Deciphering the monocyte-targeting mechanisms of PEGylated cationic liposomes by investigating the biomolecular corona

Cationic liposomes specifically target monocytes in blood, rendering them promising drug-delivery tools for cancer immunotherapy, vaccines, and therapies for monocytic leukaemia. The mechanism behind this monocyte targeting ability is, however, not understood, but may involve plasma proteins adsorbed on the liposomal surfaces. To shed light on this, we investigated the biomolecular corona of three different types of PEGylated cationic liposomes, finding all of them to adsorb hyaluronan-associated proteins and proteoglycans upon incubation in human blood plasma. This prompted us to study the role of the TLR4 co-receptors CD44 and CD14, both involved in signalling and uptake pathways of proteoglycans and glycosaminoglycans. We found that separate inhibition of each of these receptors hampered the monocyte uptake of the liposomes in whole human blood. Based on clues from the biomolecular corona, we have thus identified two receptors involved in the targeting and uptake of cationic liposomes in monocytes, in turn suggesting that certain proteoglycans and glycosaminoglycans may serve as monocyte-targeting opsonins. This mechanistic knowledge may pave the way for rational design of future monocyte-targeting drug-delivery platforms.

CLPs-miR-103a-2-5p inhibits proliferation and promotes cell apoptosis in AML cells by targeting LILRB3 and Nrf2/HO-1 axis, regulating CD8 + T cell response

BACKGROUND

LILRB3, a member of the leukocyte immunoglobulin-like receptor B (LILRB) family, has immunosuppressive functions and directly regulates cancer development, which indicates that LILRB3 is an attractive target for cancer diagnosis and therapy. Novel therapeutic treatments for acute myeloid leukemia (AML) are urgent and important, and RNA therapeutics including microRNAs (miRNAs) could be an effective option. Here, we investigate the role of dysregulated miRNA targeting LILRB3 in the AML microenvironment.

METHODS

Potential miRNAs binding to the 3'-untranslated region (3'-UTR) of the LILRB3 mRNA were predicted by bioinformatics websites. Then, we screened miRNAs targeting LILRB3 by quantitative real-time PCR, and the dual luciferase reporter assay. The expression of LILRB3 and microRNA (miR)-103a-2-5p in AML were determined and then their interactions were also analyzed. In vitro, the effects of miR-103a-2-5p were determined by CCK8, colony formation assay, and transwell assay, while cell apoptosis and cell cycle were analyzed by flow cytometry. Cationic liposomes (CLPs) were used for the delivery of miR-103a-2-5p in the AML mouse model, which was to validate the potential roles of miR-103a-2-5p in vivo.

RESULTS

LILRB3 was upregulated in AML cells while miR-103a-2-5p was dramatically downregulated. Thus, a negative correlation was found between them. MiR-103a-2-5p directly targeted LILRB3 in AML cells. Overexpressed miR-103a-2-5p significantly suppressed the mRNA and protein levels of LILRB3, thereby inhibiting AML cell growth and reducing CD8 + T cell apoptosis. In addition, overexpressed miR-103a-2-5p reduced both the relative expression of Nrf2/HO-1 pathway-related proteins and the ratio of GSH/ROS, leading to the excessive intracellular ROS that may promote AML cell apoptosis. In the mouse model, the delivery of miR-103a-2-5p through CLPs could inhibit tumor growth.

CONCLUSIONS

MiR-103a-2-5p serves as a tumor suppressor that could inhibit AML cell proliferation and promote their apoptosis by downregulating LILRB3 expression, suppressing the Nrf2/HO-1 axis, and reducing the ratio of GSH/ROS. Besides, our findings indicate that miR-103a-2-5p may enhance the CD8 + T cell response by inhibiting LILRB3 expression. Therefore, the delivery of miR-103a-2-5p through CLPs could be useful for the treatment of AML.

Tunable rigidity of PLGA shell-lipid core nanoparticles for enhanced pulmonary siRNA delivery in 2D and 3D lung cancer cell models

Faced with the threat of lung cancer-related deaths worldwide, small interfering RNA (siRNA) can silence tumor related messenger RNA (mRNA) to tackle the issue of drug resistance with enhanced anti-tumor effects. However, how to increase lung tumor targeting and penetration with enhanced gene silencing are the issues to be addressed. Thus, the objective of this study is to explore the feasibility of designing non-viral siRNA vectors for enhanced lung tumor therapy via inhalation. Here, shell-core based polymer-lipid hybrid nanoparticles (HNPs) were prepared via microfluidics by coating PLGA on siRNA-loaded cationic liposomes (Lipoplexes). Transmission electron microscopy and energy dispersive spectroscopy study demonstrated that HNP consists of a PLGA shell and a lipid core. Atomic force microscopy study indicated that the rigidity of HNPs could be well tuned by changing thickness of the PLGA shell. The designed HNPs were muco-inert with increased stability in mucus and BALF, good safety, enhanced mucus penetration and cellular uptake. Crucially, HNP1 with the thinnest PLGA shell exhibited superior transfection efficiency (84.83%) in A549 cells, which was comparable to that of lipoplexes and Lipofectamine 2000, and its tumor permeability was 1.88 times that of lipoplexes in A549-3T3 tumor spheroids. After internalization of the HNPs, not only endosomal escape but also lysosomal exocytosis was observed. The transfection efficiency of HNP1 (39.33%) was 2.26 times that of lipoplexes in A549-3T3 tumor spheroids. Moreover, HNPs exhibited excellent stability during nebulization via soft mist inhaler. In conclusion, our study reveals the great potential of HNP1 in siRNA delivery for lung cancer therapy via inhalation.

Cell-penetrating peptide and cationic liposomes mediated siRNA delivery to arrest growth of chronic myeloid leukemia cells in vitro

Gene silencing through RNA interference (RNAi) is a promising therapeutic approach for a wide range of disorders, including cancer. Non-viral gene therapy, using specific siRNAs against BCR-ABL1, can be a supportive or alternative measure to traditional chronic myeloid leukemia (CML) tyrosine kinase inhibitor (TKIs) therapies, given the prevalence of clinical TKI resistance. The main challenge for such approaches remains the development of the effective delivery system for siRNA tailored to the specific disease model. The purpose of this study was to examine and compare the efficiency of endosomolytic cell penetrating peptide (CPP) EB1 and PEG2000-decorated cationic liposomes composed of polycationic lipid 1,26-bis(cholest-5-en-3-yloxycarbonylamino)-7,11,16,20-tetraazahexacosane tetrahydrochloride (2Х3) and helper lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) for anti-bcr-abl siRNA delivery into the K562 human CML cell line. We show that both EB1 and 2Х3-DOPE-DSPE-PEG2000 (0.62 % mol.) liposomes effectively deliver siRNA into K562 cells by endocytic mechanisms, and the use of liposomes leads to more effective inhibition of expression of the targeted gene (BCR-ABL1) and cancer cell proliferation. Taken together, these findings suggest that PEG-decorated cationic liposomes mediated siRNA delivery allows an effective antisense suppression of certain oncogenes, and represents a promising new class of therapies for CML.

PEG-modified nano liposomes co-deliver Apigenin and RAGE-siRNA to protect myocardial ischemia injury

Ischemic heart disease (IHD) is a cardiac disorder in which myocardial damage occurs as a result of myocardial ischemia and hypoxia. Evidence suggests that oxidative stress and inflammatory responses are critical in the development of myocardial ischemia. Therefore, the combination of antioxidant and anti-inflammatory applications is an effective strategy to combat ischemic heart disease. In this paper, polyethylene glycol (PEG)-modified cationic liposomes were used as carriers to deliver apigenin (Apn) with small interfering RNA (siRNA) targeting the receptor for glycosylation end products (RAGE) (siRAGE) into cardiomyocytes to prevent myocardial ischemic injury through antioxidant and anti-inflammatory effects. Our results showed that we successfully prepared cationic PEG liposomes loaded with Apn and siRAGE (P-CLP-A/R) with normal appearance and morphology, particle size and Zeta potential, and good encapsulation rate, drug loading and in vitro release degree. In vitro, P-CLP-A/R was able to prevent oxidative stress injury in H9C2 cells, downregulate the expression of RAGE, reduce the secretion of cellular inflammatory factors and inhibit apoptosis through the RAGE/NF-κB pathway; In vivo, P-CLP-A/R was able to prevent arrhythmia and myocardial pathological injury, and reduce apoptosis and the area of necrotic myocardium in rats. In conclusion, P-CLP-A/R has a protective effect on myocardial ischemic injury and is expected to be a potential drug for the prevention of ischemic heart disease in the future.

