Pulmonary gene delivery by chitosan-pDNA complex powder prepared by a supercritical carbon dioxide process

Physical characteristics and stability profile of recombinant plasmid DNA within a film matrix

Plasmids are essential source material for production of biological drugs, vaccines and vectors for gene therapy. They are commonly formulated as frozen solutions. Considering the cost associated with maintenance of cold chain conditions during storage and transport, there is a significant need for alternative methods for stabilization of plasmids at ambient temperature. The objective of these studies was to identify a film-based formulation that preserved transfection efficiency of plasmids at 25 °C. A model plasmid, pAAVlacZ, was used for these studies. Transfection efficiency and agarose gel electrophoresis were utilized to assess bioactivity and changes in physical conformation of plasmid during storage. An amino acid, capable of sustaining a positive charge while supporting an alkaline environment within the film matrix, preserved transfection efficiency for 9 months at 25 °C. Addition of sugar and a plasticizer to the formulation preserved the plasmid in an amorphous state and improved handling properties of the film. The manner in which excipients were incorporated into bulk formulations and environmental humidity in which films were stored significantly impacted transfection efficiency of plasmid in the rehydrated solution. Taken together, these results suggest that plasmids can be stored for extended periods of time without refrigeration within a film matrix.

Polysaccharide-based formulations as potential carriers for pulmonary delivery - A review of their properties and fates

Polysaccharides can be elite carriers for therapeutic molecules due to their versatility and low probability to trigger toxicity and immunogenic responses. Local and systemic therapies can be achieved through particle pulmonary delivery, a promising non-invasive alternative. Successful pulmonary delivery requires particles with appropriate flowability to reach alveoli and avoid premature clearance mechanisms. Polysaccharides can form micro-, nano-in-micro-, and large porous particles, aerogels, and hydrogels. Herein, the characteristics of polysaccharides used in drug formulations for pulmonary delivery are reviewed, providing insights into structure-function relationships. Charged polysaccharides can confer mucoadhesion, whereas the ability for specific sugar recognition may confer targeting capacity for alveolar macrophages. The method of particle preparation must be chosen considering the properties of the components and the delivery device to be utilized. The fate of polysaccharide-based carriers is dependent on enzyme-triggered hydrolytic and/or oxidative mechanisms, allowing their complete degradation and elimination through urine or reutilization of released monosaccharides.

Dry powder pharmaceutical biologics for inhalation therapy

Therapeutic biologics such as genes, peptides, proteins, virus and cells provide clinical benefits and are becoming increasingly important tools in respiratory medicine. Pulmonary delivery of therapeutic biologics enables the potential for safe and effective treatment option for respiratory diseases due to high bioavailability while minimizing absorption into the systemic circulation, reducing off-target toxicity to other organs. Development of inhalable powder formulation requires stabilization of complex biological materials, and each type of biologics may present unique challenges and require different formulation strategy combined with manufacture process to ensure biological and physical stabilities during production and over shelf-life. This review examines key formulation strategies for stabilizing proteins, nucleic acids, virus (bacteriophages) and bacterial cells in inhalable powders. It also covers characterization methods used to assess physicochemical properties and aerosol performance of the powders, biological activity and structural integrity of the biologics, and chemical analysis at the nanoscale. Furthermore, the review includes manufacture technologies which are based on lyophilization and spray-drying as they have been applied to manufacture Food and Drug Administration (FDA)-approved protein powders. In perspective, formulation and manufacture of inhalable powders for biologic are highly challenging but attainable. The key requirements are the stability of both the biologics and the powder, along with the powder dispersibility. The formulation to be developed depends on the manufacture process as it will subject the biologics to different stresses (temperature, mechanical and chemical) which could lead to degradation by different pathways. Stabilizing excipients coupled with the suitable choice of process can alleviate the stability issues of inhaled powders of biologics.

Multiscale Co-reconstruction of Lung Architectures and Inhalable Materials Spatial Distribution

The effective pulmonary deposition of inhaled particulate carriers loaded with drugs is a prerequisite for therapeutic effects of drug delivery via inhalation route. Revealing the sophisticated lung scaffold and intrapulmonary distribution of particles at three-dimensional (3D), in-situ, and single-particle level remains a fundamental and critical challenge for dry powder inhalation in pre-clinical research. Here, taking advantage of the micro optical sectioning tomography system, the high-precision cross-scale visualization of entire lung anatomy is obtained. Then, co-localized lung-wide datasets of both cyto-architectures and fluorescent particles are collected at full scale with the resolution down to individual particles. The precise spatial distribution pattern reveals the region-specific distribution and structure-associated deposition of the inhalable particles in lungs, which is undetected by previous methods. Overall, this research delivers comprehensive and high-resolution 3D detection of pulmonary drug delivery vectors and provides a novel strategy to evaluate materials distribution for drug delivery.

