Effects of cell-penetrating peptides and pegylation on transfection efficiency of polyethylenimine in mouse lungs

Mucosal Penetrative Polymeric Micelle Formulations for Insulin Delivery to the Respiratory Tract

Purpose

Effective mucosal delivery of drugs continues to pose a significant challenge owing to the formidable barrier presented by the respiratory tract mucus, which efficiently traps and clears foreign particulates. The surface characteristics of micelles dictate their ability to penetrate the respiratory tract mucus. In this study, polymeric micelles loaded with insulin (INS) were modified using mucus-penetrative polymers.

Methods

We prepared and compared polyethylene glycol (PEG)-coated micelles with micelles where cell-penetrating peptide (CPP) is conjugated to PEG. Systematic investigations of the physicochemical and aerosolization properties, performance, in vitro release, mucus and cell penetration, lung function, and pharmacokinetics/pharmacodynamics (PK/PD) of polymeric micelles were performed to evaluate their interaction with the respiratory tract.

Results

The nano-micelles, with a particle size of <100 nm, exhibited a sustained-release profile. Interestingly, PEG-coated micelles exhibited higher diffusion and deeper penetration across the mucus layer. In addition, CPP-modified micelles showed enhanced in vitro cell penetration. Finally, in the PK/PD studies, the micellar solution demonstrated higher maximum concentration (Cmax) and AUC0-8h values than subcutaneously administered INS solution, along with a sustained blood glucose-lowering effect that lasted for more than 8 h.

Conclusion

This study proposes the use of mucus-penetrating micelle formulations as prospective inhalation nano-carriers capable of efficiently transporting peptides to the respiratory tract.

Automated Parameterization of Coarse-Grained Polyethylenimine under a Martini Framework

As a versatile polymer in many applications, synthesized polyethylenimine (PEI) is polydisperse with diverse branched structures that attain pH-dependent protonation states. Understanding the structure-function relationship of PEI is necessary for enhancing its efficacy in various applications. Coarse-grained (CG) simulations can be performed at length and time scales directly comparable with experimental data while maintaining the molecular perspective. However, manually developing CG forcefields for complex PEI structures is time-consuming and prone to human errors. This article presents a fully automated algorithm that can coarse-grain any branched architecture of PEI from its all-atom (AA) simulation trajectories and topology. The algorithm is demonstrated by coarse-graining a branched 2 kDa PEI, which can replicate the AA diffusion coefficient, radius of gyration, and end-to-end distance of the longest linear chain. Commercially available 25 and 2 kDa Millipore-Sigma PEIs are used for experimental validation. Specifically, branched PEI architectures are proposed, coarse-grained using the automated algorithm, and then simulated at different mass concentrations. The CG PEIs can reproduce existing experimental data on PEI's diffusion coefficient and Stokes-Einstein radius at infinite dilution as well as its intrinsic viscosity. This suggests a strategy where probable chemical structures of synthetic PEIs can be inferred computationally using the developed algorithm. The coarse-graining methodology presented here can also be extended to other polymers.

Cell penetrating peptide (CPP) gold(iii) - complex - bioconjugates: from chemical design to interaction with cancer cells for nanomedicine applications

This study promotes an innovative synthesis of a nanotheragnostic scaffold capable of targeting and destroying pancreatic cancer cells (PDAC) using the Biotinylated NFL-TBS.40-63 peptide (BIOT-NFL), known to enter various glioblastoma cancer cells (GBM) where it specifically destroys their microtubule network. This recently proposed methodology (P7391FR00-50481 LIV) applied to other peptides VIM (Vimentin) and TAT (Twin-Arginine Translocation) (CPP peptides) has many advantages, such as targeted selective internalization and high stability under experimental conditions, modulated by steric and chemical configurations of peptides. The successful interaction of peptides on gold surfaces has been confirmed by UV-visible, dynamic light scattering (DLS), Zeta potential (ZP) and Raman spectroscopy analyses. The cellular internalization in pancreatic ductal adenocarcinoma (PDAC; MIA PACA-2) and GBM (F98) cells was monitored by transmission electron microscopy (TEM) and showed a better cellular internalization in the presence of peptides with gold nanoparticles. In this work, we also evaluated the power of these hybrid peptide-nanoparticles as photothermal agents after cancer cell internalization. These findings envisage novel perspectives for the development of high peptide-nanotheragnostics.

Endosomal Escape of Bioactives Deployed via Nanocarriers: Insights Into the Design of Polymeric Micelles

Cytoplasmic delivery of bioactives requires the use of strategies such as active transport, electroporation, or the use of nanocarriers such as polymeric nanoparticles, liposomes, micelles, and dendrimers. It is essential to deliver bioactive molecules in the cytoplasm to achieve targeted effects by enabling organelle targeting. One of the biggest bottlenecks in the successful cytoplasmic delivery of bioactives through nanocarriers is their sequestration in the endosomes that leads to the degradation of drugs by progressing to lysosomes. In this review, we discussed mechanisms by which nanocarriers are endocytosed, the mechanisms of endosomal escape, and more importantly, the strategies that can be and have been employed for their escape from the endosomes are summarized. Like other nanocarriers, polymeric micelles can be designed for endosomal escape, however, a careful control is needed in their design to balance between the possible toxicity and endosomal escape efficiency. Keeping this in view, polyion complex micelles, and polymers that have the ability to escape the endosome, are fully discussed. Finally, we provided some perspectives for designing the polymeric micelles for efficient cytoplasmic delivery of bioactive agents through endosomal escape.

