Oxidized phospholipid based pH sensitive micelles for delivery of anthracyclines to resistant leukemia cells in vitro

A self-assembled micelle drug delivery system was constructed with an oxidized phospholipid for anthracycline anti-cancer drug delivery. An oxidized phospholipid, 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazPC), was chosen to fabricate micelles via both electrostatic and hydrophobic interactions for delivery of doxorubicin (DOX) and idarubicin (IDA). The formation of ion-pair complexes between PazPC and DOX was first investigated under different pH conditions. Drug-loaded PazPC micelles at a 5:1 molar ratio of lipid/drug at pH 7.0 were then prepared by the solvent evaporation method. The empty and drug-loaded PazPC micelles exhibited a small particle size (～10 nm) and high encapsulation efficiency. In vitro stability and release profile indicated that the micelles were stable at physiological conditions, but exhibited pH-sensitive behavior with accelerated release of DOX or IDA in an acidic endosome environment. Finally, in vitro uptake and cytotoxicity were evaluated for leukemia P388 and its resistant subline P388/ADR. The drug-loaded PazPC micelles enhanced drug uptake and exhibited higher cytotoxicity in both leukemia cells in comparison to free drugs. In conclusion, we developed a novel pH sensitive oxidized phospholipid-based micellar formulation which could potentially be useful in delivering anthracycline anti-cancer drugs and provide a novel strategy for increasing the therapeutic index while overcoming multidrug resistance for leukemia treatment.     

Stability Influences the Biodistribution, Toxicity, and Anti-tumor Activity of Doxorubicin Encapsulated in PEG-PE Micelles in Mice

Purpose

To investigate the influences of stability of doxorubicin (DOX) retained in PEG-PE/HSPC micelles on its biodistribution, toxicity and anti-tumor activity in mice.

Methods

We incorporated HSPC into PEG-PE micelles at various molar ratios by a self-assembly procedure. Micelles were characterized by dynamic light scattering, transmission electron microscope, atomic force microscopy. Agarose gel electrophoresis assay was used to detect stable retention of DOX in micellar preparations. Biodistribution, toxicity and anti-tumor activity of doxorubicin encapsulated in PEG-PE/HSPC micelles in mice were investigated.

Results

HSPC incorporation not only changed the size and shape of PEG-PE micelles, but also decreased the ability of DOX stable retained in PEG-PE micelles, resulting in a great discrepancy in biodistribution, toxicity and anti-tumor activity among micellar DOX preparations. DOX encapsulated in PEG-PE micelles (M₁-DOX), with narrower size distribution and greater stability, demonstrated better cytotoxicity in vitro and low systemic toxicity with superior anti-tumor metastasis activity in vivo.

Conclusions

Encapsulation of DOX into PEG-PE micelles showed the best therapeutic activity and lowest systemic toxicity compared to other HSPC-incorporated PEG-PE micellar preparations. Stable retention of drugs within micelles is important and is determined by compatibility between drugs and polymer blocks.     

NIR-/pH-Responsive Drug Delivery of Functionalized Single-Walled Carbon Nanotubes for Potential Application in Cancer Chemo-Photothermal Therapy

Purpose

To establish a NIR (near infrared)-/pH-responsive and sustained-release tumor-targeting drug delivery system (SWNT-PEI/DOX/NGR).

Methods

Functionalized SWNTs with polymerised polymeric poly(ethylene imine) was linked NGR (Asn-Gly-Arg) tumor-targeting peptide by DSPE-PEG2000-Maleimide via the maleimide group and sulfhydryl group of cysteine, in the end, doxorubicin (DOX) was attached to SWNT-PEI to obtain a SWNT-PEI/DOX/NGR delivery system.

Results

The SWNT-PEI/DOX/NGR delivery system has significantly sustained-release effect and the slow release of DOX in normal tissues contribute to reduced systemic toxicity, while under 808 nm NIR laser irradiation or under lower pH environment the release of DOX can be accelerated.

Conclusions

Due to hyperthermia sensitizer effect of DOX, chemo-photothermal exemplified by SWNT-PEI/DOX/NGR tumor-targeting delivery system is a promising approach to anticancer therapy in vivo or in vitro.     

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.

