Characteristics and biodistribution of cationic liposomes and their DNA complexes

Delivering CRISPR to the HIV-1 reservoirs

Human immunodeficiency virus type 1 (HIV-1) infection is well known as one of the most complex and difficult viral infections to cure. The difficulty in developing curative strategies arises in large part from the development of latent viral reservoirs (LVRs) within anatomical and cellular compartments of a host. The clustered regularly interspaced short palindromic repeats/ CRISPR-associated protein 9 (CRISPR/Cas9) system shows remarkable potential for the inactivation and/or elimination of integrated proviral DNA within host cells, however, delivery of the CRISPR/Cas9 system to infected cells is still a challenge. In this review, the main factors impacting delivery, the challenges for delivery to each of the LVRs, and the current successes for delivery to each reservoir will be discussed.

Delivery of gene editing therapeutics

For the past decades, gene editing demonstrated the potential to attenuate each of the root causes of genetic, infectious, immune, cancerous, and degenerative disorders. More recently, Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated protein 9 (CRISPR-Cas9) editing proved effective for editing genomic, cancerous, or microbial DNA to limit disease onset or spread. However, the strategies to deliver CRISPR-Cas9 cargos and elicit protective immune responses requires safe delivery to disease targeted cells and tissues. While viral vector-based systems and viral particles demonstrate high efficiency and stable transgene expression, each are limited in their packaging capacities and secondary untoward immune responses. In contrast, the nonviral vector lipid nanoparticles were successfully used for as vaccine and therapeutic deliverables. Herein, we highlight each available gene delivery systems for treating and preventing a broad range of infectious, inflammatory, genetic, and degenerative diseases. STATEMENT OF SIGNIFICANCE: CRISPR-Cas9 gene editing for disease treatment and prevention is an emerging field that can change the outcome of many chronic debilitating disorders.

Tumor targeted delivery of mycobacterial adjuvant encapsulated chitosan nanoparticles showed potential anti-cancer activity and immune cell activation in tumor microenvironment

Targeting immunotherapeutics inside the tumor microenvironment (TME) with intact biological activity remains a pressing issue. Mycobacterium indicus pranii (MIP), an approved adjuvant therapy for leprosy has exhibited promising results in clinical trials of lung (NSCLC) and bladder cancer. Whole MIP as well as its cell wall fraction have shown tumor growth suppression and enhanced survival in mice model of melanoma, when administered peritumorally. Clinically, peritumoral delivery remains a procedural limitation. In this study, a tumor targeted delivery system was designed, where chitosan nanoparticles loaded with MIP adjuvants, when administered intravenously showed preferential accumulation within the TME, exploiting the principle of enhanced permeability and retention effect. Bio-distribution studies revealed their highest concentration inside the tumor after 6 h of administration. Interestingly, MIP adjuvant nano-formulations significantly reduced the tumor volume in the treated groups and increased the frequency of activated immune cells inside the TME. For chemoimmunotherapeutics studies, MIP nano-formulation was combined with standard dosage regimen of Paclitaxel. Combined therapy exhibited a further reduction in tumor volume relative to either of the MIP nano formulations. From this study a three-pronged strategy emerged as the underlying mechanism; chitosan and Paclitaxel have shown direct role in tumor cell death and the MIP nano-formulation activates the tumor residing immune cells which ultimately leads to the reduced tumor growth.

A review on engineered magnetic nanoparticles in Non-Small-Cell lung carcinoma targeted therapy

There are growing appeals forthe design of efficacious treatment options for non-small-cell lung carcinoma (NSCLC) as it accrues to ~ 85% cases of lung cancer. Although platinum-based doublet chemotherapy has been the main therapeutic intervention in NSCLC management, this leads to myriad of problems including intolerability to the doublet regimens and detrimental side effects due to high doses. A new approach is therefore needed and warrants the design of targeted drug delivery systems that can halt tumor proliferation and metastasis by targeting key molecules, while exhibiting minimal side effects and toxicity. This review aims to explore the rational design of magnetic nanoparticles for the development of tumor-targeting systems for NSCLC. In the review, we explore the anticancer merits of conjugated linoleic acid (CLA) and provide a concise incursion into its application for the invention of functionalized magnetic nanoparticles in the targeted treatment of NSCLC. Recent nanoparticle-based targeted chemotherapies for targeting angiogenesis biomarkers in NSCLC will also be reviewed to further highlight versatility of magnetic nanoparticles. These developments through molecular tuning at the nanoscale and supported by comprehensive pre-clinical studies could lead to the establishment of precise nanosystems for tumor-homing cancer therapy.

Hepatic metastasis of gastric cancer is associated with enhanced expression of ethanolamine kinase 2 via the p53-Bcl-2 intrinsic apoptosis pathway

BACKGROUND

Gastric cancer (GC) with hepatic metastasis has a poor prognosis. Understanding the molecular mechanisms involved in hepatic metastasis may contribute to the development of sensitive diagnostic biomarkers and novel therapeutic strategies.

METHODS

We performed transcriptome analysis of surgically resected specimens from patients with advanced GC. One of the genes identified as specifically associated with hepatic metastasis was selected for detailed analysis. GC cell lines with knockout of the candidate gene were evaluated in vitro and in vivo. Expression of the candidate gene was analysed in GC tissues from 300 patients.

