Polymer-lipid hybrid nanomedicines to deliver siRNA in and against glioblastoma cells

Small interfering RNA (siRNA) holds great potential to treat many difficult-to-treat diseases, but its delivery remains the central challenge. This study aimed at investigating the suitability of polymer-lipid hybrid nanomedicines (HNMeds) as novel siRNA delivery platforms for locoregional therapy of glioblastoma. Two HNMed formulations were developed from poly(lactic-co-glycolic acid) polymer and a cationic lipid: 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol). After characterization of the HNMeds, a model siRNA was complexed onto their surface to form HNMed/siRNA complexes. The physicochemical properties and siRNA binding ability of complexes were assessed over a range of nitrogen-to-phosphate (N/P) ratios to optimize the formulations. At the optimal N/P ratio of 10, complexes effectively bound siRNA and improved its protection from enzymatic degradation. Using the NIH3T3 mouse fibroblast cell line, DOTAP-based HNMeds were shown to possess higher cytocompatibility in vitro over the DC-Chol-based ones. As proof-of-concept, uptake and bioefficacy of formulations were also assessed in vitro on U87MG human glioblastoma cell line expressing luciferase gene. Complexes were able to deliver anti-luciferase siRNA and induce a remarkable suppression of gene expression. Noteworthy, the effect of DOTAP-based formulation was not only about three-times higher than DC-Chol-based one, but also comparable to lipofectamine model transfection reagent. These findings set the basis to exploit this nanosystem for silencing relevant GB-related genes in further in vitro and in vivo studies.

Design of charge converting lipid nanoparticles via a microfluidic coating technique

It was the aim of this study to design charge converting lipid nanoparticles (LNP) via a microfluidic mixing technique used for the preparation and coating of LNP. LNP consisting of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol, N-(carbonyl-methoxypolyethyleneglycol-2000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (MPEG-2000-DSPE), and various cationic surfactants were prepared at diverging flow rate ratios (FRR) via microfluidic mixing. Utilizing a second chip in the microfluidic set-up, LNP were coated with polyoxyethylene (9) nonylphenol monophosphate ester (PNPP). LNP were examined for their stability in different physiologically relevant media as well as for hemolytic and cytotoxic effects. Finally, phosphate release and charge conversion of PNPP-coated LNP were evaluated after incubation with alkaline phosphatase and on Caco2-cells. LNP produced at an FRR of 5:1 exhibited a size between 80 and 150 nm and a positive zeta potential. Coating with PNPP within the second chip led to LNP exhibiting a negative zeta potential. After incubation with 1 U/ml alkaline phosphatase for 4 h, zeta potential of the LNP containing 1,2-dioleoyloxy-3-trimethylammonium-propane chloride (DOTAP) as cationic component shifted from - 35 mV to approximately + 5 mV. LNP prepared with other cationic surfactants remained slightly negative after enzymatic phosphate cleavage. Manufacturing of LNP containing PNPP and DOTAP via connection of two chips in a microfluidic instrument proves to show efficient change in zeta potential from negative to positive after incubation with alkaline phosphatase.

Exploration of mRNA nanoparticles based on DOTAP through optimization of the helper lipids

Lipid nanoparticles (LNPs) are one of the most efficient carriers for RNA packaging and delivery, and vaccines based on mRNA-LNPs have received substantial attention since the outbreak of the COVID-19 pandemic. LNPs based on 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) have been widely used in preclinical and clinical settings. A novel non-viral gene delivery system called LNP3 was previously developed, which was composed of DOTAP, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and cholesterol. One of the helper lipids in this carrier was DOPE, which belongs to phospholipids. Given that substituting DOPE with non-phospholipids as helper lipids can increase the delivery efficiency of some LNPs, this study aimed to examine whether non-phospholipids can be formulated with DOTAP as helper lipids. It was found that monoglycerides with C14:0, C16:0, C18:0, C18:1, and C18:2 mediated mRNA transfection, and the transfection efficiency varied between C18:0, C18:1, and C18:2. Furthermore, substituting of the glycerol with other moieties such as the cholesterol or the ethanolamine similarly mediated mRNA transfection. The introduction of cholesterol can further improve the transfection capacity of some DOTAP-based LNPs. One of the best-performing formulations, LNP3-MO, was used to mediate luciferase-mRNA expression in vivo, and the luminescence signal was found to be mainly enriched in the lung and spleen. In addition, the level of SARS-CoV-2 spike antibody in the serum increased after three doses of LNP3-MO mediated SARS-CoV-2 spike mRNA. Altogether, this study demonstrates that non-phospholipids are promising helper lipids that can be formulated with DOTAP to facilitate efficient delivery of mRNAs in vitro and in vivo with organ-specific targeting.

Bicontinuous Cubic Liquid Crystals as Potential Matrices for Non-Invasive Topical Sampling of Low-Molecular-Weight Biomarkers

Many skin disorders, including cancer, have inflammatory components. The non-invasive detection of related biomarkers could therefore be highly valuable for both diagnosis and follow up on the effect of treatment. This study targets the extraction of tryptophan (Trp) and its metabolite kynurenine (Kyn), two compounds associated with several inflammatory skin disorders. We furthermore hypothesize that lipid-based bicontinuous cubic liquid crystals could be efficient extraction matrices. They comprise a large interfacial area separating interconnected polar and apolar domains, allowing them to accommodate solutes with various properties. We concluded, using the extensively studied GMO-water system as test-platform, that the hydrophilic Kyn and Trp favored the cubic phase over water and revealed a preference for locating at the lipid-water interface. The interfacial area per unit volume of the matrix, as well as the incorporation of ionic molecules at the lipid-water interface, can be used to optimize the extraction of solutes with specific physicochemical characteristics. We also observed that the cubic phases formed at rather extreme water activities (>0.9) and that wearing them resulted in efficient hydration and increased permeability of the skin. Evidently, bicontinuous cubic liquid crystals constitute a promising and versatile platform for non-invasive extraction of biomarkers through skin, as well as for transdermal drug delivery.

Full Remission of CAR-Deficient Tumors by DOTAP-Folate Liposome Encapsulation of Adenovirus

Adenovirus (Ad)-based vectors have shown considerable promise for gene therapy. However, Ad requires the coxsackievirus and adenovirus receptor (CAR) to enter cells efficiently and low CAR expression is found in many human cancers, which hinder adenoviral gene therapies. Here, cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-folate liposomes (Df) encapsulating replication-deficient Ad were synthesized, which showed improved transfection efficiency in various CAR-deficient cell lines, including epithelial and hematopoietic cell types. When encapsulating replication-competent oncolytic Ad (TAV255) in DOTAP-folate liposome (TAV255-Df), the adenoviral structural protein, hexon, was readily produced in CAR-deficient cells, and the tumor cell killing ability was 5× higher than that of the non-encapsulated Ad. In CAR-deficient CT26 colon carcinoma murine models, replication-competent TAV255-Df treatment of subcutaneous tumors by intratumoral injection resulted in 67% full tumor remission, prolonged survival, and anti-cancer immunity when mice were rechallenged with cancer cells with no further treatment. The preclinical data shows that DOTAP-folate liposomes could significantly enhance the transfection efficiency of Ad in CAR-deficient cells and, therefore, could be a feasible strategy for applications in cancer treatment.

