Efficient Gene Transfer into Macrophages and Dendritic Cells by in Vivo Gene Delivery with Mannosylated Lipoplex via the Intraperitoneal Route

Harnessing adenovirus in cancer immunotherapy: evoking cellular immunity and targeting delivery in cell-specific manner

Recombinant adenovirus (rAd) regimens, including replication-competent oncolytic adenovirus (OAV) and replication-deficient adenovirus, have been identified as potential cancer therapeutics. OAV presents advantages such as selective replication, oncolytic efficacy, and tumor microenvironment (TME) remodeling. In this perspective, the principles and advancements in developing OAV toolkits are reviewed. The burgeoning rAd may dictate efficacy of conventional cancer therapies as well as cancer immunotherapies, including cancer vaccines, synergy with adoptive cell therapy (ACT), and TME reshaping. Concurrently, we explored the potential of rAd hitchhiking to adoptive immune cells or stem cells, highlighting how this approach facilitates synergistic interactions between rAd and cellular therapeutics at tumor sites. Results from preclinical and clinical trials in which immune and stem cells were infected with rAd have been used to address significant oncological challenges, such as postsurgical residual tumor tissue and metastatic tissue. Briefly, rAd can eradicate tumors through various mechanisms, resulting from tumor immunogenicity, reprogramming of the TME, enhancement of cellular immunity, and effective tumor targeting. In this context, we argue that rAd holds immense potential for enhancing cellular immunity and synergistically improving antitumor effects in combination with novel cancer immunotherapies.

A spotlight on alkaloid nanoformulations for the treatment of lung cancer

Numerous naturally available phytochemicals have potential anti-cancer activities due to their vast structural diversity. Alkaloids have been extensively used in cancer treatment, especially lung cancers, among the plant-based compounds. However, their utilization is limited by their poor solubility, low bioavailability, and inadequacies such as lack of specificity to cancer cells and indiscriminate distribution in the tissues. Incorporating the alkaloids into nanoformulations can overcome the said limitations paving the way for effective delivery of the alkaloids to the site of action in sufficient concentrations, which is crucial in tumor targeting. Our review attempts to assess whether alkaloid nanoformulation can be an effective tool in lung cancer therapy. The mechanism of action of each alkaloid having potential is explored in great detail in the review. In general, Alkaloids suppress oncogenesis by modulating several signaling pathways involved in multiplication, cell cycle, and metastasis, making them significant component of many clinical anti-cancerous agents. The review also explores the future prospects of alkaloid nanoformulation in lung cancer. So, in conclusion, alkaloid based nanoformulation will emerge as a potential gamechanger in treating lung cancer in the near future.

Mannosylated Cationic Copolymers for Gene Delivery to Macrophages

Macrophages are desirable targets for gene therapy of cancer and other diseases. Cationic diblock copolymers of polyethylene glycol (PEG) and poly-L-lysine (PLL) or poly{N-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (pAsp(DET)) are synthesized and used to form polyplexes with a plasmid DNA (pDNA) that are decorated with mannose moieties, serving as the targeting ligands for the C type lectin receptors displayed at the surface of macrophages. The PEG-b-PLL copolymers are known for its cytotoxicity, so PEG-b-PLL-based polyplexes are cross-linked using reducible reagent dithiobis(succinimidyl propionate) (DSP). The cross-linked polyplexes display low toxicity to both mouse embryonic fibroblasts NIH/3T3 cell line and mouse bone marrow-derived macrophages (BMMΦ). In macrophages mannose-decorated polyplexes demonstrate an ≈8 times higher transfection efficiency. The cross-linking of the polyplexes decrease the toxicity, but the transfection enhancement is moderate. The PEG-b-pAsp(DET) copolymers display low toxicity with respect to the IC-21 murine macrophage cell line and are used for the production of non-cross-linked pDNA-contained polyplexes. The obtained mannose modified polyplexes exhibit ca. 500-times greater transfection activity in IC-21 macrophages compared to the mannose-free polyplexes. This result greatly exceeds the targeting gene transfer effects previously described using mannose receptor targeted non-viral gene delivery systems. These results suggest that Man-PEG-b-pAsp(DET)/pDNA polyplex is a potential vector for immune cells-based gene therapy.

Understanding In Vivo Fate of Nucleic Acid and Gene Medicines for the Rational Design of Drugs

Nucleic acid and genetic medicines are increasingly being developed, owing to their potential to treat a variety of intractable diseases. A comprehensive understanding of the in vivo fate of these agents is vital for the rational design, discovery, and fast and straightforward development of the drugs. In case of intravascular administration of nucleic acids and genetic medicines, interaction with blood components, especially plasma proteins, is unavoidable. However, on the flip side, such interaction can be utilized wisely to manipulate the pharmacokinetics of the agents. In other words, plasma protein binding can help in suppressing the elimination of nucleic acids from the blood stream and deliver naked oligonucleotides and gene carriers into target cells. To control the distribution of these agents in the body, the ligand conjugation method is widely applied. It is also important to understand intracellular localization. In this context, endocytosis pathway, endosomal escape, and nuclear transport should be considered and discussed. Encapsulated nucleic acids and genes must be dissociated from the carriers to exert their activity. In this review, we summarize the in vivo fate of nucleic acid and gene medicines and provide guidelines for the rational design of drugs.

Mannosylated nanocarriers mediated site-specific drug delivery for the treatment of cancer and other infectious diseases: A state of the art review

The non-modified nanocarriers-based therapies for the treatment of cancer and other infectious diseases enhanced the chemical stability of therapeutically active agents, protected them from enzymatic degradation and extended their blood circulation time. However, the lack of specificity and off-target effects limit their applications. Mannose receptors overexpressed on antigen presenting cells such as dendritic cells and macrophages are one of the most desirable targets for treating cancer and other infectious diseases. Therefore, the development of mannosylated nanocarrier formulation is one of the most extensively explored approaches for targeting these mannose receptors. The present manuscript gives readers the background information on C-type lectin receptors followed by the roles, expression, and distribution of the mannose receptors. It further provides a detailed account of different mannosylated nanocarrier formulations. It also gives the tabular information on most relevant and recently granted patents on mannosylated systems. The overview of mannosylated nanocarrier formulations depicted site-specific targeting, enhanced pharmacokinetic/pharmacodynamic profiles, and improved transfection efficiency of the therapeutically active agents. This suggests the bright future ahead for mannosylated nanocarriers in the treatment of cancer and other infectious diseases. Nevertheless, the mechanism behind the enhanced immune response by mannosylated nanocarriers and their thorough clinical and preclinical evaluation need to explore further.