RESULTS

Ethanolamine kinase 2 (ETNK2) was differentially upregulated in GC patients with hepatic metastasis. ETNK2 expression was elevated in GC cell lines derived from haematogenous metastases. ETNK2 knockout significantly suppressed proliferation, invasion, and migration; increased apoptosis; reduced Bcl-2 protein expression; and increased phosphorylated p53 expression. In mouse xenograft models, ETNK2 knockout virtually abolished hepatic metastasis. Stratification of GC patients based on ETNK2 mRNA level revealed significant associations between high ETNK2 tumour expression and both hepatic recurrence and worse prognosis.

CONCLUSIONS

Upregulation of ETNK2 in GC enhances hepatic metastasis, possibly via dysregulation of p53-Bcl-2-associated apoptosis. ETNK2 expression may serve as a biomarker for predicting hepatic recurrence and a therapeutic target.

Progress in systemic co-delivery of microRNAs and chemotherapeutics for cancer treatment by using lipid-based nanoparticles

MicroRNAs (miRNAs) hold the potential to boost therapeutic efficacy and/or reverse drug resistance associated with traditional cancer chemotherapy. Both miRNA mimics and inhibitors have been explored in cancer therapy. Systemic co-delivery of chemotherapeutics and miRNA therapeutics represents an attractive treatment approach, but safe and efficient delivery systems are greatly needed. The regulatory approval of Onpattro^® paved the way for lipid-based nanoparticles to deliver RNA therapeutics in different settings, including in combination with chemotherapeutics to treat cancer. In this Special Report, we discuss the significance of systemic co-delivery of chemotherapeutics and miRNA therapeutics for cancer therapy and highlight the representative examples of this strategy using lipid-based nanoparticles. We also present outstanding roadblocks to clinical translation and provide the latest perspectives.

Physical Properties of Nanoparticles That Result in Improved Cancer Targeting

The therapeutic efficacy of drugs is dependent upon the ability of a drug to reach its target, and drug penetration into tumors is limited by abnormal vasculature and high interstitial pressure. Chemotherapy is the most common systemic treatment for cancer but can cause undesirable adverse effects, including toxicity to the bone marrow and gastrointestinal system. Therefore, nanotechnology-based drug delivery systems have been developed to reduce the adverse effects of traditional chemotherapy by enhancing the penetration and selective drug retention in tumor tissues. A thorough knowledge of the physical properties (e.g., size, surface charge, shape, and mechanical strength) and chemical attributes of nanoparticles is crucial to facilitate the application of nanotechnology to biomedical applications. This review provides a summary of how the attributes of nanoparticles can be exploited to improve therapeutic efficacy. An ideal nanoparticle is proposed at the end of this review in order to guide future development of nanoparticles for improved drug targeting in vivo.

Immunological and Toxicological Considerations for the Design of Liposomes

Liposomes hold great potential as gene and drug delivery vehicles due to their biocompatibility and modular properties, coupled with the major advantage of attenuating the risk of systemic toxicity from the encapsulated therapeutic agent. Decades of research have been dedicated to studying and optimizing liposomal formulations for a variety of medical applications, ranging from cancer therapeutics to analgesics. Some effort has also been made to elucidate the toxicities and immune responses that these drug formulations may elicit. Notably, intravenously injected liposomes can interact with plasma proteins, leading to opsonization, thereby altering the healthy cells they come into contact with during circulation and removal. Additionally, due to the pharmacokinetics of liposomes in circulation, drugs can end up sequestered in organs of the mononuclear phagocyte system, affecting liver and spleen function. Importantly, liposomal agents can also stimulate or suppress the immune system depending on their physiochemical properties, such as size, lipid composition, pegylation, and surface charge. Despite the surge in the clinical use of liposomal agents since 1995, there are still several drawbacks that limit their range of applications. This review presents a focused analysis of these limitations, with an emphasis on toxicity to healthy tissues and unfavorable immune responses, to shed light on key considerations that should be factored into the design and clinical use of liposomal formulations.

Post-synthesis strategy to integrate porphyrinic metal–organic frameworks with CuS NPs for synergistic enhanced photo-therapy

A multi-functional nanoplatform (PCN-CuS-FA-ICG) for combined photodynamic and photothermal therapy was presented, which demonstrated good inhibition of tumor growth.

Optimization-by-design of hepatotropic lipid nanoparticles targeting the sodium-taurocholate cotransporting polypeptide

Active targeting and specific drug delivery to parenchymal liver cells is a promising strategy to treat various liver disorders. Here, we modified synthetic lipid-based nanoparticles with targeting peptides derived from the hepatitis B virus large envelope protein (HBVpreS) to specifically target the sodium-taurocholate cotransporting polypeptide (NTCP; SLC10A1) on the sinusoidal membrane of hepatocytes. Physicochemical properties of targeted nanoparticles were optimized and NTCP-specific, ligand-dependent binding and internalization was confirmed in vitro. The pharmacokinetics and targeting capacity of selected lead formulations was investigated in vivo using the emerging zebrafish screening model. Liposomal nanoparticles modified with 0.25 mol% of a short myristoylated HBV derived peptide, that is Myr-HBVpreS2-31, showed an optimal balance between systemic circulation, avoidance of blood clearance, and targeting capacity. Pronounced liver enrichment, active NTCP-mediated targeting of hepatocytes and efficient cellular internalization were confirmed in mice by ¹¹¹In gamma scintigraphy and fluorescence microscopy demonstrating the potential use of our hepatotropic, ligand-modified nanoparticles.