Present Situation and Future Progress of Inhaled Lung Cancer Therapy: Necessity of Inhaled Formulations with Drug Delivery Functions

Inhaled lung cancer therapy is promising because of direct and noninvasive drug delivery to the lungs with low potential for severe systemic toxicity. Thus chemotherapeutic drugs have been administered clinically by nebulization of solution or suspension formulations, which demonstrated their limited pulmonary absorption and relatively mild systemic toxicity. In all these clinical trials, however, there was no obviously superior anticancer efficacy in lung cancer patients even at the maximum doses of drugs limited by pulmonary toxicity. Therefore methods that deliver both higher anticancer efficacy and lower pulmonary toxicity are strongly desired. In addition to the worldwide availability of pressured metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) to treat local respiratory diseases, recent innovations in medicines and technologies are encouraging next steps toward effective inhaled lung cancer therapy with new therapeutic or drug delivery concepts. These include the discovery of target cells/molecules and drug candidates for novel cancer therapy, the development of high-performance inhalation devices for effective pulmonary drug delivery, and the establishment of manufacturing technologies for functional nanoparticles/microparticles. This review highlights the present situation and future progress of inhaled drugs for lung cancer therapy, including an overview of available inhalation devices, pharmacokinetics, and outcomes in clinical trials so far and some novel formulation strategies based on drug delivery systems to achieve enhanced anticancer efficacy and attenuated pulmonary toxicity.

Inhalation delivery technology for genome-editing of respiratory diseases

The clustered regulatory interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system has significant therapeutic potentials for lung congenital diseases such as cystic fibrosis, as well as other pulmonary disorders like lung cancer and obstructive diseases. Local administration of CRISPR/Cas9 therapeutics through inhalation can achieve high drug concentration and minimise systemic exposure. While the field is advancing with better understanding on the biological functions achieved by CRISPR/Cas9 systems, the lack of progress in inhalation formulation and delivery of the molecule may impede their clinical translation efficiently. This forward-looking review discussed the current status of formulations and delivery for inhalation of relevant biologics such as genes (plasmids and mRNAs) and proteins, emphasising on their design strategies and preparation methods. By adapting and optimising formulation strategies used for genes and proteins, we envisage that development of inhalable CRISPR/Cas9 liquid or powder formulations for inhalation administration can potentially be fast-tracked in near future.

Dry Powder for Pulmonary Delivery: A Comprehensive Review

The pulmonary route has long been used for drug administration for both local and systemic treatment. It possesses several advantages, which can be categorized into physiological, i.e., large surface area, thin epithelial membrane, highly vascularized, limited enzymatic activity, and patient convenience, i.e., non-invasive, self-administration over oral and systemic routes of drug administration. However, the formulation of dry powder for pulmonary delivery is often challenging due to restrictions on aerodynamic size and the lung’s lower tolerance capacity in comparison with an oral route of drug administration. Various physicochemical properties of dry powder play a major role in the aerosolization, deposition, and clearance along the respiratory tract. To prepare suitable particles with optimal physicochemical properties for inhalation, various manufacturing methods have been established. The most frequently used industrial methods are milling and spray-drying, while several other alternative methods such as spray-freeze-drying, supercritical fluid, non-wetting templates, inkjet-printing, thin-film freezing, and hot-melt extrusion methods are also utilized. The aim of this review is to provide an overview of the respiratory tract structure, particle deposition patterns, and possible drug-clearance mechanisms from the lungs. This review also includes the physicochemical properties of dry powder, various techniques used for the preparation of dry powders, and factors affecting the clinical efficacy, as well as various challenges that need to be addressed in the future.

Targeted Nanotherapeutics for Respiratory Diseases: Cancer, Fibrosis, and Coronavirus

Systemic delivery of therapeutics for treatment of lung diseases has several limitations including poor organ distribution of delivered payload with relatively low accumulation of active substances in the lungs and severe adverse side effects. In contrast, nanocarrier based therapeutics provide a broad range of opportunities due to their ability to encapsulate substances with different aqueous solubility, transport distinct types of cargo, target therapeutics specifically to the deceased organ, cell, or cellular organelle limiting adverse side effects and increasing the efficacy of therapy. Moreover, many nanotherapeutics can be delivered by inhalation locally to the lungs avoiding systemic circulation. In addition, nanoscale based delivery systems can be multifunctional, simultaneously carrying out several tasks including diagnostics, treatment and suppression of cellular resistance to the treatment. Nanoscale delivery systems improve the clinical efficacy of conventional therapeutics allowing new approaches for the treatment of respiratory diseases which are difficult to treat or possess intrinsic or acquired resistance to treatment. The present review summarizes recent advances in the development of nanocarrier based therapeutics for local and targeted delivery of drugs, nucleic acids and imaging agents for diagnostics and treatment of various diseases such as cancer, cystic fibrosis, and coronavirus.