Targeted delivery of p-coumaric acid encapsulated mannosylated liposomes to the synovial macrophages inhibits osteoclast formation and bone resorption in the rheumatoid arthritis animal model

The current study aimed to target the delivery of p-coumaric acid (CA), a dietary polyphenol to the synovial macrophages of AIA rats via mannose incorporated liposomal delivery system (ML) with reference to osteoclastogenesis and bone resorption. In vivo imaging and in vitro drug release study indicated the efficiency of mannosylated liposomes to localize at the site of inflammation and increased sustain drug release respectively. Morphological assessment of isolated synovial macrophages with respect to CD86 (synovial macrophages) and CD51 (pre-/osteoclast) indicated that p-coumaric acid encapsulated mannosylated liposomes (ML-CA) inhibited the osteoclasts differentiation. ML-CA treatment inhibited the TRAP staining, downregulated the expression of MMP-9 and NFATc1 and inflammatory cytokines. The ex-vivo study specified the ability of CA to induce the OPG production in bone marrow stromal cell triggered macrophage-osteoclasts differentiation and to preserve the calcium content. Taken together, our results demonstrated that ML-CA could intervene in the osteoclast formation.

Targeted delivery of morin, a dietary bioflavanol encapsulated mannosylated liposomes to the macrophages of adjuvant-induced arthritis rats inhibits inflammatory immune response and osteoclastogenesis

The purpose of the study was to develop a liposomal drug delivery system for morin, a dietary polyphenol, in order to target the synovial macrophages and investigate the remission of disease severity in the adjuvant-induced arthritic (AIA) rats. To do so, mannose decorated liposomal morin (ML-Morin) was prepared using the thin film hydration method and the physicochemical properties were characterized. The particle size and zeta potential of liposomal morin (L-Morin) was found to be 127.9nm±2.6 and -24.5mV±0.76, whereas ML-Morin showed an increased value of 132.5nm±5.2 and -54.8mV±0.67 respectively. Further, the drug entrapment efficiency (% EE) of ML-Morin was found 86.7±3.8%. To understand the efficacy of L-Morin, ML-Morin over free-Morin; cellular uptake, production and expression of pro-inflammatory mediators, osteoclastogenic factors, and transcription factors were evaluated in primarily isolated synovial and spleen macrophages. Interestingly, confocal microscopic images showed an increased uptake of ML-Morin in the synovial and spleen macrophages than L-morin. In addition, ML-Morin significantly suppressed the production and mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-17), angiogenic factors (VEGF), an inflammatory enzyme (iNOS), and transcription factor (NF-κB-p65). Furthermore, the protein expression of TNF-α, IL-1β, IL-6, IL-17, RANKL, STAT-3, and p-STAT-3 was found to decrease with increased osteoprotegerin (OPG) expression in the ML-Morin targeted macrophages. Thus, our findings endorsed that, ML-Morin preferential internalization into the macrophages of arthritic rats effectively inhibited the inflammatory immune response and osteoclastogenesis better than the dexamethasone palmitate encapsulated mannosylated liposomes (ML-DP), a reference drug as evidenced by clinical and histological analysis.

Formulation, Pharmacokinetic, and Efficacy Studies of Mannosylated Self-Emulsifying Solid Dispersions of Noscapine

Purpose

To formulate hydroxypropyl methylcellulose-stabilized self-emulsifying solid dispersible carriers of noscapine to enhance oral bioavailability.

Methods

Formulation of noscapine (Nos) self-emulsifying solid dispersible microparticles (SESDs) was afforded by emulsification using an optimized formula of Labrafil M1944, Tween-80, and Labrasol followed by spray-drying with hydroxypropyl methylcellulose (HPMC), with and without mannosamine (Mann-Nos_SESDs and Nos_SESDs respectively); self-microemulsifying liquid dispersions (SMEDDs) with and without mannosamine (Mann-Nos_SMEDDs and Nos_SMEDDs respectively) were also prepared. SMEDDs and SESDs were characterized for size, polydispersity, surface charge, entrapment efficiency, in vitro permeability, in vitro release kinetics, and oral pharmacokinetics in Sprague-Dawley rats (10 mg/kg p.o). The antitumor efficacy of Mann-Nos_SESDs on the basis of chemosensitization to cisplatin (2.0 mg/kg, IV) was investigated in a chemorefractory lung tumor Nu/Nu mouse model up to a maximal oral dose of 300 mg/kg.

Results

The oil/surfactant/co-surfactant mixture of Labrafil M1944, Tween-80, and Labrasol optimized at weight ratios of 62.8:9.30:27.90% produced stable self-microemulsifying dispersions (SMEDDs) at a SMEDD to water ratio of 1–3:7–9 parts by weight. SMEDDs had hydrodynamic diameters between 231 and 246 nm; surface charges ranged from -16.50 to -18.7 mV; and entrapment efficiencies were between 32 and 35%. SESDs ranged in size between 5.84 and 6.60 μm with surface charges from -10.62 to -12.40 mV and entrapment efficiencies of 30.96±4.66 and 32.05±3.72% (Nos_SESDs and Mann-Nos_SESDs respectively). Mann-Nos_SESDs exhibited saturating uptake across Caco-2 monolayers (P_app = 4.94±0.18 × 10⁻⁶ cm/s), with controlled release of 50% of Nos in 6 hr at pH 6.8 following Higuchi kinetics. Mann-Nos_ SESDs was 40% more bioavailable compared to Nos_SESDs; and was effective in sensitizing H1650 SP cells to Cisplatin in vitro and in an orthotopic lung tumor model of H1650 SP origin.