How docetaxel entrapment, vesicle size, zeta potential and stability change with liposome composition-A formulation screening study

Limitations of the anticancer drug product Taxotere® have encouraged researchers to entrap the active ingredient docetaxel (DTX) into nanocarriers such as liposomes. However, until now no DTX-liposome formulation has reached the clinic. Hence, in the present study, different Soy-PC based DTX-liposome formulations were screened in an attempt to identify lipid-compositions with promising DTX-entrapment (DTX-EE). Various other quality attributes, such as vesicle size and morphology, poly dispersity index (PDI), zeta potential (ZP), stability and in vitro drug release were also investigated. In an initial study, the inclusion of charged lipids within the liposome bilayer was observed to have a positive effect on DTX-EE. Thus, cationic DOTAP (1,2-Dioleoyl-3-trimethylammonium-propane) and anionic DMPG (1,2-Dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) lipids were selected for further investigations. With anionic DMPG, only a temporary rise in EE was gained with ≥ 20% (w/w) DMPG in Soy-PC lipid-based liposomes, whereas a concentration-dependent increase in EE was observed with cationic DOTAP. A DTX-EE > 95% was obtained with only 5% (w/w) DOTAP in Soy-PC, while neutral liposomes formed from Soy-PC alone, gave 41.5% DTX-EE. In the stability study, a DOTAP concentration > 10% (w/w) in Soy-PC was found to facilitate a stable DTX-EE > 90% after 12 weeks storage. The positive effect of cationic lipids on the EE was confirmed when replacing cholesterol (CHOL), initially shown to suppress DTX-entrapment, with cationic 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]Cholesterol (DC-CHOL). Here, DTX-EE was improved from 29.8% to 92.0% (w/w) with 10% (w/w) CHOL and DC-CHOL in Soy-PC, respectively. Finally, PEGylation of DOTAP-liposomes with DSPE-PEG2000 and DSPE-PEG750 reduced the DTX-EE relative to DOTAP-liposome with no PEGylation. As with the DMPG-liposomes, a temporarily raised affinity between DTX and liposomes was obtained with anionic DSPE-PEGylation of Soy-PC liposomes, however, this effect was not maintained after 4 weeks storage. However, in a dialysis set-up, cationic DOTAP-liposomes released DTX to a higher extent than PEGylated liposomes. Thus, the optimal formulation with regard to storage stability and in vivo performance need to be investigated further, applying conditions that are closer to mimic the in vivo-situation. Applying the Dual Asymmetric Centrifugation (DAC) method in liposome production appears favourable due to its good reproducibility. The observed increase in DTX entrapment with cationic lipids or PEGylation appears scalable into pilot manufacturing scale.

Synthesis and bioactivity of readily hydrolysable novel cationic lipids for potential lung delivery application of mRNAs

Lipid nanoparticles (LNPs) mediated mRNA delivery has gained prominence due to the success of mRNA vaccines against Covid-19, without which it would not have been possible. However, there is little clinical validation of this technology for other mRNA-based therapeutic approaches. Systemic administration of LNPs predominantly targets the liver, but delivery to other organs remains a challenge. Local approaches remain a viable option for some disease indications, such as Cystic Fibrosis, where aerosolized delivery to airway epithelium is the preferred route of administration. With this in mind, novel cationic lipids (L1-L4) have been designed, synthesized and co-formulated with a proprietary ionizable lipid. These LNPs were further nebulized, along with baseline control DOTAP-based LNP (DOTAP⁺), and tested in vitro for mRNA integrity and encapsulation efficiency, as well as transfection efficiency and cytotoxicity in cell cultures. Improved biodegradability and potentially superior elimination profiles of L1-L4, in part due to physicochemical characteristics of putative metabolites, are thought to be advantageous for prospective therapeutic lung delivery applications using these lipids.

Comparison of two routes of administration of a cationic liposome formulation for a prophylactic DC vaccination in a murine melanoma model

Dendritic cell (DC) vaccination can be achieved via straight loading of vaccine into DCs ex vivo or administration to DCs in vivo. However, there is no certain consensus on which approach is preferable, and each strategy has its advantages and disadvantages, which affect the efficacy and safety of vaccines. It will also be more complicated when a vaccine delivery system is included. In this study, the efficacy of ex vivo pulsed DC-based vaccine compared with in vivo subcutaneous administration of a cationic liposomes (CLs) formulation containing gp100 antigen (gp100-CLs) was evaluated in a murine melanoma model. In combination with an anti-PD-1 antibody, the ex vivo approach of gp100-CLs yielded a significant (P < 0.01) increase in the number of antigen-specific tumors infiltrated lymphocytes (TILs) with a significant upregulation of IFN-γ (P < 0.0001) and PD-1 (P < 0.0001) expression level. They also dampened the function of immunosuppressive regulatory T cells (Tregs) via significant downregulation of IL-10 and TGF-β (P < 0.0001) expression level compared to in vivo approach in the tumor microenvironment (TME). Furthermore, prophylactic immunization with gp100-CLs pulsed DCs ex vivo delayed tumor growth and induced the survival benefit over in vivo immunization. Collectively, the ex vivo DC-based vaccination pulsed with gp100 encapsulated in liposomes synergizes with anti-PD-1 antibody and represents a preferable approach against melanoma.

Emerging advances in cationic liposomal cancer nanovaccines: opportunities and challenges

Advancements in the field of cancer therapeutics have witnessed a recent surge in the use of liposomes. The physicochemical characteristics of the liposomes and their components, including the lipid phase transition temperature, vesicular size and size distribution, surface properties, and route of administration, play a significant role in the modulation of the immune response as an adjuvant and for loaded antigen (Ag). Cationic liposomes, concerning their potential ability to amplify the immunogenicity of the loaded Ag/adjuvant, have received enormous interest as a promising vaccine delivery platform for cancer immunotherapy. In the present review, the physicochemical considerations for the development of Ag/adjuvant-loaded liposomes and the cationic liposomes' effectiveness for promoting cancer immunotherapy have been summarized.

A validated 1H-NMR method for quantitative analysis of DOTAP lipid in nanoliposomes containing soluble Leishmania antigen

Leishmaniasis is a serious health problem that needs a suitable vaccine delivery system to control the disease. Cationic lipids such as 1, 2-dioleoyl-3-trimethylammonium-propane (DOTAP) have been widely used in nanoliposomes' formulation to deliver antigen and adjuvant at the same time to induce protection against Leishmaniasis. Therefore, it is necessary to accurately quantify DOTAP concentration in the formulation and biological materials. Due to the poor UV absorbance of DOTAP, the use of the conventional HPLC-UV method was impossible. Currently, an evaporative light scattering detector (ELSD) or MS/MS detector in conjunction with HPLC is used to quantify DOTAP. These methods have several disadvantages, including time- consuming during extraction procedure and decrease or/and even remove some components of the formulation. According to the advantages of the quantitative ¹H Nuclear Magnetic Resonance (¹H-NMR) spectroscopic method, a free extraction approach was developed to the assay of DOTAP in nanoliposomes containing Leishmania antigens. This method was carried out based on the relative ratio of signal integration of DOTAP [CH₂ (CH₂-CH = CH-CH₂)] in δ 2 ppm to a definite amount of an internal standard called dimethyl sulfone (DMSO₂). The q¹H-NMR method showed good precision (intra-day RSD = 1.8 % and inter-day RSD = 2.5 %), linearity (in the ranges of 1.3-7.8 mg. mL^-1 with correlation coefficients at 1), repeatability (RSD ≤ 2.39 %), and stability (RSD ≤ 2.32 %) for the quantification of the DOTAP without any extraction method. Considering all the experiments conducted in this study, NMR can be a feasible alternative to other traditional techniques for the simultaneous quantification of lipids in liposome formulations.

