Chitooligosaccharides Modified Reduction-Sensitive Liposomes: Enhanced Cytoplasmic Drug Delivery and Osteosarcomas-Tumor Inhibition in Animal Models

Purpose

To investigate the potential of a reduction-sensitive and fusogenic liposomes, enabled by surface-coating with chotooligosaccharides (COS) via a disulfide linker, for tumor-targeted cytoplasmic drug delivery.

Methods

COS (MW2000-5000) were chemically tethered onto the liposomes through a disulfide linker (-SS-) to cholesterol (Chol). Doxorubicin (DOX) was actively loaded in the liposomes. Their reduction-sensitivities, cellular uptake, cytotoxicity, pharmacokinetics and antitumor efficacy were investigated.

Results

The Chol-SS-COS/DOX liposomes (100 nm) had zeta potential of 33.9 mV and high drug loading (13% w/w). The liposomes were stable with minimal drug leakage under physiological conditions but destabilized in the presence of reducing agents, dithiothreitol (DTT) or glutathione (GSH) at 10 mM, the cytosolic level. MTT assay revealed that the cationic Chol-SS-COS/DOX liposomes had higher cytotoxicity to MG63-osteosarcoma cells than non-reduction sensitive liposome (Chol-COS/DOX). Flow cytometry and confocal microscopy revealed that Chol-SS-COS/DOX internalized more efficiently than Chol-COS/DOX with more content to cytoplasm whereas Chol-COS/DOX located around the cell membrane. Chol-SS-COS/DOX preferentially internalized into MG63 cancer cell over LO2 normal liver cells. In rats both liposomes produced a prolonged half-life of DOX by 4 - 5.5 fold (p < 0.001) compared with the DOX solution. Chol-SS-COS/DOX exhibited strong inhibitory effect on tumor growth in MG63 cell-bearing nude mice (n = 6), and extended animal survival rate.

Conclusions

Reduction-responsive Chol-SS-COS liposomes may be an excellent platform for cytoplasmic delivery of anticancer drugs. Conjugation of liposomes with COS enhanced tumor cell uptake, antitumor effect and survival rate in animal models.

     

Novel Core-Interlayer-Shell DOX/ZnPc Co-loaded MSNs@ pH-Sensitive CaP@PEGylated Liposome for Enhanced Synergetic Chemo-Photodynamic Therapy

Purpose

This work was intended to develop novel doxorubicin (DOX)/zinc (II) phthalocyanine (ZnPc) co-loaded mesoporous silica (MSNs)@ calcium phosphate (CaP)@PEGylated liposome nanoparticles (NPs) that could efficiently achieve collaborative anticancer therapy by the combination of photodynamic therapy (PDT) and chemotherapy. The interlayer of CaP could be utilized to achieve pH-triggered controllable drug release, promote the cellular uptake, and induce cell apoptosis to further enhance the anticancer effects.

Methods

MSNs were first synthesized as core particles in which the pores were diffusion-filled with DOX, then the cores were coated by CaP followed by the liposome encapsulation with ZnPc to form the final DOX/ZnPc co-loaded MSNs@CaP@PEGylated liposome.

Results

A core-interlayer-shell MSNs@CaP@PEGylated liposomes was developed as a multifunctional theranostic nanoplatform. In vitro experiment indicated that CaP could not only achieve pH-triggered controllable drug release, promote the cellular uptake of the NPs, but also generate high osmotic pressure in the endo/lysosomes to induce cell apoptosis. Besides, the chemotherapy using DOX and PDT effect was achieved by the photosensitizer ZnPc. Furthermore, the MSNs@CaP@PEGylated liposomes showed outstanding tumor-targeting ability by enhanced permeability and retention (EPR) effect.

Conclusions

The novel prepared MSNs@CaP@PEGylated liposomes could serve as a promising multifunctional theranostic nanoplatform in anticancer treatment by synergic chemo-PDT and superior tumor-targeting ability.

