Studies on the myelosuppressive activity of doxorubicin entrapped in liposomes

Hybrid Nanosystem Formed by DOX-Loaded Liposomes and Extracellular Vesicles from MDA-MB-231 Is Effective against Breast Cancer Cells with Different Molecular Profiles

Drug delivery selectivity is a challenge for cancer treatment. A hybrid pegylated pH-sensitive liposome-extracellular vesicle isolated from human breast cancer cell MDA-MB-231 was developed to investigate its in vitro activity against breast cancer cells of different molecular profiles to overcome this inconvenience. The hybrid nanosystem was produced by film hydration, and doxorubicin (DOX) was encapsulated in this system using the ammonium sulfate gradient method. The characterization of this hybrid nanosystem revealed a mean diameter of 140.20 ± 2.70 nm, a polydispersity index of 0.102 ± 0.033, an encapsulation efficiency of doxorubicin of 88.9% ± 2.4, and a great storage stability for 90 days at 4 °C. The fusion of extracellular vesicles with liposomes was confirmed by nanoflow cytometry using PE-conjugated human anti-CD63. This hybrid nanosystem demonstrated cytotoxicity against human breast cancer cell lines with different molecular subtypes, enhanced anti-migration properties, and exhibited similar cellular uptake to the free DOX treatment. Preliminary acute toxicity assessments using Balb/C female mice indicated a median lethal dose of 15-17.5 mg/kg, with no evidence of splenic, liver, heart, bone marrow, and renal damage at a dose of 15 mg/kg. These findings suggest the hybrid formulation as a versatile nanocarrier for the treatment of various breast cancer subtypes.

Bone tumor-homing nanotherapeutics for prolonged retention in tumor microenvironment and facilitated apoptotic process via mevalonate pathway inhibition

Bone malignancy features a mineralized extracellular matrix primarily composed of hydroxyapatite, which interferes with the distribution and activity of antineoplastic agents. Herein, we report bone tumor-homing polymeric nanotherapeutics consisting of alendronate-decorated chondroitin sulfate A-graft-poly(lactide-co-glycolide) and doxorubicin (DOX), named PLCSA-AD, which displayed a prolonged retention profile in the tumor microenvironment and augmented therapeutic efficacy via inhibition of the mevalonate pathway. PLCSA-AD exhibited a 1.72-fold lower IC50 value than free DOX and a higher affinity for hydroxyapatite than PLCSA in HOS/MNNG cell-based 2D bone tumor-mimicking models. The inhibition of the mevalonate pathway by PLCSA-AD in tumor cells was verified by investigating the cytosolic fraction of unprenylated proteins, where blank PLCSA-AD significantly increased the expression of cytosolic Ras and RhoA without changing their total cellular amounts. In a bone tumor-mimicking xenografted mouse model, AD-decorated nanotherapeutics significantly increased tumor accumulation (1.73-fold) compared with PLCSA, and higher adsorption to hydroxyapatites was observed in the histological analysis of the tumor. As a result, inhibition of the mevalonate pathway and improvement in tumor accumulation led to markedly enhanced therapeutic efficacy in vivo, suggesting that PLCSA-AD could be promising nanotherapeutics for bone tumor treatment.

Role of Tissue Hydraulic Permeability in Convection-Enhanced Delivery of Nanoparticle-Encapsulated Chemotherapy Drugs to Brain Tumour

PURPOSE

Tissue hydraulic permeability of brain tumours can vary considerably depending on the tissue microstructure, compositions in interstitium and tumour cells. Its effects on drug transport and accumulation remain poorly understood.

METHODS

Mathematical modelling is applied to predict the drug delivery outcomes in tumours with different tissue permeability upon convection-enhanced delivery. The modelling is based on a 3-D realistic tumour model that is extracted from patient magnetic resonance images.

RESULTS

Modelling results show that infusing drugs into a permeable tumour can facilitate a more favourable hydraulic environment for drug transport. The infused drugs will exhibit a relatively uniform distribution and cover a larger tumour volume for effective cell killing. Cross-comparisons show the delivery outcomes are more sensitive to the changes in tissue hydraulic permeability and blood pressure than the fluid flow from the brain ventricle. Quantitative analyses demonstrate that increasing the fluid gain from both the blood and brain ventricle can further improve the interstitial fluid flow, and thereby enhance the delivery outcomes. Furthermore, similar responses to the changes in tissue hydraulic permeability can be found for different types of drugs.

CONCLUSIONS

Tissue hydraulic permeability as an intrinsic property can influence drug accumulation and distribution. Results from this study can deepen the understanding of the interplays between drug and tissues that are involved in the drug delivery processes in chemotherapy.

Intratumoral immunotherapy using platelet-cloaked nanoparticles enhances antitumor immunity in solid tumors

Intratumoral immunotherapy is an emerging modality for the treatment of solid tumors. Toll-like receptor (TLR) agonists have shown promise for eliciting immune responses, but systemic administration often results in the development of adverse side effects. Herein, we investigate whether localized delivery of the TLR agonist, resiquimod (R848), via platelet membrane-coated nanoparticles (PNP-R848) elicits antitumor responses. The membrane coating provides a means of enhancing interactions with the tumor microenvironment, thereby maximizing the activity of R848. Intratumoral administration of PNP-R848 strongly enhances local immune activation and leads to complete tumor regression in a colorectal tumor model, while providing protection against repeated tumor re-challenges. Moreover, treatment of an aggressive breast cancer model with intratumoral PNP-R848 delays tumor growth and inhibits lung metastasis. Our findings highlight the promise of locally delivering immunostimulatory payloads using biomimetic nanocarriers, which possess advantages such as enhanced biocompatibility and natural targeting affinities.