Engineered liposomes to deliver nucleic acid mimics in Escherichia coli

Antisense oligonucleotides (ASOs) composed of nucleic acid mimics (NAMs) monomers are considered as potential novel therapeutic drugs against bacterial infections. However, bacterial envelopes are generally impermeable to naked oligonucleotides. Herein, liposomes loaded with NAMs-modified oligonucleotides (LipoNAMs) were evaluated to deliver ASOs in Escherichia coli. Specifically, we tested several surface modifications that included methoxyPEG conjugated to different lipid anchors or modification of the PEG distal ends with maleimide groups and antibodies. MethoxyPEG coated LipoNAMs showed low delivery efficiency for most bacteria, but maleimide-functionalized PEG LipoNAMs were able to deliver ASOs to nearly half of the bacterial population. Conjugation of antibodies to maleimide-functionalized PEG LipoNAMs increased 1.3-fold the delivery efficiency, enhancing the selectivity towards E. coli and biocompatibility. This work demonstrated for the first time that the coupling of antibodies to PEGylated liposomes can significantly improve the delivery of ASOs in E. coli, which might bring alternative routes for the treatment of bacterial infections in the future.

Preparation and Physical Characterization of DNA Binding Cationic Liposomes

Cationic liposomes are routinely employed as one of the major nonviral transfecting agents for intracellular delivery of hydrophilic molecules such as nucleic acids, peptides, and proteins. Cationic liposomes when complexed with DNA form a strong positively charged cationic liposome-DNA complex or lipoplex. The chapter discusses, primarily, the major preparation technique for cationic liposomes and its physical characterization, with a focus on SYBR Green I dye exclusion assay and DNA encapsulation enhancement by freeze-thaw technique. SYBR Green I dye exclusion assay is a technique to determine the total amount of liposomal lipids required to bind a unit weight of DNA, which is critical for transfection experiments. Freeze-thaw technique on the other hand is one of the major techniques to improve DNA encapsulation efficiency in liposomes.

Nano-drug delivery system with enhanced tumour penetration and layered anti-tumour efficacy

The low delivery efficiency of nano-drugs and limited tumour penetration are still huge challenges in treating solid tumours. Herein, we developed a pH-responsive nano-drug delivery system, CALS/PDMA@DOX, with a size conversion-layered delivery function. The system is composed of a pH-responsive cationic liposome loaded with DOX (CALS) and a polyamidoamine dendrimer loaded with DOX (PAMAM@DOX) modified with 2,3-dimethylmaleic anhydride (PDMA@DOX) using electrostatic adsorption. In the tumour microenvironment, the positively-charged large-size CALS and the positively-charged small-size PAMAM@DOX were dissociated to exert anti-tumour effects. CALS preferentially targeted tumour angiogenesis endothelial cells. Because of its small size and positive charge, PAMAM@DOX showed excellent tumour penetration. Significant tumour suppression by the system in vivo was confirmed in a 4T1 tumour xenograft mouse model. This pH-triggered size-switching layered delivery nanosystem is a safe and effective cancer treatment delivery platform that improves drug permeability and therapeutic efficacy.

I.p.-injected cationic liposomes are retained and accumulate in peritoneally disseminated tumors

Intraperitoneal (i.p) chemotherapy is an attractive approach to treat peritoneally disseminated cancers by delivering therapeutic agents directly to the peritoneal cavity where some disseminated tumors are located. Cationic liposomes (CLs) have been used as a viable delivery carrier for i.p. chemotherapy to improve the peritoneal retention of anticancer agents. However, there are no reports on the fate of CLs following i.p. administration to the peritoneal cavity in the presence of disseminated tumors. We prepared a tumor xenograft murine model of peritoneally disseminated gastric cancer by i.p. inoculation of human gastric cancer cells and followed the fate of either CLs or PEGylated CLs (PEG-CLs) after i.p. injection in the model. I.p.-injected CLs were retained in peritoneal cavity for at least 3 days post-injection as a result of clustering with ascites fluid proteins, mainly albumin, while i.p. PEG-CLs was rapidly cleared from the peritoneal cavity to the circulation within 3 h post-injection. Importantly, i.p. CLs efficiently accumulated in the targeted disseminated tumor cells, but not in other abdominal organs including liver, spleen, and kidney. The tumor selectivity upon i.p. administration of CLs may be associated with the lymphatic drainage system. A lipoplex formulation composed of CLs with short hairpin RNA (shRNA) against luciferase, a model therapeutic agent, suppressed luciferase activity in peritoneally disseminated tumors by 80%, with no cytokine secretion in serum. This suggests that i.p. CLs can efficiently deliver a therapeutic agent to peritoneally disseminated tumors with few systemic adverse events. These results suggest that i.p. treatment with CLs or non-PEGylated lipoplexes may be a promising approach for the treatment of peritoneally disseminated cancers through their ability to selectively deliver therapeutic agents to i.p. target sites with minimal systemic adverse events.

Direct interactions between cationic liposomes and bacterial cells ameliorate the systemic treatment of invasive multidrug-resistant Staphylococcus aureus infections

Invasive infections caused by antibiotic-resistant Staphylococcus aureus have posed a great threat to human health. To tackle this problem, a cationic liposomal Curcumin (C-LS/Cur) was developed and its effect against antibiotic-resistant S. aureus was investigated in this study. As expected, C-LS/Cur exhibited greater bactericidal capacity compared with its counterparts, probably because the negatively charged S. aureus favors electrostatic interactions rather than intercalation with cationic liposomal vesicles at the beginning of endocytic process, thereby effectively delivering Cur to its targets. We confirmed this hypothesis by monitoring zeta potential variation, collecting visual evidences through CLSM, FCM and TEM, and determining binding kinetics by BLI. Moreover, an excellent therapeutic efficacy of C-LS/Cur against invasive murine infection was also observed, which was due to the enhanced accumulation and retention in the targets. Therefore, cationic liposomes have great potential for the clinical application in the treatment of invasive antibiotic-resistant S. aureus infections.

Investigating the Fate of MP1000-LPX In Vivo by Adding Serum to Transfection Medium

BACKGROUND

Cationic liposomes (CLs) based messenger RNA (mRNA) vaccine has been a promising approach for cancer treatment. However, rapid lung accumulation after intraveous injection and significantly decreased transfection efficacy (TE) in serum substantially hamper its application.

OBJECTIVE

In this study, we attempt to investigate the fate of Mannose-PEG1000-lipoplex (MP1000-LPX) in vivo, a previous reported mRNA vaccine, and potential mechanism in it.

METHODS

MP1000-CLs and different type of MP1000-LPX were produced by previous method and characterized by dynamic light scattering (DLS). Organ distribution and Luc-mRNA expression of DiD loaded luciferase (Luc-mRNA)-MP1000-LPX were evaluated by IVIS Spectrum imaging system. Cellular transfection and uptake under serum-free and serum-containing conditions were analysed by flow cytometry and counted by FlowJo software.

RESULTS

MP1000-CLs had an average size of 45.3 ± 0.9 nm, a positive charge of 39.9 ± 0.9 mV. When MP1000-LPX formed, the particle size increased to about 130 nm, and zeta potential decreased to about 30 mV. All formulations were in narrow size distribution with PDI < 0.3. 6 h after intraveous injection, Luc-MP1000-LPX mostly distributed to liver, lung and spleen, while only successfully expressed Luc in lung. DC2.4 cellular transfection assay indicated serum substantially lowered TE of MP1000-LPX. However, the cellular uptake on DC2.4 cells was enhanced in the presence of serum.

CONCLUSION

MP1000-LPX distributed to spleen but failed to transfect. Because serum dramatically decreased TE of MP1000-LPX on DC2.4 cells, but not by impeding its interaction to cell membrane. Serum resistance and avoidance of lung accumulation might be prerequisites for CLs based intravenous mRNA vaccines. Lay Summary: mRNA vaccine has been promising immunotherapy to treat cancer by delivering mRNA encoding tumor antigens to APCs and activating immune system against tumor cells. We are investigating the in vivo fate of MP1000-LPX, a CLs based mRNA vaccine. To see if serum causes the fate, we'll be looking at the influence of serum on transfection and uptake efficacy of MP1000-LPX by DC2.4 cells experiments in vitro. Our findings will imply that serum inhibits transfection but not by decreasing uptake. Thus, we can ultilize serum to enhance transfection if we make intracellular process of MP1000-LPX successful.

Bulk and Microfluidic Synthesis of Stealth and Cationic Liposomes for Gene Delivery Applications

This chapter describes the synthesis of stealth and cationic liposomes and their complexation with plasmid DNA to generate lipoplexes for gene delivery applications. Two techniques are presented: a top-down approach which requires a second step of processing for downsizing the liposomes (i.e., ethanol injection method) and a microfluidic technique that explores the diffusion of ethanol in water to allow the proper lipid self-assembly. The synthesis of stealth liposomes is also a challenge since the use of poly(ethylene glycol) favors the formation of oblate micelles. In this protocol, the stealth cationic liposome synthesis by exploring the high ionic strength to overcome the formation of secondary structures like micelles is described. Finally, the electrostatic complexation between cationic liposomes and DNA is described, indicating important aspects that guarantee the formation of uniform lipoplexes.