     

Development and Evaluation of Tri-Functional Immunoliposomes for the Treatment of HER2 Positive Breast Cancer

Purpose

Trastuzumab combined with Doxorubicin (DOX) demonstrates significant clinical activity in human epidermal growth factor receptor-2 (HER2)-positive breast cancer (BC). However, emergence of treatment resistance and trastuzumab associated cardiotoxicity remain clinical challenges. In an effort to improve patient outcome, we have developed and evaluated novel tri-functional immunoliposomes (TFIL) that target HER2-receptors on BC cells and CD3-receptors on T-lymphocytes, and deliver DOX.

Methods

Trastuzumab (anti-HER2) and OKT-3 (anti-CD3) antibodies were conjugated to liposomes using a micelle-transfer method. Cytotoxicity of targeted immunoliposomes loaded with DOX was examined in vitro on HER2-positive BC cells (BT474), with peripheral blood monocytic cells (PBMC) as immune effector cells.

Results

TFIL demonstrated high antibody-liposome conjugation ratios (100–130 μg protein/μmol phospholipid) and cargo capacity (0.21 mol:mol drug:lipid), highly efficient DOX loading (>90%), a particle size favorable for extended circulation (~150 nm), and good stability (up to 3 months at 4°C). In the presence of PBMCs, TFIL showed complete killing of BT474 cells, and were superior to mono-targeted trastuzumab-bearing liposomes, non-targeted liposomes, and free Trastuzumab and DOX.

Conclusions

Novel anti-HER2xCD3?+?DOX TFIL show promise as a means to both engage immune cells against HER2 positive breast cancer cells and deliver chemotherapy, and have the potential to improve clinical outcomes.

     

Thermo-Sensitive Liposome co-Loaded of Vincristine and Doxorubicin Based on Their Similar Physicochemical Properties had Synergism on Tumor Treatment

Purpose

To develop vincristine (VCR) and doxorubicin (DOX) co-encapsulated thermo-sensitive liposomes (VD-TSL) against drug resistance, with increased tumor inhibition rate and decreased system toxicity, improving drug targeting efficiency upon mild hyperthermia (HT) in solid tumor.

Methods

Based on similar physicochemical properties, VCR and DOX were co-loaded in TSL with pH gradient active loading method and characterized. The time-dependent drug release profiles at 37 and 42°C were assessed by HPLC. Then we analysed the phospholipids in filtrate after ultrafiltration and studied VD-TSL stability in mimic in vivo conditions and long-time storage conditions (4°C and ?20°C). Cytotoxic effect was studied on PANC and sw-620 using MTT. Intracellular drug delivery was studied by confocal microscopy on HT-1080. In vivo imaging of TSL pharmacokinetic and biodistribution was performed on MCF-7 tumor-bearing nude mice. And therapeutic efficacy on these xenograft models were followed under HT.

Results

VD-TSL had excellent particle distribution (about 90 nm), high entrapment efficiency (>95%), obvious thermo-sensitive property, and good stability. MTT proved VD-TSL had strongest cell lethality compared with other formulations. Confocal microscopy demonstrated specific accumulation of drugs in tumor cells. In vivo imaging proved the targeting efficiency of TSL under hyperthermia. Then therapeutic efficacy revealed synergism of VCR and DOX co-loaded in TSL, together with HT.

Conclusion

VD-TSL could increase drug efficacy and decrease system toxicity, by making good use of synergism of VCR and DOX, as well as high targeting efficiency of TSL.

     

Biodegradable Polymersomes as Nanocarriers for Doxorubicin Hydrochloride: Enhanced Cytotoxicity in MCF-7/ADR Cells and Prolonged Blood Circulation

Purpose

DOX is one of the most potent anticancer drugs. But its short half-life and the occurrence of multi-drug resistance (MDR) markedly limit its clinical application. To solve these problems, we develop DOX loaded polymersomes (DOX polymersomes).