The Product of Matrix Metalloproteinase Cleavage of Doxorubicin Conjugate for Anticancer Drug Delivery: Calorimetric, Spectroscopic, and Molecular Dynamics Studies on Peptide-Doxorubicin Binding to DNA

Matrix metalloproteinases (MMPs) are extracellular matrix degradation factors, promoting cancer progression. Hence, they could provide an enzyme-assisted delivery of doxorubicin (DOX) in cancer treatment. In the current study, the intercalation process of DOX and tetrapeptide–DOX, the product of the MMPs’ cleavage of carrier-linked DOX, into dsDNA was investigated using stationary and time-resolved fluorescence spectroscopy, UV-Vis spectrophotometry and isothermal titration calorimetry (ITC). The molecular dynamics (MD) simulations on the same tetrapeptide–DOX^…DNA and DOX^…DNA systems were also performed. The undertaken studies indicate that DOX and tetrapeptide–DOX can effectively bond with dsDNA through the intercalation mode; however, tetrapeptide–DOX forms less stable complexes than free DOX. Moreover, the obtained results demonstrate that the differences in DNA affinity of both forms of DOX can be attributed to different intercalation modes. Tetrapeptide–DOX shows a preference to intercalate into DNA through the major groove, whereas DOX does it through the minor one. In summary, we can conclude that the tetrapeptide–DOX intercalation to DNA is significant and that even the lack of non-specific proteases releasing DOX from the tetrapeptide conjugate, the presence of which is suggested by the literature for the efficient release of DOX, should not prevent the cytostatic action of the anthracycline.

Effects of Focused-Ultrasound-and-Microbubble-Induced Blood-Brain Barrier Disruption on Drug Transport under Liposome-Mediated Delivery in Brain Tumour: A Pilot Numerical Simulation Study

Focused ultrasound (FUS) coupled with microbubbles (MB) has been found to be a promising approach to disrupt the blood-brain barrier (BBB). However, how this disruption affects drug transport remains unclear. In this study, drug transport in combination therapy of liposomes and FUS-MB-induced BBB disruption (BBBD) was investigated based on a multiphysics model. A realistic 3D brain tumour model extracted from MR images was applied. The results demonstrated the advantage of liposomes compared to free doxorubicin injection in further improving treatment when the BBB is opened under the same delivery conditions using burst sonication. This improvement was mainly due to the BBBD-enhanced transvascular transport of free doxorubicin and the sustainable supply of the drug by long-circulating liposomes. Treatment efficacy can be improved in different ways. Disrupting the BBB simultaneously with liposome bolus injection enables more free drug molecules to cross the vessel wall, while prolonging the BBBD duration could accelerate liposome transvascular transport for more effective drug release. However, the drug release rate needs to be well controlled to balance the trade-off among drug release, transvascular exchange and elimination. The results obtained in this study could provide suggestions for the future optimisation of this FUS-MB–liposome combination therapy against brain cancer.

A multifunctional lipid that forms contrast-agent liposomes with dual-control release capabilities for precise MRI-guided drug delivery

Monitoring of nanoparticle-based therapy in vivo and controlled drug release are urgently needed for the precise treatment of disease. We have synthesized a multifunctional Gd-DTPA-ONB (GDO) lipid by introducing the Gd-DTPA contrast agent moiety into an o-nitro-benzyl ester lipid. By design, liposomes formed from the GDO lipid combine MRI tracking ability and dual-trigger release capabilities with maximum sensitivity (because all lipids bear the cleavable moiety) without reducing the drug encapsulation rate. We first confirmed that both photo-treatment and pH-triggered hydrolysis are able to cleave the GDO lipid and lyse GDO liposomes. We then investigated the efficiency of drug release via the combined release processes for GDO liposomes loaded with doxorubicin (DOX). Relative to neutral pH, the release efficiency in acidic environment increased by 10.4% (at pH = 6.5) and 13.3% (at pH = 4.2). This pH-dependent release response is conducive to distinguishing pathological tissue such as tumors and endolysosomal compartments. The photo-induced release efficiency increases with illumination time as well as with distance of the pH from neutral. Photolysis increased the release efficiency by 13.8% at pH = 4.2, which is remarkable considering the already increased amount of drug release in the acidic environment. In addition, the relaxation time of GDO liposomes was 4.1 times that of clinical Gd-DTPA, with brighter T₁-weighted imaging in vitro and in vivo. Real-time MRI imaging and in vivo fluorescence experiments demonstrated tumor targeting and MRI guided release. Furthermore, significant tumor growth inhibition in a treatment experiment using DOX-loaded GDO liposomes clearly demonstrated the benefit of photo-treatment for efficacy: the tumor size in the photo-treatment group was 3.7 times smaller than in the control group. The present study thus highlights the benefit of the design idea of combining efficient imaging/guiding, targeting, and triggerable release functions in one lipid molecule for drug delivery applications.

The influence of trapping agents on the antitumor efficacy of irinotecan liposomes: head-to-head comparison of ammonium sulfate, sulfobutylether-β-cyclodextrin and sucrose octasulfate

Remote loading technology is an outstanding achievement in liposome-based drug delivery systems.