     

Mitochondrial Delivery of Doxorubicin by Triphenylphosphonium-Functionalized Hyperbranched Nanocarriers Results in Rapid and Severe Cytotoxicity

Purpose

To develop a novel hyperbranched polymer-based nanocarrier for efficient drug delivery to cell mitochondria. Also to study for the first time the cytotoxic effect of doxorubicin via mitochondria-specific delivery system.

Methods

We introduced alkyltriphenylphosphonium groups (TPP) to a poly(ethylene imine) hyperbranched polymer (PEI). We harnessed the hydrophobic assembly of these alkylTPP functionalized PEI molecules into ~100 nm diameter nanoparticles (PEI-TPP) and further encapsulated the chemotherapy agent doxorubicin (DOX), to produce the mitotropic nanoparticles PEI-TPP-DOX.

Results

By administering PEI-TPP-DOX to human prostate carcinoma cells DU145, we found that: (i) PEI-TPP-DOX specifically localized at cell mitochondria as revealed by the inherent DOX fluorescence; (ii) in contrast to the slow apoptotic cell death incurred by DOX over the period of days at micromolar concentrations, PEI-TPP-DOX triggered rapid and severe cytotoxicity within few hours of incubation and at submicromolar incubation concentrations. This cytotoxicity was mainly found to be of a necrotic nature, not precluding autophagy related death pathways to a smaller extent.

Conclusions

We have elaborated a versatile mitotropic nanocarrier; furthermore, using this platform, we have developed a mitochondrial-doxorubicin formulation with exceptional cytocidal properties, even in nanomolar concentrations.

Ultrasound-enhanced chemotherapy of drug-resistant breast cancer tumors by micellar-encapsulated Paclitaxel

Background and aim

Currently, delivery of the poorly water-soluble chemotherapeutic agent paclitaxel is associated with a substantial array of systemic toxicities and results in low-efficiency tumor treatment. A novel on-demand delivery system based on paclitaxel encapsulated in polymeric micelles in conjunction with triggered release of the drug by local ultrasonic irradiation of the tumor was evaluated in vitro and in vivo using a drug-resistant MCF7/ADmt breast cancer human cell line.

Method

The effects of local ultrasonic tumor irradiation on cellular proliferation and intracellular drug uptake were compared for a developmental micellar paclitaxel formulation (SYP-PM) and a currently available clinical intravenous formulation of paclitaxel.

Results

Without ultrasound, the uptake of paclitaxel from the micellar formulation was significantly lower than that from the clinical formulation, which is advantageous for preventing unwanted drug interactions with healthy tissues in vivo. When micellar encapsulation was combined with ultrasonically triggered release, drug uptake from micellar paclitaxel was increased more than 20-fold and cellular proliferation was inhibited by nearly 90%. Without ultrasound, the clinical formulation of paclitaxel and SYP-PM manifested low efficacy in vivo, whereas injections of SYP-PM combined with ultrasound resulted in complete tumor resolution.

Conclusion

The ability of micellar-encapsulated paclitaxel to exert a significant cytotoxic effect only when subjected to ultrasound proves promising for the development of a tumor-targeted ultrasound-enhanced paclitaxel delivery system for clinical application. This treatment modality could be successfully used for the therapy of both drug-sensitive and drug-resistant tumors. The major advantages of a micellar formulation of paclitaxel combined with local tumor sonication are the aqueous base of the drug formulation, reduced systemic toxicity, potential for tumor targeting, and on-demand delivery of drug to tumor cells.     

PEG-Stabilized Micellar System with Positively Charged Polyester Core for Fast pH-Responsive Drug Release

Purpose

To design functional drug carriers for fast pH-responsive drug release.

Methods

Functional diblock terpolymers of monomethoxy poly(ethylene glycol)-block- copoly(6,14-dimethyl-1,3,9,11-tetraoxa-6,14-diaza-cyclohexadecane-2,10-dione-co-??-caprolactone) [mPEG-b-poly(ADMC-co-CL)] were fabricated via biosynthetic pathway. The self-assembled nanosphere and drug-loaded micelles of the copolymers were further prepared by dialysis method. The pH-tunable morphology variation and drug release pattern were observed at different pH.