Methods

An methoxy poly(ethylene glycol)-b-poly(epsilon-caprolactone) (mPEG-b-PCL) copolymer was synthesized and used to prepare DOX polymersomes. The pharmaceutical properties of DOX polymersomes were characterized. The in vitro release profile of DOX from polymersomes was investigated. The in vitro cytotoxicity and cell uptake studies were performed on MCF-7 and MCF-7/ADR cells. The in vivo pharmacokinetic profiles were investigated on Sprague–Dawley rats.

Results

DOX polymersomes had a nano-scale particle size of about 60 nm with a hydrophobic membrane about 10 nm in thickness. Release of DOX from the polymersomes took place in a sustained manner. Cell experiments showed DOX polymersomes enhanced the cytotoxicity and the intracellular accumulation of DOX in MCF-7/ADR cells, compared with free DOX. In vivo pharmacokinetic study showed the DOX polymersomes increased the bioavailability and prolonged the circulation time in rats.

Conclusions

The entrapment of DOX in biodegradable polymersomes could enhance cytotoxicity in MCF-7/ADR cells and improve its in vivo pharmacokinetic profile.

     

Real-Time UV Imaging of Nicotine Release from Transdermal Patch

Purpose

This study was conducted to characterize UV imaging as a platform for performing in vitro release studies using Nicorette® nicotine patches as a model drug delivery system.

Methods

The rate of nicotine release from 2 mm diameter patch samples (Nicorette®) into 0.067 M phosphate buffer, pH 7.40, was studied by UV imaging (Actipix SDI300 dissolution imaging system) at 254 nm. The release rates were compared to those obtained using the paddle-over-disk method.

Results

Calibration curves were successfully established which allowed temporally and spatially resolved quantification of nicotine. Release profiles obtained from UV imaging were in qualitative agreement with results from the paddle-over-disk release method.

Conclusion

Visualization as well as quantification of nicotine concentration gradients was achieved by UV imaging in real time. UV imaging has the potential to become an important technology platform for conducting in vitro drug release studies.

     

Comparative Study of Different Nano-Formulations of Curcumin for Reversal of Doxorubicin Resistance in K562R Cells

Purpose

Curcumin is very well established as a chemo-therapeutic, chemo-preventive and chemo-sensitizing agent in diverse disease conditions. As the isolated pure form has poor solubility and pharmacokinetic problems, therefore it is encapsulated in to several nano-formulations to improve its bioavailability. Here in the current study, we aim to compare different nano-formulations of curcumin for their chemo-sensitizing activity in doxorubicin (DOX) resistant K562 cells.

Methods

Four different curcumin formulations were prepared namely DMSO assisted curcumin nano-dispersion (CurD, 260 nm), liposomal curcumin (CurL, 165 nm), MPEG-PCL micellar curcumin (CurM, 18 nm) and cyclodextrin encapsulated curcumin (CurN, 37 nm). The formulations were subjected to particle characterizations (size, zeta potential, release studies), followed by biological assays such as cellular uptake, P-gp inhibitory activity and reversal of DOX resistance by co-treatment with DOX.

Results

Curcumin uptake in K562N and K562R cells was mildly reduced when treated with CurL and CurM, while for CurD and CurN the uptake remained equivalent. However, CurL retained P-gp inhibitory activity of curcumin and with a considerable chemo-sensitizing effect but CurM showed no P-gp inhibitory activity. CurN retained above biological activities, but requires a secondary carrier under in vivo conditions.

Conclusions

From the results, CurM was found to be most suitable for solubilization of curcumin where as CurL can be considered as most suitable nano-formulation for reversal of DOX resistance.

     

Drug Release from ß-Cyclodextrin Complexes and Drug Transfer into Model Membranes Studied by Affinity Capillary Electrophoresis

Purpose

Is to characterize the drug release from the ß-cyclodextrin (ß-CD) cavity and the drug transfer into model membranes by affinity capillary electrophoresis. Phospholipid liposomes with and without cholesterol were used to mimic the natural biological membrane.

