by using homing peptide-guided gene delivery systems.

Functional silica nanoparticles for redox-triggered drug/ssDNA co-delivery

A mesoporous silica nanoparticle (MSNP) based co-delivery system is developed in order to deliver simultaneously drug and single strand DNA (ssDNA) in a controlled manner. Negatively charged ssDNA as a model gene is immobilized onto the surface of positively charged ammonium-functionalized MSNPs through electrostatic interaction, effectively blocking the loaded drugs within the mesopores of MSNPs. When the pre-installed disulfide bond on the ammonium unit is broken by the addition of the reducing agent such as dithiothreitol or glutathione, the ssDNA network on the surface is freed, leading to the release of the loaded drug molecules from the mesopores. The cell investigations indicate that the functional nanoparticles have a very low cytotoxicity under the concentrations measured. The doxorubicin-loaded and ssDNA-coated nanoparticles show an enhanced cellular internalization, leading to a successful drug/ssDNA co-delivery in vitro for significant apoptosis of Hela cancer cells as compared with that of free doxorubicin. The obtained experimental results indicate promising applications of the functional nanoparticles in cancer treatment.

The effect of nanoparticle uptake on cellular behavior: disrupting or enabling functions?

Nanoparticles (NPs) are materials with overall dimensions in the nanoscale range. They have unique physicochemical properties, and have emerged as important players in current research in modern medicine. In the last few decades, several types of NPs and microparticles have been synthesized and proposed for use as contrast agents for diagnostics and imaging and for drug delivery; for example, in cancer therapy. Yet specific targeting that will improve their delivery still represents an unsolved challenge. The mechanism by which NPs enter the cell has important implications not only for their fate but also for their impact on biological systems. Several papers in the literature discuss the potential risks related to NP exposure, and more recently the concept that even sublethal doses of NPs may elicit a cell response has been proposed. In this review, we intend to present an overall view of cell mechanisms that may be perturbed by cell-NP interaction. Published data, in fact, emphasize that NPs should no longer be viewed only as simple carriers for biomedical applications, but that they can also play an active role in mediating biological effects.

Functional RNA delivery targeted to dendritic cells by synthetic nanoparticles

Dendritic cells (DCs) are essential to many aspects of immune defense development and regulation. They provide important targets for prophylactic and therapeutic delivery. While protein delivery has had considerable success, RNA delivery is still expanding. Delivering RNA molecules for RNAi has shown particular success and there are reports on successful delivery of mRNA. Central, therein, is the application of cationic entities. Following endocytosis of the delivery vehicle for the RNA, cationic entities should promote vesicular membrane perturbation, facilitating cytosolic release. The present review explains the diversity of DC function in immune response development and control. Promotion of delivered RNA cytosolic release is discussed, relating to immunoprophylactic and therapeutic potential, and DC endocytic machinery is reviewed, showing how DC endocytic pathways influence the handling of internalized material. The potential advantages for application of replicating RNA are presented and discussed, in consideration of their value and development in the near future.

Design of polymeric nanoparticles for biomedical delivery applications

Polymeric nanoparticles-based therapeutics show great promise in the treatment of a wide range of diseases, due to the flexibility in which their structures can be modified, with intricate definition over their compositions, structures and properties. Advances in polymerization chemistries and the application of reactive, efficient and orthogonal chemical modification reactions have enabled the engineering of multifunctional polymeric nanoparticles with precise control over the architectures of the individual polymer components, to direct their assembly and subsequent transformations into nanoparticles of selective overall shapes, sizes, internal morphologies, external surface charges and functionalizations. In addition, incorporation of certain functionalities can modulate the responsiveness of these nanostructures to specific stimuli through the use of remote activation. Furthermore, they can be equipped with smart components to allow their delivery beyond certain biological barriers, such as skin, mucus, blood, extracellular matrix, cellular and subcellular organelles. This tutorial review highlights the importance of well-defined chemistries, with detailed ties to specific biological hurdles and opportunities, in the design of nanostructures for various biomedical delivery applications.

Surface conjugation of triphenylphosphonium to target poly(amidoamine) dendrimers to mitochondria

Dendrimers have emerged as promising carriers for the delivery of a wide variety of pay-loads including therapeutic drugs, imaging agents and nucleic acid materials into biological systems. The current work aimed to develop a novel mitochondria-targeted generation 5 poly(amidoamine) (PAMAM) dendrimer (G(5)-D). To achieve this goal, a known mitochondriotropic ligand triphenylphosphonium (TPP) was conjugated on the surface of the dendrimer. A fraction of the cationic surface charge of G(5)-D was neutralized by partial acetylation of the primary amine groups. Next, the mitochondria-targeted dendrimer was synthesized via the acid-amine-coupling conjugation reaction between the acid group of (3-carboxypropyl)triphenyl-phosphonium bromide and the primary amines of the acetylated dendrimer (G(5)-D-Ac). These dendrimers were fluorescently labeled with fluorescein isothiocyanate (FITC) to quantify cell association by flow cytometry and for visualization under confocal laser scanning microscopy to assess the mitochondrial targeting in vitro. The newly developed TPP-anchored dendrimer (G(5)-D-Ac-TPP) was efficiently taken up by the cells and demonstrated good mitochondrial targeting. In vitro cytotoxicity experiments carried out on normal mouse fibroblast cells (NIH-3T3) had greater cell viability in the presence of the G(5)-D-Ac-TPP compared to the parent unmodified G(5)-D. This mitochondria-targeted dendrimer-based nanocarrier could be useful for imaging as well as for selective delivery of bio-actives to the mitochondria for the treatment of diseases associated with mitochondrial dysfunction.