Lung cancer targeting efficiency of Silibinin loaded Poly Caprolactone /Pluronic F68 Inhalable nanoparticles: In vitro and In vivo study

Silibinin (SB) is shown to have an anticancer properties. However, its clinical therapeutic effects have been restricted due to its low water solubility and poor absorption after oral administration. The aim of this study was to develop SB-loaded PCL/Pluronic F68 nanoparticles for pulmonary delivery in the treatment of lung cancer. A modified solvent displacement process was used to make nanoparticles, which were then lyophilized to make inhalation powder, Nanoparticles were characterized with DSC, FTIR,SEM and In vitro release study. Further, a validated HPLC method was developed to investigate the Biodistribution study, pharmacokinetic parameters. Poly Caprolactone PCL / Pluronic F68 NPs showed the sustained release effect up to 48 h with an emitted (Mass median Aerodynamic diameter)MMAD and (Geometric size distribution)GSD were found to be 4.235 ±0.124 and 1.958±1.23 respectively. More specifically, the SB Loaded PCL/Pluronic F 68 NPs demonstrated long circulation and successful lung tumor-targeting potential due to their cancer-targeting capabilities. SB Loaded PCL/Pluronic F68 NPs significantly inhibited tumour growth in lung cancer-induced rats after inhalable administration. In a pharmacokinetics study, PCL/ Pluronic F68 NPs substantially improved SB bioavailability, with a more than 4-fold rise in AUC when compared to IV administration. These findings indicate that SB-loaded PCL/PluronicF68 nanoparticles may be a successful lung cancer therapy delivery system.

Silibinin loaded inhalable solid lipid nanoparticles for lung targeting

AIM

In the current study, efforts are being made to prepare Inhalable Silibinin loaded solid lipid nanoparticles (SLNs) with narrow size distribution with improved bioavailability.

METHODS

SLNs were formulated by high shear homogenisation method SLNs were characterised, including Differential Scanning Calorimetry (DSC), Fourier transform infra-red spectroscopy (FTIR), particle size analysis, entrapment efficiency with Aerodynamic behaviour. The MTT assay was performed against A549 cell line, to measure their anticancer cell activity with In vivo study.

RESULTS

Optimized formulation exhibited spherical surface with a mean particle size of 221 ± 1.251 nm, PI of 0.121 ±  0.081, zeta potential of -4.12 ± 0.744. Aerodynamic behaviour such as Mass median aerodynamic diameter (MMAD) and Geometric size distribution (GSD) were found to be 5.487 ± 0.072 and 2.321 ± 0.141 respectively proved formulation is suitable for inhalation. In vitro cellular efficacy against A549 cells, revealed that the optimised formulations were more effective and potent.

CONCLUSION

The Inhalable SLNs approach was successfully engineered and administered to the lungs safely without causing any problems.

Development and in vitro-in vivo performances of an inhalable indole-3-carboxaldehyde dry powder to target pulmonary inflammation and infection

A tryptophan metabolite of microbial origin, indole-3-carboxaldehyde (3-IAld), has been recently identified as a Janus molecule that, acting at the host-pathogen interface and activating the aryl hydrocarbon receptor, can result as a potential candidate to treat infections as well as diseases with an inflammatory and/or immune component. In this work, an inhaled dry powder of 3-IAld was developed and evaluated for its efficacy, compared to oral and intranasal administration using an aspergillosis model of infection and inflammation. The obtained inhalable dry powder was shown to: i) be suitable to be delivered for pulmonary administration, ii) possess good toxicological safety, and iii) be superior to other administration modalities (oral and intranasal) in reducing disease scores by acting on infection and inflammation. This study supports the use of 3-IAld inhalable dry powders as a potential novel therapeutic tool to target inflammation and infection in pulmonary diseases.

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.

Photoinduced Endosomal Escape Mechanism: A View from Photochemical Internalization Mediated by CPP-Photosensitizer Conjugates

Endosomal escape in cell-penetrating peptide (CPP)-based drug/macromolecule delivery systems is frequently insufficient. The CPP-fused molecules tend to remain trapped inside endosomes and end up being degraded rather than delivered into the cytosol. One of the methods for endosomal escape of CPP-fused molecules is photochemical internalization (PCI), which is based on the use of light and a photosensitizer and relies on photoinduced endosomal membrane destabilization to release the cargo molecule. Currently, it remains unclear how this delivery strategy behaves after photostimulation. Recent findings, including our studies using CPP-cargo-photosensitizer conjugates, have shed light on the photoinduced endosomal escape mechanism. In this review, we discuss the structural design of CPP-photosensitizer and CPP-cargo-photosensitizer conjugates, and the PCI mechanism underlying their application.