Methods

The interaction of cationic and anionic drugs with ß-CD and the interaction of the drugs with liposomes were detected separately by measuring the drug mobility in ß-CD containing buffer and liposome containing buffer; respectively. Moreover, the kinetics of drug release from ß-CD and its transfer into liposomes with or without cholesterol was studied by investigation of changes in the migration behaviours of the drugs in samples, contained drug, ß-CD and liposome, at 1:1:1 molar ratio at different time intervals; zero time, 30 min, 1, 2, 4, 6, 8, 10 and 24 h. Lipophilic drugs such as propranolol and ibuprofen were chosen for this study, because they form complexes with ß-CD.

Results

The mobility of the both drug liposome mixtures changed with time to a final state. For samples of liposomal membranes with cholesterol the final state was faster reached than without cholesterol.

Conclusions

The study confirmed that the drug release from the CD cavity and its transfer into the model membrane was more enhanced by the competitive displacement of the drug from the ß-CD cavity by cholesterol, the membrane component. The ACE method here developed can be used to optimize the drug release from CD complexes and the drug transfer into model membranes.

     

Effect of Chemical Binding of Doxorubicin Hydrochloride to Gold Nanoparticles, <Emphasis Type="Italic">Versus</Emphasis> Electrostatic Adsorption,on the <Emphasis Type="Italic">In Vitro</Emphasis> Drug Release and Cytotoxicity to Breast Cancer Cells

Purpose

The selective delivery of chemotherapeutic agent to the affected area is mainly dependent on the mode of drug loading within the delivery system. This study aims to compare the physical method to the chemical method on the efficiency of loading DOX.HCl to GNPs and the specific release of the loaded drug at certain tissue.

Method

Bifunctional polyethylene glycol with two different functionalities, the alkanethiol and the carboxyl group terminals, was synthesized. Then, DOX·HCl was covalently linked via hydrazone bond, a pH sensitive bond, to the carboxyl functional group and the produced polymer was used to prepare drug functionalized nanoparticles. Another group of GNPs was coated with carboxyl containing polymer; loading the drug into this system by the means of electrostatic adsorption. Finally, the prepared system were characterized with respect to size, shape and drug release in acetate buffer pH 5 and PBS pH 7.4 Also, the effect of DOX.HCl loaded systems on cell viability was assessed using MCF-7 breast cancer cell line.

Results

The prepared nanoparticles were spherical in shape, small in size and monodisperse. The release rate of the chemically bound drug in the acidic pH was higher than the electrostatically adsorbed one. Moreover, both systems show little release at pH 7.4. Finally, cytotoxicity profiles against human breast adenocarcinoma cell line (MCF-7) exhibited greater cytotoxicity of the chemically bound drug over the electrostatically adsorbed one.

Conclusion

Chemical binding of DOX·HCl to the carboxyl group of PEG coating GNPs selectively delivers high amount of drug to tumour-affected tissue which leads to reducing the unwanted effects of the drug in the non-affected ones.

     

Sustained Release from Ionic-Gradient Liposomes Significantly Decreases ETIDOCAINE Cytotoxicity

Purpose

Etidocaine (EDC) is a long lasting local anesthetic, which alleged toxicity has restricted its clinical use. Liposomes can prolong the analgesia time and reduce the toxicity of local anesthetics. Ionic gradient liposomes (IGL) have been proposed to increase the upload and prolong the drug release, from liposomes.

Methods

First, a HPLC method for EDC quantification was validated. Then, large unilamellar vesicles composed of hydrogenated soy phosphatidylcholine:cholesterol with 250 mM (NH₄)₂SO₄ - inside gradient - were prepared for the encapsulation of 0.5% EDC. Dynamic light scattering, nanotracking analysis, transmission electron microscopy and electron paramagnetic resonance were used to characterize: nanoparticles size, polydispersity, zeta potential, concentration, morphology and membrane fluidity. Release kinetics and in vitro cytotoxicity tests were also performed.