Inhaled Micro/Nanoparticulate Anticancer Drug Formulations: An Emerging Targeted Drug Delivery Strategy for Lung Cancers

Local delivery of drug to the target organ via inhalation offers enormous benefits in the management of many diseases. Lung cancer is the most common of all cancers and it is the leading cause of death worldwide. Currently available treatment systems (intravenous or oral drug delivery) are not efficient in accumulating the delivered drug into the target tumor cells and are usually associated with various systemic and dose-related adverse effects. The pulmonary drug delivery technology would enable preferential accumulation of drug within the cancer cell and thus be superior to intravenous and oral delivery in reducing cancer cell proliferation and minimising the systemic adverse effects. Site-specific drug delivery via inhalation for the treatment of lung cancer is both feasible and efficient. The inhaled drug delivery system is non-invasive, produces high bioavailability at a low dose and avoids first pass metabolism of the delivered drug. Various anticancer drugs including chemotherapeutics, proteins and genes have been investigated for inhalation in lung cancers with significant outcomes. Pulmonary delivery of drugs from dry powder inhaler (DPI) formulation is stable and has high patient compliance. Herein, we report the potential of pulmonary drug delivery from dry powder inhaler (DPI) formulations inhibiting lung cancer cell proliferation at very low dose with reduced unwanted adverse effects.

Application of nanomaterials in three-dimensional stem cell culture

Petri dish cultured cells have for long provided scientists an aperture to understanding cell's behavior both in normal and disease states as well as in vitro and in vivo. But recent advances have brought to light how the architecture and composite nature of the immediate environment within which the cell is proliferated can profoundly influence its phenotypic features and functions, thus making obvious, limitations of the conventional two-dimensional cell culture despite it cost effectiveness. Fortunately, the transition to three-dimensional (3D) cell culture has occurred concurrently with expanded knowledge of nanoscience and materials, thereby lending significant impetus for innovative research. This review is focused on the application of nanoparticles in 3D stem cell breeding, recent trends and developments in medical sciences for improved drug delivery, and treatment approaches to some human diseases. We also reviewed prevailing challenges and concerns of nanotoxicity as it continues to impede and delay clinical applications as well the ongoing concerted and multidisciplinary efforts to overcome them.

Naked pDNA Inhalation Powder Composed of Hyaluronic Acid Exhibits High Gene Expression in the Lungs

Gene therapy is a breakthrough treatment strategy against several intractable and lethal diseases that previously lacked established treatments. Viral and nonviral vectors have been studied to realize higher gene transfection efficiencies and to suppress the degradation of gene by nucleolytic enzymes in vivo. However, it is often the case that the addition of a vector results in adverse effects. In this study, we identified formulations of dry naked plasmid DNA (pDNA) powders with no vector showing significantly higher gene expression than pDNA solutions including vectors such as polyethylenimine (PEI) in the lungs of mice. We prepared the naked pDNA powders by spray-freeze-drying with various excipients. The gene expression of naked pDNA powders exceeded those of pDNA solutions containing PEI, naked pDNA solution, and reconstituted pDNA powder. Gene expression of each naked pDNA powder was dependent on the composition of excipients. Among them, the mice that were administered the pDNA powder composed of low-molecular-weight hyaluronic acid (LHA) as an excipient showed the highest gene expression. The lactate dehydrogenase activity and concentration of inflammatory cytokines in bronchoalveolar lavage fluid were comparable to those caused by ultrapure water. The results suggest that useful dry naked nucleic acid powders for inhalation could be created by optimizing the excipients, offering new insights into the development of pulmonary gene therapy.

The potential for targeted rewriting of epigenetic marks in COPD as a new therapeutic approach

Chronic obstructive pulmonary disease (COPD) is an age and smoking related progressive, pulmonary disorder presenting with poorly reversible airflow limitation as a result of chronic bronchitis and emphysema. The prevalence, disease burden for the individual, and mortality of COPD continues to increase, whereas no effective treatment strategies are available. For many years now, a combination of bronchodilators and anti-inflammatory corticosteroids has been most widely used for therapeutic management of patients with persistent COPD. However, this approach has had disappointing results as a large number of COPD patients are corticosteroid resistant. In patients with COPD, there is emerging evidence showing aberrant expression of epigenetic marks such as DNA methylation, histone modifications and microRNAs in blood, sputum and lung tissue. Therefore, novel therapeutic approaches may exist using epigenetic therapy. This review aims to describe and summarize current knowledge of aberrant expression of epigenetic marks in COPD. In addition, tools available for restoration of epigenetic marks are described, as well as delivery mechanisms of epigenetic editors to cells. Targeting epigenetic marks might be a very promising tool for treatment and lung regeneration in COPD in the future.