PEGylation and Cell-Penetrating Peptides: Glimpse into the Past and Prospects in the Future

Several drug molecules have shown low bioavailability and pharmacokinetic profile due to metabolism by enzymes, excretion by the renal system, or due to other physiochemical properties of drug molecules. These problems have resulted in the loss of efficacy and the gain of side effects associated with drug molecules. PEGylation is one of the strategies to overcome these pharmacokinetic issues and has been successful in the clinic. Cell-penetrating Peptides (CPPs) help to deliver molecules across biological membranes and could be used to deliver cargo selectively to the intracellular site or to the drug target. Hence CPPs could be used to improve the efficacy and selectivity of the drug. However, due to the peptidic nature of CPPs, they have a low pharmacokinetic profile. Using PEGylation and CPPs together as a component of a drug delivery system, the and efficacy of drug molecules could be improved. The other important pharmacokinetic properties such as short half-life, solubility, stability, absorption, metabolism, and elimination could be also improved. Here in this review, we summarized PEGylated CPPs or PEGylation based formulations for CPPs used in a drug delivery system for several biomedical applications until August 2019.

Biodegradable Polymers for Gene Delivery

The cellular transport process of DNA is hampered by cell membrane barriers, and hence, a delivery vehicle is essential for realizing the potential benefits of gene therapy to combat a variety of genetic diseases. Virus-based vehicles are effective, although immunogenicity, toxicity and cancer formation are among the major limitations of this approach. Cationic polymers, such as polyethyleneimine are capable of condensing DNA to nanoparticles and facilitate gene delivery. Lack of biodegradation of polymeric gene delivery vehicles poses significant toxicity because of the accumulation of polymers in the tissue. Many attempts have been made to develop biodegradable polymers for gene delivery by modifying existing polymers and/or using natural biodegradable polymers. This review summarizes mechanistic aspects of gene delivery and the development of biodegradable polymers for gene delivery.

Sonochemical One-Step Synthesis of Polymer-Capped Metal Oxide Nanocolloids: Antibacterial Activity and Cytotoxicity

Most antibacterial agents demand their action in the form of a liquid for compatibility and ease of use in biosystems, which are mainly composed of biological fluids. Controlling the colloidal stability of metal oxide nanocolloids, in parallel with minimizing the effect of using a large amount of surfactant on their biocidal activity and cytotoxicity, remains a challenge. Here, we address the stability of nanocolloids of ZnO and CuO in the presence of polymer surfactants and the influence of the surface capping on their antibacterial activity and cytotoxicity. The metal oxide nanoparticles (NPs) were synthesized sonochemically in a single step and tested against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus to validate their biocidal efficacy. Cytotoxicity studies were performed on human alveolar epithelial cells. Polyethylene glycol- and polyvinyl alcohol-capped NPs are observed to show the minimum cytotoxicity whereas polyethylene imine-capped and pristine metal oxide NPs are toxic to the mammalian cells. The cytotoxic and antibacterial properties of the stable nanocolloids displayed an inverse relation, highlighting the role and significance of the polymer capping. The nontoxic biocidal nanocolloids showed an effective antibacterial efficacy of 99.9% in 2 h.

Dual-stimuli-responsive albumin-polyplex nanoassembly for spatially controlled gene release in metastatic breast cancer

Stimuli-responsive polymeric nanoparticles are useful for overcoming challenges such as transfection efficiency and the specific and safe delivery of genes to cancer cells. Transfection outcomes can be improved through spatially and temporally controlled gene release. We formulated a nanoassembly comprising a disulfide-crosslinked polyethylenimine (ssPEI) conjugated with a tumor-specific cell-penetrating peptide (DS 4-3) (SPD) polyplex and bovine serum albumin (BSA)-loaded IR780 (BI) nanoparticle, thereby forming a dual-stimulus-triggered, tumor-penetrating and gene-carrying nanoassembly (BI-SPD) via electrostatic complexing. BI-SPD nanoassembly were composed of highly stable nanosized complexes with an average size of 457 ± 27.5 nm, exhibiting an up to two-fold enhanced transfection efficiency with no sign of potential cytotoxicity in breast cancer cells. Moreover, upon laser irradiation, a four-fold increase in transfection efficiency was achieved due to the rapid endosomal escape of polyplexes triggered by the local heat induced by the BI-SPD nanoassembly. Additionally, the high redox environment in tumor cells facilitated the disassembly of the SPD polyplex for efficient plasmid release in the cytosol. The BI-SPD nanoassembly also exhibited high penetration and enhanced photothermally triggered gene expression in the 4T1 spheroid model. This BI-SPD nanoassembly has the potential to enhance the expression of therapeutic genes in tumor models without causing significant toxicity to surrounding healthy tissues, since it has shown higher tumor targeting and accumulation in the 4T1 tumor in mice model.