Non-viral Vector for Muscle-Mediated Gene Therapy

Non-viral gene delivery to skeletal muscle was one of the first applications of gene therapy that went into the clinic, mainly because skeletal muscle is an easily accessible tissue for local gene transfer and non-viral vectors have a relatively safe and low immunogenic track record. However, plasmid DNA, naked or complexed to the various chemistries, turn out to be moderately efficient in humans when injected locally and very inefficient (and very toxic in some cases) when injected systemically. A number of clinical applications have been initiated however, based on transgenes that were adapted to good local impact and/or to a wide physiological outcome (i.e., strong humoral and cellular immune responses following the introduction of DNA vaccines). Neuromuscular diseases seem more challenging for non-viral vectors. Nevertheless, the local production of therapeutic proteins that may act distantly from the injected site and/or the hydrodynamic perfusion of safe plasmids remains a viable basis for the non-viral gene therapy of muscle disorders, cachexia, as well as peripheral neuropathies.

Effect of cationic lipid in cationic liposomes on siRNA delivery into the lung by intravenous injection of cationic lipoplex

Cationic liposomes composed of dialkyl cationic lipid such as 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) can efficiently deliver siRNA to the lungs following the intravenous injection of cationic liposome/siRNA complexes (lipoplexes). In this study, we examined the effect of cationic lipid of cationic liposomes on siRNA delivery to the lungs after intravenous injection. We used six kinds of cationic cholesterol derivatives and 11 kinds of dialkyl or trialkyl cationic lipids as cationic lipids, and prepared 17 kinds of cationic liposomes composed of a cationic lipid and 1,2-dioleoyl-L-α-glycero-3-phosphatidylethanolamine (DOPE) for evaluation of siRNA biodistribution and in vivo gene silencing effects. Among cationic liposomes, those composed of N-hexadecyl-N,N-dimethylhexadecan-1-aminium bromide (DC-1-16), N,N-dimethyl-N-octadecyloctadecan-1-aminium bromide (DC-1-18), 2-((1,5-bis(octadecyloxy)-1,5-dioxopentan-2-yl)amino)-N,N,N-trimethyl-2-oxoethan-1-aminium chloride (DC-3-18D), 11-((1,3-bis(dodecanoyloxy)-2-((dodecanoyloxy)methyl)propan-2-yl)amino)-N,N,N-trimethyl-11-oxoundecan-1-aminium bromide (TC-1-12), or cholesteryl (3-((2-hydroxyethyl)amino)propyl)carbamate hydroiodide (HAPC-Chol) with DOPE exhibited high accumulation of siRNA in the lung and significant suppression of Tie2 mRNA expression after the intravenous injection of cationic lipoplexes with Tie2 siRNA. Furthermore, DC-1-16/DOPE and DC-1-18/DOPE lipoplexes with protein kinase N3 (PKN3) siRNA could suppress the tumour growth when intravenously injected into mice with lung LLC metastasis. These findings indicate that the siRNA biodistribution and in vivo knockdown efficiency after the intravenous injection of cationic lipoplexes were strongly affected by the type of cationic lipid of cationic liposomes.

ROS-induced NO generation for gas therapy and sensitizing photodynamic therapy of tumor

This study reports a tumor-specific ROS-responsive nanoplatform capable of the combination of nitric oxide (NO)-based gas therapy and sensitized photodynamic therapy (PDT). The nanoplatform is constructed on porous coordination network (PCN), which contains NO donor L-Arg and is concurrently coated with cancer cell membrane (L-Arg@PCN@Mem). Under near infrared light (NIR) irradiation, L-Arg@PCN@Mem produces plenty of reactive oxygen species (ROS) directly for PDT therapy, while a part of ROS take the role of oxidative to converse L-Arg into NO for combined gas therapy. The results indicate that the transformation of ROS to NO can enhance PDT efficacy in hypoxic tumors owing to the ability of NO in freely diffusing into deep hypoxic tumor site. Moreover, homologous targeting function originated from the coating of cancer cells membrane further improves the tumor treatment effect owing to the biotargeting toward homologous tumors. This L-Arg@PCN@Mem nanoplatform provides a new therapy paradigm of overcoming the hypoxia barrier of tumor therapy, and holds great potential for the treatment of tumor and NO-related diseases.

Liposomal CpG-ODN: An in vitro and in vivo study on macrophage subtypes responses, biodistribution and subsequent therapeutic efficacy in mice models of cancers

CpG oligodeoxynucleotides (CpG-ODN), a common immune stimulator and vaccine adjuvant, was reported to switch Tumor Associated Macrophages (TAMs) from M2 to M1 phenotype inducing anti-tumor responses. Liposomes are of the successfully applied carriers for CpG-ODN. The aim of present study was design and preparation of a liposomal formulation containing phosphodiester CpG-ODN, evaluation of its effect on macrophages responses, and subsequent antitumor responses in mice. Liposomal formulations containing phosphodiester CpG-ODN or non-CpG-ODN were prepared and characterized. MTT reduction assay in four different cell lines, uptake, arginase and iNOS activity evaluation in macrophage cell lines, biodistribution study and therapeutic anti-tumor effects of formulations in mice bearing C26 colon carcinoma or B16F0 melanoma were carried out. The size of liposomes containing CpG-ODN was ~200 nm with the encapsulation efficiency of 33%. The iNOS activity assay showed high nitric oxide (NO) level in M2 phenotype of macrophage cell lines treated by liposomes containing CpG-ODN. In mice which received liposomes containing CpG-ODN as a monotherapy, maximum tumor growth delay with remarkable survival improvement was observed compared to control groups. Biodistribution study showed the accumulation of liposomal formulation in tumor micro-environment. In conclusion, considerable anti-tumor responses observed by liposomes containing CpG-ODN was due to enhanced delivery of CpG-ODN to immune cells and subsequent initiation of anti-tumoral immune responses.