Results

IGL_EDC showed average diameters of 172.3?±?2.6 nm, low PDI (0.12?±?0.01), mean particle concentration of 6.3?±?0.5?×?10¹²/mL and negative zeta values (?10.2?±?0.4 mV); parameters that remain stable during storage at 4°C. The formulation, with 40% encapsulation efficiency, induced the sustained release of EDC (ca. 24 h), while reducing its toxicity to human fibroblasts.

Conclusion

A novel formulation is proposed for etidocaine that promotes sustained release and reduces its cytotoxicity. IGL_EDC can come to be a tool to reintroduce etidocaine in clinical use.

     

Electrosprayed Myocet-like Liposomes: An Alternative to Traditional Liposome Production

Purpose

Although doxorubicin (DXR) has been on the market for many years as an anti-cancer drug, a number of serious dose-limiting toxicities hinder its widespread use. To reduce the known toxicities of soluble DXR, various liposomes have been designed including Doxil, Caelyx, and Myocet. Myocet, a non-PEGylated liposomal formulation containing DXR, was found to reduce the toxicities associated with soluble DXR and has been used in Europe and Canada (but not the US) as a first line therapy. While regarded as successful, Myocet does have some formulation drawbacks including stability, drug release, and an arduous formulation and remote loading method for preparation.

Methods

Our lab has developed a liposomal electrospray process in which formulation and remote loading occurs continuously in one step, cutting down on the total time of production and increasing the drug retention in the liposomes with respect to more conventional methods. Electrosprayed Myocet-like liposomes were then tested in vitro for release kinetics and cytotoxicity with respect to a more conventional formulation method.

Results

Myocet-like liposomes manufactured via electrospray had similar DXR loadings, hydrodynamic diameters, morphologies, and cytotoxic profiles as their thin-film hydration counterparts, but their release profiles were drastically prolonged.

Conclusions

Our findings indicate that electrospray is a viable manufacturing procedure to scalably produce Myocet-like liposomes that appear to be more stable than those formulated through thin-film hydration.

     

Hollow Microparticles as a Superior Delivery System over Solid Microparticles for the Encapsulation of Peptides

Purpose

Peptides are gaining significant interests as therapeutic agents due to their high targeting specificity and potency. However, their low bioavailability and short half-lives limit their massive potential as therapeutics. The use of dense, solid particles of biodegradable polymer as a universal carrier for peptides also has its challenges, such as inefficient peptide release and low bioactivity. In this paper, it was established that hollow microparticles (h-MPs) instead of solid microparticles (s-MPs), as peptide carriers, could improve the release efficiency, while better preserving their bioactivity.

Methods

Glucagon like Peptide-1 (GLP-1) was encapsulated as a model peptide. Mass loss, average molecular weight changes, intraparticle pH, polymer-peptide interaction and release studies, together with bioactivity assessment of the peptide for s-MPs and h-MPs were systematically analyzed and evaluated for efficacy.

Results

The intraparticle pH of s-MPs was as low as 2.64 whereas the pH of h-MPs was 4.99 by day 7. Consequently, 93% of the peptide extracted from h-MPs was still bioactive while only 58% of the peptide extracted from s-MPs was bioactive. Likewise, the cumulative release of GLP-1 by day 14 from h-MPs showed a cumulative amount of 88?±?8% as compared to 33?±?6% for s-MPs.

Conclusions

The cumulative release of peptide can be significantly improved, and the bioactivity can be better preserved by simply using h-MPs instead of s-MPs as carriers.

     

Quantitative <Emphasis Type="BoldItalic">In Vitro</Emphasis> Assessment of Liposome Stability and Drug Transfer Employing Asymmetrical Flow Field-Flow Fractionation (AF4)

Purpose

In the present study we introduce an efficient approach for a size-based separation of liposomes from plasma proteins employing AF4. We investigated vesicle stability and release behavior of the strongly lipophilic drug temoporfin from liposomes in human plasma for various incubation times at 37°C.

Methods

We used the radioactive tracer cholesteryl oleyl ether (COE) or dipalmitoyl-phosphocholine (DPPC) as lipid markers and ¹⁴C-labeled temoporfin. First, both lipid labels were examined for their suitability as liposome markers. Furthermore, the influence of plasma origin on liposome stability and drug transfer was investigated. The effect of membrane fluidity and PEGylation on vesicle stability and drug release characteristics was also analyzed.