Main trends of immune effects triggered by nanomedicines in preclinical studies

The application of nanotechnology to emerging medicinal products is a crucial parameter for the implementation of personalized medicine. For example, sophisticated drug delivery systems can target the diseased tissue by recognizing patient-specific biomarkers while carrying pharmacologically active molecules. However, such nanomedicines can be recognized by the immune system as foreign triggering unexpected biological reactions. The anticipation of the immunogenic potential of emerging nanotechnology-based products in the preclinical phase is challenging due to high interspecies variations between the immune systems of laboratory animals and humans. A close monitoring of the scientific literature is required to better understand the relationship between various immune reactions and the diversity of nanomedicines currently in the development pipeline. We have reviewed the most frequent immune reactions induced by the nanomaterials in vivo and have identified the main effects triggered by lipid-based, polymer-based and inorganic nanoparticles, as the main categories of nanomaterials used in medicine. According to our results, almost 50% of the investigated nanomaterials induced effects related to the activation of the immune system. Among them, complement activation-related hypersensitivity reactions and activation of adaptive immune response were the most frequent effects reported for the lipid-based nanoparticles. However, many of these effects are not or are only partially covered by the current regulatory framework applicable for nanomedicines. In addition, we extracted the most relevant nanospecific properties responsible for the observed biological effects. Our analysis led to identification of the most prevalent measurement endpoints relevant for the assessment of the immunotoxic potential of the nanotechnology-based products and will support the smooth and safe translation of the new formulations to clinical applications.

Convection enhanced delivery of liposome encapsulated doxorubicin for brain tumour therapy

Convection enhanced delivery is promising to overcome the blood brain barrier. However, the treatment is less efficient in clinic due to the rapid elimination of small molecular drugs in brain tumours. In this study, numerical simulation is applied to investigate the convection enhanced delivery of liposome encapsulated doxorubicin under various conditions, based on a 3-D brain tumour model that is reconstructed from magnetic resonance images. Treatment efficacy is evaluated in terms of the tumour volume where the free doxorubicin concentration is above LD90. Simulation results denote that intracerebral infusion is effective in increasing the interstitial fluid velocity and inhibiting the fluid leakage from blood around the infusion site. Comparisons with direct doxorubicin infusion demonstrate the advantages of liposomes in enhancing the doxorubicin accumulation and penetration in the brain tumour. Delivery outcomes are determined by both the intratumoural environment and properties of therapeutic agents. The treatment efficacy can be improved by either increasing the liposome solution concentration and infusion rate, administrating liposomes in the tumour with normalised microvasculature density, or using liposomes with low vascular permeability. The delivery is less sensitive to liposome diffusivity in the examined range (E-11~E-7 cm²/s) as convective transport is dominative in determining the liposome migration. Drug release rate is able to be optimised by keeping a trade-off between enhancing the drug penetration and providing sufficient free doxorubicin for effective cell killing. Results from this study can be used to improve the regimen of CED treatments.

Extracellular Vesicles Released by Cardiomyocytes in a Doxorubicin-Induced Cardiac Injury Mouse Model Contain Protein Biomarkers of Early Cardiac Injury

Purpose: Cardiac injury is a major cause of death in cancer survivors, and biomarkers for it are detectable only after tissue injury has occurred. Extracellular vesicles (EV) remove toxic biomolecules from tissues and can be detected in the blood. Here, we evaluate the potential of using circulating EVs as early diagnostic markers for long-term cardiac injury.Experimental Design: Using a mouse model of doxorubicin (DOX)-induced cardiac injury, we quantified serum EVs, analyzed proteomes, measured oxidized protein levels in serum EVs released after DOX treatment, and investigated the alteration of EV content.Results: Treatment with DOX caused a significant increase in circulating EVs (DOX_EV) compared with saline-treated controls. DOX_EVs exhibited a higher level of 4-hydroxynonenal adducted proteins, a lipid peroxidation product linked to DOX-induced cardiotoxicity. Proteomic profiling of DOX_EVs revealed the distinctive presence of brain/heart, muscle, and liver isoforms of glycogen phosphorylase (GP), and their origins were verified to be heart, skeletal muscle, and liver, respectively. The presence of brain/heart GP (PYGB) in DOX_EVs correlated with a reduction of PYGB in heart, but not brain tissues. Manganese superoxide dismutase (MnSOD) overexpression, as well as pretreatment with cardioprotective agents and MnSOD mimetics, resulted in a reduction of EV-associated PYGB in mice treated with DOX. Kinetic studies indicated that EVs containing PYGB were released prior to the rise of cardiac troponin in the blood after DOX treatment, suggesting that PYGB is an early indicator of cardiac injury.Conclusions: EVs containing PYGB are an early and sensitive biomarker of cardiac injury. Clin Cancer Res; 24(7); 1644-53. ©2017 AACRSee related commentary by Zhu and Gius, p. 1516.

A herbal formula, SYKT, reverses doxorubicin‑induced myelosuppression and cardiotoxicity by inhibiting ROS‑mediated apoptosis

Doxorubicin (DOX) is an antineoplastic drug widely used for the treatment of various types of cancer; however, it can induce severe side effects, such as myelosuppression and cardiotoxicity. Sanyang Xuedai (SYKT) is a natural medicine originating from an ancient prescription of the Dai nationality in Southwest China. With eight Chinese herbal medicines, including sanguis draconis, radix et rhizoma notoginseng, radix et rhizoma glycyrrhizae and radix angelicae sinensis as the primary ingredients, SYKT has been reported to possess numerous biological functions. The present study investigated whether SYKT can confer protection against DOX-induced myelosuppression and cardiotoxicity, and explored the potential mechanism involved. Mice were treated with DOX, SYKT or a combination of the two; hematopoietic functions were assessed by measuring the number of peripheral blood cells, cluster of differentiation CD34+/CD44+ bone marrow cells and apoptotic cells. Myocardial enzymes, including aspartate aminotransferase, lactate dehydrogenase, creatine kinase (CK) and its isoform CK-MB, were assessed using a biochemical analyzer. The apoptotic rate of cardiomyocytes was assessed using flow cytometry. Histopathological analysis was conducted using hematoxylin-eosin staining. Intracellular reactive oxygen species (ROS) production was evaluated using a dichlorofluorescein intensity assay. The mice treated with DOX exhibited a reduced survival rate, reduced peripheral blood and CD34+/CD44+ cell counts, elevated myocardial enzymes and apoptotic indices in bone marrow cells and cardiomyocytes, all of which were effectively prevented by SYKT co-administration. Furthermore, bone marrow cells and myocytes from mice treated with DOX demonstrated increased dichlorofluorescein intensity, which was attenuated by SYKT. Notably, SYKT did not interfere with the effects of DOX on tumor volume or the induction of tumor cell apoptosis in tumor-bearing mice. The present study indicated that SYKT may counteract DOX-induced myelosuppression and cardiotoxicity through inhibiting ROS-mediated apoptosis. These findings suggested that SYKT may have potential as a means to counteract the potentially fatal hematopoietic and cardiac complications associated with DOX treatment.