Physical characterization and in vivo organ distribution of coated iron oxide nanoparticles

Citrate-stabilized iron oxide magnetic nanoparticles (MNPs) were coated with one of carboxymethyl dextran (CM-dextran), polyethylene glycol-polyethylene imine (PEG-PEI), methoxy-PEG-phosphate+rutin, or dextran. They were characterized for size, zeta potential, hysteresis heating in an alternating magnetic field, dynamic magnetic susceptibility, and examined for their distribution in mouse organs following intravenous delivery. Except for PEG-PEI-coated nanoparticles, all coated nanoparticles had a negative zeta potential at physiological pH. Nanoparticle sizing by dynamic light scattering revealed an increased nanoparticle hydrodynamic diameter upon coating. Magnetic hysteresis heating changed little with coating; however, the larger particles demonstrated significant shifts of the peak of complex magnetic susceptibility to lower frequency. 48 hours following intravenous injection of nanoparticles, mice were sacrificed and tissues were collected to measure iron concentration. Iron deposition from nanoparticles possessing a negative surface potential was observed to have highest accumulation in livers and spleens. In contrast, iron deposition from positively charged PEG-PEI-coated nanoparticles was observed to have highest concentration in lungs. These preliminary results suggest a complex interplay between nanoparticle size and charge determines organ distribution of systemically-delivered iron oxide magnetic nanoparticles.

Surface phosphorylation of nanoparticles by hexokinase: A powerful tool for cellular uptake improvement

The aim of the study was to develop zeta potential changing nanoparticles (NPs) via surface phosphorylation in order to improve their uptake by epithelial cells. Polymeric NPs were formed via in situ gelation between chitosan (CS) and chondroitin sulphate (ChS). Phosphorylation of these NPs was carried out by using hexokinase. The resulting phosphorylated NPs (p-NPs) were characterized in respect of their size and zeta potential. Phosphate release was quantified by incubating the particles with isolated as well as cell-associated intestinal alkaline phosphatase (AP). In parallel, resulting change in zeta potential was monitored. In-vitro mucus permeation of these particles was evaluated on porcine intestinal mucus. Furthermore, toxicity and cellular uptake studies were performed on Caco-2 cells. p-NPs exhibited a mean size of 412 ± 3.24 nm and a zeta potential of -12.4 mV. When these p-NPs were incubated with isolated as well as cell-associated AP, a significant amount of phosphate was released within 4 h and zeta potential raised up to -1.2 mV. p-NPs showed improved mucus permeation in comparison to unmodified NPs. Due to de-phosphorylation by AP, cellular uptake of p-NPs increased almost 2-fold. Moreover, particles displayed no toxicity. Findings of this study show that zeta potential changing p-NPs provide effective mucus permeation and enhanced cellular uptake.

Diacetylenic lipids in the design of stable lipopolymers able to complex and protect plasmid DNA

Different viral and non-viral vectors have been designed to allow the delivery of nucleic acids in gene therapy. In general, non-viral vectors have been associated with increased safety for in vivo use; however, issues regarding their efficacy, toxicity and stability continue to drive further research. Thus, the aim of this study was to evaluate the potential use of the polymerizable diacetylenic lipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) as a strategy to formulate stable cationic lipopolymers in the delivery and protection of plasmid DNA. Cationic lipopolymers were prepared following two different methodologies by using DC8,9PC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and the cationic lipids (CL) 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), stearylamine (SA), and myristoylcholine chloride (MCL), in a molar ratio of 1:1:0.2 (DMPC:DC8,9PC:CL). The copolymerization methodology allowed obtaining cationic lipopolymers which were smaller in size than those obtained by the cationic addition methodology although both techniques presented high size stability over a 166-day incubation period at 4°C. Cationic lipopolymers containing DOTAP or MCL were more efficient in complexing DNA than those containing SA. Moreover, lipopolymers containing DOTAP were found to form highly stable complexes with DNA, able to resist serum DNAses degradation. Furthermore, neither of the cationic lipopolymers (with or without DNA) induced red blood cell hemolysis, although metabolic activity determined on the L-929 and Vero cell lines was found to be dependent on the cell line, the formulation and the presence of DNA. The high stability and DNA protection capacity as well as the reduced toxicity determined for the cationic lipopolymer containing DOTAP highlight the potential advantage of using lipopolymers when designing novel non-viral carrier systems for use in in vivo gene therapy. Thus, this work represents the first steps toward developing a cationic lipopolymer-based gene delivery system using polymerizable and cationic lipids.