An RNAi therapeutic, DFP-10825, for intraperitoneal and intrapleural malignant cancers

RNA interference (RNAi), a potent post-transcriptional gene-silencing action, has received considerable attentions as a novel therapeutic tool to treat intractable cancers. In recent days, we have developed a novel RNAi-based therapeutic formulation, DFP-10825, for the treatment of intractable advanced cancers developed in coelomic cavities. DFP-10825 was composed of chemically synthesized short hairpin RNA (shRNA) against thymidylate synthase (TS), a key enzyme for cancer proliferation, and cationic liposomes, and achieved high therapeutic effect on the mouse models of peritoneally disseminated gastric and ovarian cancers and malignant pleural mesothelioma without severe side effects by intracoelomic direct treatment. We further designed a freeze-dried DFP-10825 formulation for mass industrial production. DFP-10825 is undergoing in pre-clinical phase and goes to clinical trials. This review introduces a DFP-10825 formulation, a potent novel RNAi-based therapeutic maximizing the benefit of RNAi molecule (shRNA).

Liposomes: Advancements and innovation in the manufacturing process

Liposomes are well recognised as effective drug delivery systems, with a range of products approved, including follow on generic products. Current manufacturing processes used to produce liposomes are generally complex multi-batch processes. Furthermore, liposome preparation processes adopted in the laboratory setting do not offer easy translation to large scale production, which may delay the development and adoption of new liposomal systems. To promote advancement and innovation in liposome manufacturing processes, this review considers the range of manufacturing processes available for liposomes, from laboratory scale and scale up, through to large-scale manufacture and evaluates their advantages and limitations. The regulatory considerations associated with the manufacture of liposomes is also discussed. New innovations that support leaner scalable technologies for liposome fabrication are outlined including self-assembling liposome systems and microfluidic production. The critical process attributes that impact on the liposome product attributes are outlined to support potential wider adoption of these innovations.

Synthesis of protein conjugates adsorbed on cationic liposomes surface

The well-known Toll like receptor 9 (TLR9) agonist CpG ODN has shown promising results as vaccine adjuvant in preclinical and clinical studies, however its in vivo stability and potential systemic toxicity remain a concern. In an effort to overcome these issues, different strategies have been explored including conjugation of CpG ODN with proteins or encapsulation/adsorption of CpG ODN into/onto liposomes. Although these methods have resulted in enhanced immunopotency compared to co-administration of free CpG ODN and antigen, we believe that this effect could be further improved. Here, we designed a novel delivery system of CpG ODN based on its conjugation to serve as anchor for liposomes. Thiol-maleimide chemistry was utilised to covalently ligate model protein with the CpG ODN TLR9 agonist. Due to its negative charge, the protein conjugate readily electrostatically bound cationic liposomes composed of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol and dimethyldioctadecylammonium bromide (DDA) in a very high degree. The novel cationic liposomes-protein conjugate complex shared similar vesicle characteristics (size and charge) compared to free liposomes. The conjugation of CpG ODN to protein in conjunction with adsorption on cationic liposomes, could promote co-delivery leading to the induction of immune response at low antigen and CpG ODN doses.•

The CpG ODN Toll-like receptor (TLR) 9 agonist was conjugated to protein antigens via thiol-maleimide chemistry.

•

Due to their negative charge, protein conjugates readily electrostatically bound cationic liposomes composed of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol and dimethyldioctadecylammonium bromide (DDA) resulting to the design of novel cationic liposomes-protein conjugate complexes.

•

The method is suited for the liposomal delivery of a variety of adjuvant-protein conjugates.

Lipid-based Nanocarriers for siRNA Delivery: Challenges, Strategies and the Lessons Learned from the DODAX: MO Liposomal System

The possibility of using the RNA interference (RNAi) mechanisms in gene therapy was one of the scientific breakthroughs of the last century. Despite the extraordinary therapeutic potential of this approach, the need for an efficient gene carrier is hampering the translation of the RNAi technology to the clinical setting. Although a diversity of nanocarriers has been described, liposomes continue to be one of the most attractive siRNA vehicles due to their relatively low toxicity, facilitated siRNA complexation, high transfection efficiency and enhanced pharmacokinetic properties. This review focuses on RNAi as a therapeutic approach, the challenges to its application, namely the nucleic acids' delivery process, and current strategies to improve therapeutic efficacy. Additionally, lipid-based nanocarriers are described, and lessons learned from the relation between biophysical properties and biological performance of the dioctadecyldimethylammonium:monoolein (DODAX: MO) system are explored. Liposomes show great potential as siRNA delivery systems, being safe nanocarriers to protect nucleic acids in circulation, extend their half-life time, target specific cells and reduce off-target effects. Nevertheless, several issues related to delivery must be overcome before RNAi therapies reach their full potential, namely target-cell specificity and endosomal escape. Understanding the relationship between biophysical properties and biological performance is an essential step in the gene therapy field.

A mechanistic explanation of the inhibitory role of the protein corona on liposomal gene expression

The past three decades have witnessed fast advances in the use of cationic liposome-DNA complexes (lipoplexes) for gene delivery applications. However, no lipoplex formulation has reached into the clinical practice so far. The primary drawback limiting clinical use of lipoplexes is the lack of mechanistic understanding of their low transfection efficiency (TE) in vivo. In physiological environments, lipoplexes are coated by a protein corona (PC) that mediates the interactions with the cell machinery. Here we show that the formation of PC can change the interactions of multicomponent (MC) lipoplexes with our cell model (i.e., HeLa). At the highest lipoplex concentration, the formation of PC can reduce the TE of MC lipoplexes from 60% to <5%. Combining dynamic light scattering and synchrotron small-angle X-ray scattering (SAXS), we clarify that the formation of PC modifies physical-chemical properties of MC lipoplexes so as to affect their TE. Moreover, we examined single transfection barriers by a combination of fluorescence-activated cell sorting, single-cell real-time fluorescence confocal microscopy, and synchrotron SAXS. We demonstrate that PC formation has the ability to modify the relative contribution of caveolae-mediated endocytosis and macropinocytosis in lipoplexes uptake, in favor of the latter, increasing accumulation of PC-decorated lipoplexes into degradative lysosomal compartments. Finally, we report evidences that PC reduces the structural stability of lipoplexes against solubilization by cellular lipids, likely favoring premature DNA release and cytosolic digestion by DNAase. These combined effects revealed here offer a comprehensive mechanistic explanation on the reason behind reduction in gene expression of MC lipoplexes.

Improving the clearance of protein-bound uremic toxins using cationic liposomes as an adsorbent in dialysate

Anionic and protein-bound uremic toxins, represented by indoxyl sulfate (IS), may be associated with cardiovascular outcomes and the progression of chronic kidney disease in cases of injured kidney function and are not easily cleared by traditional dialysis therapy. We fabricated cationic liposomes that were modified with polyethyleneimine (PEI), octadecylamine (Oct), and hexadecyl trimethyl ammonium bromide (CTAB), and evaluated the effects on the clearance of the representative protein-bound uremic toxins (PBUTs). The binding rate was obtained by ultrafiltration and in vitro dialysis was performed in a Rapid Equilibrium Dialysis (RED) device to assay the clearing efficiency of the dialysate supported by three types of cationic liposomes. The cationic liposomes showed a higher binding rate with IS (1.24-1.38 fold higher) and p-cresol (1.07-1.09 fold higher) than in the unmodified plain liposomes. The dialysate supported by cationic liposomes also exhibited better clearing efficiency for IS (PEI-20: 57.65 ± 1.74 %; Oct-5: 62.80 ± 0.69 %; CTAB-10: 66.54 ± 0.91 %; p < 0.05) and p-cresol (PEI-20: 67.05 ± 3.09 %; Oct-5: 79.26 ± 0.43 %; CTAB-5: 68.45 ± 1.72 %; p < 0.05) than for phosphate buffer saline (IS: 29.70 ± 2.38 %; p-cresol: 33.59 ± 3.44 %) or dialysate supported by bovine serum albumin (IS: 50.00 ± 4.01 %; p-cresol: 53.06 ± 0.97 %). In conclusion, cationic liposomes are efficient in the clearance of anionic PBUTs, and these modified liposomes suggest a potential application in blood purification.