Antioxidants selenomethionine and D-pantethine decrease the negative side effects of doxorubicin in NL/Ly lymphoma-bearing mice

Aim

To investigate the potential tissue-protective effects of antioxidants selenomethionine and D-pantethine applied together with doxorubicin (Dx) on NK/Ly lymphoma-bearing mice. The impact of this chemotherapy scheme on animal survival, blood cell profile, hepatotoxicity, glutathione level, and activity of glutathione-converting enzymes in the liver was compared with the action of Dx applied alone.

Methods

The hematological profile of animals was studied by the analysis of blood smears under light microscopy. Hepatotoxicity of studied drugs was evaluated measuring the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes, De Ritis ratio, and coenzyme A fractions by McDougal assay. Glutathione level in animal tissues was measured with Ellman reagent, and the activity of glutathione reductase, transferase, and peroxidase was measured using standard biochemical assays.

Results

D-pantethine (500 mg/kg) and, to a lower extent, selenomethionine (600 µg/kg) partially reduced the negative side effects (leukocytopenia and erythropenia) of Dx (5 mg/kg) in NK/Ly lymphoma bearing animals on the 14th day of their treatment. This increased animal survival time from 47-48 to 60+ days and improved the quality of their life. This ability of D-pantethine and selenomethionine was realized via hepatoprotective and immunomodulating activities. D-pantethine also restored the levels of acid-soluble and free CoA in the liver of tumor-bearing animals, while selenomethionine caused the recovery of glutathione peroxidase levels in the liver, which was significantly diminished under Dx treatment. Both compounds decreased glutathione level in the liver, which was considerably induced by Dx.

Conclusions

Antioxidants selenomethionine and D-pantethine partially reversed the negative side effects of Dx in NK/Ly lymphoma-bearing mice and significantly increased the therapeutic efficiency of this drug in tumor treatment.

A Novel Folate-Targeted Nanoliposomal System of Doxorubicin for Cancer Targeting

Targeted drug delivery systems for cancer improves anti-tumor efficacy and reduces systemic toxicity by restricting availability of cytotoxic drugs within tumors. Targeting moieties, such as natural ligands (folic acid, transferrin, and biotin) which are overexpressed on tumors, have been used to enhance liposome-encapsulated drug accumulation within tumors and resulted in better control. In this report, we explored the scope of targeting ligand folic acid, which is incorporated in liposome systems using folic acid-modified cholesterol (CPF), enabled highly selective tumor-targeted delivery of liposome-encapsulated doxorubicin and resulted in increased cytotoxicity within tumors. Folate-tagged poloxamer-coated liposomes (FDL) were found to have significantly higher cellular uptake than conventional poloxamer-coated liposomes (DL), as confirmed by fluorometric analysis in B16F10 melanoma cells. Biodistribution study of the radiolabeled liposomal system indicated the significantly higher tumor uptake of FDL as compared to DL. Anti-tumor activity of FDL against murine B16F10 melanoma tumor-bearing mice revealed that FDL inhibited tumor growth more efficiently than the DL. Taken together, the results demonstrated the significant potential of the folate-conjugated nanoliposomal system for drug delivery to tumors.

Advanced therapeutic approach for the treatment of malignant pleural mesothelioma via the intrapleural administration of liposomal pemetrexed

Malignant pleural mesothelioma (MPM) is an aggressive cancer that proliferates in the pleural cavity. Pemetrexed (PMX) in combination with cisplatin is currently the approved standard care for MPM, but a dismal response rate persists. Recently, we prepared various liposomal PMX formulations using different lipid compositions and evaluated their in vitro cytotoxicity against human mesothelioma cells (MSTO-211H). In the present study, we investigated the in vivo therapeutic effect of our liposomal PMX formulations using an orthotopic MPM tumor mouse model. PMX encapsulated within either cholesterol-containing (PMX/Chol CL) or cholesterol-free (PMX/Non-Chol CL) cationic liposome was intrapleurally injected into tumor-bearing mice. PMX encapsulated in cholesterol-free liposomes (PMX/Non-Chol CL) drastically inhibited the tumor growth in the pleural cavity, while free PMX and PMX encapsulated in cholesterol-containing liposomes (PMX/Chol CL) barely inhibited the tumor growth. The enhanced in vivo anti-tumor efficacy of PMX/Non-Chol CL was credited, on the one hand, for prolonging the retention of cationic liposomes in the pleural cavity via their electrostatic interaction with the negatively charged membranes of tumor cells, but on the other hand, it was charged with contributing to a higher drug release from the "fluid" liposomal membrane following intrapleural administration. This therapeutic strategy of direct intrapleural administration of liposomal PMX, along with the great advances in CL-guided therapeutics, might be a promising therapeutic approach to conquering the poor prognosis for MPM.