Critical Parameters for Particle-Based Pulmonary Delivery of Chemotherapeutics

Targeted delivery of chemotherapeutics through the respiratory system is a potential approach to improve drug accumulation in the lung tumor, while decreasing their negative side effects. However, elimination by the pulmonary clearance mechanisms, including the mucociliary transport system, and ingestion by the alveolar macrophages, rapid absorption into the blood, enzymatic degradation, and low control over the deposition rate and location remain the main complications for achieving an effective pulmonary drug delivery. Therefore, particle-based delivery systems have emerged to minimize pulmonary clearance mechanisms, enhance drug therapeutic efficacy, and control the release behavior. A successful implementation of a particle-based delivery system requires understanding the influential parameters in terms of drug carrier, inhalation technology, and health status of the patient's respiratory system. This review aims at investigating the parameters that significantly drive the clinical outcomes of various particle-based pulmonary delivery systems. This should aid clinicians in appropriate selection of a delivery system according to their clinical setting. It will also guide researchers in addressing the remaining challenges that need to be overcome to enhance the efficiency of current pulmonary delivery systems for aerosols.

Supercritical Fluid Technology: An Emphasis on Drug Delivery and Related Biomedical Applications

During the past few decades, supercritical fluid (SCF) has emerged as an effective alternative for many traditional pharmaceutical manufacturing processes. Operating active pharmaceutical ingredients (APIs) alone or in combination with various biodegradable polymeric carriers in high-pressure conditions provides enhanced features with respect to their physical properties such as bioavailability enhancement, is of relevance to the application of SCF in the pharmaceutical industry. Herein, recent advances in drug delivery systems manufactured using the SCF technology are reviewed. We provide a brief description of the history, principle, and various preparation methods involved in the SCF technology. Next, we aim to give a brief overview, which provides an emphasis and discussion of recent reports using supercritical carbon dioxide (SC-CO2 ) for fabrication of polymeric carriers, for applications in areas related to drug delivery, tissue engineering, bio-imaging, and other biomedical applications. We finally summarize with perspectives.

Recent advances in chitosan-based nanoparticulate pulmonary drug delivery

The advent of biodegradable polymer-encapsulated drug nanoparticles has made the pulmonary route of administration an exciting area of drug delivery research. Chitosan, a natural biodegradable and biocompatible polysaccharide has received enormous attention as a carrier for drug delivery. Recently, nanoparticles of chitosan (CS) and its synthetic derivatives have been investigated for the encapsulation and delivery of many drugs with improved targeting and controlled release. Herein, recent advances in the preparation and use of micro-/nanoparticles of chitosan and its derivatives for pulmonary delivery of various therapeutic agents (drugs, genes, vaccines) are reviewed. Although chitosan has wide applications in terms of formulations and routes of drug delivery, this review is focused on pulmonary delivery of drug-encapsulated nanoparticles of chitosan and its derivatives. In addition, the controversial toxicological effects of chitosan nanoparticles for lung delivery will also be discussed.

Preparation, characterization, and potential application of chitosan, chitosan derivatives, and chitosan metal nanoparticles in pharmaceutical drug delivery

Naturally occurring polymers, particularly of the polysaccharide type, have been used pharmaceutically for the delivery of a wide variety of therapeutic agents. Chitosan, the second abundant naturally occurring polysaccharide next to cellulose, is a biocompatible and biodegradable mucoadhesive polymer that has been extensively used in the preparation of micro-as well as nanoparticles. The prepared particles have been exploited as a potential carrier for different therapeutic agents such as peptides, proteins, vaccines, DNA, and drugs for parenteral and nonparenteral administration. Therapeutic agent-loaded chitosan micro- or nanoparticles were found to be more stable, permeable, and bioactive. In this review, we are highlighting the different methods of preparation and characterization of chitosan micro- and nanoparticles, while reviewing the pharmaceutical applications of these particles in drug delivery. Moreover, the roles of chitosan derivatives and chitosan metal nanoparticles in drug delivery have been illustrated.