Cancer Cell Membrane Camouflaged Cascade Bioreactor for Cancer Targeted Starvation and Photodynamic Therapy

Selectively cuting off the nutrient supply and the metabolism pathways of cancer cells would be a promising approach to improve the efficiency of cancer treatment. Here, a cancer targeted cascade bioreactor (designated as mCGP) was constructed for synergistic starvation and photodynamic therapy (PDT) by embedding glucose oxidase (GOx) and catalase in the cancer cell membrane-camouflaged porphyrin metal-organic framework (MOF) of PCN-224 (PCN stands for porous coordination network). Due to biomimetic surface functionalization, the immune escape and homotypic targeting behaviors of mCGP would dramatically enhance its cancer targeting and retention abilities. Once internalized by cancer cells, mCGP was found to promote microenvironmental oxygenation by catalyzing the endogenous hydrogen peroxide (H₂O₂) to produce oxygen (O₂), which would subsequently accelerate the decomposition of intracellular glucose and enhance the production of cytotoxic singlet oxygen (¹O₂) under light irradiation. Consequently, mCGP displayed amplified synergistic therapeutic effects of long-term cancer starvation therapy and robust PDT, which would efficiently inhibit the cancer growth after a single administration. This cascade bioreactor would further facilitate the development of complementary modes for spatiotemporally controlled cancer treatment.

PDMS-b-PMOXA polymersomes for hepatocyte targeting and assessment of toxicity

Nanoparticles, such as polymersomes, can be directed to the hepatic asialoglycoprotein receptor to achieve targeted drug delivery. In this study, we prepared asialofetuin conjugated polymersomes based on the amphiphilic di-block copolymer poly(dimethylsiloxane)-b-poly(2-methyloxazoline) (PDMS-b-PMOXA). They had an average diameter of 150nm and formed monodisperse vesicles. Drug encapsulation and sustained release was monitored using the hydrophilic model compound carboxyfluorescein. Asialoglycoprotein receptor specific uptake by HepG2 cells in vitro was energy dependent and could be competitively inhibited by the free targeting ligand. Mechanistic uptake studies revealed intracellular trafficking of asialofetuin conjugated polymersomes from early endosomes and to the lysosomal compartment. Polymersomes showed no toxicity in the MTT assay up to concentrations of 500μg/mL. In addition, acute toxicity and tolerability of our PDMS-b-PMOXA polymersome formulations was assessed in vivo using zebrafish embryos as a vertebrate screening model. In conclusion, a hepatocyte specific drug delivery system was designed, which is safe and biocompatible and which can be used to implement liver-specific targeting strategies.

Vesicular melatonin efficiently downregulates sodium fluoride-induced rat hepato- and broncho-TNF-α, TGF-β expressions, and associated oxidative injury: a comparative study of liposomal and nanoencapsulated forms

The importance of fluoride as a natural and industrial toxicant is recognized worldwide. We evaluated the regulating role and biological effect of vesicular (liposomal and nanoencapsulated) melatonin (N-acetyl-5-methoxytryptamine) for drug delivery and controlled release on the depletion of inflammatory mediators, as well as oxidative damage in sodium fluoride (NaF)-treated lungs and liver. Hepatic and bronchial damage was induced in Swiss albino rats with a single acute ingestion of NaF (48 mg/kg body weight, oral gavage). NaF exposure caused the generation of reactive oxygen species (ROS); upregulation of TNF-α and TGF-β; decreased activities of antioxidant systems (glutathione, glutathione-S-transferase, superoxide dismutase, catalase), succinate dehydrogenase, membrane microviscosity, and membrane potential; increased activity of lipid peroxidation and nicotinamide adenine dinucleotide hydride oxidase; and increased hepatic and nephrite toxicities (P<0.001) compared to those in normal animals. Charge (-ve/+ve)-specific single liposomal (dicetyl phosphate/stearylamine) and nanoencapsulated melatonin (4.46 mg/kg body weight, intravenous) treatments (2 hours after NaF exposure) significantly (P<0.01/0.001) and maximally (P<0.001) inhibited all alterations developed in NaF-mediated oxidative injuries in rat liver (+ve) and lungs (-ve), demonstrating their strong free radical scavenging, antioxidant and antigenotoxic properties, and vesicular efficiencies of targeting. Overall, these results suggest that nanoencapsulated melatonin might be considered as a more powerful remedial therapy in comparison to liposomes, in terms of its efficacy in regulating NaF-intoxicated oxidative injury.

Effects of surface charges of gold nanoclusters on long-term in vivo biodistribution, toxicity, and cancer radiation therapy

Gold nanoclusters (Au NCs) have exhibited great advantages in medical diagnostics and therapies due to their efficient renal clearance and high tumor uptake. The in vivo effects of the surface chemistry of Au NCs are important for the development of both nanobiological interfaces and potential clinical contrast reagents, but these properties are yet to be fully investigated. In this study, we prepared glutathione-protected Au NCs of a similar hydrodynamic size but with three different surface charges: positive, negative, and neutral. Their in vivo biodistribution, excretion, and toxicity were investigated over a 90-day period, and tumor uptake and potential application to radiation therapy were also evaluated. The results showed that the surface charge greatly influenced pharmacokinetics, particularly renal excretion and accumulation in kidney, liver, spleen, and testis. Negatively charged Au NCs displayed lower excretion and increased tumor uptake, indicating a potential for NC-based therapeutics, whereas positively charged clusters caused transient side effects on the peripheral blood system.