In vitro investigation of self-assembled nanoparticles based on hyaluronic acid-deoxycholic acid conjugates for controlled release doxorubicin: effect of degree of substitution of deoxycholic acid

Self-assembled nanoparticles based on a hyaluronic acid-deoxycholic acid (HD) chemical conjugate with different degree of substitution (DS) of deoxycholic acid (DOCA) were prepared. The degree of substitution (DS) was determined by titration method. The nanoparticles were loaded with doxorubicin (DOX) as the model drug. The human cervical cancer (HeLa) cell line was utilized for in vitro studies and cell cytotoxicity of DOX incorporated in the HD nanoparticles was accessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In addition, cellular uptake of fluorescently labeled nanoparticles was also investigated. An increase in the degree of deoxycholic acid substitution reduced the size of the nanoparticles and also enhanced their drug encapsulation efficiency (EE), which increased with the increase of DS. A higher degree of deoxycholic acid substitution also lead to a lower release rate and an initial burst release of doxorubicin from the nanoparticles. In summary, the degree of substitution allows the modulation of the particle size, drug encapsulation efficiency, drug release rate, and cell uptake efficiency of the nanoparticles. The herein developed hyaluronic acid-deoxycholic acid conjugates are a good candidate for drug delivery and could potentiate therapeutic formulations for doxorubicin–mediated cancer therapy.

Cardiovascular effects of Phaleria macrocarpa extracts combined with mainstay FAC regimen for breast cancer

DLBS1425 is a bioactive compound extracted from Phaleria macrocarpa, with anti-proliferative, anti-inflammatory and anti-angiogenic properties against cancer cells. The present study was aimed to assess cardiotoxicity of DLBS1425, compared to the mainstay regimen for breast cancer, 5-fluorouracil:doxorubicin:cyclophosphamide (FAC, given at 500/50/500 mg/m(2)). Treatment with FAC regimen at standard dose resulted in very severe toxicity, so mice had no chance to survive for more than 7 days following initial drug treatment. Furthermore, histological examination on the heart revealed severe muscular damage when mice were given the FAC regimen alone (severe toxicity). FAC as chemotherapeutic regimen exerted high toxicity profile to the cardiovascular cells in this experiment. Meanwhile, treatment with DLBS1425 alone up to a dose equivalent to as high as 300 mg three times daily in human had no hazardous consequences on the heart, hematological feature, as well as general safety. In the cardiovascular cells, DLBS1425 in the presence of FAC regimen (one-eight of the initial dose) gave protection to the cardiac muscle cells as well as other hematological features. Taken together, results of the present study suggest that DLBS1425 is safe when used as adjuvant therapy for breast cancer and may be even protective against cardiac cellular damage produced by chemotherapeutic regimen.

In vitro evaluation of polymeric micelles based on hydrophobically-modified sulfated chitosan as a carrier of doxorubicin

Four types of doxorubicin (DOX)-loaded polymeric micelles based on hydrophobically-modified sulfated chitosan (SCTS) were prepared. The hydrophobic group was composed of glycyrrhetinic acid (GA), cholic acid, stearic acid (SA) or lauric aldehyde. DOX encapsulation depended on several parameters, including the degree of substitution of the sulfate group and the hydrophobic group, and the type of hydrophobic group. Of these micelles, GA-SCTS micelles had the best capability to solubilize DOX. In addition, GA-SCTS micelles had the ability to target HepG(2) cells, and the IC50 for DOX-loaded GA-SCTS micelles was 54.7 ng/mL, which was much lower than that of the other micelles. Further studies on the DOX-loaded GA-SCTS micelles showed that they were stable in salt and protein solutions, in cell culture media, and during long-term storage (6 months). Based on these results, these micelles may be a promising DOX-encapsulated formulation, particularly, GA-SCTS as a potential vehicle for liver-targeted delivery.

Evaluation of triblock copolymeric micelles of δ- valerolactone and poly (ethylene glycol) as a competent vector for doxorubicin delivery against cancer

Background

Specific properties of amphiphilic copolymeric micelles like small size, stability, biodegradability and prolonged biodistribution have projected them as promising vectors for drug delivery. To evaluate the potential of δ-valerolactone based micelles as carriers for drug delivery, a novel triblock amphiphilic copolymer poly(δ-valerolactone)/poly(ethylene glycol)/poly(δ-valerolactone) (VEV) was synthesized and characterized using IR, NMR, GPC, DTA and TGA. To evaluate VEV as a carrier for drug delivery, doxorubicin (DOX) entrapped VEV micelles (VEVDMs) were prepared and analyzed for in vitro antitumor activity.

Results

VEV copolymer was successfully synthesized by ring opening polymerization and the stable core shell structure of VEV micelles with a low critical micelle concentration was confirmed by proton NMR and fluorescence based method. Doxorubicin entrapped micelles (VEVDMs) prepared using a modified single emulsion method were obtained with a mean diameter of 90 nm and high encapsulation efficiency showing a pH dependent sustained doxorubicin release. Biological evaluation in breast adenocarcinoma (MCF7) and glioblastoma (U87MG) cells by flow cytometry showed 2-3 folds increase in cellular uptake of VEVDMs than free DOX. Block copolymer micelles without DOX were non cytotoxic in both the cell lines. As evaluated by the IC₅₀ values VEVDMs induced 77.8, 71.2, 81.2% more cytotoxicity in MCF7 cells and 40.8, 72.6, 76% more cytotoxicity in U87MG cells than pristine DOX after 24, 48, 72 h treatment, respectively. Moreover, VEVDMs induced enhanced apoptosis than free DOX as indicated by higher shift in Annexin V-FITC fluorescence and better intensity of cleaved PARP. Even though, further studies are required to prove the efficacy of this formulation in vivo the comparable G2/M phase arrest induced by VEVDMs at half the concentration of free DOX confirmed the better antitumor efficacy of VEVDMs in vitro.