Conclusions

Mannosylated noscapine self-emulsifying solid dispersions (Mann-Nos_SESDs) are bioavailable and potentiate the antineoplastic effect of cisplatin-based chemotherapy in cisplatin-resistant NSCLC.

Critical considerations for developing nucleic acid macromolecule based drug products

Protein expression therapy using nucleic acid macromolecules (NAMs) as a new paradigm in medicine has recently gained immense therapeutic potential. With the advancement of nonviral delivery it has been possible to target NAMs against cancer, immunodeficiency and infectious diseases. Owing to the complex and fragile structure of NAMs, however, development of a suitable, stable formulation for a reasonable product shelf-life and efficacious delivery is indeed challenging to achieve. This review provides a synopsis of challenges in the formulation and stability of DNA/m-RNA based medicines and probable mitigation strategies including a brief summary of delivery options to the target cells. Nucleic acid based drugs at various stages of ongoing clinical trials are compiled.

Tumour-associated macrophages targeted transfection with NF-κB decoy/mannose-modified bubble lipoplexes inhibits tumour growth in tumour-bearing mice

Tumour-associated macrophages (TAM) exhibit an M2 phenotype that promotes tumour progression, and conversion of M2 TAM toward a tumouricidal M1 phenotype is a promising anti-cancer therapy. As NF-κB is a key regulator of macrophage polarization, we developed an in vivo TAM-targeting delivery system that combines mannose-modified bubble liposomes/NF-κB decoy complexes (Man-PEG bubble lipoplexes) and ultrasound (US) exposure. We investigated the effects of NF-κB decoy transfection on TAM phenotype in solid tumour-bearing mice. Post-transfection tumour growth and survival rates were also recorded. Th2 cytokine (IL-10) level in TAM was significantly lower by NF-κB decoy transfection using Man-PEG bubble lipoplexes and US exposure, while Th1 cytokine levels (IL-1β, TNF-α and IL-6) were significantly higher when compared with controls. In addition, mRNA levels of vascular endothelial growth factor, matrix metalloproteinase-9 and arginase were significantly lower in TAM post-NF-κB decoy transfection. Importantly, TAM-targeted NF-κB decoy transfection inhibited tumour growth and prolonged survival rates in mice. Therefore, TAM-targeted NF-κB decoy transfection using Man-PEG bubble lipoplexes and US exposure may be an effective approach for anti-cancer therapy based on TAM phenotypic conversion from M2 toward M1.

In vitro evaluation of inhibitory effect of nuclear factor-kappaB activity by small interfering RNA on pro-tumor characteristics of M2-like macrophages

Tumor-associated macrophages (TAMs) have an alternatively activated macrophage phenotype (M2) and promote cancer cell proliferation, angiogenesis and metastasis. Nuclear factor-kappaB (NF-κB) is one of the master regulators of macrophage polarization. Here, we investigated the effect of inhibition of NF-κB activity by small interfering RNA (siRNA) on the pro-tumor response of macrophages located in the tumor microenvironment in vitro. We used mouse peritoneal macrophages cultured in conditioned medium from colon-26 cancer cells as an in vitro TAM model (M2-like macrophages). Transfection of NF-κB (p50) siRNA into M2-like macrophages resulted in a significant decrease in the secretion of interleukin (IL)-10 (a T helper 2 (Th2) cytokine) and a significant increase of T helper 1 (Th1) cytokine production (IL-12, tumor necrosis factor-α, and IL-6). Furthermore, vascular endothelial growth factor production and matrix metalloproteinase-9 mRNA expression in M2-like macrophages were suppressed by inhibition of NF-κB expression with NF-κB (p50) siRNA. In addition, there was a reduction of arginase mRNA expression and increase in nitric oxide production. The cytokine secretion profiles of macrophages cultured in conditioned medium from either B16BL6 or PAN-02 cancer cells were also converted from M2 to classically activated (M1) macrophages by transfection of NF-κB (p50) siRNA. These results suggest that inhibition of NF-κB activity in M2-like macrophages alters their phenotype toward M1.

On the efficacy of malaria DNA vaccination with magnetic gene vectors

We investigated the efficacy and types of immune responses from plasmid malaria DNA vaccine encoding VR1020-PyMSP119 condensed on the surface of polyethyleneimine (PEI)-coated SPIONs. In vivo mouse studies were done firstly to determine the optimum magnetic vector composition, and then to observe immune responses elicited when magnetic vectors were introduced via different administration routes. Higher serum antibody titers against PyMSP119 were observed with intraperitoneal and intramuscular injections than subcutaneous and intradermal injections. Robust IgG2a and IgG1 responses were observed for intraperitoneal administration, which could be due to the physiology of peritoneum as a major reservoir of macrophages and dendritic cells. Heterologous DNA prime followed by single protein boost vaccination regime also enhanced IgG2a, IgG1, and IgG2b responses, indicating the induction of appropriate memory immunity that can be elicited by protein on recall. These outcomes support the possibility to design superparamagnetic nanoparticle-based DNA vaccines to optimally evoke desired antibody responses, useful for a variety of diseases including malaria.

Efficient in vivo gene transfer by intraperitoneal injection of plasmid DNA and calcium carbonate microflowers in mice

Gene transfer to intraperitoneal organs is thought to be a promising approach to treat such conditions as peritoneal fibrosis and peritoneal dissemination of cancers. We previously discovered that simple instillation of naked plasmid DNA (pDNA) onto intraperitoneal organs such as the liver and stomach could effectively transfer foreign genes in mice. In this study, we developed a novel nonviral method to enhance transfection efficiency of naked pDNA to intraperitoneal organs using a calcium carbonate suspension containing pDNA. Using commercially available calcium carbonate, we successfully transfected pDNA to the stomach. Handling of commercially available calcium carbonate, however, was troublesome owing to rapid precipitation and caking. To obtain slowly settling particles of calcium carbonate, we tried to synthesize novel versions of such particles and succeeded in creating flower-shaped particles, named calcium carbonate microflowers. Sedimentation of calcium carbonate microflowers was sufficiently slow for in vivo experiments. Moreover, the transfection efficiency of the suspension of calcium carbonate microflowers to the stomach was more effective than that of commercially available calcium carbonate, especially at low concentrations. Intraperitoneal injection of the suspension of calcium carbonate microflowers containing pDNA greatly enhanced naked pDNA transfer to whole intraperitoneal organs in mice. Furthermore, lactate dehydrogenase activities in intraperitoneal fluid and plasma were not raised by the suspension of calcium carbonate microflowers.