Results

Surprisingly, we observed an enzymatic transfer of ³H-COE to lipoproteins due to the cholesterol ester transfer protein (CETP) in human plasma in dependence on membrane rigidity and were able to inhibit this transfer by plasma preincubation with the CETP inhibitor torcetrapib. This effect was not seen when liposomes were incubated in rat plasma. DPPC labels suffered from hydrolysis effects during preparation and/or storage. Fluid liposomes were less stable in human plasma than their PEGylated analogues or a rigid formulation. In contrast, the transfer of the incorporated drug to lipoproteins was higher for the rigid formulations.

Conclusions

The observed effects render COE-labels questionable for in vivo studies using CEPT-rich species. Here, choline labelled ¹⁴C-DPPC was found to be the most promising alternative. Bilayer composition has a high influence on stability and drug release of a liposomal formulation in human plasma.

     

Reversion of Multidrug Resistance by Co-Encapsulation of Doxorubicin and Metformin in Poly(lactide-co-glycolide)-d-α-tocopheryl Polyethylene Glycol 1000 Succinate Nanoparticles

Purpose

P-glycoprotein (P-gp) mediated multidrug resistance (MDR) has been recognized as the main obstacle against successful cancer treatment. To address this problem, co-encapsulated doxorubicin (DOX) and metformin (Met) in a biodegradable polymer composed of poly(lactide-co-glycolide) (PLGA) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) was prepared. We reported in our previous study that Met inhibits P-gp in DOX resistant breast cancer (MCF-7/DOX) cells. TPGS is a bioactive compound which has also been shown to inhibit P-gp, further to its pharmaceutical advantages.

Methods

The DOX/Met loaded PLGA-TPGS nanoparticles (NPs) were prepared by double emulsion method and characterized for their surface morphology, size and size distribution, and encapsulation efficiencies of drugs in NPs.

Results

All NPs were found to be spherical-shaped with the size distribution below 100 nm and encapsulation efficiencies were 42.26?±?2.14% for DOX and 7.04?±?0.52% for Met. Dual drug loaded NPs showed higher cytotoxicity and apoptosis in MCF-7/DOX cells in comparison to corresponding free drugs. The higher cytotoxicity of dual drug loaded NPs was attributed to the enhanced intracellular drug accumulation due to enhanced cellular uptake and reduced drug efflux which was obtained by combined effects of Met and TPGS in reducing cellular ATP content and inhibiting P-gp.

Conclusion

Simultaneous delivery of DOX and Met via PLGA-TPGS NPs would be a promising approach to overcome MDR in breast cancer chemotherapy.

     

A Multi-Functional Tumor Theranostic Nanoplatform for MRI Guided Photothermal-Chemotherapy

Purpose

To develop a multi-functional theranostic nanoplatform with increased tumor retention, improving antitumor efficacy and decreased side effects of chemotherapy drugs.

Methods

GO@Gd nanocomposites was synthesized via decorating gadolinium (Gd) nanoparticles (GdNP) onto graphene oxide (GO), and then functionalized by polyethylene glycol (PEG2000), folic acid (FA), a widely used tumor targeting molecule, was linked to GO@Gd-PEG, finally, doxorubicin (DOX) was loaded onto GO@Gd-PEG-FA and obtained a tumor-targeting drug delivery system (GO@Gd-PEG-FA/DOX). GO@Gd-PEG-FA/DOX was characterized and explored its theranostic applications both in a cultured MCF-7 cells and tumor-bearing mice.