Treatment of Yersinia similis with the cationic lipid DOTAP enhances adhesion to and invasion into intestinal epithelial cells - A proof-of-principle study

The monocationic quaternary surfactant DOTAP has been used for the delivery of nucleic acids and peptides into mammalian cells. This study tested the applicability of DOTAP for the enhancement of adhesion and invasion frequencies of Yersinia (Y.) similis to enable the analysis of the effects of low-pathogenic bacteria on intestinal epithelial cells. Incubation of Y. similis with DOTAP ahead of infection of C2BBe1 intestinal epithelial cells increased invasion and adhesion frequency four- and five-fold, respectively, in plating assays. Proteomic approaches confirmed the increased bacterial load on infected cells: analysis of protein extracts by two-dimensional difference gel electrophoresis (2D-DIGE) revealed higher amounts of bacterial proteins present in the cells infected with DOTAP-treated bacteria. MALDI-TOF mass spectrometry of selected spots from gel-separated protein extracts confirmed the presence of both bacterial and human cell proteins in the samples. Label-free quantitative proteomics analysis identified 1170 human cell proteins and 699 bacterial proteins. Three times more bacterial proteins (279 vs. 93) were detected in C2BBe1 cells infected with DOTAP-treated bacteria compared to infections with untreated bacteria. Infections with DOTAP-treated Y. similis led to a significant upregulation of the stress-inducible ubiquitin-conjugating enzyme UBE2M in C2BBe1 cells. This points towards a stronger impact of the stress and infection responsive transcription factor AP-1 by enhanced bacterial load. DOTAP-treatment of uninfected C2BBe1 cells led to a significant downregulation of the transmembrane trafficking protein TMED10. The application of DOTAP could be helpful for investigating the impact of otherwise low adherent or invasive bacteria on cultivated mammalian cells without utilisation of genetic modifications.

Liposomal TLR9 Agonist Combined with TLR2 Agonist-Fused Antigen Can Modulate Tumor Microenvironment through Dendritic Cells

Dendritic cells (DCs) are antigen-presenting cells involved in T cell activation and differentiation to regulate immune responses. Lipoimmunogens can be developed as pharmaceutical lipoproteins for cancer immunotherapy to target DCs via toll-like receptor 2 (TLR2) signaling. Previously, we constructed a lipoimmunogen, a lipidated human papillomavirus (HPV) E7 inactive mutant (rlipoE7m), to inhibit the growth of HPV16 E7-expressing tumor cells in a murine model. Moreover, this antitumor effect could be enhanced by a combinatory treatment with CpG oligodeoxynucleotides (ODN). To improve safety, we developed a rlipoE7m plus DOTAP liposome-encapsulated native phosphodiester CpG (POCpG/DOTAP) treatment to target DCs to enhance antitumor immunity. We optimized the formulation of rlipoE7m and POCpG/DOTAP liposomes to promote conventional DC and plasmacytoid DC maturation in vitro and in vivo. Combination of rlipoE7m plus POCpG/DOTAP could activate conventional DCs and plasmacytoid DCs to augment IL-12 production to promote antitumor responses by intravenous injection. In addition, the combination of rlipoE7m plus POCpG/DOTAP could elicit robust cytotoxic T lymphocytes (CTLs) by intravenous immunization. Interestingly, the combination of rlipoE7m plus POCpG/DOTAP could efficiently inhibit tumor growth via intravenous immunization. Moreover, rlipoE7m plus POCpG/DOTAP combined reduced the number of tumor-infiltrating regulatory T cells dramatically due to downregulation of IL-10 production by DCs. These results showed that the combination of rlipoE7m plus POCpG/DOTAP could target DCs via intravenous delivery to enhance antitumor immunity and reduce the number of immunosuppressive cells in the tumor microenvironment.

Targeting EZH2 for glioma therapy with a novel nanoparticle-siRNA complex

Background

For the past few years, gene-therapy has recently shown considerable clinical benefit in cancer therapy, and the applications of gene therapies in cancer treatments continue to increase perennially. EZH2, an ideal candidate for tumor gene therapy, plays an important role in the tumorigenesis.

Methods

In this study, we developed a novel gene delivery system with a self-assembly method by Methoxy polyethylene glycol-polycaprolactone (MPEG-PCL) and DOTAP(DMC). And EZH2si-DMC was used to research anti-glioma both in vitro and in vivo.

Results

DMC with zeta-potential value of 36.7 mV and size of 35.6 nm showed good performance in the delivery siRNA to glioma cell in vitro with high 98% transfection efficiency. EZH2si-DMC showed good anti-glioma effect in vitro through inducing cell apoptosis and inhibiting cell growth. What’s more, treatment of tumor-bearing mice with DMC-EZH2si complex had significantly inhibited tumor growth at the subcutaneous model in vivo by inhibiting EZH2 protein expression, promoting apoptosis and reducing proliferation.

Conclusion

The EZH2 siRNA and DMC complex may be used to treat the glioma in clinical as a new drug.

DOTAP, a lipidic transfection reagent, triggers Arabidopsis plant defense responses

DOTAP triggers Arabidopsis thaliana immunity and by priming the defense response is able to reduce bacterial pathogen attack. DOTAP is a cationic lipid widely used as a liposomal transfection reagent and it has recently been identified as a strong activator of the innate immune system in animal cells. Plants are sessile organisms and unlike mammals, that have innate and acquired immunity, plants possess only innate immunity. A key feature of plant immunity is the ability to sense potentially dangerous signals, as it is the case for microbe-associated, pathogen-associated or damage-associated molecular patterns and by doing so, trigger an active defense response to cope with the perturbing stimulus. Here, we evaluated the effect of DOTAP in plant basal innate immunity. An initial plant defense response was induced by the cationic lipid DOTAP in the model plant Arabidopsis thaliana, assessed by callose deposition, reactive oxygen species production, and plant cell death. In addition, a proteomic analysis revealed that these responses are mirrored by changes in the plant proteome, such as up-regulation of proteins related to defense responses, including proteins involved in photorespiration, cysteine and oxylipin synthesis, and oxidative stress response; and down-regulation of enzymes related to photosynthesis. Furthermore, DOTAP was able to prime the defense response for later pathogenic challenges as in the case of the virulent bacterial pathogen Pseudomonas syringae pv. tomato. Disease outcome was diminished in DOTAP-pre-treated leaves and bacterial growth was reduced 100 times compared to mock leaves. Therefore, DOTAP may be considered a good candidate as an elicitor for the study of plant immunity.

Increasing Cellular Immune Response in Liposomal Formulations of DOTAP Encapsulated by Fusion Protein Hspx, PPE44, And Esxv, as a Potential Tuberculosis Vaccine Candidate

BACKGROUND

Due to the ineffectiveness of the BCG vaccine, especially in adult pulmonary tuberculosis (TB), and variable efficacies against childhood forms of TB, developing an effective TB vaccine is a major priority in controlling this disease. The aim of this study was to evaluate the immunogenicity of a DOTAP liposome formulation containing a fusion protein (FP) containing Mycobacterium tuberculosis HspX, PPE44, and EsxV.