Results

A collection of three PEGylated terpolymers with varied compositions in poly(ADMC-co-CL) block was designed with high cell-biocompatibility. The copolymers could readily self-assemble into nanoscale micelles (~ 100?nm) in aqueous medium and exhibit high stability over 80-h incubation in different mediums including deionized water, neutral NaCl solution, and heparin sodium solution. Due to the protonation-deprotonation of tertiary amine groups in ADMC units, acid-induced structural deformation of micelles was disclosed in terms of the variation in CAC value and hydrodynamic size at different pH. Drug loading efficiency was comparable to that of reported PEG-polyester micelles with specifically designed structures purposed for drug-loading improvement. Remarkably accelerated drug release triggered by acidity was distinctly detected for ibuprofen-loaded mPEG-b-poly(ADMC-co-CL) micelle system, suggesting a fast pH-responsive characteristic.

Conclusion

Functional PEG-stabilized micellar carriers with positively charged polyester core were successfully developed for fast pH-responsive drug release.     

Photo-Inducible Crosslinked Nanoassemblies for pH-Controlled Drug Release

Purpose

To control drug release from block copolymer nanoassemblies by variation in the degree of photo-crosslinking and inclusion of acid sensitive linkers.

Methods

Poly(ethylene glycol)-poly(aspartate-hydrazide-cinnamate) (PEG-CNM) block copolymers were prepared and conjugated with a model drug, doxorubicin (DOX), through acid sensitive hydrazone linkers. The block copolymers formed photo-inducible, self-assembled nanoassemblies (piSNAs), which were used to produce photo-inducible crosslinked nanoassemblies (piCNAs) through UV crosslinking. The nanoassemblies were characterized to determine particle size, surface charge, pH- and crosslinking-dependent DOX release, in vitro cytotoxicity, and intracellular uptake as a function of photo-crosslinking degree.

Results

Nanoassemblies with varying photo-crosslinking degrees were successfully prepared while retaining particle size and surface charge. Photo-crosslinking caused no noticeable change in DOX release from the nanoassemblies at pH 7.4, but the DOX-loaded nanoassemblies modulated drug release as a function of crosslinking at pH 6.0. The nanoassemblies showed similar cytotoxicity regardless of crosslinking degrees, presumably due to the low cellular uptake and cell nucleus drug accumulation.

Conclusions

Photo-crosslinking is useful to control drug release from pH-sensitive block copolymer nanoassemblies as a function of crosslinking without altering the particle properties, and thus providing unique tools to investigate the pharmaceutical effects of drug release on cellular response.     

Simulation of Stimuli-Responsive and Stoichiometrically Controlled Release Rate of Doxorubicin from Liposomes in Tumor Interstitial Fluid

Purpose

To simulate the stimuli-responsive and stoichiometrically controlled doxorubicin (DOX) release from liposomes in in vivo tumor interstitial fluid (TIF), the effect of ammonia concentration and pH on the DOX release from liposomes in human plasma at 37°C was quantitatively evaluated in vitro and the release rate was calculated as a function of ammonia concentration and pH.

Methods

Human plasma samples spiked with DOX-loaded PEGylated liposomes (PLD) or Doxil^®, containing ammonia (0.3–50 mM) at different pH values, were incubated at 37°C for 24 h. After incubation, the concentration of encapsulated DOX in the samples was determined by validated solid-phase extraction (SPE)-SPE-high performance liquid chromatography.

Results

Accelerated DOX release (%) from liposomes was observed as the increase of ammonia concentration and pH of the matrix, and the decrease of encapsulated DOX concentration. The release rate was expressed as a function of the ammonia concentration and pH by using Henderson-Hasselbalch equation.

Conclusions

The DOX release from PLD in TIF was expressed as a function ammonia concentration and pH at various DOX concentrations. Further, it was found that the DOX release from liposomes in a simulated TIF was more than 15 times higher than in normal plasma.

     

Hyaluronic Acid Derivative-Based Self-Assembled Nanoparticles for the Treatment of Melanoma

Purpose

Hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs) were developed for the targeted delivery of doxorubicin (DOX), and their antitumor efficacy for melanoma was evaluated.

Methods

DOX-loaded HACE-based self-assembled NPs were prepared and their physicochemical properties were characterized. The in vitro cytotoxicity of HACE was measured using an MTS-based assay. The cellular uptake efficiency of DOX into mouse melanoma B16F10 cells was assessed by confocal laser scanning microscopy and flow cytometry. Tumor growth and body weight were monitored after the intratumoral and intravenous injection of DOX-loaded NPs into a B16F10 tumor-bearing mouse model.