Results

GO@Gd-PEG-FA/DOX could efficiently cross the cell membranes, lead to more apoptosis and afford higher antitumor efficacy without obvious toxic effects to normal organs owing to its prolonged blood circulation and 7.6-fold higher DOX uptake of tumor than DOX. Besides, GO@Gd-PEG-FA/DOX also served as a powerful photothermal therapy (PTT) agent for thermal ablation of tumor and a strong T1-weighted contrast agent for tumor MRI diagnosis. The multi-functional nanoplatform also could selectively kill cancer cells in highly localized regions via the excellent tumor-targeting and MRI guided PTT abilities.

Conclusions

GO@Gd-PEG-FA/DOX exhibited excellent photothermal-chemotherapeutic efficacy, tumor-targeting property and tumor diagnostic ability.

     

Pharmacokinetics,Tissue Distribution and Therapeutic Effect of Cationic Thermosensitive Liposomal Doxorubicin Upon Mild Hyperthermia

Purpose

To evaluate pharmacokinetic profile, biodistribution and therapeutic effect of cationic thermosensitive liposomes (CTSL) encapsulating doxorubicin (Dox) upon mild hyperthermia (HT).

Methods

Non-targeted thermosensitive liposomes (TSL) and CTSL were developed, loaded with Dox and characterized. Blood kinetics and biodistribution of Dox-TSL and Dox-CTSL were followed in B16BL6 tumor bearing mice upon normothermia (NT) or initial hyperthermia conditions. Efficacy study in B16BL6 tumor bearing mice was followed with Dox-TSL or Dox-CTSL upon NT or HT. Efficacy study in LLC tumor bearing mice was performed upon two HT conditions. Intravital microscopy was performed on B16BL6 tumors implanted in dorsal-skin fold window-bearing mice.

Results

Targeting did not cause faster blood clearance of CTSL compared to TSL. Highest uptake of liposomes was observed in spleen, kidneys and liver. Applying HT prior to CTSL administration increased drug delivery to the tumor and CTSL delivered ~1.7 fold higher Dox concentration compared to TSL. Efficacy in B16BL6 murine melanoma showed that HT had a significant effect on CTSL in tumor suppression and prolonged survival. Efficacy in LLC Lewis lung carcinoma tumor model demonstrates that two HT treatments hold promises for a successful treatment option.

Conclusion

CTSL have potency to increase drug efficacy in tumors due to their targeted and drug release functions.

     

Co-Delivery of Ciprofloxacin and Colistin in Liposomal Formulations with Enhanced <Emphasis Type="BoldItalic">In Vitro</Emphasis> Antimicrobial Activities against Multidrug Resistant <Emphasis Type="BoldItalic">Pseudomonas aeruginosa</Emphasis>

Purpose

This study aims to develop liposomal formulations containing synergistic antibiotics of colistin and ciprofloxacin for the treatment of infections caused by multidrug-resistant Pseudomonas aeruginosa.

Methods

Colistin (Col) and ciprofloxacin (Cip) were co-encapsulated in anionic liposomes by ammonium sulfate gradient. Particle size, encapsulation efficiency, in vitro drug release and in vitro antibiotic activities were evaluated.

Results

The optimized liposomal formulation has uniform sizes of approximately 100 nm, with encapsulation efficiency of 67.0% (for colistin) and 85.2% (for ciprofloxacin). Incorporation of anionic lipid (DMPG) markedly increased encapsulation efficiency of colistin (from 5.4 to 67.0%); however, the encapsulation efficiency of ciprofloxacin was independent of DMPG ratio. Incorporation of colistin significantly accelerated the release of ciprofloxacin from the DMPG anionic liposomes. In vitro release of ciprofloxacin and colistin in the bovine serum for 2 h were above 70 and 50%. The cytotoxicity study using A549 cells showed the liposomal formulation is as non-toxic as the drug solutions. Liposomal formulations of combinations had enhanced in vitro antimicrobial activities against multidrug resistant P. aeruginosa than the monotherapies.

Conclusions

Liposomal formulations of two synergistic antibiotics was promising against multidrug resistant P. aeruginosa infections.