Preparation, characterization, and in vivo evaluation of cyclosporine cationic liposomes for the treatment of psoriasis

Cyclosporine (CYC), a calcineurin inhibitor acts specifically on T-cells and is one of the most effective treatment options for psoriasis. Systemic administration of the drug has been associated with dose-dependent toxic effects, while its topical delivery is a challenging task due to unfavourable physicochemical properties of drug. The aim of the present study is to develop and evaluate the efficacy of topical liposomal gel containing CYC loaded cationic liposomal nanocarriers in imiquimod induced psoriatic plaque model. Liposomes composed of DOTAP and cholesterol was formulated by different liposomal preparation techniques. Optimized liposomal carriers prepared by ethanol injection method were characterized with respect to size, zeta potential, entrapment efficiency, stability, in vitro drug release and in vivo studies. Cationic liposomes with particle size of 111 ± 1.62 nm, PDI of 0.27 ± 0.08, entrapment efficiency of 93 ± 2.12%, and zeta potential of 41.12 ± 3.56 mV were obtained. Drug loaded liposomal gels showed shear thinning behaviour, which is suitable for topical application. Topical application of CYC liposomal gels on imiquimod induced psoriatic plaque model reduced the symptoms of psoriasis and levels of key psoriatic cytokines such as tumour necrosis factor-α, IL-17, and IL-22. In conclusion, the developed liposomal carrier of CYC was found to be effective and can find application in treatment of psoriasis.

Anti-EGF antibody cationic polymeric liposomes for delivery of the p53 gene for ovarian carcinoma therapy

Cationic polymeric liposomes (CPLs) were successfully prepared using a tumor-targeting EGF protein modification for the systemic delivery of the p53 gene in ovarian cancer. These functional CPL nanoparticles (NPs) can be used as effective gene delivery vectors and are composed of an EGF derivative (EGF-GHDC), cholesterol, and DOPE, which have lower gene transfection efficiencies compared with Lipofectamine 2000. The increased therapeutic efficiency of p53 gene-loaded EGF-CPL was tested in SKOV3 cells and compared with p53 gene-loaded CPL and free p53 gene in solution. In addition, EGF-CPL (effective diameter: 95.01±4.05 nm; polydispersity index: 0.270) significantly enhanced luciferase gene expression in vivo 3 days post-injection of pGL-3/NPs complexes. In conclusion, EGF-targeted CPL has the potential for use as an effective drug delivery system.

Evaluation of Immune Response against Leishmaniasis in BALB/c Mice Immunized with Cationic DOTAP/DOPE/CHOL Liposomes Containing Soluble Leishmania major Antigens

BACKGROUND

Whole killed Leishmania vaccine reached phase III clinical trials but failed to display significant efficacy in human mainly due to limited Th1 inducer adjuvant. Liposomes consisting of 1, 2-dioleoyl-3trimethylammonium-propane (DOTAP) bearing an inherent adjuvanticity and 1, 2-dioleoyl-L-α-glycero-3-phosphatidylethanolamine (DOPE) is well known to intensify the efficacy of positively charged liposomes.

METHODS

Soluble Leishmania major antigens (SLA) encapsulated in cationic liposomes using lipid film method in 2016). BALB/c mice were immunized subcutaneously (SC), three times in a 2-wk interval, with Lip (DOTAP)-SLA+, Lip (DOTAP/DOPE)-SLA+, Lip (DOTAP/DOPE/CHO)-SLA+, Lip (DOTAP/DOPE/CHO), Lip (DOPE/CHO), SLA or HEPES buffer. At week 2 after the last booster injection, immunized mice have challenged SC in the footpad with L. major parasites. To investigate the rate of protection and the type of immune response generated in mice, lesions development was assessed, IL-4 and IFN-γ levels with the ratio of IgG2a/IgG1 isotype were studied to describe the type of generated immune response.

RESULTS

Mice immunized with all liposomal form of SLA showed smaller footpad swelling and lower parasite burden in the spleen and footpad compared to the group of mice received buffer. However, these formulations did not show protection against leishmaniosis because of a generated mixed Th1/Th2 response in mice characterized by high production of IFN-γ and IL4 and a high titer of IgG1 and IgG2a antibody.

CONCLUSION

Immunization with Lip (DOTAP/DOPE/CHO)-SLA+ was not an appropriate strategy to protect mice against leishmaniosis.

Suicide Gene Therapy for Oral Squamous Cell Carcinoma

Suicide gene therapy has been tested for the treatment of a variety of cancers, including oral cancer. Among the various suicide gene therapy approaches that have been reported, the Herpes Simplex Virus thymidine kinase (HSV-tk)/ganciclovir (GCV) system is one of the most extensively studied systems, holding great promise in cancer therapy. In this chapter, we describe methods to use the HSV-tk/GCV system to achieve antitumor activity, both in cultured oral cancer cells and in orthotopic and subcutaneous murine models of oral squamous cell carcinoma, using ligand-associated lipoplexes for enhancing therapeutic delivery.

Azithromycin-loaded liposomes for enhanced topical treatment of methicillin-resistant Staphyloccocus aureus (MRSA) infections

Antibiotic delivery via liposomal encapsulation represents a promising approach for the efficient topical treatment of skin infections. The present study aimed to investigate the potential of using different types of azithromycin (AZT)-loaded liposomes to locally treat skin infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains. Conventional liposomes (CLs), deformable liposomes (DLs), propylene glycol-containing liposomes (PGLs) and cationic liposomes (CATLs) encapsulating AZT were prepared, and their physical characteristics, drug release profiles, ex vivo skin penetration/deposition abilities, in vitro anti-MRSA activities (planktonic bacteria and biofilm) and cell biocompatibilities were assessed. The (phospho)lipid composition and presence of surfactant or propylene glycol affected the physical characteristics of the liposomes, the release profile of AZT, its deposition inside the skin, as well as in vitro antibacterial efficacy and tolerability with the skin cells. All the liposomes retained AZT inside the skin more efficiently than did the control and were biocompatible with keratinocytes and fibroblasts. CATLs, DLs and PGLs efficiently inhibited MRSA strain growth and were superior to free AZT in preventing biofilm formation, exhibiting minimal inhibitory concentrations and minimal biofilm inhibitory concentrations up to 32-fold lower than those of AZT solution, thus confirming their potential for improved topical treatment of MRSA-caused skin infections.

Lipid conjugation of TLR7 agonist Resiquimod ensures co-delivery with the liposomal Cationic Adjuvant Formulation 01 (CAF01) but does not enhance immunopotentiation compared to non-conjugated Resiquimod+CAF01

Pattern recognition receptors, including the Toll-like receptors (TLRs), are important in the induction and activation of two critical arms of the host defence to pathogens and microorganisms: the rapid innate immune response (as characterised by the production of Th1 promoting cytokines and type 1 interferons) and the adaptive immune response. Through this activation, ligands and agonists of TLRs can enhance immunotherapeutic efficacy. Resiquimod is a small (water-soluble) agonist of the endosome-located Toll-like receptors 7 and 8 (TLR7/8). However due to its molecular attributes it rapidly distributes throughout the body after injection. To circumvent this, these TLR agonists can be incorporated within delivery systems, such as liposomes, to promote the co-delivery of both antigen and agonists to antigen presenting cells. In this present study, resiquimod has been chemically conjugated to a lipid to form a lipid-TLR7/8 agonist conjugate which can be incorporated within immunogenic cationic liposomes composed of dimethyldioctadecylammonium bromide (DDA) and the immunostimulatory glycolipid trehalose 6,6' - dibehenate (TDB). This DDA:TDB-TLR7/8 formulation offers similar vesicle characteristics to DDA:TDB (size and charge) and offers high retention of both resiquimod and the electrostatically adsorbed TB subunit antigen Ag85B-ESAT6-Rv2660c (H56). Following immunisation through the intramuscular (i.m.) route, these cationic DDA:TDB-TLR7/8 liposomes form a vaccine depot at the injection site. However, immunisation studies have shown that this biodistribution does not translate into notably increased antibody nor Th1 responses at the spleen and draining popliteal lymph node compared to DDA:TDB liposomes. This work demonstrates that the conjugation of TLR7/8 agonists to cationic liposomes can promote co-delivery but the immune responses stimulated do not merit the added complexity considerations of the formulation.