Self-replicating RNA vaccine functionality modulated by fine-tuning of polyplex delivery vehicle structure

The major limitations with large and complex self-amplifying RNA vaccines (RepRNA) are RNase-sensitivity and inefficient translation in dendritic cells (DCs). Condensing RepRNA with polyethylenimine (PEI) gave positive in vitro readouts, but was largely inferior to virus-like replicon particles (VRP) or direct electroporation. In the present study, we improved such polyplex formulation and determined that fine-tuning of the polyplex structure is essential for ensuring efficacious translation. Thereby, three parameters dominate: (i) PEI molecular weight (MW); (ii) RepRNA:PEI (weight:weight) ratio; and (iii) inclusion of cell penetrating peptides (CPPs). Seven commercially available linear PEIs (MW 2,500-250,000) were classified as strong, intermediate or low for their aptitude at complexing and protecting RepRNA for delivery into porcine blood DCs. Inclusion of (Arg)₉ or TAT(57-57) CPPs further modified the translation readouts, but varied for different gene expressions. Dependent on the formulation, translation of the gene of interest (GOI) inserted into the RepRNA (luciferase, or influenza virus hemagglutinin or nucleoprotein) could decrease, while the RepRNA structural gene (E2) translation increased. This was noted in the porcine SK6 cell line, as well as both porcine and, for the first time, human DCs. Two formulations - [Rep/PEI-4,000 (1:3)] and [Rep/PEI-40,000 (1:2)/(Arg)₉] were efficacious in vivo in mice and pigs, where specific CD8⁺ T and CD4⁺ T-cell responses against the GOI-encoded antigen were observed for the first time. The results demonstrate that different polyplex formulations differ in their interaction with the RepRNA such that only certain genes can be translated. Thus, delivery of these large self-replicating RNA molecules require definition with respect to translation of different genes, rather than just the GOI as is the norm, for identifying optimal delivery for the desired immune activation in vivo.

Exploring the role of peptides in polymer-based gene delivery

Polymers are widely studied as non-viral gene vectors because of their strong DNA binding ability, capacity to carry large payload, flexibility of chemical modifications, low immunogenicity, and facile processes for manufacturing. However, high cytotoxicity and low transfection efficiency substantially restrict their application in clinical trials. Incorporating functional peptides is a promising approach to address these issues. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we systematically summarize the role of peptides in polymer-based gene delivery, and elaborate how to rationally design polymer-peptide based gene delivery vectors.

STATEMENT OF SIGNIFICANCE

Polymers are widely studied as non-viral gene vectors, but suffer from high cytotoxicity and low transfection efficiency. Incorporating short, bioactive peptides into polymer-based gene delivery systems can address this issue. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we highlight the peptides' roles in polymer-based gene delivery, and elaborate how to utilize various functional peptides to enhance the transfection efficiency of polymers. The optimized peptide-polymer vectors should be able to alter their structures and functions according to biological microenvironments and utilize inherent intracellular pathways of cells, and consequently overcome the barriers during gene delivery to enhance transfection efficiency.

Barriers to inhaled gene therapy of obstructive lung diseases: A review

Knowledge of genetic origins of obstructive lung diseases has made inhaled gene therapy an attractive alternative to the current standards of care that are limited to managing disease symptoms. Initial lung gene therapy clinical trials occurred in the early 1990s following the discovery of the genetic defect responsible for cystic fibrosis (CF), a monogenic disorder. However, despite over two decades of intensive effort, gene therapy has yet to help patients with CF or any other obstructive lung disease. The slow progress is due in part to poor understanding of the biological barriers to inhaled gene therapy. Encouragingly, clinical trials have shown that inhaled gene therapy with various viral vectors and non-viral gene vectors is well tolerated by patients, and continued research has provided valuable lessons and resources that may lead to future success of this therapeutic strategy. In this review, we first introduce representative obstructive lung diseases and examine limitations of currently available therapeutic options. We then review key components for successful execution of inhaled gene therapy, including gene delivery systems, primary physiological barriers and strategies to overcome them, and advances in preclinical disease models with which the most promising systems may be identified for human clinical trials.

Biodistribution and Efficacy of Targeted Pulmonary Delivery of a Protein Kinase C-δ Inhibitory Peptide: Impact on Indirect Lung Injury