Results

DOX-loaded NPs, with a mean diameter of ~110?nm, a narrow size distribution, and high drug entrapment efficiency, were prepared. A sustained DOX release pattern was shown, and drug release was enhanced at pH 5.5 compared with pH 7.4. The cytotoxicity of HACE to B16F10 cells was negligible. It was assumed that DOX was taken up into the B16F10 cells through receptor-mediated endocytosis. A significant inhibitory effect was observed on tumor growth, without any serious changes in body weight, after the injection of DOX-loaded NPs into the B16F10 tumor-bearing mouse model.

Conclusions

DOX-loaded HACE-based NPs were successfully developed and their antitumor efficacy against B16F10 tumors was demonstrated.     

Is an Alternative Drug Delivery System Needed for Docetaxel? The Role of Controlling Epimerization in Formulations and Beyond

Purpose

The presence of 7-epidocetaxel in docetaxel injection and in vivo epimerisation has been reported to be the cause for development of tumor resistance to chemotherapy including docetaxel by inducing tumor cell protein cytochrome P450 1B1. The objective of this study was to determine systemic toxicity of Taxotere® containing 10% 7-epidocetaxel and to develop PEGylated liposomal injection that could resist epimerization in vivo. Another need for PEGylated liposomal delivery of docetaxel is to avoid reported hypersensitivity reactions of marketed products like Taxotere® and Duopafei® containing high concentration of tween-80.

Methods

The PEGylated liposomes loaded with docetaxel were prepared using thin film hydration method. The in vivo toxicity of Taxotere® containing 10% 7-epimer was studied in B16F10 experimental metastasis model.

Results

B16F10 experimental metastasis model using C57BL/6 mice injected with Taxotere® containing 10% 7-epimer showed higher weight loss as compared to Taxotere® containing no epimer at single dose of 40 mg/kg indicating higher systemic toxicity. Incubation of PEGylated liposomes with phosphate buffer saline (pH 7.4) containing 0.1% w/v Tween-80 for 48 h showed better resistance to docetaxel degradation when compared with Taxotere® injection indicating better in vivo stability of liposomal docetaxel. In addition, PEGylated liposomes showed enhanced in vitro cytotoxicity, against A549 and B16F10 cells, than Taxotere®.

Conclusion

We can therefore expect less in vivo conversion of liposomal loaded docetaxel into 7-epimer, more passive targeting to tumor tissues, decreased 7-epimer induced systemic toxicity and tumor resistance to chemotherapy compared to Taxotere®. Further in vivo studies are needed to ascertain these facts.     

Chitosan-Based Polyelectrolyte Complexes as Potential Nanoparticulate Carriers: Physicochemical and Biological Characterization

Purpose

To investigate the effect of polyelectrolytes on the formation and physicochemical properties of chitosan nanoparticles (CS-NPs) used for the delivery of an anticancer drug, doxorubicin (DOX).

Method

Three DOX-loaded CS-NPs were formulated with tripolyphosphate (CS-TP/DOX NPs), dextran sulfate (CS-DS/DOX NPs), and hyaluronic acid (CS-HA/DOX NPs) by using ionotropic gelation or complex coacervation.

Results

CS-TP/DOX NPs were the smallest, with an average size of ~100 nm and a narrow size distribution, while CS-DS/DOX and CS-HA/DOX NPs were ~200 nm in size. Transmission electron microscopy clearly showed a spherical shape for all the NPs. The strong binding affinity of DOX for the multiple sulfate groups in DS resulted in a sustained release profile from CS-DS/DOX NPs at pH 7.4, while CS-HA/DOX NPs exhibited faster DOX release. This trend was also present under acidic conditions, where release of DOX was significantly augmented because of polymer protonation. Compared to CS-TP/DOX or CS-DS/DOX NPs, CS-HA/DOX NPs showed superior cellular uptake and cytotoxicity in MCF-7 and A-549 cells, because of their ability to undergo CD44-mediated endocytosis. Pharmacokinetic studies clearly showed that all CS-NPs tested significantly improved DOX plasma circulation time and decreased its elimination rate constant. Consistent with the in vitro release data, CS-DS/DOX NPs exhibited a relatively better DOX plasma profile and enhanced blood circulation, compared to CS-HA/DOX or CS-TP/DOX NPs. Overall, these results demonstrated how NP design can influence their function.