METHODS

The FP was expressed in E. coli BL21 cells and confirmed by SDS-PAGE and Western blots. The FP was then encapsulated in various liposomal formulations. Afterwards, liposomal size, zeta potential, and encapsulation efficiency were evaluated. Mice were subcutaneously vaccinated on days 0, 14, and 28 with liposomes containing the FP. Two weeks after the last injection, IFN-γ, IL-4, IL-17, and IL-12 in spleen cell culture supernatants, and IgG2a, IgG1, and IgG2b titers in sera were measured.

RESULTS

The FP concentration was 1mg/ml. The encapsulation efficiency of the liposomes varied from 69% in Lip (DOTAP/TDB/CHOL/FP) to 80% in Lip (DOTAP/CHOL/FP). The greatest IFN-γ and IL-12 levels were observed in BCG-primed mice that were boosted with Lip (DOTAP/CHOL/FP). In addition, IL-17 production was significantly greater in all groups than controls except in those that received histidine buffer and FP. The IgG2a/IgG1 ratios were greater in the Lip (DOTAP/TDB/CHOL/FP), Lip (DOTAP/CHOL/FP), Lip (DOTAP/CHOL), and BCG-primed and Lip (DOTAP/CHOL/FP)-boosted groups than in the other groups, indicating a cellular immune response.

CONCLUSION

The liposomes containing DOTAP combined with the fusion protein induced a Th1 response. The mice that first received BCG and then Lip (DOTAP/CHOL/FP), produced the most IFN-γ and IL-12, indicating a strong Th1 response.

Delivery siRNA with a novel gene vector for glioma therapy by targeting Gli1

Background

Gene therapy has recently shown considerable clinical benefit in cancer therapy during the past few years, and the application of this choice in cancer treatments is increasing continually. Gli1 is an ideal candidate target for cancer gene therapy and is important for tumorigenesis.

Methods

In this study, we developed a novel gene delivery system with a self-assembly method by using a 1,2-dioleoyl-3-trimethylammonium-propane and methoxy poly (ethylene glycol)-poly(lactide) copolymer (DMP), with zeta potential of 32.7 mV and measuring 35.6 nm. The effect of this delivery system was tested in vitro and in vivo.

Results

DMP showed good performance in delivering siRNA to glioma cells in vitro with high transfection performance (98%). Moreover, DMP–Gli1si shows a satisfactory anti-glioma effect via induction of cell apoptosis and cell growth inhibition in vitro. Furthermore, for subcutaneous tumor-bearing mice, treatment with the DMP–Gli1si complex significantly inhibited tumor growth by inhibiting Gli1 protein expression, promoting apoptosis, and reducing proliferation.

Conclusion

The complex of Gli1 siRNA and DMP may potentially play an important role as a new drug in the clinical treatment of gliomas.

Powerful anti-colon cancer effect of modified nanoparticle-mediated IL-15 immunogene therapy through activation of the host immune system

Rationale: Colorectal cancer (CRC) is the third most commonly diagnosed cancer around the world. Over the past several years, immunotherapy has demonstrated considerable clinical benefit in CRC therapy, and the number of immunologic therapies for cancer treatment continues to climb each year. Interleukin-15 (IL15), a potent pro-inflammatory cytokine, has emerged as a candidate immunomodulator for the treatment of CRC. Methods: In this study, we developed a novel gene delivery system with a self-assembly method using DOTAP and MPEG-PLA (DMA) to carry pIL15, denoted as DMA-pIL15 which was used to treat tumor-bearing mice. Results: Supernatant from lymphocytes treated with supernatant derived from CT26 cells transfected with DMA-pIL15 inhibited the growth of CT26 cells and induced cell apoptosis in vitro. Treatment of tumor-bearing mice with DMA-pIL15 complex significantly inhibited tumor growth in both subcutaneous and peritoneal models in vivo by inhibiting angiogenesis, promoting apoptosis, and reducing proliferation through activation of the host immune system. Conclusion: The IL-15 plasmid and DMA complex showed promise for treating CRC clinically as an experimental new drug.

Effect of Laminaria japonica polysaccharides on lipids monolayers at the air-water surface

In this paper, we examined the effect of Laminaria japonica polysaccharides (LJP) on cationic 1,2-Dioleoyl-3-Trimethylammonium-Propane (DOTAP) and anionic 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-1-glycerol] (DPPG) monolayers at the air-water interface by the pressure-area isotherms (π-A), adsorption curves (π-t) and morphology measurements with atomic force microscopy (AFM) technique. The π-A curves revealed that the isotherms shifted to larger mean molecular area with progressive addition of LJP into subphase for both DOTAP and DPPG monolayers. And the compression modulus Cs-1 obtained from π-A curves showed that the elasticity of the films decreased with the addition of LJP. Adsorption curves were measured at the surface pressure of 10 and 20mN/m, which were fitted by the adsorption kinetics equation. It revealed that DOTAP monolayer changed into a mixed film with the insertion of polysaccharides molecules. However, there was no significant effect on the surface pressure for DPPG monolayer. Besides, surface morphology was observed by AFM, which was consistent with the results of fitted adsorption curves.

Engineering of budesonide-loaded lipid-polymer hybrid nanoparticles using a quality-by-design approach

Chronic obstructive pulmonary disease (COPD) is a complex disease, characterized by persistent airflow limitation and chronic inflammation. The purpose of this study was to design lipid-polymer hybrid nanoparticles (LPNs) loaded with the corticosteroid, budesonide, which could potentially be combined with small interfering RNA (siRNA) for COPD management. Here, we prepared LPNs based on the biodegradable polymer poly(dl-lactic-co-glycolic acid) (PLGA) and the cationic lipid dioleyltrimethylammonium propane (DOTAP) using a double emulsion solvent evaporation method. A quality-by-design (QbD) approach was adopted to define the optimal formulation parameters. The quality target product profile (QTPP) of the LPNs was identified based on risk assessment. Two critical formulation parameters (CFPs) were identified, including the theoretical budesonide loading and the theoretical DOTAP loading. The CFPs were linked to critical quality attributes (CQAs), which included the intensity-based hydrodynamic particle diameter (z-average), the polydispersity index (PDI), the zeta-potential, the budesonide encapsulation efficiency, the actual budesonide loading and the DOTAP encapsulation efficiency. A response surface methodology (RSM) was applied for the experimental design to evaluate the influence of the CFPs on the CQAs, and to identify the optimal operation space (OOS). All nanoparticle dispersions displayed monodisperse size distributions (PDI<0.2) with z-averages of approximately 150nm, suggesting that the size is not dependent on the investigated CFPs. In contrast, the zeta-potential was highly dependent on the theoretical DOTAP loading. Upon increased DOTAP loading, the zeta-potential reached a maximal point, after which it remained stable at the maximum value. This suggests that the LPN surface is covered by DOTAP, and that the DOTAP loading is saturable. The actual budesonide loading of the LPNs was mainly dependent on the initial amount of budesonide, and a clear positive effect was observed, which shows that the interaction between drug and PLGA increases when increasing the initial amount of budesonide. The OOS was modeled by applying the QTPP. The OOS had a budesonide encapsulation efficiency higher than 30%, a budesonide loading above 15μg budesonide/mg PLGA, a zeta-potential higher than 35mV and a DOTAP encapsulation efficiency above 50%. This study shows the importance of systematic formulation design for understanding the effect of formulation parameters on the characteristics of LPNs, eventually resulting in the identification of an OOS.