Development of Biodegradable Polycation-Based Inhalable Dry Gene Powders by Spray Freeze Drying

In this study, two types of biodegradable polycation (PAsp(DET) homopolymer and PEG-PAsp(DET) copolymer) were applied as vectors for inhalable dry gene powders prepared by spray freeze drying (SFD). The prepared dry gene powders had spherical and porous structures with a 5~10-μm diameter, and the integrity of plasmid DNA could be maintained during powder production. Furthermore, it was clarified that PEG-PAsp(DET)-based dry gene powder could more sufficiently maintain both the physicochemical properties and in vitro gene transfection efficiencies of polyplexes reconstituted after powder production than PAsp(DET)-based dry gene powder. From an in vitro inhalation study using an Andersen cascade impactor, it was demonstrated that the addition of l-leucine could markedly improve the inhalation performance of dry powders prepared by SFD. Following pulmonary delivery to mice, both PAsp(DET)- and PEG-PAsp(DET)-based dry gene powders could achieve higher gene transfection efficiencies in the lungs compared with a chitosan-based dry gene powder previously reported by us.

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.

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.

Drying of a plasmid containing formulation: chitosan as a protecting agent

BACKGROUND

The purpose of the study. Along with research on development of more efficient gene delivery systems, it is necessary to search on stabilization processes to extend their active life span. Chitosan is a nontoxic, biocompatible and available gene delivery carrier. The aim of this study was to assess the ability of this polymer to preserve transfection efficiency during spray-drying and a modified freeze-drying process in the presence of commonly used excipients.

METHOD

Molecular weight of chitosan was reduced by a chemical reaction and achieved low molecular weight chitosan (LMWC) was complexed with pDNA. Obtained nanocomplex suspensions were diluted by solutions of lactose and leucine, and these formulations were spray dried or freeze dried using a modified technique. Size, polydispersity index, zeta potential, intensity of supercoiled DNA band on gel electrophoresis, and transfection efficiency of reconstituted nanocomplexes were compared with freshly prepared ones.

RESULTS AND MAJOR CONCLUSION

Size distribution profiles of both freeze dried, and 13 out of 16 spray-dried nanocomplexes remained identical to freshly prepared ones. LMWC protected up to 100% of supercoiled structure of pDNA in both processes, although DNA degradation was higher in spray-drying of the nanocomplexes prepared with low N/P ratios. Both techniques preserved transfection efficiency similarly even in lower N/P ratios, where supercoiled DNA content of spray dried formulations was lower than freeze-dried ones. Leucine did not show a significant effect on properties of the processed nanocomplexes. It can be concluded that LMWC can protect DNA structure and transfection efficiency in both processes even in the presence of leucine.

Drying of a plasmid containing formulation: chitosan as a protecting agent

Background

Along with research on development of more efficient gene delivery systems, it is necessary to search on stabilization processes to extend their active life span. Chitosan is a nontoxic, biocompatible and available gene delivery carrier. The aim of this study was to assess the ability of this polymer to preserve transfection efficiency during spray-drying and a modified freeze-drying process in the presence of commonly used excipients.

Methods

Molecular weight of chitosan was reduced by a chemical reaction and achieved low molecular weight chitosan (LMWC) was complexed with pDNA. Obtained nanocomplex suspensions were diluted by solutions of lactose and leucine, and these formulations were spray dried or freeze dried using a modified technique. Size, polydispersity index, zeta potential, intensity of supercoiled DNA band on gel electrophoresis, and transfection efficiency of reconstituted nanocomplexes were compared with freshly prepared ones.

Results and conclusion

Size distribution profiles of both freeze dried, and 13 out of 16 spray-dried nanocomplexes remained identical to freshly prepared ones. LMWC protected up to 100% of supercoiled structure of pDNA in both processes, although DNA degradation was higher in spray-drying of the nanocomplexes prepared with low N/P ratios. Both techniques preserved transfection efficiency similarly even in lower N/P ratios, where supercoiled DNA content of spray dried formulations was lower than freeze-dried ones. Leucine did not show a significant effect on properties of the processed nanocomplexes. It can be concluded that LMWC can protect DNA structure and transfection efficiency in both processes even in the presence of leucine.

Vectors for inhaled gene therapy in lung cancer. Application for nano oncology and safety of bio nanotechnology

Novel aerosol therapeutic modalities have been investigated for lung cancer. Inhaled gene therapy has presented safety and effectiveness previously in cystic fibrosis. However, safety concerns have been raised regarding the safety of non-viral vectors for inhaled gene therapy in lung cancer, and therefore small steps have been made towards this multifunctional treatment modality. During the last decade, numerous new nanocomplexes have been created and investigated as a safe gene delivery nano-vehicle. These formulations are multifunctional; they can be used as either local therapy or carrier for an effective inhaled gene therapy for lung cancer. Herein, we present current and future perspectives of nanocomplexes for inhaled gene therapy treatment in lung cancer.