Transgene expression and local tissue distribution of naked and polymer-condensed plasmid DNA after intradermal administration in mice

DNA vaccination using cationic polymers as carriers has the potential to be a very powerful method of immunotherapy, but typical immune responses generated have been less than robust. To better understand the details of DNA vaccine delivery in vivo, we prepared polymer/DNA complexes using three structurally distinct cationic polymers and fluorescently labeled plasmid DNA and injected them intradermally into mice. We analyzed transgene expression (luciferase) and the local tissue distribution of the labeled plasmid at the injection site at various time points (from hours to days). Comparable numbers of luciferase expressing cells were observed in the skin of mice receiving naked plasmid or polyplexes one day after transfection. At day 4, however, the polyplexes appeared to result in more transfected skin cells than naked plasmid. Live animal imaging revealed that naked plasmid dispersed quickly in the skin of mice after injection and had a wider distribution than any of the three types of polyplexes. However, naked plasmid level dropped to below detection limit after 24h, whereas polyplexes persisted for up to 2 weeks. The PEGylated polyplexes had a significantly wider distribution in the tissue than the nonPEGylated polyplexes. PEGylated polyplexes also distributed more broadly among dermal fibroblasts and allowed greater interaction with antigen-presenting cells (APCs) (dendritic cells and macrophages) starting at around 24h post-injection. By day 4, co-localization of polyplexes with APCs was observed at the injection site regardless of polymer structure, whereas small amounts of polyplexes were found in the draining lymph nodes. These in vivo findings demonstrate the superior stability of PEGylated polyplexes in physiological milieu and provide important insight on how cationic polymers could be optimized for DNA vaccine delivery.

Polymer-mediated DNA vaccine delivery via bystander cells requires a proper balance between transfection efficiency and cytotoxicity

Direct targeting of dendritic cells is an ideal goal for DNA vaccine delivery in order to stimulate both arms of the immune system. However, dendritic cells are often difficult to transfect using nonviral polyplexes. Here we show that transfecting bystander cells such as fibroblasts with PEI/DNA complexes leads to efficient cross-presentation of a model antigen by dendritic cells and subsequent activation of antigen-specific CD8(+) T cells. Maturation of dendritic cells is also stimulated after co-culture with transfected fibroblasts. Such outcomes depend on a proper balance between transfection efficiency and polyplex-induced cytotoxicity in the fibroblasts. In fact, substantial cytotoxicity is desirable and even necessary for cross-presentation and cross-priming of T cells. This study illustrates a new pathway of polymer-based DNA vaccine delivery via bystander cells without direct targeting of antigen-presenting cells and highlights the importance of exploiting polymer-induced cytotoxicity for the benefit of immune activation.

Biodistribution and blood clearance of plasmid DNA administered in arginine peptide complexes

Background

Peptide/DNA complexes have great potential as non-viral methods for gene delivery. Despite promising results for peptide-mediated gene delivery technology, an effective systemic peptide-based gene delivery system has not yet been developed.

Methods

This study used pCMV-Luc as a model gene to investigate the biodistribution and the in vivo efficacy of arginine peptide-mediated gene delivery by polymerase chain reaction (PCR).

Results

Plasmid DNA was detected in all organs tested 1 h after intraperitoneal administration of arginine/DNA complexes, indicating that the arginine/DNA complexes disseminated widely through the body. The plasmid was primarily detected in the spleen, kidney, and diaphragm 24 h post administration. The mRNA expression of plasmid DNA was noted in the spleen, kidney, and diaphragm for up to 2 weeks, and in the other major organs, for at least 1 week. Blood clearance studies showed that injected DNA was found in the blood as long as 6 h after injection.

Conclusions

Taken together, our results demonstrated that arginine/DNA complexes are stable in blood and are effective for in vivo gene delivery. These findings suggest that intraperitoneal administration of arginine/DNA complexes is a promising tool in gene therapy.

Enhancement of dendritic cells transfection in vivo and of vaccination against B16F10 melanoma with mannosylated histidylated lipopolyplexes loaded with tumor antigen messenger RNA

We report the preparation of mannosylated nanoparticles loaded with messenger RNA (mRNA) that enhance the transfection of dendritic cells (DCs) in vivo and the anti-B16F10 melanoma vaccination in mice. Mannosylated and histidylated lipopolyplexes (Man(11)-LPR100) were obtained by adding mannosylated and histidylated liposomes to mRNA-PEGylated histidylated polylysine polyplexes. Upon intravenous injection, ∼9% of the radioactivity of technetium 99 m-labeled lipopolyplexes measured in the liver, spleen, lungs, and kidneys was found in the spleen. We demonstrate that spleen from mice injected with enhanced green fluorescent protein (EGFP) mRNA-loaded Man(11)-LPR100 contained four times more DCs expressing EGFP than that from mice injected with sugar-free LPR100. This better transfection of DCs is correlated with a better inhibition of B16F10 melanoma growth and an increased survival time when mice were immunized with MART-1 mRNA-loaded Man(11)-LPR100. These results indicate that mannosylated and histidylated LPR is an efficient system for the delivery of tumor antigen mRNA in splenic DCs aiming to induce an anticancer immune response.

FROM THE CLINICAL EDITOR

This paper discusses the preparation of mannosylated nanoparticles loaded with messenger RNA that enhance the transfection of dendritic cells (DCs) in vivo and the anti-B16F10 melanoma vaccination in mice. The authors describe an efficient system for the delivery of tumor antigen mRNA in splenic DCs aiming to induce an anticancer immune response.