Conclusions

Our studies clearly indicate that VEVDMs possess great therapeutic potential for long-term tumor suppression. Furthermore, our results launch VEV as a promising nanocarrier for an effective controlled drug delivery in cancer chemotherapy.

Synthesis of sol-gel mesoporous silica materials providing a slow release of doxorubicin

Samples of mesoporous base-catalysed silica xerogel materials made by the sol-gel process were impregnated with an anticancer drug--doxorubicin, followed by different times of ageing at room temperature. The effect of ageing time on the physical and structural properties as well as sorption-desorption of the drug was investigated. The obtained results suggest an inverse relationship with a solid density and surface area increasing as the pore size and volume decrease during ageing time. These results also revealed the effect of ageing time on the efficiency of sorption-desorption of the drug. An increase in ageing time results in an increase of the efficiency of drug sorption and a decrease in the rate of drug release.

MMPs-specific PEGylated peptide-DOX conjugate micelles that can contain free doxorubicin

The goal of this study was to develop anti-cancer drug conjugates with increased anti-tumor effect and reduced toxicity. In this regard, we utilized the physiological characteristics of tumors such as angiogenesis, the expression of matrix metalloproteinases (MMPs) and the enhanced permeability and retention (EPR) effect, and designed MMPs-specific PEGylated peptide-DOX conjugate micelles containing doxorubicin. These conjugates were prepared by using two peptides, GPLGV and GPLGVRG (P5D and P7D, respectively), and doxorubicin was loaded into micelles formed by each conjugate. P5D and P7D were specifically cleaved by active MMP-2 and all conjugates showed significantly better cell viability than doxorubicin at equivalent concentrations. In vivo, animals treated with PEGylated peptide-DOX conjugate micelles showed approximately 50% of the tumor growth of the control, and doxorubicin-loaded conjugates micelles inhibited tumor growth up to about 72% compared with the control, which matched the effect of doxorubicin. Doxorubicin-loaded PEGylated peptide-DOX conjugate micelles exhibited longer half-lives and maintained higher concentrations of doxorubicin in plasma than PEGylated peptide-DOX conjugate micelles alone. Doxorubicin-loaded PEGylated peptide-DOX conjugate micelles might offer a cancer therapy with an activity that is similar to that of the parent drug but with reduced toxicity.

Novel drug delivery system using thermoreversible gelation polymer for malignant glioma

Many approaches to local tumor treatment have been reported and their efficacy demonstrated in patients with malignant glioma. We studied thermoreversible gelation polymer (TGP) as a novel drug delivery system (DDS) for treating this type of tumor. TGP exhibits sol-gel transition i.e., is water-soluble in the sol phase below the chosen sol-gel transiting temperature and water-insoluble in the gel phase above this temperature. We conjugated doxorubicin with TGP to prepare doxorubicin-TGP (DXR-TGP), then studied the kinetics of doxorubicin release from TGP and the antitumor activity of DXR-TGP in vitro and in vivo. The diffusive speed of doxorubicin from TGP was 9.4x10(-7) cm(2)/s and doxorubicin was reliably released from TGP. DXR-TGP showed antitumor activity against the human glioma cell lines T98G and U87MG and in a subcutaneous tumor model in nude mice. Pathologically, detection of the proliferation marker Ki-67 was considerably lower in the DXR-TGP group than in the control group (30-40% vs. 60-70%, respectively). This is to the best of our knowledge the first report of TGP as a novel drug delivery system, and further we provide evidence that TGP exhibits potential for use as a novel DDS for malignant glioma.

Drug release rate influences the pharmacokinetics, biodistribution, therapeutic activity, and toxicity of pegylated liposomal doxorubicin formulations in murine breast cancer

The pharmacokinetics (PK), biodistribution (BD), and therapeutic activity of pegylated liposomal doxorubicin formulations with different drug release rates were studied in an orthotopic 4T1 murine mammary carcinoma model. The focus of these experiments was to study the effects of different release rates on the accumulation of liposomal lipid and doxorubicin (DXR) into the tumor and cutaneous tissues of mice (skin and paws). These tissues were chosen because the clinical formulation of pegylated liposomal doxorubicin (Caelyx)/Doxi) causes mucocutaneous reactions such as palmar-plantar erythrodysesthesia (PPE). Liposomes with different doxorubicin (DXR) leakage rates were prepared by altering liposome fluidity through changing the fatty acyl chain length and/or degree of saturation of the phosphatidylcholine component of the liposome. Liposomes with fast, intermediate, and slow rates of drug release were studied. The plasma PK of the liposomal lipid was similar for all formulations, while the plasma PK of the DXR component was dependent on the liposome formulation. Liposomal lipid accumulated to similar levels in tumor and cutaneous tissues for all three formulations tested, while the liposomes with the slowest rates of DXR release produced the highest DXR concentrations in both cutaneous tissues and in tumor. Liposomes with the fastest drug release rates resulted in low DXR concentrations in cutaneous tissues and tumor. The formulation with intermediate release rates produced unexpected toxicity that was not related to the lipid content of the formulation. The liposomes with the slowest rate of drug leakage had the best therapeutic activity of the formulations tested.