Sepsis and sepsis-induced lung injury remain a leading cause of death in intensive care units. We identified protein kinase C-δ (PKCδ) as a critical regulator of the acute inflammatory response and demonstrated that PKCδ inhibition was lung-protective in a rodent sepsis model, suggesting that targeting PKCδ is a potential strategy for preserving pulmonary function in the setting of indirect lung injury. In this study, whole-body organ biodistribution and pulmonary cellular distribution of a transactivator of transcription (TAT)-conjugated PKCδ inhibitory peptide (PKCδ-TAT) was determined following intratracheal (IT) delivery in control and septic [cecal ligation and puncture (CLP)] rats to ascertain the impact of disease pathology on biodistribution and efficacy. There was negligible lung uptake of radiolabeled peptide upon intravenous delivery [<1% initial dose (ID)], whereas IT administration resulted in lung retention of >65% ID with minimal uptake in liver or kidney (<2% ID). IT delivery of a fluorescent-tagged (tetramethylrhodamine-PKCδ-TAT) peptide demonstrated uniform spatial distribution and cellular uptake throughout the peripheral lung. IT delivery of PKCδ-TAT at the time of CLP surgery significantly reduced PKCδ activation (tyrosine phosphorylation, nuclear translocation and cleavage) and acute lung inflammation, resulting in improved lung function and gas exchange. Importantly, peptide efficacy was similar when delivered at 4 hours post-CLP, demonstrating therapeutic relevance. Conversely, spatial lung distribution and efficacy were significantly impaired at 8 hours post-CLP, which corresponded to marked histopathological progression of lung injury. These studies establish a functional connection between peptide spatial distribution, inflammatory histopathology in the lung, and efficacy of this anti-inflammatory peptide.

Nanocomplexes for gene therapy of respiratory diseases: Targeting and overcoming the mucus barrier

Gene therapy, i.e. the delivery and expression of therapeutic genes, holds great promise for congenital and acquired respiratory diseases. Non-viral vectors are less toxic and immunogenic than viral vectors, although they are characterized by lower efficiency. However, they have to overcome many barriers, including inflammatory and immune mediators and cells. The respiratory and airway epithelial cells, the main target of these vectors, are coated with a layer of mucus, which hampers the effective reaching of gene therapy vectors carrying either plasmid DNA or small interfering RNA. This barrier is thicker in many lung diseases, such as cystic fibrosis. This review summarizes the most important advancements in the field of non-viral vectors that have been achieved with the use of nanoparticulate (NP) systems, composed either of polymers or lipids, in the lung gene delivery. In particular, different strategies of targeting of respiratory and airway lung cells will be described. Then, we will focus on the two approaches that attempt to overcome the mucus barrier: coating of the nanoparticulate system with poly(ethylene glycol) and treatment with mucolytics. Our conclusions are: 1) Ligand and physical targeting can direct therapeutic gene expression in specific cell types in the respiratory tract; 2) Mucopenetrating NPs are endowed with promising features to be useful in treating respiratory diseases and should be now advanced in pre-clinical trials. Finally, we discuss the development of such polymer- and lipid-based NPs in the context of in vitro and in vivo disease models, such as lung cancer, as well as in clinical trials.

Peptide GE11-Polyethylene Glycol-Polyethylenimine for targeted gene delivery in laryngeal cancer

The objective of this study was to evaluate the possibility of using GE11-polyethylene glycol-polyethylenimine (GE11-PEG-PEI) for targeted gene delivery to treat epidermal growth factor receptor (EGFR)-overexpressing laryngeal cancer. This study described the design, characterization, and in vitro and in vivo study of the nanocarrier GE11-PEG-PEI for gene delivery to treat laryngeal cancer. Analysis of the sizes and zeta potentials indicated that the formation of PEGylated complexes was dependent on the N/P ratio, and these complexes were capable of binding plasmid DNA and condensing DNA into small positively charged nanoparticles. The results also revealed that GE11-PEG-PEI had a weaker effect on cell survival in vitro. Gene transfection was performed on human laryngeal cancer Hep-2 cells in vitro and in vivo. Both the in vitro and in vivo results demonstrated that GE11-PEG-PEI had greater transfection efficiency than mPEG-PEI. Compared with mPEG-PEI/pORF-hTRAIL and saline, GE11-PEG-PEI/pORFh-TRAIL significantly (p < 0.05) reduced tumor growth in nude mice with laryngeal cancer. Moreover, the GE11-PEG-PEI/pORF-hTRAIL-treated groups showed more apoptosis than the mPEG-PEI/pORF-hTRAIL-treated groups. Therefore, our results showed that the peptide GE11 conjugated to PEG-PEI delivered significantly more genes to EGFR-overexpressing laryngeal cancer cells in vivo, indicating that GE11-PEG-PEI may be a suitable gene vector for treating EGFR-overexpressing laryngeal cancer.

Evaluation of [(18)F]-CP18 as a PET imaging tracer for apoptosis

PURPOSE

We identified and validated [(18)F]-CP18, a DEVD (the caspase 3 substrate recognition motif) containing substrate-based compound as an imaging tracer for caspase-3 activity in apoptotic cells.

PROCEDURES

CP18 was radiolabeled with fluorine-18 using click chemistry. The affinity and selectivity of CP18 for caspase-3 were evaluated in vitro. The biodistribution and metabolism pattern of [(18)F]-CP18 were assessed in vivo. [(18)F]-CP18 positron emission tomography (PET) scans were performed in a dexamethasone-induced thymic apoptosis mouse model. After imaging, the mice were sacrificed, and individual organs were collected, measured in a gamma counter, and tested for caspase-3 activity.