T cell-dependent antigen adjuvanted with DOTAP-CpG-B but not DOTAP-CpG-A induces robust germinal center responses and high affinity antibodies in mice

The development of vaccines for infectious diseases for which we currently have none, including HIV, will likely require the use of adjuvants that strongly promote germinal center responses and somatic hypermutation to produce broadly neutralizing antibodies. Here we compared the outcome of immunization with the T-cell dependent antigen, NP-conjugated to chicken gamma globulin (NP-CGG) adjuvanted with the toll-like receptor 9 (TLR9) ligands, CpG-A or CpG-B, alone or conjugated with the cationic lipid carrier, DOTAP. We provide evidence that only NP-CGG adjuvanted with DOTAP-CpG-B was an effective vaccine in mice resulting in robust germinal center responses, isotype switching and high affinity NP-specific antibodies. The effectiveness of DOTAP-CpG-B as an adjuvant was dependent on the expression of the TLR9 signaling adaptor MyD88 in immunized mice. These results indicate DOTAP-CpG-B but not DOTAP-CpG-A is an effective adjuvant for T cell-dependent protein antigen-based vaccines.

Phase-Separated Liposomes Enhance the Efficiency of Macromolecular Delivery to the Cellular Cytoplasm

INTRODUCTION

From viruses to organelles, fusion of biological membranes is used by diverse biological systems to deliver macromolecules across membrane barriers. Membrane fusion is also a potentially efficient mechanism for the delivery of macromolecular therapeutics to the cellular cytoplasm. However, a key shortcoming of existing fusogenic liposomal systems is that they are inefficient, requiring a high concentration of fusion-promoting lipids in order to cross cellular membrane barriers.

OBJECTIVES

Toward addressing this limitation, our experiments explore the extent to which membrane fusion can be amplified by using the process of lipid membrane phase separation to concentrate fusion-promoting lipids within distinct regions of the membrane surface.

METHODS

We used confocal fluorescence microscopy to investigate the integration of fusion-promoting lipids into a ternary lipid membrane system that separated into liquid-ordered and liquid-disordered membrane phases. Additionally, we quantified the impact of membrane phase separation on the efficiency with which liposomes transferred lipids and encapsulated macromolecules to cells, using a combination of confocal fluorescence imaging and flow cytometry.

RESULTS

Here we report that concentrating fusion-promoting lipids within phase-separated lipid domains on the surfaces of liposomes significantly increases the efficiency of liposome fusion with model membranes and cells. In particular, membrane phase separation enhanced the delivery of lipids and model macromolecules to the cytoplasm of tumor cells by at least 4-fold in comparison to homogenous liposomes.

CONCLUSIONS

Our findings demonstrate that phase separation can enhance membrane fusion by locally concentrating fusion-promoting lipids on the surface of liposomes. This work represents the first application of lipid membrane phase separation in the design of biomaterials-based delivery systems. Additionally, these results lay the ground work for developing fusogenic liposomes that are triggered by physical and molecular cues associated with target cells.

A generic RNA pulsed DC based approach for developing therapeutic intervention against nasopharyngeal carcinoma

The recurrent nasopharyngeal carcinoma of head-and-neck cancers pathology showed unique symptoms and clinical characteristics. The complexity of pathology poses challenges for developing therapeutic interventional approaches against nasopharyngeal carcinoma (NPC). The conventional treatment regimens offer limited local control and survival, which, leads to adverse delayed complications. Our study present a generic monocyte derived dendritic cell (MoDC) vaccine strategy for NPC in which RNA is used as a source of tumor-associated antigens (TAAgs). The RNA extracted from well-characterized highly immunogenic NPC cells (C666-1) was transfected into MoDCs. The formulated and characterized cationic liposomes were used to achieving efficient RNA transfection of immature DCs. Further, DCs were forcibly matured with a cytokine cocktail to achieve greater expression of MHC and co-stimulatory molecules. Moreover, our results did not see any effect of RNA or lipids on MoDCs phenotype or cytokine expression. RNA loaded DCs derived from HLA-A2-positive donors were shown to activate effector memory cytotoxic T lymphocytes (CTLs) specific for TAAg ligand expressed by C666-1 cells. Our results show the comparison of cytotoxic response mounted against RNA-loaded DCs with those directly stimulated by C666-1 tumor cells. Our findings suggest that DCs expressing tumor cell RNA primed naïve T cells show T cells priming with lesser cytotoxicity and cytokine secretion when exposed with with C666-1 tumor cells. These results surface the potential of DCs to deliver RNA in NPCs, sufficient presentation of RNA to provoke perdurable immune responses against nasopharyngeal carcinoma. Our results implies that DC based vaccine approach may be useful to develop therapeutic interventional approach in the form of vaccine to address NPCs.

Cooperative Strategies for Enhancing Performance of Photothermal Therapy (PTT) Agent: Optimizing Its Photothermal Conversion and Cell Internalization Ability

Photothermal conversion ability (PCA) and cell internalization ability (CIA) are two key factors for determining the performance of photothermal agents. The previous studies mostly focus on improving the PCA by exploring new photothermal nanomaterials. Herein, the authors take the hybrids of graphene and gold nanostar (GGN) as an example to investigate the gradually enhanced phototherapy effect by changing the PCA and CIA of photothermal therapy (PTT) agent simultaneously. Based on the GGN, the GGN and the reduced GGN protected by bovine serum albumin (BSA) or BSA-FA (folic acid) are prepared, which are named as GGNB, rGGNB, and rGGNB-FA, respectively. The rGGNB showed an enhanced PCA compared to GGNB, leading to strong cell ablation. On the other hand, the 1,2-dioleoyl-3-trimethylammoniumpropan (DOTAP) can activate the endocytosis and promote the CIA of rGGNB, further help rGGNB to be more internalized into the cells. Finally, rGGNB-FA with the target ability can make itself further internalized into the cells with the aid of DOTAP, which can significantly destroy the cancer cells even at the low laser density of 0.3 W cm^-2 . Therefore, a new angle of view is brought out for researching the PTT agents of high performance.

A novel "in-feed" delivery platform applied for oral DNA vaccination against IPNV enables high protection in Atlantic salmon (Salmon salar)

BACKGROUND

DNA vaccination has emerged as a promising tool against infectious diseases of farmed fish. Oral delivery allows stress-free administration that is ideal for mass immunization and of paramount importance for infectious pancreatic necrosis (IPN) and other viral disease that affect young salmonids and cause economic losses in aquaculture worldwide.

METHODS

We describe the development and in vivo assessment of an "in-feed" formulation strategy for oral immunization with liposomal DNA vaccines, by delivering a vaccine construct coding for an immunogenic region of the VP2 capsid protein. A challenge against IPNV was carried out to determine the vaccine efficacy, by comparing the mortality of pre-smolt Atlantic salmons immunized and non-immunized with the oral vaccine. The antibody response (ELISA) and hematological parameters after immunization were examined, as well as the vaccine effect on the growth and internal structures of fry salmons (histological analysis). The vaccine distribution in the experimental tank after oral administration was investigated by HPLC and PCR amplification.

RESULTS

The oral vaccine induced detectable levels of VP2-specific antibodies and conferred significant protection following IPNV challenge, with relative percent survivals (RPS) of 58.2%, for single dose (1mg_pDNA/kg_fish⋅d), and 66% for double dose (2mg_pDNA/kg_fish⋅d). We further provide evidence in favour of the vaccine safety to fish and demonstrated absence of pDNA in the tank water, but presence of vaccine residues in faeces and unconsumed feed sediments (solid wastes).