Proposition of a new system of medicine based on tolerance principle

The author proposes an explanatory model to modify Hahnemann's old tool--"similia similibus curantur"--and suggested a new experimental design to be used to detect the root cause of several chronic diseases and to treat them. All the biochemical reactions of an ideal cell are interlinked by enzymes like a network and shortfall of any one of them may create specific combination of symptoms (e.g., phenylketonuria, alkaptonuria, etc.), due to lack of one or more products that enables us to identify the responsible enzyme. Sometimes malsynthesis of an unknown enzyme(s) or receptors are responsible for a chronic disease and it becomes difficult to identify them by merely observing symptoms. Hence involvement of a normal healthy person ("prover") would be essential to detect it. If an inhibitor that comes from a drug is able to bring the same combination of symptoms in prover it may be predicted that the drug is able to bind and inhibit the responsible enzyme or its product. Minute doses of the same inhibitor(s) can cure the disease if it can act as the ligand of the same enzyme(s), by increasing the rate of transcription (by a positive feedback loop), to compensate the loss of product of the same. The ligand-inhibitor should be trapped in by an organic molecule, like ethanol by the process of potentization to increase the invasiveness of the medicine and to avoid detoxification mechanism, baffling of which increases the concentration of inhibitor inside the cell in course. The cells able to cope up with the stress by the operation of positive feedback loop or compensation cycle synthesize more enzymes and multiply rapidly, but those cells unable to tolerate such stress gradually perish. Thus Hahnemann's principle being dependent on the cause of symptoms becomes modified as "similia similibus curantur causosymptomically".

Tumour targeted delivery of encapsulated dextran-doxorubicin conjugate using chitosan nanoparticles as carrier

Doxorubicin (DXR) commonly used in cancer therapy produces undesirable side effects such as cardiotoxicity. To minimize these, attempts have been made to couple the drug with dextran (DEX) and then to encapsulate this drug conjugate in hydrogel nanoparticles. By encapsulation of the drug conjugate in biodegradable, biocompatible long circulating hydrogel nanoparticles, we further improved the therapeutic efficacy of the conjugate. The size of these nanoparticles as determined by quasi-elastic light scattering, was found to be 100+/-10 nm diameter, which favors the enhanced permeability and retention effect (EPR) as observed in most solid tumors. The antitumor effect of these DEX-DXR nanoparticles, was evaluated in J774A.1 macrophage tumor cells implanted in Balb/c mice. The in vivo efficacy of these nanoparticles as antitumor drug carriers, was determined by tumor regression and increased survival time as compared to drug conjugate and free drug. These results suggest that encapsulation of the conjugate in nanoparticles not only reduces the side effects, but also improves its therapeutic efficacy in the treatment of solid tumors.

The size of liposomes: a factor which affects their targeting efficiency to tumors and therapeutic activity of liposomal antitumor drugs

The size of liposomes has been shown to be an important factor in the efficient delivery of an antitumor agent to a tumor. In this paper, the effects of the size of liposomes on the pharmacokinetics of liposomes and liposome-encapsulated drugs are discussed with reference to: (1) the circulation amount and residence time of liposomes in the blood, (2) the accumulation of liposomes in the tumor, and (3) in vivo drug release from liposomes. In addition, the effect of size on therapeutic activity (antitumor efficacy and toxicity) of a liposomal anticancer preparation is discussed. Finally we discuss the importance of liposome size in the design of a more effective liposomal antitumor preparation.

Loading of doxorubicin into liposomes by forming Mn2+-drug complexes

A new procedure for loading doxorubicin into large unilamellar vesicles (LUVs) is characterized. It is shown that doxorubicin can be loaded into LUVs composed of sphingomyelin/cholesterol (55:45 mole/mole) in response to a transmembrane MnSO4 gradient in the absence of a transmembrane pH gradient. Complex formation between doxorubicin and Mn2+ is found to be a driving force for doxorubicin uptake. Uptake levels approaching 100% can be achieved up to a drug-to-lipid molar ratio of 0.5 utilizing an encapsulated MnSO4 concentration of 0.30 M. In vitro leakage assays show excellent retention properties over a 24 h period. The possible advantages of a liposomal formulation of doxorubicin loaded in response to entrapped MnSO4 are discussed.

An immune response to ovalbumin covalently coupled to liposomes is prevented when the liposomes used contain doxorubicin

It is now well established that liposomes with surface associated proteins are immunogenic. Repeated administration of protein coated liposomes elicits the generation of antibodies and the elimination of proteoliposome increases markedly in animals 'immunized' with such liposomes. This immune response compromises the therapeutic potential of liposomal formulations that rely on the use of protein- or peptide-based targeting ligands to enhance cell specificity. Strategies to suppress or inhibit such immune responses must be developed if this technology is going to prove therapeutically viable. This study evaluates whether an immune response to a protein, covalently attached to liposomes by a thioether bond between N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP)-modified-protein and N-(4-(P-maleimidophenyl)butyryl) (MPB)-activated lipids, can be suppressed when the liposomes used contain the anti-cancer drug doxorubicin. To assess this, the highly immunogenic protein ovalbumin was conjugated onto liposomes composed of distearoylphosphatidylcholine/cholesterol (DSPC/Chol) with sufficient poly(ethylene glycol)-modified distearoyl phosphatidylethanolamine (PEG-DSPE) (2 mol%) to prevent liposome aggregation during protein coupling and to engender increased circulation lifetimes. The immune response to these liposomes with and without encapsulated doxorubicin was measured by: (1) monitoring liposome elimination after 3 weekly i.v. injections in C3H/HeJ mice and (2) measuring the anti-ovalbumin antibody levels by an ELISA assay. One week after a single dose of ovalbumin-coated PEG liposomes (50 microg protein/mouse) the immune response resulted in rapid elimination of a second dose of ovalbumin-coated PEG liposomes. Rapid liposome elimination was correlated to generation of high levels (> 9 microg/ml plasma) of circulating anti-ovalbumin IgG. In contrast, anti-ovalbumin antibodies were not detected when the liposomes used contained doxorubicin. Plasma elimination of these drug loaded protein coated liposomes decreased following repeated weekly i.v. doses, an effect that is consistent with liposomal doxorubicin mediated suppression of phagocytic cells in the liver.