RESULTS

In vitro enzymatic caspase-3 assay demonstrated specific cleavage of CP18. In vivo, [(18)F]-CP18 is predominantly cleared through the kidneys and urine, and is rapidly eliminated from the bloodstream. There was a sixfold increase in caspase activity and a fourfold increase of [(18)F]-CP18 retention in the dexamethasone-induced thymus of treated versus control mice.

CONCLUSIONS

We report the use [(18)F]-CP18 as a PET tracer for imaging apoptosis. Our data support further development of this tracer for clinical PET applications.

A paradigm change: efficient transfection of human leukemia cells by stimuli-responsive multicompartment micelles

The controlled nonviral delivery of genetic material using cationic polymers into cells has been of interest during the past three decades, yet the ideal delivery agent featuring utmost transfection efficiency and low cytotoxicity still has to be developed. Here, we demonstrate that multicompartment micelles from stimuli-responsive triblock terpolymers, polybutadiene-block-poly(methacrylic acid)-block-poly(2-(dimethylamino)ethyl methacrylate) (BMAAD), are promising candidates. The structures exhibit a patchy shell, consisting of amphiphilic (interpolyelectrolyte complexes, MAA and D) and cationic patches (excess D), generating a surface reminiscent to those of certain viruses and capable of undergoing pH-dependent changes in charge stoichiometry. After polyplex formation with plasmid DNA, superior transfection efficiencies can be reached for both adherent cells and human leukemia cells. Compared to the gold standard PEI, remarkable improvements and a number of advantages were identified for this system, including increased cellular uptake and an improved release of the genetic material, accompanied by fast and efficient endosomal escape. Furthermore, high sedimentation rates might be beneficial regarding in vitro applications.

From rationally designed polymeric and peptidic systems to sophisticated gene delivery nano-vectors

Lack of safe, efficient and controllable methods for delivering therapeutic genes appears to be the most important factor preventing human gene therapy. Safety issues encountered with viral vectors have prompted substantial attention to in vivo investigations with non-viral vectors throughout the past decade. However, developing non-viral vectors with effectiveness comparable to viral ones has been a challenge. The strategy of designing multifunctional synthetic carriers targeting several extracellular and intracellular barriers in the gene transfer pathway has emerged as a promising approach to improving the efficacy of gene delivery systems. This review will explain how sophisticated synthetic vectors can be created by combining conventional polycationic vectors such as polyethylenimine and basic amino acid peptides with additional polymers and peptides that are designed to overcome potential barriers to the gene delivery process.

Emerging applications of nanoparticles for lung cancer diagnosis and therapy

Lung cancer is by far the leading cause of cancer-related mortality worldwide, most of them being active tobacco smokers. Non small cell lung cancer accounts for around 85% to 90% of deaths, whereas the rest is contributed by small cell lung cancer. The extreme lethality of lung cancer arises due to lack of suitable diagnostic procedures for early detection of lung cancer and ineffective conventional therapeutic strategies. In course with desperate attempts to address these issues independently, a multifunctional nanotherapeutic or diagnostic system is being sought as a favorable solution. The manifestation of physiochemical properties of such nanoscale systems is tuned favorably to come up with a versatile cancer cell targeted diagnostic and therapeutic system. Apart from this, the aspect of being at nanoscale by itself confers the system with an advantage of passive accumulation at the site of tumor. This review provides a broad perspective of three major subclasses of such nanoscale therapeutic and diagnostic systems which include polymeric nanoparticles-based approaches, metal nanoparticles-based approaches, and bio-nanoparticles-based approaches. This review work also serves the purpose of gaining an insight into the pros and cons of each of these approaches with a prospective improvement in lung cancer therapeutics and diagnostics.

Pharmaceutical applications of the Calu-3 lung epithelia cell line

INTRODUCTION

The Calu-3 lung cell line has been shown to be a promising in vitro model of airway epithelia due to its similarity to in vivo physiology. Hence, over the past decade, it has found increasing applications in the pharmaceutical industry.

AREAS COVERED

This review focuses on the pharmaceutical applications of the Calu-3 cell line in areas such as mechanisms of drug transport, studying aerosol deposition, controlled release studies and identification of possible drug-drug interactions. The main findings of various studies, as well as the predictive potential of this model, are presented and discussed in this review.

EXPERT OPINION

There is still a lack of mechanistic knowledge regarding transport of inhaled therapeutics across the lungs. Cell culture models such as Calu-3 provide a simple and reproducible system to study the underlying mechanisms by which inhaled therapeutics interact with the lungs. However, more complex systems that integrate particle deposition onto different cell culture systems may be useful in addressing some fundamental questions to generate a better understanding of determinants that influences pulmonary drug dissolution, absorption, metabolism and efficacy. Ultimately the use of the Calu-3 cell line provides a basic research tool that enables the development of safer and more effective inhaled therapeutics.