CONCLUSION

The delivery platform for liposomal DNA vaccination via feed was successfully proved against IPNV in Atlantic salmon, showing the oral vaccine to be immunogenic and safe for fish, and providing significant protection after oral administration. The "in-feed" technology for oral DNA vaccination holds potential to be applied against IPNV and other pathogens that currently threaten the aquaculture worldwide.

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.

A novel liposomal recombinant lipoimmunogen enhances anti-tumor immunity

Synthetic liposomes provide a biocompatible and biodegradable approach for delivering drugs and antigens. In addition, self-adjuvanting recombinant lipoproteins (rlipoproteins) can enhance Th1 anti-tumor immune responses via the TLR2 signaling pathway. To generate a liposomal rlipoprotein for a cancer immunotherapeutic vaccine, we assessed 3 types of synthetic liposomes for use with the rlipoproteins rlipoE7m and rlipoOVA. We determined that the cationic liposome DOTAP could stabilize anionic rlipoproteins and delay rlipoprotein release. Surprisingly, rlipoproteins and DOTAP could synergistically up-regulate CD83 expression in bone marrow-derived dendritic cells (BMDCs). Compared with other liposome formulations, the rlipoprotein/DOTAP formulation elicited higher cytotoxic T-lymphocyte (CTL) responses. To explore the mechanism of BMDC activation by rlipoprotein/DOTAP, we assessed the production of reactive oxygen species (ROS) and the TNF-α secretion of BMDCs. We observed that rlipoprotein/DOTAP induced ROS to the same extent as DOTAP did. In addition, TLR2 signaling was also required for the TNF-α secretion of rlipoprotein/DOTAP-treated BMDCs. Moreover, compared with rlipoOVA-treated BMDCs, rlipoOVA/DOTAP-treated BMDCs increased the levels of IFN-γ produced by OVA-specific T cells. We also observed that rlipoE7m/DOTAP treatment but not rlipoE7m treatment delayed tumor growth. These results indicate that the rlipoprotein/DOTAP formulation can synergistically activate BMDCs via ROS and the TLR2 signaling pathway. In summary, rlipoprotein/DOTAP is a novel and stable formulation for cancer immunotherapy.

Intracellular trafficking of hybrid gene delivery vectors

Viral and non-viral gene delivery vectors are in development for human gene therapy, but both exhibit disadvantages such as inadequate efficiency, lack of cell-specific targeting or safety concerns. We have recently reported the design of hybrid delivery vectors combining retrovirus-like particles with synthetic polymers or lipids that are efficient, provide sustained gene expression and are more stable compared to native retroviruses. To guide further development of this promising class of gene delivery vectors, we have investigated their mechanisms of intracellular trafficking. Moloney murine leukemia virus-like particles (M-VLPs) were complexed with chitosan (Chi) or liposomes (Lip) comprising DOTAP, DOPE and cholesterol to form the hybrid vectors (Chi/M-VLPs and Lip/M-VLPs, respectively). Transfection efficiency and cellular internalization of the vectors were quantified in the presence of a panel of inhibitors of various endocytic pathways. Intracellular transport and trafficking kinetics of the hybrid vectors were dependent on the synthetic component and used a combination of clathrin- and caveolar-dependent endocytosis and macropinocytosis. Chi/M-VLPs were slower to transfect compared to Lip/M-VLPs due to the delayed detachment of the synthetic component. The synthetic component of hybrid gene delivery vectors plays a significant role in their cellular interactions and processing and is a key parameter for the design of more efficient gene delivery vehicles.

Mechanistic profiling of the siRNA delivery dynamics of lipid-polymer hybrid nanoparticles

Understanding the delivery dynamics of nucleic acid nanocarriers is fundamental to improve their design for therapeutic applications. We investigated the carrier structure-function relationship of lipid-polymer hybrid nanoparticles (LPNs) consisting of poly(DL-lactic-co-glycolic acid) (PLGA) nanocarriers modified with the cationic lipid dioleoyltrimethyl-ammoniumpropane (DOTAP). A library of siRNA-loaded LPNs was prepared by systematically varying the nitrogen-to-phosphate (N/P) ratio. Atomic force microscopy (AFM) and cryo-transmission electron microscopy (cryo-TEM) combined with small angle X-ray scattering (SAXS) and confocal laser scanning microscopy (CLSM) studies suggested that the siRNA-loaded LPNs are characterized by a core-shell structure consisting of a PLGA matrix core coated with lamellar DOTAP structures with siRNA localized both in the core and in the shell. Release studies in buffer and serum-containing medium combined with in vitro gene silencing and quantification of intracellular siRNA suggested that this self-assembling core-shell structure influences the siRNA release kinetics and the delivery dynamics. A main delivery mechanism appears to be mediated via the release of transfection-competent siRNA-DOTAP lipoplexes from the LPNs. Based on these results, we suggest a model for the nanostructural characteristics of the LPNs, in which the siRNA is organized in lamellar superficial assemblies and/or as complexes entrapped in the polymeric matrix.

Relating toxicity to transfection: using sphingosine to maintain prolonged expression in vitro

Cationic reagents are commonly used to facilitate DNA delivery, and transfection experiments are typically initiated in cell culture where the optimal charge ratio is determined. While transfection rates are often enhanced at higher +/- charge ratios, the cellular toxicity associated with the greater amounts of cationic components at elevated charge ratios is often not considered. In addition, the prolonged effects of cationic lipid uptake on cell viability are not evident in a typical 24-48 h transfection experiment. In this study, we compare the transfection efficiency of cationic lipoplexes to effects on viability of cultured cells in both the short and long term (7 days). Our results indicate that, while minimal toxicity is evident 24 h after exposure to DOTAP-based lipoplexes, cell viability continues to decline and ultimately compromises reporter gene expression at longer times. Substitution of a naturally occurring cationic amphiphile, sphingosine, for DOTAP greatly reduces toxicity and allows high expression to be maintained over prolonged periods.

Do lipids show state-dependent affinity to the voltage-gated potassium channel KvAP?

As all integral membrane proteins, voltage-gated ion channels are embedded in a lipid matrix that regulates their channel behavior either by physicochemical properties or by direct binding. Because manipulation of the lipid composition in cells is difficult, we investigated the influence of different lipids on purified KvAP channels reconstituted in planar lipid bilayers of known composition. Lipids developed two distinct and independent effects on the KvAP channels; lipids interacting with the pore lowered the energy barriers for the final transitions, whereas voltage sensor-bound lipids shifted the midpoint of activation dependent on their electrostatic charge. Above all, the midpoint of activation was determined only by those lipids the channels came in contact with first after purification and can seemingly only be exchanged if the channel resides in the open state. The high affinity of the bound lipids to the binding site has implications not only on our understanding of the gating mechanism but also on the general experimental design of any lipid dependence study.