N-glycan targeted gene delivery to the dendritic cell SIGN receptor

A novel nonviral gene delivery vector composed of a high-mannose N-glycan conjugated to a polyacridine peptide was prepared. The glycopeptide was designed to bind to plasmid DNA by a combination of polyintercalation and ionic binding, and to the DC-SIGN (dendritic cell-specific intracellular adhesion molecule-3 grabbing nonintegrin) receptor expressed on CHO cells by recognition of the high-mannose N-glycan. The glycopeptide conjugate was prepared by purification of a high-mannose N-glycan from affinity fractionated soybean agglutinin (SBA). The SBA was proteolyzed to release the N-glycan which was then modified on its N-terminus with Tyr and a propionate maleimide. A DNA binding polyacridine peptide, Cys-(Acr-Lys)(4), was prepared by solid-phase peptide synthesis using Fmoc-Lys(Acr), then conjugated to the maleimide on the N-glycan to produce a glycopeptide. The glycopeptide bound to DNA with high affinity as determined by fluorophore displacement assay and DNA band shift on agarose gel. When bound to Cy5 labeled DNA, the glycopeptide mediated specific uptake in DC-SIGN CHO (+) cells as determined by FACS analysis. In vitro gene transfer studies established that the glycopeptide increased the specificity of gene transfer in DC-SIGN CHO (+) cells 100-fold relative to CHO (-) cells. These studies suggest that a high-mannose N-glycan conjugated to a polyacridine peptide may also facilitate receptor mediated gene delivery in dendritic cells and thereby find utility in the delivery of DNA vaccines.

Synthetic vehicles for DNA vaccination

DNA vaccination is an attractive immunization method able to induce robust cellular immune responses in pre-clinical models. However, clinical DNA vaccination trials performed thus far have resulted in marginal responses. Consequently, strategies are currently under development to improve the efficacy of DNA vaccines. A promising strategy is the use of synthetic particle formulations as carrier systems for DNA vaccines. This review discusses commonly used synthetic carriers for DNA vaccination and provides an overview of in vivo studies that use this strategy. Future recommendations on particle characteristics, target cell types and evaluation models are suggested for the potential improvement of current and novel particle delivery systems. Finally, hurdles which need to be tackled for clinical evaluation of these systems are discussed.

Gene carriers and transfection systems used in the recombination of dendritic cells for effective cancer immunotherapy

Dendritic cells (DCs) are the most potent antigen-presenting cells. They play a vital role in the initiation of immune response by presenting antigens to T cells and followed by induction of T-cell response. Reported research in animal studies indicated that vaccine immunity could be a promising alternative therapy for cancer patients. However, broad clinical utility has not been achieved yet, owing to the low transfection efficiency of DCs. Therefore, it is essential to improve the transfection efficiency of DC-based vaccination in immunotherapy. In several studies, DCs were genetically engineered by tumor-associated antigens or by immune molecules such as costimulatory molecules, cytokines, and chemokines. Encouraging results have been achieved in cancer treatment using various animal models. This paper describes the recent progress in gene delivery systems including viral vectors and nonviral carriers for DC-based genetically engineered vaccines. The reverse and three-dimensional transfection systems developed in DCs are also discussed.

Development of Time-Programmed, Dual-Release System Using Multilayered Fiber Mesh Sheet by Sequential Electrospinning

In general clinical pharmacotherapy, multidrug therapy is performed with a view to enhancing drug efficacy or reducing drug’s side effects. It is essential that a Drug Delivery System (DDS) for plural drugs be developed to make multidrug therapy more functional and effective. In this review, we summarize prior DDS research and recent developmental efforts for multi-DDS, as well as of the electrospinning (ELSP) method, which has recently attracted great attention as preparation technique of fine polymer fiber in various fields. We also describe a time-programmed dual-drug controlled-release system using multilayered fiber mesh sheets that have been fabricated by a sequential ELSP method we developed. In addition, we address developmental approaches for DDS devices using micromachining technologies (MEMS) as well as issues and future expectations for robotics in DDS research.

Micro- and nanocarrier-mediated lung targeting

IMPORTANCE OF THE FIELD

Drug delivery to lungs appears to be an attractive proposition on account of the large surface area of the alveolar region; it provides tremendous opportunities to improve drug therapies both systemically and locally using new drug delivery systems. Administration of drugs directly to the lungs is the most appropriate route in the treatment of asthma and other pulmonary diseases such as tuberculosis, chronic obstructive pulmonary disease and lung cancer.

AREAS COVERED IN THIS REVIEW

This review focuses on the utilization of nano- and microcarriers such as microspheres, nanoparticles, liposomes, niosomes and dendrimers for targeted delivery of bioactive molecules to lungs.

WHAT THE READER WILL GAIN

This review sheds light on the current status of nano- and microcarrier-mediated lung targeting of bioactive compounds.

TAKE HOME MESSAGE

The literature review shows that carriers could supplement sustained drug delivery to the lungs, extended duration of action, reduced therapeutic dose, improved patient compliance, and reduced adverse effects of highly toxic drugs. There is still a need to identify more specific receptors that are present exclusively in the lungs. The identification of such receptors may also facilitate drug targeting to further specific parts of the lungs, such as bronchioles and alveoli.