Surface modified poly(β amino ester)-containing nanoparticles for plasmid DNA delivery

The use of biodegradable polymers provides a potentially safe and effective alternative to viral and liposomal vectors for the delivery of plasmid DNA to cells for gene therapy applications. In this work we describe the formulation of a novel nanoparticle (NP) system containing a blend of poly(lactic-co-glycolic acid) and a representative poly(beta-amino) ester (PLGA and PBAE respectively) for use as gene delivery vehicles. Particles of different weight/weight (wt/wt) ratios of the two polymers were characterized for size, morphology, plasmid DNA (pDNA) loading and surface charge. NPs containing PBAE were more effective at cellular internalization and transfection (COS-7 and CFBE41o-) than NPs lacking the PBAE polymer. However, along with these delivery benefits, PBAE exhibited cytotoxic effects that presented an engineering challenge. Surface coating of these blended particles with the cell-penetrating peptides (CPPs) mTAT, bPrPp and MPG via a PEGylated phospholipid linker (DSPE-PEG2000) resulted in NPs that reduced surface charge and cellular toxicity to levels comparable with NPs formulated with only PLGA. Additionally, these coated nanoparticles showed an improvement in pDNA loading, intracellular uptake and transfection efficiency, when compared to NPs lacking the surface coating. Although all particles with a CPP coating outperformed unmodified NPs, respectively, bPrPp and MPG coating resulted in 3 and 4.5× more pDNA loading than unmodified particles and approximately an order of magnitude improvement on transfection efficiency in CFBE41o- cells. These results demonstrate that surface-modified PBAE containing NPs are a highly effective and minimally toxic platform for pDNA delivery.

Optimized preparation of pDNA/poly(ethylene imine) polyplexes using a microfluidic system

Poly(ethylene imine) (PEI) is an established non-viral vector system for the delivery of various nucleic acids in gene therapy applications. Polyelectrolyte complexes between both compounds, so called polyplexes, are formed by electrostatic interactions of oppositely charged macromolecules and are thought to facilitate uptake into cells. Such complexes form spontaneously and on lab scale they are usually prepared by mixing solutions through pipetting. Hence, an optimized preparation procedure allowing the scale-up of well-defined polyplexes would be of general interest. We developed a new method for microfluidic polyplex preparation on a chip. The mixing behaviour within the microfluidic channels was evaluated. Polyplexes with PEI and plasmid DNA were prepared using this method, in comparison to the standard pipetting procedure. Sizes and polydispersity indices of these complexes were examined. The influence of various parameters on the polyplex characteristics and the suitability of this production procedure for other PEI-based complexes were also evaluated. It was shown that polyplexes could easily be prepared by microfluidics. The ratio of PEI to DNA was most important for the formation of small polyplexes, whereas other parameters had minor influence. The size of polyplexes prepared with this new method was observed to be relatively constant between 140 nm and 160 nm over a wide range of complex concentrations. In comparison, the size of polyplexes prepared by pipetting (approximately 90 nm to 160 nm) varied considerably. The versatility of this system was demonstrated with different (targeted) PEI-based vectors for the formation of complexes with pDNA and siRNA. In conclusion, polyplex preparation using microfluidics could be a promising alternative to the standard pipetting method due to its suitability for preparation of well-defined complexes with different compositions over a wide range of concentrations.

Selective stimulation of caveolae-mediated endocytosis by an osmotic polymannitol-based gene transporter

Controlling the cellular uptake mechanism and consequent intracellular route of polyplexes is important to improve the transfection efficiency of the non-viral gene delivery. Here, we report a new non-viral vector, polymannitol-based gene transporter (PMT), generated by crosslinking low molecular weight polyethylenimine with mannitol diacrylate, which has low cytotoxicity and good transfection efficiency. Interestingly, the uptake pathway of PMT/DNA complexes was shifted into caveolae-mediated endocytosis, avoiding lysosomal degradation. The mechanism of increased caveolae-mediated endocytosis of PMT/DNA complexes was found to be correlated with mechanosensing signal transduction by the hyperosmotic polymannitol part. Our results suggested that PMT, polymannitol-based gene transporter, is a safe and efficient gene delivery system with a well-modulated uptake pathway and intracellular route for gene therapy.

Pulmonary gene delivery using polymeric nonviral vectors

Pulmonary delivery provides an easy and well tolerated means of access for the administration of biomacromolecules to the pulmonary epithelium and could therefore be an attractive approach for local and systemic therapies. A growing number of reports, which are summarized in this review, mirror the viability of pulmonary gene delivery. Special attention has been paid to the biological barriers in the lung that must be overcome for successful delivery, and which can be divided into anatomic, physical, immunologic, and metabolic barriers. In light of these barriers, successful nonviral polymer-based formulations of therapeutic genes are presented depending on the chemical nature of the polymer. In addition to polyethyleneimine-based nonviral vectors, which have been most intensively studied for pulmonary gene delivery in the past, other polymeric, dendritic, and targeted materials are also described here, including novel and biodegradable polymers. As new materials need in vitro or ex vivo testing before in vivo application, sophisticated models for all three approaches have been illustrated. Although pulmonary siRNA delivery enjoys popularity in clinical trials, pulmonary gene delivery has so far not been translated into clinical applications. With this review, potential hurdles are demonstrated, but novel approaches that may lead to optimized systems are described as well.