Comparative pharmacokinetics and tissue distribution analysis of systemically administered 17-β-estradiol and its metabolites in vivo delivered using a cationic nanoemulsion or a peptide-modified nanoemulsion system for targeting atherosclerosis

The primary objective of this study was to compare the biodistribution and pharmacokinetic profile of 17-β-estradiol (17-βE) on systemic delivery using either the cationic or the CREKA-peptide-modified (Cysteine-Arginine-Glutamic-acid-Lysine-Alanine) omega-3-fatty acid oil containing nanoemulsion system in vivo in the wild type C57BL/6 mice. Higher blood concentrations of 17-βE, higher accumulation in the tissues of interest - heart and aorta, and higher accumulation within the other tissues - liver and kidney was observed on delivering 17-βE using the CREKA-peptide-modified nanoemulsion system (AUClast in plasma - 263.89±21.81min*%/injected dose/ml) as compared to the cationic nanoemulsion (AUClast in plasma - 20.2±1.86min*%/injected dose/ml) and solution form (AUClast in plasma - 44.9±1.24min*%/injected dose/ml) respectively. Both, the cationic nanoemulsion and the CREKA-peptide-modified nanoemulsion showed a higher relative targeting efficiency of 4.57 and 4.86 respectively for 17-βE than the relative targeting efficiency of 1.78 observed with the solution form. In conclusion, since the maximum exposure (highest AUClast for plasma and tissues) for 17-βE was observed with the CREKA-peptide-modified nanoemulsion system, the study shows that CREKA-peptide-modified nanoemulsion system was the most suitable vehicle for systemic delivery of 17-βE in the wild type C57BL/6 mice.

Induction of protection against leishmaniasis in susceptible BALB/c mice using simple DOTAP cationic nanoliposomes containing soluble Leishmania antigen (SLA)

A suitable adjuvant and delivery system are needed to develop an effective vaccine against leishmaniasis. To induce a Th1 type of response and protection in BALB/c mice against Leishmania major infection, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) nanoliposomes bearing an intrinsic adjuvanticity, were used as an antigen delivery system and immunoadjuvant for soluble Leishmania antigens (SLA). DOTAP liposomes containing different concentrations of SLA were prepared by using lipid film method followed by sonication. The prepared vesicles showed a diameter of about 100nm, a positive zeta potential and approximately 70% encapsulation efficiency of SLA. BALB/c mice were immunized subcutaneously (SC), three times in a 3-week interval with different concentrations of liposomal SLA (12.5, 25, and 50μg of SLA/50μl/mice), free SLA and as well as free liposome. The group of mice received 50μg of SLA in DOTAP-nanoliposomes showed a significantly (p<0.001) smaller footpad swelling and the lowest spleen and footpad parasite burden after the challenge. This group also showed the highest IFN-γ production compared to the other groups, lower IL-4 level and higher IgG2a antibody titer. Taken together, the results indicated that simple DOTAP nanoliposome containing 1μg/μl SLA are appropriate delivery systems to induce a Th1 type of immune response and protection against L. major infection in BALB/c mice.

Phage protein-targeted cancer nanomedicines

Nanoencapsulation of anticancer drugs improves their therapeutic indices by virtue of the enhanced permeation and retention effect which achieves passive targeting of nanoparticles in tumors. This effect can be significantly enhanced by active targeting of nanovehicles to tumors. Numerous ligands have been proposed and used in various studies with peptides being considered attractive alternatives to antibodies. This is further reinforced by the availability of peptide phage display libraries which offer an unlimited reservoir of target-specific probes. In particular landscape phages with multivalent display of target-specific peptides which enable the phage particle itself to become a nanoplatform creates a paradigm for high throughput selection of nanoprobes setting the stage for personalized cancer management. Despite its promise, this conjugate of combinatorial chemistry and nanotechnology has not made a significant clinical impact in cancer management due to a lack of using robust processes that facilitate scale-up and manufacturing. To this end we proposed the use of phage fusion protein as the navigating modules of novel targeted nanomedicine platforms which are described in this review.

Impact of anti-PLK1 siRNA-containing F3-targeted liposomes on the viability of both cancer and endothelial cells

We have previously described the development of novel sterically stabilized F3-targeted pH-sensitive liposomes, which exhibited the ability to target both cancer and endothelial cells. Herein, the therapeutic potential of those liposomes was assessed upon encapsulation of a siRNA against a well-validated molecular target, PLK1. Treatment of prostate cancer (PC3) and angiogenic endothelial (HMEC-1) cells with F3-targeted liposomes containing anti-PLK1 siRNA resulted in a significant decrease in cell viability, which was mediated by a marked PLK1 silencing, both at the mRNA and protein levels. Furthermore, pre-treatment of PC3 cells with F3-targeted liposomes containing anti-PLK1 siRNA enabled a 3-fold reduction of paclitaxel IC50 and a 2.5-fold augment of the percentage of cancer cells in G2/mitosis arrest, which ultimately culminated in cell death. Overall, the F3-targeted nanocarrier containing an anti-PLK1 siRNA might constitute a valuable system for prostate cancer treatment, either applied in a single schedule or combined with conventional chemotherapy.

Polypurine reverse Hoogsteen hairpins as a gene therapy tool against survivin in human prostate cancer PC3 cells in vitro and in vivo

As a new approach for gene therapy, we recently developed a new type of molecule called polypurine reverse Hoogsteen hairpins (PPRHs). We decided to explore the in vitro and in vivo effect of PPRHs in cancer choosing survivin as a target since it is involved in apoptosis, mitosis and angiogenesis, and overexpressed in different tumors. We designed four PPRHs against the survivin gene, one of them directed against the template strand and three against different regions of the coding strand. These PPRHs were tested in PC3 prostate cancer cells in an in vitro screening of cell viability and apoptosis. PPRHs against the promoter sequence were the most effective and caused a decrease in survivin mRNA and protein levels. We confirmed the binding between the selected PPRHs and their target sequences in the survivin gene. In addition we determined that both the template- and the coding-PPRH targeting the survivin promoter were interfering with the binding of transcription factors Sp1 and GATA-3, respectively. Finally, we conducted two in vivo efficacy assays using the Coding-PPRH against the survivin promoter and performing two routes of administration, namely intratumoral and intravenous, in a subcutaneous xenograft tumor model of PC3 prostate cancer cells. The results showed that the chosen Coding-PPRH proved to be effective in decreasing tumor volume, and reduced the levels of survivin protein and the formation of blood vessels. These findings represent the preclinical proof of principle of PPRHs as a new silencing tool for cancer gene therapy.

Multifunctional nanoparticles co-delivering Trp2 peptide and CpG adjuvant induce potent cytotoxic T-lymphocyte response against melanoma and its lung metastasis

Immunotherapy has shown the potential to become an essential component of the successful treatment of various malignancies. In many cases, such as in melanoma, however, induction of a potent and specific T-cell response against the endogenous antigen or self-antigen still remains a major challenge. To induce a potent MHC I-restricted cytotoxic T-lymphocyte (CTL) response, cytosol delivery of an exogenous antigen into dendritic cells is preferred, if not required. Lipid-calcium-phosphate (LCP) nanoparticles represent a new class of intracellular delivery systems for impermeable drugs. We are interested in exploring the potential of LCP NPs for use as a peptide vaccine delivery system for cancer therapy. To increase the encapsulation of Trp2 peptide into the calcium phosphate precipitate core of LCP, two phosphor-serine residues were added to the N-terminal of the peptide (p-Trp2). CpG ODN was also co-encapsulated with p-Trp2 as an adjuvant. The NPs were further modified with mannose to enhance and prolong the cargo deposit into the lymph nodes (LNs), which ensured persistent antigen loading and stimulation. Compared with free Trp2 peptide/CpG, vaccination with LCP encapsulating p-Trp2 and CpG resulted in superior inhibition of tumor growth in both B16F10 subcutaneous and lung metastasis models. An IFN-γ production assay and in vivo CTL response study revealed that the improved efficacy was a result of a Trp2-specific immune response. Thus, encapsulation of phospho-peptide antigens into LCP may be a promising strategy for enhancing the immunogenicity of poorly immunogenic self-antigens for cancer therapy.