Selective gene delivery in dendritic cells with mannosylated and histidylated lipopolyplexes

We report for the first time preparation of mannosylated and histidylated lipopolyplexes (Man-LPD100) with uptake and transfection selectivity for dendritic cells (DCs). Man-LPD100 were prepared by addition of mannosylated and histidylated liposomes (Man-Lip100) on preformed PEGylated histidylated polylysine/DNA polyplexes. Man-Lip100 comprised a cationic [O,O-dioleyl-N-(3N-(N-methylimidazolium iodide)propylene) phosphoramidate)] lipid, a neutral [O,O-dioleyl-N-histamine Phosphoramidate] co-lipid and β-D-mannopyranosyl-N-dodecylhexadecanamide (Man-lipid). At the best, Man-Lip100 containing 11 mol % Man-lipid was obtained. We found that dialysis of liposomes completely abolished cytotoxicity. We showed that the uptake of Man(11)-LPD100 by the murine DC line (DC2.4 cells) was at least 10-fold higher than that of Lac(6)-LPD100. A confocal microscopy study with DC2.4 cells expressing Rab5-EGFP or Rab7-EGFP, revealed that DNA uptake occurred through clathrin-mediated endocytosis. The transfection of DC2.4 cells with Man(11)-LPD100 containing DNA encoding luciferase gene gave luciferase activity two to three times higher (9 × 10(5) RLU/mg protein) than with non-mannosylated LPD100. In contrast to the latter, it was inhibited by 90% in the presence of mannose. Overall, the results indicate that mannosylated and histidylated LPD is a promising system for a selective DNA delivery in DCs.

Green fluorescent protein as indicator of nonviral transient transfection efficiency in endometrial and testicular biopsies

In the last years, physical and chemical methods of plasmid delivery have revolutionized the efficiency of nonviral gene transfer, and the success of gene therapy is largely dependent upon the development of gene-delivery methods. The nonviral techniques that lead to a direct transfer of DNA into tissue fragments, like electroporation (EP) and lipofection delivery systems are still insufficiently investigated. Our aim was to test the efficiency of EP and lipofection protocols in endometrial and testicular tissue fragments, using a naked plasmid DNA encoding green fluorescent protein (GFP). Because the transfection efficiency depends upon several factors, we tried to optimize the transfection conditions by testing different lipofectamine 2000 and plasmid ratios, electrical parameters, and culture after transfection. Our results show that these two nonviral methods of gene delivery are feasible and efficient in gene transfection of endometrial and testicular tissue biopsies. We found that the most performing ratio of plasmid:lipofectamine was 10:50 for transient lipofection, whereas two pulses for 10 s at 960 microF of capacitance, 200 V of voltage were the most favorable electrical parameters for EP efficiency in the presence of 5 microL of phMGFP plasmid. After lipofection and EP, the highest GFP intensity was observed respectively after 48 and 72 h of tissue fragment culturing. In conclusion, nonviral methods are attractive for an improvement of the gene therapy and our protocol could provide useful indications for in vivo gene therapy applications.

Immune responses to polyethylenimine-mannose-delivered plasmid DNA encoding a Fasciola gigantica fatty acid binding protein in mice

Fasciola gigantica fatty acid binding protein (FABP) was evaluated for evoking an immune response in mice, by delivering the gene coding for this protein with mannosylated-polyethylenimine (PEI) to peritoneal cells. Mice were immunized with 50 microg recombinant plasmid DNA (Group I) or DNA-PEI-mannose (a 22 kDa linear cationic polymer with mannose ligand) (Group II) via the intraperitoneal route. Antibody studies showed no significant humoral immune response evoked to this DNA immunization with either PEI-mannose-delivered or naked DNA. However, on protein boosting of these DNA-primed mice there was a significant enhancement of antibody titre. Flow cytometric bead array was used to measure quantities of interleukin (IL)-2, IL-4, IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF) cytokines. Overexpression of T-helper 1 (Th1) cytokines such as IFN-gamma and TNF, with a lower but significant expression of the T-helper 2 (Th2) cytokine IL-5 was detected. Gene delivery using polyethylenimine-mannose ligand showed significant expression of IFN-gamma and TNF (P < 0.05), but no significant difference in IL-2, IL-4 and IL-5 (P>0.05) cytokine expression was observed between naked-DNA- and mannosylated PEI-DNA-delivered mice. Naked- or PEI-delivered-DNA immunization produced insignificant levels of IL-2 and IL-4 (P>0.05) cytokines in both groups of mice.

Siglecs as targets for therapy in immune-cell-mediated disease

The sialic-acid-binding immunoglobulin-like lectins (siglecs) comprise a family of receptors that are differentially expressed on leukocytes and other immune cells. The restricted expression of several siglecs to one or a few cell types makes them attractive targets for cell-directed therapies. The anti-CD33 (also known as Siglec-3) antibody gemtuzumab (Mylotarg) is approved for the treatment of acute myeloid leukemia, and antibodies targeting CD22 (Siglec-2) are currently in clinical trials for treatment of B cell non-Hodgkins lymphomas and autoimmune diseases. Because siglecs are endocytic receptors, they are well suited for a 'Trojan horse' strategy, whereby therapeutic agents conjugated to an antibody, or multimeric glycan ligand, bind to the siglec and are efficiently carried into the cell. Although the rapid internalization of unmodified siglec antibodies reduces their utility for induction of antibody-dependent cellular cytotoxicity or complement-mediated cytotoxicity, antibody binding of Siglec-8, Siglec-9 and CD22 has been demonstrated to induce apoptosis of eosinophils, neutrophils and depletion of B cells, respectively. Here, we review the properties of siglecs that make them attractive for cell-targeted therapies.

The development of gene therapy: from monogenic recessive disorders to complex diseases such as cancer

During the last 4 decades, gene therapy has moved from preclinical to clinical studies for many diseases ranging from monogenic recessive disorders such as hemophilia to more complex diseases such as cancer, cardiovascular disorders, and human immunodeficiency virus (HIV). To date, more than 1,340 gene therapy clinical trials have been completed, are ongoing, or have been approved in 28 countries, using more than 100 genes. Most of those clinical trials (66.5%) were aimed at the treatment of cancer. Early hype, failures, and tragic events have now largely been replaced by the necessary stepwise progress needed to realize clinical benefits. We now understand better the strengths and weaknesses of various gene transfer vectors; this facilitates the choice of appropriate vectors for individual diseases. Continuous advances in our understanding of tumor biology have allowed the development of elegant, more efficient, and less toxic treatment strategies. In this introductory chapter, we review the history of gene therapy since the early 1960s and present in detail two major recurring themes in gene therapy: (1) the development of vector and delivery systems and (2) the design of strategies to fight or cure particular diseases. The field of cancer gene therapy experienced an "awkward adolescence." Although this field has certainly not yet reached maturity, it still holds the potential of alleviating the suffering of many individuals with cancer.