A novel cationic liposome formulation for efficient gene delivery via a pulmonary route

The clinical success of gene therapy for lung cancer is not only dependent on efficient gene carriers but also on a suitable delivery route. A pulmonary delivery route can directly deliver gene vectors to the lung which is more efficient than a systemic delivery route. For gene carriers, cationic liposomes have recently emerged as leading non-viral vectors in worldwide gene therapy clinical trials. However, cytotoxic effects or apoptosis are often observed which is mostly dependent on the cationic lipid used. Therefore, an efficient and safe cationic lipid, 6-lauroxyhexyl lysinate (LHLN), previously synthesized by our group was first used to prepare cationic liposomes. Physicochemical and biological properties of LHLN-liposomes were investigated. LHLN-liposome/DNA complexes showed positive surface charge, spherical morphology, a relatively narrow particle size distribution and strong DNA binding capability. Compared with Lipofectamine2000, the new cationic liposome formulation using LHLN exhibited not only lower cytotoxicity (P < 0.05) but also similar transfection efficiency in A549 and HepG2 lung cancer cells for in vitro tests. When administered by intratracheal instillation into rat lungs for in vivo evaluation, LHLN-liposome/DNA complexes exhibited higher pulmonary gene transfection efficiency than Lipofectamine2000/DNA complexes (P < 0.05). These results suggested that LHLN-liposomes may have great potential for efficient pulmonary gene delivery.

Cellular delivery and antisense effects of peptide nucleic acid conjugated to polyethyleneimine via disulfide linkers

Peptide nucleic acid (PNA) is potentially an attractive antisense and antigene agent for which more efficient cellular delivery systems are still warranted. The cationic polymer polyethylenimine (PEI) is commonly used for cellular transfection of DNA and RNA complexes, but is not readily applicable for PNA due to the (inherent) charge neutrality of PNA. However, PEI could function as an efficient scaffold for PNA via chemical conjugation. Accordingly, we modified PEI with the amine-reactive heterobifunctional linker agent N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP) (with and without a PEG moiety) and further reacted this with a cysteine PNA. The level of modification was determined spectrophotometrically with high accuracy, and the PNA transfection efficiency of the conjugates was evaluated in an antisense luciferase splice-correction assay using HeLa pLuc705 cells. We find that PEI is an efficient vector for PNA delivery yielding significantly higher (up to 10-fold) antisense activity than an analogous PNA-octaarginine conjugate, even in the presence of chloroquine, which only slightly enhances the PEI-PNA activity. The PEI-PEG conjugates are preferred due to lower acute cellular toxicity. Finally, the method can be easily modified to allow for co-conjugation of other small molecules in a high-throughput screening assay that does not require a purification step.

Intestinal delivery of non-viral gene therapeutics: physiological barriers and preclinical models

The future of nucleic acid-based therapeutics is dependent on achieving successful delivery. Recently, there has been an increasing interest in delivery via the gastrointestinal tract. Gene therapy via this route has many advantages, including non-invasive access and the versatility to treat local diseases, such as inflammatory bowel disease, as well as systemic diseases, such as haemophilia. However, the intestine presents several distinct barriers and, therefore, the design of robust non-viral delivery systems is key to future success. Several non-viral delivery strategies have provided evidence of activity in vivo. To facilitate the design of more efficient and safe gene medicines, more physiologically relevant models, at both the in vitro and in vivo levels, are essential.

Chip-based impedance measurement on single cells for monitoring sub-toxic effects on cell membranes

There is a lack of methods suitable for generation of data about the dynamics of effects on cell membranes with a high sensitivity. Such methods are urgently needed to support the optimisation of interaction of substances, particles or materials with cell. The goal of this article is to use an improved microhole chip system to monitor the alterations of cells due to the interactions of polymer-DNA complexes. This should demonstrate exemplarily that subtoxic effect of biological relevant particles or substances at relevant concentrations can be monitored for several hours. By using a microhole cell chip and a microfluidic unit single cells can be electrically interfaced via microholes and the use of small electrodes with high impedances is not necessary. For separation and positioning of the cells onto the hole negative pressure is applied on the reverse side of the chip. Under cell culture conditions the cell starts to spread on the biocompatible insulating chip membrane resulting in a stable interface to an adherent growing cell. After the spreading process is finished, the polymer/polyplex solution is added and the impedance is measured with respect to time. To illustrate the cellular parameter which can affect the measured impedance a simple simulation based on the finite element method (FEM) is performed. It was shown for the first time that the impedance-based method predicated on the microhole chip can be used for biological relevant substances at relevant concentrations and that it is more sensitive than the well-established biological marker.