     

Combined Used of Rheology and LF-NMR for the Characterization of PVP-Alginates Gels Containing Liposomes

Purpose

This paper is based on the characterization of the rheological and Low Field NMR (LF-NMR) properties of an interpenetrated hydrogel made up by poly(N-vinyl-2-pyrrolidone) and sodium alginate. The final aim is to use the hydrogel as a delivery matrix for liposomes, widely used tools in the drug delivery field.

Methods

Rheology, LF-NMR, TEM, cryo-TEM, confocal laser scanning microscopy and release test were employed to characterize the interpenetrated hydrogel. Different theoretical approaches such as Flory, Chui, Scherer and Schurz theories were used to interpret the experimental results.

Results

We found that the crosslinking mechanisms of the two polymers produced an anti-synergistic effect on the final mechanical properties of the interpenetrated hydrogel. Instead of creating a continuous network, alginate formed isolated, cross-linked, clusters embedded in a continuous network of poly(N-vinyl-2-pyrrolidone). Additionally, gel structure significantly influenced liposome delivery.

Conclusions

The rheological and LF-NMR characterization were confirmed and supported by the independent techniques TEM, cryo-TEM and release tests Thus, our findings reiterate the potentiality of both rheology and LF-NMR for the characterisation of soft materials such as interpenetrated polymeric networks.

     

The Effect of Surface Charges on the Cellular Uptake of Liposomes Investigated by Live Cell Imaging

Purpose

Liposomes have been developed as versatile nanocarriers for various pharmacological agents. The effect of surface charges on the cellular uptake of the liposomes has been studied by various methods using mainly fixed cells with inevitable limitations. Live cell imaging has been proposed as an alternative methods to overcome the limitations of the fixed cell-based analysis. In this study, we aimed to investigate the effects of surface charges on cellular association and internalization of the liposomes using live cell imaging.

Methods

We studied the cellular association and internalization of liposomes with different surface charge using laser scanning confocal microscopy (LSCM) equipped with live cell chamber system. Flow cytometry was also carried out using flow cytometer (FACS) for comparison.

Results

All of the cationic, neutral and anionic liposomes showed time-dependent cellular uptake through specific endocytic pathways. In glioblastoma U87MG cells, the cationic and anionic liposomes were mainly taken up via macropinocytosis, while the neutral liposomes mainly via caveolae-mediated endocytosis. In fibroblast NIH/3T3 cells, all of the three liposomes entered into the cell via clathrin-mediated endocytosis.

Conclusions

This study provides a better understanding on the cellular uptake mechanisms of the liposomes, which could contribute significantly to development of liposome-based drug delivery systems.

     

A Cell Assay for Detecting Anti-PEG Immune Response against PEG-Modified Therapeutics

Purpose

Immunogenicity of PEGylated proteins and nanomedicines represents a potential impediment against their development and use in clinical settings. The purpose of this study is to develop a method for detecting anti-PEG immunity of PEGylated proteins and/or nanomedicines using flow cytometry.

Methods

The binding of fluorescence-labeled mPEG-modified liposomes to HIK-G11 cells, PEG-specific hybridoma cells, or spleen cells was evaluated by flow cytometry for detecting immunogenicity of PEGylated therapeutics.

Results

The fluorescence-labeled methoxy PEG (mPEG)-modified liposomes were efficiently bound to HIK-G11 cells. Such staining with fluorescence-labeled mPEG-modified liposomes was significantly inhibited in the presence of either non-labeled mPEG-modified liposomes or mPEG-modified ovalbumin (OVA) but not polyglycerol-modified liposomes. In addition, we found that mPEG-modified liposomes, highly immunogenic, caused proliferation of PEG-specific cells, while hydroxyl PEG-modified liposomes, less immunogenic, scarcely caused. Furthermore, after intravenous injection of mPEG-modified liposomes, the percentage of PEG-specific cells in the splenocytes, as determined by flow cytometry, corresponded well with the production level of anti-PEG antibodies, as determined by ELISA.

Conclusions

PEG-specific B cell assay we introduced may become a useful method to detect an anti-PEG immune response against PEGylated therapeutics and clarify the mechanism for anti-PEG immune responses.