Conclusions

Taken together, CS-based polyelectrolyte complexes could provide a versatile delivery system with enormous potential in the pharmaceutical and biomedical sectors.     

The Co-Delivery of Oxaliplatin Abrogates the Immunogenic Response to PEGylated siRNA-Lipoplex

Purpose

In vivo application of siRNA/PEGylated cationic liposome complex (lipoplex) is impeded by two main obstacles: cytokine responses and anti-PEG IgM responses to PEGylated siRNA-lipoplex. Here, we investigated whether co-administration of oxaliplatin (l-OHP) abrogates the cytokine release and anti-PEG IgM production by PEGylated siRNA-lipoplex.

Methods

Free l-OHP was administered either simultaneously or 30 min prior to PEGylated siRNA-lipoplex administration, and cytokine response and anti-PEG IgM production were evaluated. In addition, the effect of the liposomal encapsulation of l-OHP on the immunogenic response of PEGylated siRNA-lipoplex was investigated.

Results

Simultaneous co-administration of free l-OHP with PEGylated siRNA-lipoplex caused a significant reduction in anti-PEG IgM production, along with an increase in the cytokine response. Free l-OHP injected prior to the lipoplex injection, however, successfully reduced cytokine release and anti-PEG IgM response. Platination of siRNA by simultaneously administered free l-OHP might facilitate the dissociation of double-stranded siRNA to single-stranded siRNA, resulting in the inducement of a potent immuno-stimulation of siRNA via endosomal toll-like receptors (TLRs). On the other hand, encapsulation of l-OHP into the siRNA-lipoplex resulted in a reduction of both anti-PEG IgM production and cytokine responses.

Conclusions

Our results suggest that, besides the expected therapeutic efficacy of co-administration, encapsulation of l-OHP into the PEGylated siRNA-lipoplex has great potential for minimizing the immunostimulation of PEGylated siRNA-lipoplex, resulting in a safe, applicable, and compliant treatment regimen for sequential clinical administration.     

PEGylated Multi-Walled Carbon Nanotubes for Encapsulation and Sustained Release of Oxaliplatin

Purpose

To develop PEGylated multi-walled carbon nanotubes as a sustained release drug delivery system.

Methods

Oxaliplatin was incorporated into inner cavity of PEGylated multi-walled carbon nanotubes (MWCNT-PEG) using nano-extraction. Oxaliplatin release rates from MWCNT-PEG-Oxaliplatin were investigated using dialysis tubing. Cytotoxicity of oxaliplatin, MWCNT-Oxaliplatin and MWCNT-PEG-Oxaliplatin were evaluated in HT29 cell by MTT assay, Pt-DNA adducts formation, γ-H2AX formation and cell apoptosis assay.

Results

Loading of oxaliplatin into MWCNT-PEG was ~43.6%. Sustained release occurred to MWCNT-PEG-Oxaliplatin, with only 34% of oxaliplatin released into medium within 6 h. In MTT assay, MWCNT-PEG-Oxaliplatin showed slightly decreased cytotoxic effect when cell viability was assessed at 12 and 24 h. A drastic increase of cytotoxicity was found when cell viability was assessed at 48 and 96 h. Pt-DNA adducts formation, γ-H2AX formation and cell apoptosis assay results showed the same trend as the MTT assay, suggesting sustained-release for MWCNT-Oxaliplatin and MWCNT-PEG-Oxaliplatin formulations.

Conclusions

PEGylated multi-walled carbon nanotubes can be used as sustained release drug delivery system, thus remarkably improving cytotoxicity of oxaliplatin on HT-29 cells.     

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.

     

The Shape/Morphology Balance: A Study of Stealth Liposomes via Fractal Analysis and Drug Encapsulation

Purpose

Fractal analysis was used as a tool in order to study the morphological characteristics of PEGylated liposomes. We report on the morphological characteristics of stealth liposomes composed of DPPC and DPPE-PEG 3000 in two dispersion media using fractal analysis.

Methods

Light scattering techniques were used in order to elucidate the size, the morphology and the surface charge of PEGylated liposomes as a function of PEGylated lipid concentration and temperature. Fluorescence spectroscopy studies revealed a microenvironment of low polarity inside the liposomal membranes.