Long-Circulating Polymeric Nanovectors for Tumor-Selective Gene Delivery

Significant advances in the understanding of the genetic abnormalities that lead to the development, progression, and metastasis of neoplastic diseases has raised the promise of gene therapy as an approach to medical intervention. Most of the clinical protocols that have been approved in the United States for gene therapy have used the viral vectors because of the high efficiency of gene transfer. Conventional means of gene delivery using viral vectors, however, has undesirable side effects such as insertion of mutational viral gene into the host genome and development of replication competent viruses. Among non-viral gene delivery methods, polymeric nanoparticles are increasingly becoming popular as vectors of choice. The major limitation of these nanoparticles is poor transfection efficiency at the target site after systemic administration due to uptake by the cells of reticuloendothelial system (RES). In order to reduce the uptake by the cells of the RES and improve blood circulation time, these nanoparticles are coated with hydrophilic polymers such as poly(ethylene glycol) (PEG). This article reviews the use of such hydrophilic polymers employed for improving the circulation time of the nanocarriers. The mechanism of polymer coating and factors affecting the circulation time of these nanocarriers will be discussed. In addition to the long circulating property, modifications to improve the target specificity of the particles and the limitations of steric protection will be analyzed.

Biocompatible polymer-Peptide hybrid-based DNA nanoparticles for gene delivery

Currently, research on polymers to be used as gene delivery systems is one of the most important directions in both polymer science and biomedicine. In this report, we describe a five-step procedure to synthesize a novel polymer-peptide hybrid system for gene transfection. The block copolymer based on the biocompatible polymer poly(2-methyl-2-oxazoline) (PMOXA) was combined with the biocleavable peptide block poly(aspartic acid) (PASP) and finally modified with diethylenetriamine (DET). PMOXA-b-PASP(DET) was produced in high yield and characterized by (1)H NMR and FT-IR. Our biopolymer complexed plasmid DNA (pDNA) efficiently, and highly uniform nanoparticles with a slightly negative zeta potential were produced. The polymer-peptide hybrid system was able to efficiently transfect HEK293 and HeLa cells with GFP pDNA in vitro. Unlike the commonly used polymer, 25 kDa branched poly(ethylenimine), our biopolymer had no adverse effects on cell growth and viability. In summary, the present work provides valuable information for the design of new polymer-peptide hybrid-based gene delivery systems with biocompatible and biodegradable properties.

PEGylated cationic nanoemulsions can efficiently bind and transfect pIDUA in a mucopolysaccharidosis type I murine model

Mucopolysaccharidosis type I (MPS I) is an autosomal disease caused by alpha-L-iduronidase deficiency. This study proposed the use of cationic nanoemulsions as non-viral vectors for a plasmid (pIDUA) containing the gene that codes for alpha-L-iduronidase. Nanoemulsions composed of medium chain triglycerides (MCT)/1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)/1,2-dioleoyl-sn-glycero-3-trimethylammonium propane (DOTAP)/1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG) were prepared by high pressure homogenization. Formulations were prepared by the adsorption or encapsulation of preformed pIDUA-DOTAP complexes into the oil core of nanoemulsions at different charge ratios. pIDUA complexed was protected from enzymatic degradation by DNase I. The physicochemical characteristics of complexes in protein-containing medium were mainly influenced by the presence of DSPE-PEG. Bragg reflections corresponding to a lamellar organization were identified for blank formulations by energy dispersive X-ray diffraction, which could not be detected after pIDUA complexation. The intravenous injection of these formulations in MPS I knockout mice led to a significant increase in IDUA activity (fluorescence assay) and expression (RT-qPCR) in different organs, especially the lungs and liver. These findings were more significant for formulations prepared at higher charge ratios (+4/-), suggesting a correlation between charge ratio and transfection efficiency. The present preclinical results demonstrated that these nanocomplexes represent a potential therapeutic option for the treatment of MPS I.

Cationic bovine serum albumin based self-assembled nanoparticles as siRNA delivery vector for treating lung metastatic cancer

It is generally believed that intravenous application of cationic vectors is limited by the binding of abundant negatively charged serum components, which may cause rapid clearance of the therapeutic agent from the blood stream. However, previous studies show that systemic delivery of cationic gene vectors mediates specific and efficient transfection within the lung, mainly as a result of interaction of the vectors with serum proteins. Based on these findings, a novel and charge-density-controllable siRNA delivery system is developed to treat lung metastatic cancer by using cationic bovine serum albumin (CBSA) as the gene vector. By surface modification of BSA, CBSA with different isoelectric points (pI) is synthesized and the optimal cationization degree of CBSA is determined by considering the siRNA binding and delivery ability, as well as toxicity. The CBSA can form stable nanosized particles with siRNA and protect siRNA from degradation. CBSA also shows excellent abilities to intracellularly deliver siRNA and mediate significant accumulation in the lung. When Bcl2-specific siRNA is introduced to this system, CBSA/siRNA nanoparticles exhibit an efficient gene-silencing effect that induces notable cancer cell apoptosis and subsequently inhibits the tumor growth in a B16 lung metastasis model. These results indicate that CBSA-based self-assembled nanoparticles can be a promising strategy for a siRNA delivery system for lung targeting and metastatic cancer therapy.