Incorporation of histone derived recombinant protein for enhanced disassembly of core-membrane structured liposomal nanoparticles for efficient siRNA delivery

A novel recombinant protein tetra-H2A (TH) derived from histone H2A has been developed to replace protamine as a conditionally reversible, nucleic acid condensing agent. The novel protein will address the insufficient release of nucleic acid therapeutics, which is captured by protamine for siRNA delivery. TH is composed of 4 tandem repeats of the histone H2A N-terminal sequence, intervened by the cathepsin D cleavage site. The repeating H2A sequence enhances the binding affinity to anionic nucleic acids, forming more stable condensates, as demonstrated by the binding affinity assay. The TH/siRNA condensates are formulated into a core-membrane structured liposomal nanoparticle (NP). The endosomes of cancer cells are rich in cathepsin D, allowing on-site degradation of TH and facilitating the intracellular release of siRNA. The NPs assembled with TH produced a higher silencing efficiency of target genes in vitro and in vivo than the NPs assembled with protamine as the nucleic acid condensing agent. The exploitation of TH in the NP formulation exhibited a biocompatibility profile similar to that of protamine, with minimal immunostimulating and systemic toxicity observed after repeated administration.

Evidence for the role of hydrophobic forces on the interactions of nucleotide-monophosphates with cationic liposomes

In this work, the interaction of nucleotide-monophosphates (NMPs) with unilamellar liposomes made of 1,2-Dioleoyl-3-Trimethylammonium-Propane (DOTAP) and 1,2-Dioleoyl-sn-Glycero-3-Phosphoethanolamine (DOPE) was investigated. Here, we demonstrate how adsorption is affected by the type of nucleotide-monophosphate. Dynamic light scattering (DLS) results revealed, for each NMP, that a distinguishable concentration exists at which a significant growth of the aggregates occurs. Adenosine 5'-monophosphate (AMP) and guanosine 5'-monophosphate (GMP) have shown a higher propensity to induce liposome aggregation process and in particular GMP appears to be the most effective. From ζ-potential experiments we found that liposomes loaded with purine based nucleotides (AMP and GMP) are able to decrease the ζ-potential values to a greater extent in comparison with the pyrimidine based nucleotides thimydine 5'-monophosphate (TMP) and uridine 5'-monophosphate (UMP). Moreover, a careful analysis of nucleotide-liposome interactions revealed that nucleotides have different capacity to induce the formation of nucleotide-liposome complexes, and purine based nucleotides have higher affinities with lipid membranes. On the whole, the data emphasize that the mechanisms driving the interactions between liposomes and NMPs are also influenced by the existence of hydrophobic forces.

Insights in the chemical components of liposomes responsible for P-glycoprotein inhibition

In this work we investigated how the surface charge and the presence of polyethylene glycol (PEG) on liposome carriers affect the delivery of the encapsulated doxorubicin in P-glycoprotein (Pgp)-overexpressing cells. We found that neutral net charge was critical to favour the liposome uptake and decrease the Vmax of doxorubicin efflux. PEG-coating was necessary to increase the Km of doxorubicin for Pgp. In particular the PEGylated phospholipid present in neutral liposomes, i.e. PEGylated distearoyl-phosphatidylethanolamine (DSPE-PEG), was a Pgp allosteric inhibitor, increased doxorubicin Km and inhibited Pgp ATPase activity. Site-directed mutagenesis experiments suggested that the domain centred around glycine 185 of Pgp was necessary for these inhibitory properties of DSPE-PEG and PEGylated neutral liposomes. We conclude that both surface charge and PEGylation must be considered to optimize the doxorubicin delivery within chemoresistant cells. DSPE-PEG-enriched particles may represent promising tools for therapeutic and diagnostic applications in tissues with high levels of Pgp.

FROM THE CLINICAL EDITOR

These authors investigated how surface charge and PEGylation of liposome carriers affect the delivery of encapsulated doxorubicin to Pgp-overexpressing cells, concluding that both factors need to be considered in order to optimize doxorubicin delivery to chemoresistant cells.

Turning an antiviral into an anticancer drug: nanoparticle delivery of acyclovir monophosphate

Anti-herpes simplex virus (HSV) drug acyclovir (ACV) is phosphorylated by the viral thymidine kinase (TK), but not the cellular TK. Phosphorylated ACV inhibits cellular DNA synthesis and kills the infected cells. We hypothesize that ACV monophosphate (ACVP), which is an activated metabolite of ACV, should be efficient in killing cells independent of HSV-TK. If so, ACVP should be a cytotoxic agent if properly delivered to the cancer cells. The Lipid/Calcium/Phosphate (LCP) nanoparticles (NPs) with a membrane/core structure were used to encapsulate ACVP to facilitate the targeted delivery of ACVP to the tumor. The LCP NPs showed entrapment efficiency of ~70%, the nano-scaled particle size and positive zeta potential. Moreover, ACVP-loaded LCP NPs (A-LCP NPs) exhibited concentration-dependent cytotoxicity against H460 cells and increased S-phase arrest. More importantly, a significant reduction of the tumor volume over 4 days following administration (p<0.05-0.005) of A-LCP NPs, suggests excellent in vivo efficacy. Whereas, two free drugs (ACV and ACVP) and blank LCP NPs showed little or no therapeutic effect. It was also found that the high efficacy of A-LCP NPs was associated with the ability to induce dramatic apoptosis of the tumor cells, as well as significantly inhibit tumor cell proliferation and cell cycle progression. In conclusion, with the help of LCP NPs, monophosphorylation modification of ACV can successfully modify an HSV-TK-dependent antiviral drug into an anti-tumor drug.

In vitro and in vivo effects of polyethylene glycol (PEG)-modified lipid in DOTAP/cholesterol-mediated gene transfection

Background:

DOTAP/cholesterol-based lipoplexes are successfully used for delivery of plasmid DNA in vivo especially to the lungs, although low systemic stability and circulation have been reported. To achieve the aim of discovering the best method for systemic delivery of DNA to disseminated tumors we evaluated the potential of formulating DOTAP/cholesterol lipoplexes with a polyethylene glycol (PEG)-modified lipid, giving the benefit of the shielding and stabilizing properties of PEG in the bloodstream.

Method:

A direct comparison of properties in vitro and in vivo of 4 different DOTAP/cholesterol-based lipoplexes containing 0%, 2%, 4%, and 10% PEG was performed using reporter gene activity and radioactive tracer lipid markers to monitor biodistribution.

Results:

We found that 10% PEGylation of lipoplexes caused reduced retention in lung and heart tissues of nude mice compared to nonPEGylated lipoplexes, however no significant delivery to xenograft flank tumors was observed. Although PEGylated and nonPEGylated lipoplexes were delivered to cells the ability to mediate successful transfection is hampered upon PEGylation, presumably due to a changed uptake mechanism and intracellular processing.

Conclusion:

The eminent in vivo transfection potency of DOTAP/cholesterol-based lipoplexes is well established for expression in lung tumors, but it is unsuitable for expression in non first pass organs such as xenograft flank tumors in mice even after addition of a PEG-lipid in the formulation.