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.

Surface characterisation of bioadhesive PLGA/chitosan microparticles produced by supercritical fluid technology

PURPOSE

Novel biodegradable and mucoadhesive PLGA/chitosan microparticles with the potential for use as a controlled release gastroretentive system were manufactured using supercritical CO(2) (scCO(2)) by the Particle Gas Saturated System (PGSS) technique (also called CriticalMix(TM)).

METHODS

Microparticles were produced from PLGA with the addition of mPEG and chitosan in the absence of organic solvents, surfactants and crosslinkers using the PGSS technique. Microparticle formulations were morphologically characterized by scanning electron microscope; particle size distribution was measured using laser diffraction. Microparticle surface was analyzed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to evaluate the presence of chitosan on the surface. Mucoadhesiveness of the microparticles was evaluated in vitro using a mucin assay employing two different kinds of mucin (Mucin type III and I-S) with different degrees of sialic acid contents, 0.5-1.5% and 9-17%, respectively.

RESULTS

The two analytical surface techniques (XPS and ToF-SIMS) demonstrated the presence of the chitosan on the surface of the particles (<100 μm), dependent on the polymer composition of the microparticles. The interaction between the mucin solutions and the PLGA/chitosan microparticles increased significantly with an increasing concentration of mucin and chitosan.

CONCLUSIONS

The strong interaction of mucin with the chitosan present on the surface of the particles suggests a potential use of the mucoadhesive carriers for gastroretentive and oral controlled drug release.

Preparation and evaluation of chitosan-DNA-FAP-B nanoparticles as a novel non-viral vector for gene delivery to the lung epithelial cells

Gene delivery using cationic polymers such as chitosan shows good biocompatibility, but reveals low transfection efficiency. Fibronectin Attachment Protein of Mycobacterium bovis (FAP-B) which is responsible for the attachment of many Mycobacteria on the Fibronectin molecule of epithelial cell membrane can be considered as a new targeting ligand and can improve transfection rates in epithelial cells. In this study, chitosan-DNA nanoparticles were prepared using coacervation process. The effect of stirring speed and charge ratio (N/P) on the size and zeta potential of nanoparticles were evaluated. FAP-B ligand was added to nanoparticles at the specific condition to form chitosan-DNA-FAP-B nanoparticles via electrostatic attraction. Transfection efficiency of the final nanoparticles was investigated in A549 (alveolar epithelial cells). Cell viability was investigated using MTT assay. The optimum speed of stirring which was yielded the smallest chitosan-DNA nanoparticles with a narrow distribution (227±43 nm), was 500 rpm with the corresponding N/P ratio of 20. Chitosan-DNA-FAP-B nanoparticles presented the size of 279±27 nm with transfection efficiency about 10-fold higher than chitosan-DNA nanoparticles and resulted in 97.3% cell viability compared to 71.7% using Turbofect controls. Chitosan-DNA-FAP-B nanoparticles showed good transfection efficiency without cell toxicity. They have small particle size around 279 nm which make them a promising candidate as a novel non-viral gene vector for gene delivery to lung epithelial cells.

Sorption efficiency of chitosan nanofibers toward metal ions at low concentrations

Chitosan fibers showing narrow diameter distribution with a mean of 42 nm were produced by electrospinning and utilized for the sorption of Fe(III), Cu(II), Ag(I), and Cd(II) ions from aqueous solutions. The ion concentrations in the supernatant solutions were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The filtration efficiency of the fibers toward these ions was studied by both batch and microcolumn methods. High efficiency in sorption of the metal ions was obtained in the both methods. The effects of sorbent amount (0.10-0.50 mg), shaking time (15-120 min), initial metal ion concentration (10.0-1000.0 μg·L(-1)), and temperature (25 and 50 °C) on the extent of sorption were examined. The sorbent amount did not significantly alter the efficiency of sorption; however, shaking time, temperature, and metal ion concentration were found to have a strong influence on sorption. By virtue of its mechanical integrity, the applicability of the chitosan mat in solid phase extraction under continuous flow looks promising.