Results

All formulations were found to retain their physicochemical characteristics for at least 3 weeks. The hydrodynamic radii (R_h) of stealth liposomes were stable in the process of heating up to 50°C; while the fractal dimension values (d_f) which correspond to their morphology, have been changed during heating. Hence, these results are a first indication of the presence of a heterogeneous microdomain structure of the stealth liposomal system. The amphiphilic drug indomethacin (IND) was successfully encapsulated within the liposomes and led to an increased size of stealth liposomes, while the morphology of liposomal vectors changed significantly at the highest molar ratio of PEGylated lipid.

Conclusions

We can state that this approach can promote a new analytical concept based on the morphological characteristics and quantify the shape of drug carriers complementary to that of the conventional analytical techniques.     

Anti-angiogenic and anti-inflammatory effects of long-circulating liposomes co-encapsulating curcumin and doxorubicin on C26 murine colon cancer cells

Background

Emerging treatment options for colon cancer are needed to overcome the limitations regarding the side effects of current chemotherapeutics and drug resistance. The goal of this study was to assess the antitumor actions of PEGylated long-circulating liposomes (LCL) co-delivering curcumin (CURC) and doxorubicin (DOX) on murine colon carcinoma cells (C26).

Liposomal Co-Delivery of Omacetaxine Mepesuccinate and Doxorubicin for Synergistic Potentiation of Antitumor Activity

Purpose

Anticancer chemotherapy usually involves the administration of several anticancer drugs that differ in their action mechanisms. Here, we aimed to test whether the combination of omacetaxine mepesuccinate (OMT) and doxorubicin (DOX) could show synergism, and whether the liposomal co-delivery of these two drugs could enhance their antitumor effects in cervical carcinoma model.

Method

OMT-loaded liposomes (OL) were prepared by loading the drug in the lipid bilayers. OL were then electrostatically complexed with DOX, yielding double-loaded liposomes (DOL). DOX-loaded liposomes (DL) were formulated by electrostatic interaction with negatively charged empty liposomes (EL). The combination index (CI) values were calculated to evaluate the synergism of two drugs. In vitro antitumor effects against HeLa cells were measured using CCK-8, calcein staining, and crystal violet staining. In vivo antitumor effects of various liposomes were tested using HeLa cell-bearing mice.

Results

Combination of DOX and OMT had ratio-dependent synergistic activities, with very strong synergism observed at a molar ratio of 4:1 (DOX:OMT). The sizes of EL, DL, OL, and DOL did not significantly differ, but the zeta potentials of DL and DOL were slightly higher than those of OL and EL. In vitro, DOL showed higher antitumor activity than OL, DL or EL in cervical carcinoma HeLa cells. In vivo, unlike other liposomes, DOL reduced the tumor growths by 98.6% and 97.3% relative to the untreated control on day 15 and 25 after the cessation of treatment, respectively.

Conclusions

These results suggest that liposomal co-delivery of DOX and OMT could synergistically potentiate antitumor effects.     

Pharmaceutical Differences Between Block Copolymer Self-Assembled and Cross-Linked Nanoassemblies as Carriers for Tunable Drug Release

Purpose

To identify the effects of cross-linkers and drug-binding linkers on physicochemical and biological properties of polymer nanoassembly drug carriers.

Methods

Four types of polymer nanoassemblies were synthesized from poly(ethylene glycol)-poly(aspartate) [PEG-p(Asp)] block copolymers: self-assembled nanoassemblies (SNAs) and cross-linked nanoassemblies (CNAs) to each of which an anticancer drug doxorubicin (DOX) was loaded by either physical entrapment or chemical conjugation (through acid-sensitive hydrazone linkers).

Results

Drug loading in nanoassemblies was 27?~?56% by weight. The particle size of SNA changed after drug and drug-binding linker entrapment (20?~?100 nm), whereas CNAs remained 30?~?40 nm. Drug release rates were fine-tunable by using amide cross-linkers and hydrazone drug-binding linkers in combination. In vitro cytotoxicity assays using a human lung cancer A549 cell line revealed that DOX-loaded nanoassemblies were equally potent as free DOX with a wide range of drug release half-life (t_1/2?=?3.24?~?18.48 h, at pH 5.0), but 5 times less effective when t_1/2?=?44.52 h.

Conclusion

Nanoassemblies that incorporate cross-linkers and drug-binding linkers in combination have pharmaceutical advantages such as uniform particle size, physicochemical stability, fine-tunable drug release rates, and maximum cytotoxicity of entrapped drug payloads.