Mixed cationic liposomes for brain delivery of drugs by the intranasal route: The acetylcholinesterase reactivator 2-PAM as encapsulated drug model

New mixed cationic liposomes based on L-α-phosphatidylcholine and dihexadecylmethylhydroxyethylammonium bromide (DHDHAB) were designed to overcome the BBB crossing by using the intranasal route. Synthesis and self-assembly of DHDHAB were performed. A low critical association concentration (0.01 mM), good solubilization properties toward hydrophobic dye Orange OT and antimicrobial activity against gram-positive bacteria Staphylococcus aureus (MIC=7.8 μg mL^-1) and Bacillus cereus (MIC=7.8 μg mL^-1), low hemolytic activities against human red blood cells (less than 10%) were achieved. Conditions for preparation of cationic vesicles and mixed liposomes with excellent colloidal stability at room temperature were determined. The intranasal administration of rhodamine B-loaded cationic liposomes was shown to increase bioavailability into the brain in comparison to the intravenous injection. The cholinesterase reactivator, 2-PAM, was used as model drug for the loading in cationic liposomes. 2-PAM-loaded cationic liposomes displayed high encapsulation efficiency (∼ 90%) and hydrodynamic diameter close to 100 nm. Intranasally administered 2-PAM-loaded cationic liposomes were effective against paraoxon-induced acetylcholinesterase inhibition in the brain. 2-PAM-loaded liposomes reactivated 12 ± 1% of brain acetylcholinesterase. This promising result opens the possibility to use marketed positively charged oximes in medical countermeasures against organophosphorus poisoning for reactivation of central acetylcholinesterase by implementing a non-invasive approach, via the "nose-brain" pathway.

Cationic liposomes induce cytotoxicity in HepG2 via regulation of lipid metabolism based on whole-transcriptome sequencing analysis

Backgroud

Cationic liposomes (CLs) can be used as non-viral vectors in gene transfer and drug delivery. However, the underlying molecular mechanism of its cytotoxicity has not been well elucidated yet.

Methods

We herein report a systems biology approach based on whole-transcriptome sequencing coupled with computational method to identify the predominant genes and pathways involved in the cytotoxicity of CLs in HepG2 cell line.

Results

Firstly, we validated the concentration-dependent cytotoxicity of CLs with an IC₅₀ of 120 μg/ml in HepG2 exposed for 24 h. Subsequently, we used whole-transcriptome sequencing to identify 220 (77 up- and 143 down-regulated) differentially expressed genes (DEGs). Gene ontology (GO) and pathway analysis showed that these DEGs were mainly related to cholesterol, steroid, lipid biosynthetic and metabolic processes. Additionally, “key regulatory” genes were identified using gene act, pathway act and co-expression network analysis, and expression levels of 11 interested altered genes were confirmed by quantitative real time PCR. Interestingly, no cell cycle arrest was observed through flow cytometry.

Conclusions

These data are expected to provide deep insights into the molecular mechanism of CLs cytotoxicity.

Combination of Anti-miRNAs Oligonucleotides with Low Amounts of Chemotherapeutic Agents for Pancreatic Cancer Therapy

Pancreatic ductal adenocarcinoma (PDAC) is the most predominant type of pancreatic cancer and presents one of the highest mortality rates when compared with other carcinomas. The absence of efficient treatment options for PDAC prompted us to investigate whether microRNA inhibition, combined or not with chemotherapeutic agents, would constitute a promising therapeutic approach for this disease. In this chapter, we describe several methods and procedures that can be used to evaluate the potential of new therapeutic strategies involving oligonucleotides against overexpressed microRNAs, in PDAC, either alone or in combination with low amounts of chemotherapeutic drugs.

Edaravone, a cytoprotective drug, enhances transgene expression mediated by lipoplexes in HepG2 cells and mice

A requirement of gene therapy is efficient nucleic acid delivery. However, the application of cationic liposomes to gene therapy is restricted by their inefficient transfection capacity, which may be caused by cytotoxicity. This cytotoxicity is highly dependent on cationic lipid-induced reactive oxygen species (ROS). Here, to provide cellular protection, we used edaravone, an efficacious anti-oxidative drug, to scavenge ROS during transfection using cationic liposome/plasmid DNA complexes (lipoplexes). Both free edaravone and edaravone-loaded liposomes (EDLPs) enhanced transgene expression in the human hepatoma cell line, HepG2, while EDLPs decreased the effective dose of edaravone. The cellular protective effect of edaravone was found to decrease the cytotoxicity of cationic liposomes. Edaravone was also effective in the commercial product, Lipofectamine® 3000, which may expand the application of edaravone to promote transfection efficiency. Compared with free edaravone, EDLPs also showed superior transgene expression in mice. Our findings will promote the development of efficient and safe gene therapy.

Cationic lipid/DNA complexes manufactured by microfluidics and bulk self-assembly exhibit different transfection behavior

Recent advances in biochemical and biophysical research have been achieved through the employment of microfluidic devices. Microfluidic mixing of therapeutic agents with biomaterials yields systems with finely tuned physical-chemical properties for applications in drug and gene delivery. Here, we investigate the role of preparation technology (microfluidic mixing vs. bulk self-assembly) on the transfection efficiency (TE) and cytotoxicity of multicomponent cationic liposome/DNA complexes (lipoplexes) in live Chinese hamster ovarian (CHO) cells. Decoupling TE and cytotoxicity allowed us to combine them in a unique coherent vision. While bulk self-assembly produces highly efficient and highly toxic MC lipoplexes, microfluidics manufacture leads to less efficient, but less cytotoxic complexes. This discrepancy is ascribed to two main factors controlling lipid-mediated cell transfection, i.e. the lipoplex concentration at the cell surface and the lipoplex arrangement at the nanoscale. Further research is required to optimize microfluidic manufacturing of lipoplexes to obtain highly efficient and not cytotoxic gene delivery systems.

Effects of sucrose ester structures on liposome-mediated gene delivery

Sucrose esters (SEs) have great potential applications in gene delivery because of their low toxicity, excellent biocompatibility, and biodegradability. By using tripeptide-based lipid (CDO) as a model lipid and SEs as helper lipids, a series of liposomes were prepared. The SEs with hydrophilic-lipophilic balance (HLB) values of 1, 6, 11, or 16 and the fatty acids of laurate, stearate, or oleate were used in the liposomes. We investigated the effect of HLB values of SEs and fatty acid types on gene transfection efficiency and toxicity of liposomes. The results showed that transfection efficiencies of the liposomes containing SEs with HLB value of 6 were superior to other liposomes in HeLa, MCF-7, NCI-H460, and A549 tumor cells. For the same HLB value, liposomes of laurate SEs were preferable to transfect cells compared to SEs of stearate and oleate. The liposomes with SEs showed higher cellular uptake than liposome without SEs (LipoCDO). LipoL12-6/Luc-siRNA treatment on tumor-bearing mice exhibited about 60% in vivo gene silencing of luciferase, and LipoL12-6 could mediate IGF-1R siRNA to greatly inhibit tumor growth. Moreover, liposomes with SEs revealed remarkably low toxicity in vitro and in vivo. The illustration of SE structures on gene delivery will promote the use of SEs for clinical trials of liposomes.

STATEMENT OF SIGNIFICANCE

This article is the first to study the effects of various chain lengths and hydrophilic-lipophilic balance (HLB) of sucrose esters (SEs) on gene transfection efficiency and safety of liposomes for gene delivery. The in vitro delivery of pDNA and siRNA by lipoplexes against HeLa, MCF-7, NCI-H460, and A549 tumor cells showed that the lipoplexes could lead to better transfection and lower cytotoxicity after the addition of SEs. SEs with shorter chain and a median HLB value could provide the liposomes with much higher gene transfection efficiency than others. The in vivo delivery of siRNA to tumor-bearing mice further confirmed that liposome containing laurate SE (LipoL12-6) could be a potential therapeutic vector, as it delivered siRNA to silence nearly 60% of the luciferase in tumors and also greatly inhibited the tumor growth. Therefore, the addition of SEs to liposomes proved to be relatively safe in vitro and in vivo. These preliminary results demonstrated that SEs show great potential for constructing controlled-release systems for gene delivery. The readers will get insights into a series of gene vectors and deepen their understanding about gene delivery.

α-Tocopherol-ascorbic acid hybrid antioxidant based cationic amphiphile for gene delivery: Design, synthesis and transfection

Natural antioxidants and vitamins have potential to protect biological systems from peroxidative damage induced by peroxyl radicals, α-tocopherol (Vitamin E, lipid soluble) and ascorbic acid (vitamin C, water soluble), well known natural antioxidant molecules. In the present study we described the synthesis and biological evaluation of hybrid of these two natural antioxidants with each other via ammonium di-ethylether linker, Toc-As in gene delivery. Two control cationic lipids N14-As and Toc-NOH are designed in such a way that one is with ascorbic acid moiety and no tocopherol moiety; another is with tocopherol moiety and no ascorbic acid moiety respectively. All the three cationic lipids can form self-assembled aggregates. The antioxidant efficiencies of the three lipids were compared with free ascorbic acid. The cationic lipids (Toc-As, N14-As and Toc-NOH) were formulated individually with a well-known fusogenic co-lipid DOPE and characterization studies such as DNA binding, heparin displacement, size, charge, circular dichroism were performed. The biological characterization studies such as cell viability assay and in vitro transfection studies were carried out with the above formulations in HepG2, Neuro-2a, CHO andHEK-293T cell lines. The three formulations showed their transfection efficiencies with highest in Toc-As, moderate inN14-As and least in Toc-NOH. Interestingly, the transfection efficiency observed with the antioxidant based conjugated lipid Toc-As is found to be approximately two and half fold higher than the commercially available lipofectamine 2000 at 4:1 charge ratio in Hep G2 cell lines. In the other cell lines studied the efficiency of Toc-As is found to be either higher or similarly active compared to lipofectamine 2000. The physicochemical characterization results show that Toc-As lipid is showing maximum antioxidant potency, strong binding with pDNA, least size and optimal zeta potential. It is also found to be least toxic in all the cell lines studied especially in Neuro-2a cell lines when compared to other two lipids. In summary, the designed antioxidant lipid can be exploited as a delivering system for treating ROS related diseases such as malignancy, brain stroke, etc.