Protein/peptide and DNA vaccine delivery by targeting C-type lectin receptors

C-type lectin receptors (CLRs) are a class of pathogen-recognition receptors that are actively investigated in the field of vaccine delivery. Many of their properties have functions linked to the immune system. These receptors are expressed abundantly on antigen-presenting cells and are considered to be the sentinels of immune surveillance owing to their endocytic nature and the ability to recognize a diverse range of pathogens through recognition of pathogen-associated molecular patterns. CLRs are also involved in the processes of antigen presentation mediated through the induction of dendritic cell maturation and cytokine production. These properties engender CLRs to be ideal for vaccine targeting. Conversely, CLRs also function to recognize glycosylated self-antigens to induce homeostatic control and tolerance. In this review, we will describe the various preclinical/clinical vaccination strategies to target antigens and plasmid DNA to this diverse class of receptors.

Molecular imaging with nanoparticles: giant roles for dwarf actors

Molecular imaging, first developed to localise antigens in light microscopy, now encompasses all imaging modalities including those used in clinical care: optical imaging, nuclear medical imaging, ultrasound imaging, CT, MRI, and photoacoustic imaging. Molecular imaging always requires accumulation of contrast agent in the target site, often achieved most efficiently by steering nanoparticles containing contrast agent into the target. This entails accessing target molecules hidden behind tissue barriers, necessitating the use of targeting groups. For imaging modalities with low sensitivity, nanoparticles bearing multiple contrast groups provide signal amplification. The same nanoparticles can in principle deliver both contrast medium and drug, allowing monitoring of biodistribution and therapeutic activity simultaneously (theranostics). Nanoparticles with multiple bioadhesive sites for target recognition and binding will be larger than 20 nm diameter. They share functionalities with many subcellular organelles (ribosomes, proteasomes, ion channels, and transport vesicles) and are of similar sizes. The materials used to synthesise nanoparticles include natural proteins and polymers, artificial polymers, dendrimers, fullerenes and other carbon-based structures, lipid-water micelles, viral capsids, metals, metal oxides, and ceramics. Signal generators incorporated into nanoparticles include iron oxide, gadolinium, fluorine, iodine, bismuth, radionuclides, quantum dots, and metal nanoclusters. Diagnostic imaging applications, now appearing, include sentinal node localisation and stem cell tracking.

Use of mannosylated cationic liposomes/ immunostimulatory CpG DNA complex for effective inhibition of peritoneal dissemination in mice

BACKGROUND

Immunotherapy using immunostimulatory CpG DNA could be a promising new therapeutic approach to combat refractory peritoneal dissemination. In the present study, we report the use of a mannosylated cationic liposomes/immunostimulatory CpG DNA complex (Man/CpG DNA lipoplex) for effective inhibition of peritoneal dissemination in mice.

METHODS

The immune response characteristics of the Man/CpG DNA lipoplex were evaluated by measuring tumor necrosis factor (TNF)-alpha production using primary cultured mouse peritoneal macrophages. Subsequently, Man/CpG DNA lipoplex was administered intraperitoneally (i.p.) to peritoneal dissemination model mice, and the number of tumor cells (colon26/Luc) was quantitatively evaluated by measuring luciferase activity. The effect on survival time of the Man/CpG DNA lipoplex was also investigated. The serum transaminase levels of mice receiving i.p. Man/CpG DNA lipoplex treatment were measured to evaluate systemic toxicity.

RESULTS

The Man/CpG DNA lipoplex induced higher TNF-alpha production from macrophages than CpG DNA complexed with conventional cationic liposomes and galactosylated cationic liposomes (Bare/CpG DNA lipoplex and Gal/CpG DNA lipoplex), suggesting mannose receptor-mediated CpG DNA transfer. Intraperitoneal administration of Man/CpG DNA lipoplex inhibited the proliferation of tumor cells in the greater omentum and the mesentery more efficiently than Bare/CpG DNA lipoplex and Gal/CpG DNA lipoplex. Furthermore, the survival time of the peritoneal dissemination model mice was prolonged by i.p. administration of Man/CpG DNA lipoplex. The serum transaminase levels of mice receiving i.p. Man/CpG DNA lipoplex were found to be the same as those of untreated mice.

CONCLUSIONS

The results obtained suggest that i.p. administered Man/CpG DNA lipoplex can be used for efficient immunotherapy to combat peritoneal dissemination.

Enhanced anti-inflammation of inhaled dexamethasone palmitate using mannosylated liposomes in an endotoxin-induced lung inflammation model

Inhalation of bacterial endotoxin induces pulmonary inflammation by activation of nuclear factor kappaB (NFkappaB), production of cytokines and chemokines, and neutrophil activation. Although glucocorticoids are the drugs of choice, administration of free drugs results in adverse effects as a result of a lack of selectivity for the inflammatory effector cells. Because alveolar macrophages play a key role in the inflammatory response in the lung, selective targeting of glucocorticoids to alveolar macrophages offers efficacious pharmacological intervention with minimal side effects. We have demonstrated previously the selective targeting of mannosylated liposomes to alveolar macrophages via mannose receptor-mediated endocytosis after intratracheal administration. In this study, the anti-inflammatory effects of dexamethasone palmitate incorporated in mannosylated liposomes (DPML) at 0.5 mg/kg via intratracheal administration were investigated in lipopolysaccharide-induced lung inflammation in rats. DPML significantly inhibited tumor necrosis factor alpha, interleukin-1beta, and cytokine-induced neutrophil chemoattractant-1 levels, suppressed neutrophil infiltration and myeloperoxidase activity, and inhibited NFkappaB and p38 mitogen-activated protein kinase activation in the lung. These results prove the value of inhaled mannosylated liposomes as powerful targeting systems for the delivery of anti-inflammatory drugs to alveolar macrophages to improve their efficacy against lung inflammation.