Lipid nanoparticles for gene delivery

Nonviral vectors which offer a safer and versatile alternative to viral vectors have been developed to overcome problems caused by viral carriers. However, their transfection efficacy or level of expression is substantially lower than viral vectors. Among various nonviral gene vectors, lipid nanoparticles are an ideal platform for the incorporation of safety and efficacy into a single delivery system. In this chapter, we highlight current lipidic vectors that have been developed for gene therapy of tumors and other diseases. The pharmacokinetic, toxic behaviors and clinic trials of some successful lipids particles are also presented.

The influence of lipid composition and surface charge on biodistribution of intact liposomes releasing from hydrogel-embedded vesicles

Mixed drug delivery systems possess advantages over discrete systems, and can be used as a strategy to design more effective formulations. They are more valuable if the embedded particles perform well, rather than using drugs that have been affected by the surrounding vehicle. In order to address this concept, different liposomes have been incorporated into hydrogel to evaluate the potential effect on the controlled release of liposomes. Radiolabeled liposomes, with respect to different acyl chain lengths (DMPC, DPPC, or DSPC) and charges (neutral, negative [DSPG], or positive [DOTAP]) were integrated into chitosan-glycerophosphate. The results obtained from the biodistribution showed that the DSPC liposomes had the highest area under the curve (AUC) values, both in the blood (206.5%ID/gh(-1)) and peritoneum (622.3%ID/gh(-1)), when compared to the DPPC and DMPC formulations, whether in liposomal hydrogel or dispersion. Interesting results were observed in that the hydrogel could reverse the peritoneal retention of negatively charged liposomes, increasing to 8 times its AUC value, to attain the highest amount among all formulations. The interactions between the liposomes and chitosan-glycerophosphate, confirmed by the Fourier transform infrared (FTIR) spectra as shifted characteristic peaks, were observed in the combined systems. Overall, the hydrogel could control the release of intact liposomes, which could be manipulated by both the liposome type and interactions between the two vehicles.

Cell penetrating peptide tethered bi-ligand liposomes for delivery to brain in vivo: Biodistribution and transfection

Targeted nano-particulate systems hold extraordinary potential for delivery of therapeutics across blood brain barrier (BBB). In this work, we investigated the potential of novel bi-ligand (transferrin-poly-l-arginine) liposomal vector for delivery of desired gene to brain, in vivo. The in vivo evaluation of the delivery vectors is essential for clinical translation. We followed an innovative approach of combining transferrin receptor targeting with enhanced cell penetration to design liposomal vectors for improving the transport of molecules into brain. The biodistribution profile of 1, 1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine iodide(DiR)-labeled liposomes was evaluated in adult rats after single intravenous injection at dose of 15.2μmoles of phospholipids/kg body weight. We demonstrated that bi-ligand liposomes accumulated in rat brain at significantly (p<0.05) higher concentrations as compared to the single-ligand (transferrin) or plain liposomes. In addition, the bi-ligand liposomes resulted in increased expression of β-galactosidase(β-gal) plasmid in rat brain tissue in comparison to the single-ligand liposomes. Histological examination of the transfected tissues did not show any signs of tissue necrosis or inflammation. Hemolysis assay further authenticated the biocompatibility of bi-ligand liposomes in blood up to 600 nmoles of phospholipids/1.4×10(7) erythrocytes. The findings of this study provide important and detailed information regarding the distribution of bi-ligand liposomes in vivo and accentuate their ability to demonstrate improved brain penetration and transfection potential over single-ligand liposomes.

In vivo delivery of RNAi with lipid-based nanoparticles

RNA interference (RNAi) technology represents a fundamentally new category of treatments for human disease by addressing targets that are traditionally considered undruggable with existing medicines. The major challenge for RNAi-based therapy is the delivery system that meets human therapeutic needs. Therefore, engineering vectors with good delivery efficiency and safety profile is an intense area of research. Lipid-based nanoparticles for RNAi have yielded successful advances in vivo and to an extent in clinical trials. In this review, we discuss the barriers in developing lipid-based nanoparticles for in vivo RNAi and different strategies to overcome them. Rational designs that address safety concerns and ensure effective delivery will aid the translation of engineered lipid-based nanoparticles toward the clinic in the foreseeable future.

MicroRNA delivery by cationic lipoplexes for lung cancer therapy

Lung cancer is the leading cause of cancer deaths in western countries and carries a poor overall five year survival rate. Several studies demonstrate that microRNAs (miRNAs or miRs) are actively involved in tumor development by serving as tumor suppressors, oncogenes or both. In lung cancer, miRNAs may serve as both diagnostic and prognostic biomarkers as well as regulate in vitro and in vivo tumor progression. However, miRNA-based therapy is faced with several challenges including lack of tissue specificity, lack of optimal delivery systems, poor cellular uptake and risk of systemic toxicity. Here, we report a cationic lipid based miRNA delivery system to address some of these challenges. Among many lung cancer related miRNAs, miR-133b, a tumor suppressor, was selected as a therapeutic target because it directly targets the prosurvival gene MCL-1 thus regulating cell survival and sensitivity of lung cancer cells to chemotherapeutic agents. The efficacy of pre-miR-133b containing lipoplexes was evaluated in A549 non-small cell lung cancer (NSCLC) cells. Compared with siPORT NeoFX transfection agent, lipoplexes delivered pre-miR-133b in a more efficient manner with ~2.3-fold increase in mature miR-133b expression and ~1.8-fold difference in MCL-1 protein downregulation in vitro. In the in vivo biodistribution study, lipoplexes achieved ~30% accumulation in lung tissue, which was ~50-fold higher than siPORT NeoFX transfection agent. Mice treated with pre-miR-133b containing lipoplexes had mature miR-133b expression in lung ~52-fold higher than untreated mice. Our results demonstrated that cationic lipoplexes are a promising carrier system for the development of miRNA-based therapeutics in lung cancer treatment.