Targeted delivery of nucleic acids into xenograft tumors mediated by novel folate-equipped liposomes

Folate receptors (FR) are cellular markers highly expressed in various cancer cells. Here, we report on the synthesis of a novel folate-containing lipoconjugate (FC) built of 1,2-di-O-ditetradecyl-rac-glycerol and folic acid connected via a PEG spacer, and the evaluation of the FC as a targeting component of liposomal formulations for nucleic acid (NA) delivery into FR expressing tumor cells. FR-targeting liposomes, based on polycationic lipid 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetraazahexacosan tetrahydrochloride (2X3), lipid helper dioleoylphosphatidylethanolamine (DOPE) and novel FC, formed small compact particles in solution with diameters of 60 ± 22 nm, and were not toxic to cells. Complexes of NAs with the liposomes were prepared at various nitrogen to phosphate ratios (N/P) to optimize liposome/cell interactions. We showed that FR-mediated delivery of different nucleic acids mediated by 2X3-DOPE/FC liposomes occurs in vitro at low N/P (1/1 and 2/1); under these conditions FC-containing liposomes display 3-4-fold higher transfection efficiency in comparison with conventional formulation. Lipoplexes formed at N/P 1/1 by targeted liposomes and cargo (Cy7-labeled siRNA targeting MDR1 mRNA) in vivo efficiently accumulate in tumor (∼15-18% of total amount), and kidneys (71%), and were retained there for more than 24 h, causing efficient downregulation of p-glycoprotein expression (to 40% of control) in tumors. Thus, FC containing liposomes provide effective targeted delivery of nucleic acids into tumor cells in vitro and in xenograft tumors in vivo.

Cationic liposomal vectors incorporating a bolaamphiphile for oligonucleotide antimicrobials

Antibacterial resistance has become a serious crisis for world health over the last few decades, so that new therapeutic approaches are strongly needed to face the threat of resistant infections. Transcription factor decoys (TFD) are a promising new class of antimicrobial oligonucleotides with proven in vivo activity when combined with a bolaamphiphilic cationic molecule, 12-bis-THA. These two molecular species form stable nanoplexes which, however, present very scarce colloidal stability in physiological media, which poses the challenge of drug formulation and delivery. In this work, we reformulated the 12-bis-THA/TFD nanoplexes in a liposomal carrier, which retains the ability to protect the oligonucleotide therapeutic from degradation and deliver it across the bacterial cell wall. We performed a physical-chemical study to investigate how the incorporation of 12-bis-THA and TFD affects the structure of POPC- and POPC/DOPE liposomes. Analysis was performed using dynamic light scattering (DLS), ζ-potential measurements, small-angle x-ray scattering (SAXS), and steady-state fluorescence spectroscopy to better understand the structure of the liposomal formulations containing the 12-bis-THA/TFD complexes. Oligonucleotide delivery to model Escherichia coli bacteria was assessed by means of confocal scanning laser microscopy (CLSM), evidencing the requirement of a fusogenic helper lipid for transfection. Preliminary biological assessments suggested the necessity of further development by modulation of 12-bis-THA concentration in order to optimize its therapeutic index, i.e. the ratio of antibacterial activity to the observed cytotoxicity. In summary, POPC/DOPE/12-bis-THA liposomes appear as promising formulations for TFD delivery.

Asymmetric cationic liposomes designed for heat-activated association with cells

Improved anticancer drugs and drug carriers are needed in combination therapies, such as hyperthermia-assisted chemotherapy. Liposomal drug carriers with advanced functions are attractive candidates for targeted accumulation and drug release in response to heat stimulus. We report on the design of liposomes with a heat-activated surface function. Our design is based on asymmetric lipid membranes with a defined gel to liquid-crystalline phase-transition temperature around 41°C. Asymmetry between the inner and the outer membrane leaflets was generated through selective PEGylation of cationic lipids in the outer membrane leaflet. In a physiological buffer, the PEGylated asymmetric liposomes had a neutral zeta potential and did not bind to planar anionic model membranes. In contrast, following upon heat-activation, binding of liposomes to the model membranes occurred. Release of a hydrophilic dye encapsulated in the asymmetric liposomes occurred at 40°C. Enhanced uptake of the asymmetric liposomes by hypopharyngeal carcinoma cells (FaDu cells) was observed when hyperthermia was applied compared to experiments performed at 37°C. These results show the potential of asymmetric liposomes for localized delivery of drugs into cells in response to (external) temperature stimulus.

Design, synthesis and transfection efficiency of a novel redox-sensitive polycationic amphiphile

A novel redox-sensitive polycationic amphiphile (2S3) with disulphide linkers for nucleic acid delivery was developed. Cationic liposomes formed by 2S3 and the helper lipid DOPE demonstrated effective DNA delivery into HEK293 cells with a maximal transfection activity that is superior than both nonredox-sensitive cationic liposomes and Lipofectamine® 2000 at an N/P ratio of 6/1. Redox-sensitivity was tested by experiments with extracellular glutathione which shown the ability of disulphide linker degradation. Our results suggest that polycationic amphiphile 2S3 is a promising candidate for nucleic acid delivery.

The biological activity of cationic liposomes in drug delivery and toxicity test in animal models

In the study we made use of DOTAP (1,2-dioleoyl-3-trimethylammonium), DOPE (1,2-dioleoyl-snglycero-3-phosphoethanolamine) and PEG-PE (polyethylene glycol- polyethylene) to make cationic PEG-liposomes by ultrasonic dispersion method. The plasmid pGPU6 combined with cationic PEG-liposomes or Liopofectamin 2000 was used to transfect PC3 cells to judge the transfection efficiency. HE staining showed that the pGUP6-shAurora B plasmid/liposomes complex could significantly inhibit tumor growth in mice tumor model. The results indicated that there was no remarkable difference between the homemade liposomes and Lipofectamin 2000 after transfection, with transfection efficiency over 80%. And the homemade liposomes also had high transfection efficiency in vivo. No significant side effects were observed on weight, coat condition, behavior or appetite and the life span of mice treated with pGPU6-shAurora B were extended. Beyond that, there were no differences in mortality or in pathological changes to the heart, liver, spleen, lungs and kidneys among all the mice.

Liposome-based intranasal delivery of lipopeptide vaccine candidates against group A streptococcus

Group A streptococcus (GAS), an exclusively human pathogen, causes a wide range of diseases ranging from trivial to life threatening. Treatment of infection is often ineffective following entry of bacteria into the bloodstream. To date, there is no vaccine available against GAS. In this study, cationic liposomes encapsulating lipopeptide-based vaccine candidates against GAS have been employed for intranasal vaccine delivery. Cationic liposomes were prepared with dimethyldioctadecylammonium bromide (DDAB) using the film hydration method. Female Swiss mice were immunized intranasally with the liposomes. In contrast to unmodified peptides, lipopeptides entrapped by liposomes induced both mucosal and systemic immunity, IgA and IgG (IgG1 and IgG2a) production in mice, respectively. High levels of antibody (IgA and IgG) titres were detected even five months post immunization. Thus, the combination of lipopeptides and liposomes generates a very promising delivery system for intranasal vaccines.

STATEMENT OF SIGNIFICANCE

Group A streptococcus, causing rheumatic heart diseases, kills approximately half a million people annually. There is no vaccine available against the infection. Mucosal immunity is vital in ensuring an individual is protected as this gram positive bacteria initially colonizes at the throat. Herein, we demonstrated that lipopeptides entrapped by liposomes induced both mucosal and systemic immunity. High levels of antibody (IgA and IgG) titres were detected even five months post immunization and lead vaccine candidate was able to induce humoral immune responses even after single immunization. Thus, the combination of lipopeptides and liposomes generates a very promising delivery system for intranasal vaccines.