Nanomedicine for respiratory diseases

Treatment of respiratory diseases and infections has proved to be a challenging task, with the incidence of these ailments increasing worldwide. Nanotechnology-based drug and gene delivery systems offer a possible solution to some of the shortfalls of the current treatment regimen. Nanobased drug delivery systems have revolutionised the field of pharmacotherapy by presenting the ability to alter the pharmacokinetics of the conventional drugs to extend the drug retention time, reduce the toxicity and increase the half-life of the drugs. Delivery of exogenous genes to the airway epithelium in vivo has been limited by several physiological barriers, resulting in the low success rate of these systems. With the advent of nanotechnology, DNA compacted with cationic polymers to produce nanoparticles has exhibited a significant increase in the transfection efficiencies. With nanoparticulate drug/gene delivery systems, specific cells can be targeted by functionalising the polymeric nanoparticles with ligands that allow the particles to dock at a specific site of the cell. In addition, polymeric systems allow for the cargo to be released in a controlled and stimuli-responsive manner. The advantages that nanoparticulate delivery systems present in the treatment of respiratory diseases and infections are summarised in this review.

Chitosan-based delivery systems for protein therapeutics and antigens

Therapeutic peptides/proteins and protein-based antigens are chemically and structurally labile compounds, which are almost exclusively administered by parenteral injections. Recently, non-invasive mucosal routes have attracted interest for administration of these biotherapeutics. Chitosan-based delivery systems enhance the absorption and/or cellular uptake of peptides/proteins across mucosal sites and have immunoadjuvant properties. Chitosan is a mucoadhesive polysaccharide capable of opening the tight junctions between epithelial cells and it has functional groups for chemical modifications, which has resulted in a large variety of chitosan derivatives with tunable properties for the aimed applications. This review provides an overview of chitosan-based polymers for preparation of both therapeutic peptides/protein and antigen formulations. The physicochemical properties of these carrier systems as well as their applications in protein and antigen delivery through parenteral and mucosal (particularly nasal and pulmonary) administrations are summarized and discussed.

Gene delivery nanoparticles fabricated by supercritical fluid extraction of emulsions

Non-viral polymeric gene delivery systems offer increased protection from nuclease degradation, enhanced plasmid DNA (pDNA) uptake, and controlled dosing to sustain the duration of pDNA action. Such gene delivery systems can be formulated from biocompatible and biodegradable polymers such as poly(D,L-lactic-co-glycolic) acid (PLGA). Experimental loading of hydrophilic macromolecules such as pDNA is low in polymeric particles. The study purpose was to develop a supercritical fluid extraction of emulsions (SFEE) process based on CO(2) for preparing pEGFP-PLGA nanoparticles with high plasmid loading and loading efficiency. Another objective was to determine the efficacy of pFlt23k, an anti-angiogenic pDNA capable of inhibiting vascular endothelial growth factor (VEGF) secretion, following nanoparticle formation using the SFEE process. Results indicated that the SFEE process allows high actual loading of pDNA (19.7%, w/w), high loading efficiency (>98%), and low residual solvents (<50 ppm), due to rapid particle formation from efficient solvent removal provided by the SFEE process. pFlt23K-PLGA nanoparticles were capable of in vitro transfection, significantly reducing secreted VEGF from human lung alveolar epithelial cells (A549) under normoxic and hypoxic conditions. pFlt23K-PLGA nanoparticles did not exhibit cytotoxicity and are of potential value in treating neovascular disorders wherein VEGF levels are elevated.

Biocompatibility study of theophylline/chitosan/beta-cyclodextrin microspheres as pulmonary delivery carriers

To evaluate the biocompatibility of the theophylline/chitosan/beta-cyclodextrin microspheres, which has a potential application in pulmonary delivery system. The detection of LDH and protein in BALF was examined acute cell toxicity, hemolysis test was carried out to estimate blood toxicity; Micronucleus Test was reckoned to identify genotoxicity, MTT assay was used to evaluate in vitro cytotoxicity, and muscle implantation investigated the tissue biocompatibility. The results demonstrated that the total contents of protein and LDH in BALF were not significantly different from that of normal group. The experiments showed that the cytotoxicity was depended on the concentration and had no cytoxicity at low concentration and no hemolysis activity. The micronucleus frequency of MS B was 0.99 per thousand, which showed no genotoxic effects either. The results of implantation showed that the microspheres had no effect on hemoglobin and no toxicity in the liver and kidney. The inflammations of muscle tissue were not significantly different from that of operative suture, therefore, the MS B possess high good biocompatibility and can be applied in pulmonary sustained release systems.