Comparison between a multifunctional envelope-type nano device and lipoplex for delivery to the liver

The utility of using a multifunctional envelope-type nano device (MEND) for delivering a gene to the liver was examined. Lipotrust, a commercially available transfection reagent whose lipid composition is DC6- 14 :DOPE: cholesterol=4 : 3 : 3, was used as a reference. When Lipotrust was administrated intravenously, luciferase activity of the lung was 25 times higher than that of the liver. The luciferase activity of the lung was greatly reduced when a MEND was administered, even though the lipid composition of the lipid envelope was the same in both devices. Furthermore, the luciferase activity of the liver was 5 times higher than that for lipotrust, suggesting that the encapsulation of plasmid DNA (pDNA) in liposomes is more advantageous for delivering pDNA to the liver than complex formation. The isolation of parenchymal cells (PCs) and non-parenchymal cells (NPCs) showed that the MEND system is capable of expressing the luciferase protein more preferentially in NPCs than the lipoplex system. In addition, when the surface was modified with a pH-sensitive fusogenic peptide (GALA) used as a device for endosomal escape, overall liver luciferase activity was greatly enhanced. This suggests that endosomal escape is a limiting step for the MEND system. In the case of the GALA-modified MEND, the luciferase activity of PCs and NPCs was 18 times and 11 times higher than MEND system, while the transfection efficiency of NPCs was significantly higher compared to that of PCs. Collectively, these data show that a GALA-modified MEND prepared with DC6-14 :DOPE: cholesterol represents a promising device for NPCtargeting gene delivery in vivo.

Triazine dendrimers as nonviral vectors for in vitro and in vivo RNAi: the effects of peripheral groups and core structure on biological activity

A family of triazine dendrimers, differing in their core flexibility, generation number, and surface functionality, was prepared and evaluated for its ability to accomplish RNAi. The dendriplexes were analyzed with respect to their physicochemical and biological properties, including condensation of siRNA, complex size, surface charge, cellular uptake and subcellular distribution, their potential for reporter gene knockdown in HeLa/Luc cells, and ultimately their stability, biodistribution, pharmacokinetics and intracellular uptake in mice after intravenous (iv) administration. The structure of the backbone was found to significantly influence siRNA transfection efficiency, with rigid, second generation dendrimers displaying higher gene knockdown than the flexible analogues while maintaining less off-target effects than Lipofectamine. Additionally, among the rigid, second generation dendrimers, those with either arginine-like exteriors or peripheries containing hydrophobic functionalities mediated the most effective gene knockdown, thus showing that dendrimer surface groups also affect transfection efficiency. Moreover, these two most effective dendriplexes were stable in circulation upon intravenous administration and showed passive targeting to the lung. Both dendriplex formulations were taken up into the alveolar epithelium, making them promising candidates for RNAi in the lung. The ability to correlate the effects of triazine dendrimer core scaffolds, generation number, and surface functionality with siRNA transfection efficiency yields valuable information for further modifying this nonviral delivery system and stresses the importance of only loosely correlating effective gene delivery vectors with siRNA transfection agents.

Targeting anticancer drugs to tumor vasculature using cationic liposomes

Liposomal drug delivery systems improve the therapeutic index of chemotherapeutic agents, and the use of cationic liposomes to deliver anticancer drugs to solid tumors has recently been recognized as a promising therapeutic strategy to improve the effectiveness of conventional chemotherapeutics. This review summarizes the selective targeting of cationic liposomes to tumor vasculature, the merits of incorporating the polymer polyethylene-glycol (PEG), and the impact of the molar percent of the cationic lipid included in cationic liposomes on liposomal targeting efficacy. In addition, the discussion herein includes the therapeutic benefit of a dual targeting approach, using PEG-coated cationic liposomes in vascular targeting (of tumor endothelial cells), and tumor targeting (of tumor cells) of anticancer drugs. Cationic liposomes have shown considerable promise in preclinical xenograft models and are poised for clinical development.

Recent advances in tumor vasculature targeting using liposomal drug delivery systems

Tumor vessels possess unique physiological features that might be exploited for improved drug delivery. The targeting of liposomal anticancer drugs to tumor vasculature is increasingly recognized as an effective strategy to obtain superior therapeutic efficacy with limited host toxicity compared with conventional treatments. This review introduces recent advances in the field of liposomal targeting of tumor vasculature, along with new approaches that can be used in the design and optimization of liposomal delivery systems. In addition, cationic liposome is focused on as a promising carrier for achieving efficient vascular targeting. The clinical implications are discussed of several approaches using a single liposomal anticancer drug formulation: dual targeting, vascular targeting (targeting tumor endothelial cells) and tumor targeting (targeting tumor cells).