A novel liposome adjuvant DPC mediates Mycobacterium tuberculosis subunit vaccine well to induce cell-mediated immunity and high protective efficacy in mice

Tuberculosis (TB) is a serious disease around the world, and protein based subunit vaccine is supposed to be a kind of promising novel vaccine against it. However, there is no effective adjuvant available in clinic to activate cell-mediated immune responses which is required for TB subunit vaccine. Therefore, it is imperative to develop new adjuvant. Here we reported an adjuvant composed of dimethyl dioctadecylammonium (DDA), Poly I:C and cholesterol (DPC for short). DDA can form a kind of cationic liposome with the ability to deliver and present antigen and can induce Th1 type cell-mediated immune response. Poly I:C, a ligand of TLR3 receptor, could attenuate the pathologic reaction induced by following Mycobacterium tuberculosis challenge. Cholesterol, which could enhance rigidity of lipid bilayer, is added to DDA and Poly I:C to improve the stability of the adjuvant. The particle size and Zeta-potential of DPC were analyzed in vitro. Furthermore, DPC was mixed with a TB fusion protein ESAT6-Ag85B-MPT64(190-198)-Mtb8.4-Rv2626c (LT70) to construct a subunit vaccine. The subunit vaccine-induced immune responses and protective efficacy against M. tuberculosis H37Rv infection in C57BL/6 mice were investigated. The results showed that the DPC adjuvant with particle size of 400 nm and zeta potential of 40 mV was in good stability. LT70 in the adjuvant of DPC generated strong antigen-specific humoral and cell-mediated immunity, and induced long-term higher protective efficacy against M. tuberculosis infection (5.41 ± 0.38log10CFU) than traditional vaccine Bacillus Calmette-Guerin (BCG) (6.01 ± 0.33log10CFU) and PBS control (6.53 ± 0.26log10CFU) at 30 weeks post-vaccination. In conclusion, DPC would be a promising vaccine adjuvant with the ability to stimulate Th1 type cell-mediated immunity, and could be used in TB subunit vaccine.

Brain tumor-targeted delivery and therapy by focused ultrasound introduced doxorubicin-loaded cationic liposomes

Brain tumor lacks effective delivery system for treatment. Focused ultrasound (FUS) can reversibly open BBB without impacts on normal tissues. As a potential drug carrier, cationic liposomes (CLs) have the ability to passively accumulate in tumor tissues for their positive charge. In this study, FUS introduced doxorubicin-loaded cationic liposomes (DOX-CLs) were applied to improve the efficiency of glioma-targeted delivery. Doxorubicin-loaded CLs (DOX-CLs) and quantum dot-loaded cationic liposomes (QD-CLs) were prepared using extrusion technology, and their characterizations were evaluated. With the advantage of QDs in tracing images, the glioma-targeted accumulation of FUS + CLs was evaluated by fluorescence imaging and flow cytometer. Cell survival rate, tumor volume, animal survival time, and brain histology in C6 glioma model were investigated to evaluate the glioma-targeted delivery of FUS + DOX-CLs. DOX-CLs and QD-CLs had suitable nanoscale sizes and high entrapment efficiency. The combined strategy of FUS introduced CLs significantly increased the glioma-targeted accumulation for load drugs. FUS + DOX-CLs showed the strongest inhibition on glioma based on glioma cell in vitro and glioma model in vivo experiments. From MRI and histological analysis, FUS + DOX-CLs group strongly suppressed the glioma progression and extended the animal survival time to 81.2 days. Among all the DOX treatment groups, FUS + DOX-CLs group showed the best cell viability and highest level of tumor apoptosis and necrosis. Combining the advantages of BBB reversible opening by FUS and glioma-targeted binding by CLs, ultrasound introduced cationic liposomes could achieve glioma-targeted delivery, which might be developed as a potential strategy for future brain tumor therapy.

Multifunctional quantum dots-based cancer diagnostics and stem cell therapeutics for regenerative medicine

A field of recent diagnostics and therapeutics has been advanced with quantum dots (QDs). QDs have developed into new formats of biomolecular sensing to push the limits of detection in biology and medicine. QDs can be also utilized as bio-probes or labels for biological imaging of living cells and tissues. More recently, QDs has been demonstrated to construct a multifunctional nanoplatform, where the QDs serve not only as an imaging agent, but also a nanoscaffold for diagnostic and therapeutic modalities. This review highlights the promising applications of multi-functionalized QDs as advanced nanosensors for diagnosing cancer and as innovative fluorescence probes for in vitro or in vivo stem cell imaging in regenerative medicine.

Potential effect of cationic liposomes on interactions with oral bacterial cells and biofilms

CONTEXT

Although oral infectious diseases have been attributed to bacteria, drug treatments remain ineffective because bacteria and their products exist as biofilms. Cationic liposomes have been suggested to electrostatically interact with the negative charge on the bacterial surface, thereby improving the effects of conventional drug therapies. However, the electrostatic interaction between oral bacteria and cationic liposomes has not yet been examined in detail.

OBJECTIVE

The aim of the present study was to examine the behavior of cationic liposomes and Streptococcus mutans in planktonic cells and biofilms.

MATERIALS AND METHODS

Liposomes with or without cationic lipid were prepared using a reverse-phase evaporation method. The zeta potentials of conventional liposomes (without cationic lipid) and cationic liposomes were -13 and 8 mV, respectively, and both had a mean particle size of approximately 180 nm. We first assessed the interaction between liposomes and planktonic bacterial cells with a flow cytometer. We then used a surface plasmon resonance method to examine the binding of liposomes to biofilms. We confirmed the binding behavior of liposomes with biofilms using confocal laser scanning microscopy.

RESULTS

The interactions between cationic liposomes and S. mutans cells and biofilms were stronger than those of conventional liposomes. Microscopic observations revealed that many cationic liposomes interacted with the bacterial mass and penetrated the deep layers of biofilms.

DISCUSSION AND CONCLUSION

In this study, we demonstrated that cationic liposomes had higher affinity not only to oral bacterial cells, but also biofilms than conventional liposomes. This electrostatic interaction may be useful as a potential drug delivery system to biofilms.

The antitumor activity of PNA modified vinblastine cationic liposomes on Lewis lung tumor cells: In vitro and in vivo evaluation

Non-small cell lung cancer (NSCLC) is one of the frequently-occurring disease in the world, and the treatment effects are usually unsatisfactory. Vinblastine is an anti-microtubule drug in clinic. In this study, a nanostructured liposome was designed and prepared for treating NSCLC. In the liposomes, peanut agglutinin (PNA) was modified on the liposomal surface, 3-(N-(N',N'-dimethylaminoethane)carbamoyl) cholesterol was used as cationic materials, and vinblastine was encapsulated in the aqueous core of liposomes, respectively. The PNA modified vinblastine cationic liposomes were approximately 100 nm in size with a positive potential. In vitro results showed that the targeting liposomes could significantly enhance cellular uptake, selectively accumulate in LLT cells, and dramatically initiate apoptosis via activating pro-apoptotic proteins and apoptotic enzymes, thus leading to the strongest antitumor efficacy to LLT cells. In vivo results demonstrated that the targeting liposomes could display a prolonged circulation time in the blood, accumulate more drug in tumor location, and induce most of tumor cells apoptosis. As a result, a robust overall antitumor efficacy in tumor-bearing mice was observed subsequently. In conclusion, the chemotherapy using the PNA modified vinblastine cationic liposomes could provide a potential strategy for treating non-small cell lung cancer.

Zwitterionic poly(carboxybetaine)-based cationic liposomes for effective delivery of small interfering RNA therapeutics without accelerated blood clearance phenomenon

For efficient delivery of small interfering RNA (siRNA) to the target diseased site in vivo, it is important to design suitable vehicles to control the blood circulation of siRNA. It has been shown that surface modification of cationic liposome/siRNA complexes (lipoplexes) with polyethylene glycol (PEG) could enhance the circulation time of lipoplexes. However, the first injection of PEGylated lipoplexes in vivo induces accelerated blood clearance and enhances hepatic accumulation of the following injected PEGylated lipoplexes, which is known as the accelerated blood clearance (ABC) phenomenon. Herein, we developed zwitterionic poly(carboxybetaine) (PCB) modified lipoplexes for the delivery of siRNA therapeutics, which could avoid protein adsorption and enhance the stability of lipoplexes as that for PEG. Quite different from the PEGylation, the PCBylated lipoplexes could avoid ABC phenomenon, which extended the blood circulation time and enhanced the tumor accumulation of lipoplexes in vivo. After accumulation in tumor site, the PCBylation could promote the cellular uptake and endosomal/lysosomal escape of lipoplexes due to its unique chemical structure and pH-sensitive ability. With excellent tumor accumulation, cellular uptake and endosomal/lysosomal escape abilities, the PCBylated lipoplexes significantly inhibited tumor growth and induced tumor cell apoptosis.