Nonviral approaches for targeted delivery of plasmid DNA and oligonucleotide

Successful gene therapy depends on the development of efficient delivery systems. Although pDNA and ODN are novel candidates for nonviral gene therapy, their clinical applications are generally limited owing to their rapid degradation by nucleases in serum and rapid clearance. A great deal of effort had been devoted to developing gene delivery systems, including physical methods and carrier-mediated methods. Both methods could improve transfection efficacy and achieve high gene expression in vitro and in vivo. As for carrier-mediated delivery in vivo, since gene expression depends on the particle size, charge ratio, and interaction with blood components, these factors must be optimized. Furthermore, a lack of cell-selectivity limits the wide application to gene therapy; therefore, the use of ligand-modified carriers is a promising strategy to achieve well-controlled gene expression in target cells. In this review, we will focus on the in vivo targeted delivery of pDNA and ODN using nonviral carriers.

[Immunotherapy against peritoneal dissemination by immunostimulatory CpG DNA]

Peritoneal dissemination is one of the most common causes of metastasis from malignancies in the abdominal cavity. However, the treatment of peritoneal dissemination is difficult; patients receiving normal chemotherapy have a 0-1% chance of surviving for 5 years. Milky spots in the greater omentum are considered to facilitate the adhesion and invasion of abdominal free cancer cells, and subsequently lymph node metastasis occurs. Since immune cells such as macrophages and lymphocytes are present in the greater omentum and lymph nodes, the activation of immune cells would be a promising strategy for treatment. Single-stranded oligonucleotides containing CpG dinucleotides (CpG DNA) are recognized by Toll-like receptor-9 on antigen-presenting cells such as macrophages to stimulate Th-1-type immune responses. However, a delivery system for CpG DNA to immune cells is essential to develop effective therapy against peritoneal dissemination. Here we review the pathophysiologic basis of peritoneal dissemination and introduce our approach that employs cationic liposomes as a carrier for CpG DNA as a new approach in the treatment of peritoneal dissemination.

Efficient targeting to alveolar macrophages by intratracheal administration of mannosylated liposomes in rats

The success of targeting systems to alveolar macrophages critically depends on internalization into these cells for pharmacological intervention. Direct respiratory delivery via inhalation of mannose modified liposomal carriers to alveolar macrophages is of great interest. To evaluate the targeting efficiency to alveolar macrophages by intratracheal administration of mannosylated liposomes (Man-liposomes), Man-liposomes with various ratio of mannosylated cholesterol derivatives, cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) as mannose receptor ligand were investigated with regard to their in vitro uptake in primary cultured alveolar macrophages and in vivo intratracheal administration in rats. The in vitro uptake of Man-liposomes took place in a concentration-dependent manner. The internalization of Man-liposomes with 7.5% (Man-7.5-liposomes) and 5.0% (Man-5.0-liposomes) Man-C4-Chol was considerably higher than that of Man-liposomes with 2.5% of Man-C4-Chol (Man-2.5-liposomes) and Bare-liposomes and significantly inhibited by an excess of mannan, suggesting mannose receptor-mediated endocytosis. After intratracheal administration of Man-7.5 and Man-5.0-liposomes in rats, a significantly high internalization and selective targeting to alveolar macrophages was observed. The enhanced cellular uptake in alveolar macrophages related to the mannose density of Man-liposomes was also confirmed both in vitro and in vivo confocal microscopy studies. These results demonstrate the efficient targeting to alveolar macrophages by the intratracheally administered Man-liposomes via mannose receptor-mediated endocytosis.

Galactosylated chitosan-graft-polyethylenimine as a gene carrier for hepatocyte targeting

Chitosans have been proposed as alternative, biocompatible cationic polymers for nonviral gene delivery. However, the low transfection efficiency and low specificity of chitosan need to be addressed before clinical application. We prepared galactosylated chitosan-graft-polyethylenimine (GC-g-PEI) copolymer by an imine reaction between periodate-oxidized GC and low-molecular-weight PEI. The molecular weight and composition were characterized using gel permeation chromatography column with multi-angle laser scattering and (1)H nuclear magnetic resonance, respectively. The copolymer was complexed with plasmid DNA in various copolymer/DNA (N/P) charge ratios, and the complexes were characterized. GC-g-PEI showed good DNA-binding ability and superior protection of DNA from nuclease attack and had low cytotoxicity compared to PEI 25K. GC-g-PEI/DNA complexes showed higher transfection efficiency than PEI 25K in both HepG2 and HeLa cell lines. Transfection efficiency into HepG2, which has asialoglycoprotein receptors, was higher than that into HeLa, which does not. GC-g-PEI/DNA complexes also transfected liver cells in vivo after intraperitoneal (i.p.) administration more effectively than PEI 25K. These results suggest that GC-g-PEI can be used in gene therapy to improve transfection efficiency and hepatocyte specificity in vitro and in vivo.

Development of an antigen-presenting cell-targeted DNA vaccine against melanoma by mannosylated liposomes

As part of our research involving the targeted delivery of plasmid DNA (pDNA) to antigen-presenting cells (APCs), we developed mannosylated cationic liposomes: N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA)/cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosyl-ethyl)amino)butyl)formamide (Man-C4-Chol)/Chol (Man liposomes). In this study, we used melanoma-associated antigen expressing pDNA; pUb-M and Man liposomes to create a novel APC-targeted DNA vaccine against melanoma and examined its potency by measuring the Ub-M mRNA expression in splenic dendritic cells and macrophages, the cytotoxic T lymphocyte (CTL) activity against melanoma B16BL6 cells and the melanoma B16BL6-specific anti-tumor effect after intraperitoneal (i.p.) administration. We verified that Man lipoplex induces significantly higher pUb-M gene transfection into dendritic cells and macrophages than unmodified lipoplex and naked DNA and it also strongly induces CTL activity against melanoma, inhibits its growth and prolongs the survival after tumor challenge compared with unmodified liposomes and the standard method (naked pDNA, intramuscular (i.m.)). These results demonstrate that Man liposomes are a potent APCs-targeted vector that induce strong immunopotency of DNA vaccine against melanoma.