Toxicological evaluation of lactose and chitosan delivered by inhalation

These days, inhalation constitutes a promising administration route for many drugs. However, this route exhibits unique limitations, and formulations aimed at pulmonary delivery should include as few as possible additives in order to maintain lung functionality. The purpose of this work was to investigate the safety of lactose and chitosan to the pulmonary tissue when delivered by inhalation. The study was carried out with 18 Wistar rats divided in three groups receiving distilled water, lactose or chitosan. A solution of each excipient was administered by inhalation at a dose of 20 mg. The lungs were excised and processed to determine several biochemical parameters used as toxicity biomarkers. Protein and carbonyl group content, lipid peroxidation, reduced and oxidized glutathione (GSSG), myeloperoxidase (MPO), cooper/zinc and manganese superoxide dismutase, catalase, glutathione S-transferase and glutathione peroxidase were determined. Results of myeloperoxidase activity and glutathione disulfide lung concentrations showed a relevant decrease for chitosan group compared to control: 4.67 +/- 2.27 versus 15.10 +/- 7.27 (P = 0.011) for MPO and 0.89 +/- 0.68 versus 2.02 +/- 0.22 (P = 0.014) for GSSG. The other parameters did not vary significantly among groups. Lactose and chitosan administered by inhalation failed to show toxic effects to the pulmonary tissue. A protective effect against oxidative stress might even be attributed to chitosan, since some biomarkers had values significantly lower than those observed in the control group when this product was inhaled. Nevertheless, caution must be taken regarding chemical composition and technological processes applied to incorporate these products during drug formulation, in particular for dry powder inhalators.

Applications of supercritical CO2 in the fabrication of polymer systems for drug delivery and tissue engineering

Supercritical CO(2) has the potential to be an excellent environment within which controlled release polymers and dry composites may be formed. The low temperature and dry conditions within the fluid offer obvious advantages in the processing of water, solvent or heat labile molecules. The low viscosity and high diffusivity of scCO(2) offer the possibility of novel processing routes for polymer drug composites, but there are still technical challenges to overcome. Moreover, the low solubility of most drug molecules in scCO(2) presents both challenges and advantages. This review explores the current methods that use high pressure and scCO(2) for the production of drug delivery systems and the more specialized application of the fluid in the formation of highly porous tissue engineering scaffolds.

Application of supercritical fluid to preparation of powders of high-molecular weight drugs for inhalation

The application of supercritical carbon dioxide to particle design has recently emerged as a promising way to produce powders of macromolecules such as proteins and genes. Recently, an insulin powder for inhalation was approved by authorities in Europe and the USA. Other macromolecules for inhalation therapy will follow. In the 1990s proteins were precipitated with supercritical CO(2) from solutions in an organic solvent such as dimethylsulfoxide, which caused significant unfolding of protein. Since 2000, aqueous solutions of proteins and genes have generally been used with a cosolvent such as ethanol to precipitate in CO(2). Operating conditions such as temperature, pressure, flow rates, and concentration of ingredients affect the particle size and integrity of proteins or genes. By optimizing these conditions, the precipitation of proteins and genes with supercritical CO(2) is a promising way to produce protein and gene particles for inhalation.

Biodegradable particle formation for drug and gene delivery using supercritical fluid and dense gas

Recent developments in biodegradable particle formation using supercritical fluids and dense gases have been reviewed with an emphasis on studies of micronizing and encapsulating poorly-soluble pharmaceuticals and gene. General review articles published in previous years have then been provided. A brief description of the operating principles of some types of particle formation processes is given. These include the rapid expansion of supercritical solutions (RESS), the particles from gas-saturated solution (PGSS) processes, the gas antisolvent process (GAS), and the supercritical antisolvent process (SAS). The papers have been reviewed under two groups, one involving the production of particles from pure biodegradable substances, and the other involving coating, capsule, and impregnation that contain active components, especially those that relate to pharmaceuticals. This review is a comprehensive review specifically focused on the formation of biodegradable particles for drug and gene delivery system using supercritical fluid and dense gas.

Preparation and characterization of theophylline loaded chitosan/beta-cyclodextrin microspheres

The purpose of this project was to develop sustained release chitosan/beta-cyclodextrin microspheres of theophylline (TH) prepared by spray drying method. The effect of several formulation variables on the characteristics of microspheres was studied. The B microspheres had a narrower particle size distribution with the diameter between l and 10 microm. SEM showed spherical microspheres with smooth or slightly wrinkled surfaces. FT-IR spectroscopy revealed that hydrogen bonds were formed between TH and chitosan or beta-cyclodextrin. The drug entrapments significantly increased from 13.33 to 35.70% with an increase of the ratio of drug/polymer. The encapsulation efficiencies were from 85.16 to 91.40%. The in vitro release of TH from microspheres was related to the pH of the medium, swelling ability, especially in the ratio of drug/polymer. The B microspheres had a prolonged release pattern with the release rate of 60.20% (pH 6.8) within 8 h.