Polyene-based cationic lipids as visually traceable siRNA transfer reagents

Cationic lipids are promising non-viral vectors for the cellular delivery of nucleic acids. Important considerations for the development of new delivery vectors are enhanced uptake efficiency, low toxicity and traceability. Traceable gene transfer systems however typically require the inclusion of a labeled excipient, and highly sensitive imaging instrumentation to detect the presence of the label. Recently, we reported the synthesis and characterization of colored, polyene cationic phospholipidoids composed of a rigid, polyenoic acid of predetermined dimension (C20:5 and C30:9) paired with flexible saturated alkyl chains of varying lengths (12:0, 14:0, 16:0, 18:0, 20:0 carbons). Herein, the potential of these cationic phospholipids as siRNA carriers was evaluated through standard liposomal formulations in combination with a neutral helper lipid DOPE. The polyene-based lipids were compared with a standard cationic lipid for siRNA-delivery into luciferase expressing HR5-CL11 cells. Within the series of lipids screened, knockdown results indicated that polyene cationic phospholipids paired with longer saturated alkyl chains are more effective as gene transfer agents, and perform comparably with the commercial lipid EPC. Furthermore, the chromophore associated with the polyene chain allowed tracking of the siRNA delivery using direct observation. The polyene lipoplexes were tracked on both a macroscopic and microscopic level either as a single-component or as a multi-component lipoplex formulation. When combined with a reference EPC, effective knockdown and tracking abilities were combined in a single preparation.

Predicting diffusive transport of cationic liposomes in 3-dimensional tumor spheroids

Nanotechnology is widely used in cancer research. Models that predict nanoparticle transport and delivery in tumors (including subcellular compartments) would be useful tools. This study tested the hypothesis that diffusive transport of cationic liposomes in 3-dimensional (3D) systems can be predicted based on liposome-cell biointerface parameters (binding, uptake, retention) and liposome diffusivity. Liposomes comprising different amounts of cationic and fusogenic lipids (10-30mol% DOTAP or 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine, 1-20mol% DOPE or 1,2-dioleoyl-3-trimethylammonium-propane, +25 to +44mV zeta potential) were studied. We (a) measured liposome-cell biointerface parameters in monolayer cultures, and (b) calculated effective diffusivity based on liposome size and spheroid composition. The resulting parameters were used to simulate the liposome concentration-depth profiles in 3D spheroids. The simulated results agreed with the experimental results for liposomes comprising 10-30mol% DOTAP and ≤10mol% DOPE, but not for liposomes with higher DOPE content. For the latter, model modifications to account for time-dependent extracellular concentration decrease and liposome size increase did not improve the predictions. The difference among low- and high-DOPE liposomes suggests concentration-dependent DOPE properties in 3D systems that were not captured in monolayers. Taken together, our earlier and present studies indicate the diffusive transport of neutral, anionic and cationic nanoparticles (polystyrene beads and liposomes, 20-135nm diameter, -49 to +44mV) in 3D spheroids, with the exception of liposomes comprising >10mol% DOPE, can be predicted based on the nanoparticle-cell biointerface and nanoparticle diffusivity. Applying the model to low-DOPE liposomes showed that changes in surface charge affected the liposome localization in intratumoral subcompartments within spheroids.

Antiviral effects of locked nucleic acid antisense oligonucleotides targeting the HBV preS1 gene in HepG2 2.2.15 cells

AIM: To investigate the inhibitory effects of locked nucleic acid (LNA) antisense oligonucleotides targeting the purine region of the hepatitis B virus (HBV) preS1 gene in HepG2 2.2.15 cells, and to screen effective LNA anti-gene oligonucleotides.

METHODS: LNA anti-gene oligonucleotides of different lengths that were complementary to the purine-abundant regions (2 941-2 962 nt, 3 015-3 036 nt and 3 089-3 110 nt) of the HBV preS1 gene were designed, synthesized, and introduced into HepG2 2.2.15 cells by cationic liposome-mediated transfection. Hepatitis B surface antigen (HBsAg) and HBV DNA levels in cell supernatants were tested by time-resolved fluorescence immune assay (TRFIA) and fluorescent quantitative polymerase chain reaction (FQ-PCR) 1, 3, 5 and 7 d after transfection. The cell toxicity of LNA anti-gene oligonucleotides was detected by methyl thiazolyl tetrazolium (MTT) assay.

RESULTS: LNA anti-gene oligonucleotides targeting the HBV preS1 gene showed strong inhibitory effects on HBV DNA replication and HBsAg expression in vitro, and the effects were time-dependent. Seven days after transfection, the reduced rates of HBV DNA and HBsAg levels were 64.32% and 67.51%, respectively. The inhibitory effects were significantly different between each experimental group and control group (all P < 0.05). The inhibitory effect of the LNA anti-gene oligonucleotide targeting the region 2 941-2 962 nt was most strong. The optimal length of LNA anti-gene oligonucleotides ranges from 20 to 30 bases. No obvious cell toxicity was observed with LNA anti-gene oligonucleotides.

CONCLUSION: LNA anti-gene oligonucleotides targeting the HBV preS1 gene showed strong inhibitory effects on HBV replication in vitro. The inhibitory effect of the LNA anti-gene oligonucleotide targeting the region 2 941-2 962 nt was most strong, and the optimal length of LNA anti-gene oligonucleotides ranges from 20 to 30 bases.

Antiviral effects of locked nucleic acid antisense oligonucleotides targeting HBV S gene mRNA in HepG2 2.2.15 cells

AIM: To investigate the inhibitory effects of locked nucleic acid (LNA) antisense oligonucleotides targeting hepatitis B virus (HBV) S gene in HepG2 2.2.15 cells, and screen effective LNA antisense oligonucleotides.

METHODS: Four LNA antisense oligonucleotides of different lengths that are complementary to the translation initiation region of HBV S gene were designed, synthesized, and introduced into HepG2 2.2.15 cells by cationic liposome-mediated transfection. Hepatitis B surface antigen (HBsAg) and HBV DNA levels in cell supernatant were tested by enzyme-linked immunosorbent assay (ELISA) and fluorescent quantitative-polymerase chain reaction (FQ-PCR) 24, 48 and 72 h after transfection. The cell toxicity of LNA antisense oligonucleotides was detected by methyl thiazolyl tetrazolium (MTT) assay.

RESULTS: All four LNA antisense oligonucleotides (10, 15, 20 and 25 base, respectively) could inhibit the expression of HBsAg and the replication of HBV DNA. Seventy-two hours after transfection, the reduced rates of HBsAg and HBV DNA levels were 46.58%, 54.38%, 72.43% and 69.92% as well as 27.09%, 28.77%, 34.71% and 32.68%, respectively. No obvious cell toxicity of LNA antisense oligonucleotides was noted.

CONCLUSION: LNA antisense oligonucleotides targeting HBV S gene show strong inhibitory effects on HBV replication in vitro. The optimal length of LNA antisense oligonucleotides ranges from 15 to 25 base. LNA antisense oligonucleotides targeting HBV S gene have a therapeutic potential in patients infected with HBV.

HBV S gene-specific antisense locked nucleic acid significantly inhibits HBV replication and expression in HBV transgenic mice

AIM: To investigate the inhibitory effects of hepatitis B virus (HBV) S gene-specific antisense locked nucleic acid (LNA) on HBV replication and expression.

METHODS: Thirty HBV transgenic mice were randomly divided into five groups (n = 6): glucose (5% GLU solution) control group, empty liposome control group, LNA group, S-ASODN-liposome group and LNA-liposome group. Antisense LNA was injected into mice via the tail vein. Serum HBsAg was quantified by ELISA. Serum HBV DNA was quantified by PCR. The expression of HBsAg in the liver was detected by immunohistochemistry. Serum ALB, ALT, BUN, CR, ApoA1 and ApoB were measured using an automatic biochemical analyzer. The effects of antisense LNA on mouse organs were investigated by HE staining of mouse liver and kidney sections.

RESULTS: On days 1, 3, 7 and 14 after LNA injection, serum HBsAg levels in the LNA-liposome group were reduced by 41.7%, 52.8%, 57.8% and 30.5%, respectively, while serum HBV DNA expression levels were decreased by 18.5%, 36.1%, 52.9% and 32.7%, respectively. These values were significantly higher than those in the control groups (all P < 0.05). No significant differences were noted in serum ALB, ALT, BUN, CR, ApoA1 and ApoB between the experiment group and the control groups (all P > 0.05). The expression level of HBsAg in the liver in the LNA-liposome group was significantly lower than those in the control groups. No significant histological abnormalities were found in the liver in all groups.

CONCLUSION: HBV S gene-specific antisense LNA can significantly inhibit the replication and expression of HBV.