Anthracyclines in haematology: preclinical studies, toxicity and delivery systems

The anthracyclines are widely used in the treatment of haematological and non-haematological malignancy and there is now more than 30 years' clinical experience with these agents but despite this, their mechanism of action is incompletely understood. The anthracyclines have been shown to intercalate with DNA and indirectly inhibit the activity of the enzyme topoisomerase II, resulting in DNA strand breaks. More recently, workers have focused on induction of apoptosis and have shown that daunorubicin stimulates production of the apoptotic mediator, ceramide and that the activity of doxorubicin can be blocked by inhibitors of CD95 (fas). One of the major problems with anthracycline therapy is the development of resistance which may be mediated by p-glycoprotein or by other mechanisms. Much recent research has concentrated on methods to modulate the drug-resistant phenotype and these include development of new analogues and use of specific reversal agents. The toxicity profile of the anthracyclines includes bone marrow suppression, severe local reaction following extravasation, radiation recall, alopecia, gastrointestinal and hepatic effects, development of secondary malignancies and significant cardiac toxicity. The risk factors for the development of anthracycline-related cardiac toxicity are well documented and several methods have been exploited in attempts at prevention. Finally, a number of drug delivery systems have been developed in order to improve therapeutic response and reduce toxicity to normal tissues, including the use of liposomal preparations.

Liposomal doxorubicin

Doxorubicin is a potent antineoplastic agent with activity against numerous human cancers. Encapsulation of doxorubicin inside a liposome alters bioavailability, biodistribution and thus its biological activity significantly. The physical properties of the liposome (size, lipid components and lipid dose) play a major role in determining drug retention and pharmacokinetics. The therapeutic benefits of liposomal doxorubicin will therefore depend on these physical characteristics. Here we review the toxicity and efficacy of liposomal doxorubicin determined for various liposome compositions (size, lipid composition and drug-to-lipid ratio). These physical properties can be independently varied using the transmembrane pH gradient-dependent drug encapsulation procedure. The results show that the toxicity of the formulation is related to drug retention in the circulation. The antitumor activity is more sensitive to the size of the liposomes. By optimizing these parameters, liposomal doxorubicin formulations can be optimized for improved therapeutic activity.

Drug distribution and a pulmonary adverse effect of intraperitoneally administered doxorubicin niosomes in the mouse

Niosomes (non-ionic surfactant vesicles) prepared from C16G2 (a hexadecyl-diglycerol ether), and loaded with doxorubicin, were administered intraperitoneally to male AKR mice at dose levels of 0, 2.5, 5.0, and 10.0 mg kg-1. Free drug was given at 10.0 mg kg-1 by the intraperitoneal route. At a dose level of 10.0 mg kg-1, peak doxorubicin levels in the central compartment were attained faster with the free drug than with the niosome formulation. However, the peak plasma levels were similar for the free drug and the niosome preparation at the 10 mg kg-1 dose level. With doxorubicin administered as the niosome preparation by the intraperitoneal route at 2.5, 5.0, and 10.0 mg kg-1, mean peak plasma concentrations of the drug showed a tendency to be dose-related although the differences were not significant. Over the 24 h period of the experiment, with doxorubicin at 10 mg kg-1, the niosome formulation delivered significantly more drug to the plasma compartment than the free drug (p < 0.05). When doxorubicin was given in niosomes at 2.5, 5.0 and 10.0 mg kg-1 by the intraperitoneal route, the resulting levels of doxorubicin in cardiac tissue were not dose related and the differences not significant and, although the mean peak cardiac-tissue concentration was higher in animals receiving the free drug at 10.0 mg kg-1 intraperitoneally than in mice given intraperitoneal doxorubicin niosomes at this dose level, the differences were again not significant. There were clinical signs of toxicity in mice given doxorubicin-containing niosomes intraperitoneally at 5.0 and 10.0 mg kg-1, and at post-mortem an accumulation of fluid in the pleural cavity was evident. These changes were not seen in mice dosed intraperitoneally with free drug at 10 mg kg-1, or in animals given doxorubicin niosomes intraperitoneally at 2.5 mg kg-1. In mice dosed intraperitoneally with doxorubicin niosomes at 12.0 mg kg-1 and at a dose volume of 0.2-0.4 mL, histological examination of the lungs demonstrated a congestion of the alveolar capillaries, and an increased number of acute inflammatory cells in the alveolar walls. There was no histological evidence of lung toxicity in mice dosed with doxorubicin niosomes at 12.0 mg kg-1 when the formulation was administered with the higher dose volume of 1.8-2.0 mL. Importantly there was no histological evidence of lung toxicity in mice dosed with empty niosomes intraperitoneally or with doxorubicin niosomes given intravenously at 12.0 mg kg-1.

Liposomal doxorubicin in the treatment of AIDS-associated Kaposi's sarcoma: clinical, histological and cell biological evaluation

AIDS-associated Kaposi's sarcoma (KS) in eight patients was treated with the systemic application of liposomal doxorubicin (20 mg/m2 per cycle). After six cycles of treatment a significant regression of KS was observed in all patients. Tumour volume was reduced from 556 +/- 635 mm3 before therapy to 42 +/- 134 mm3 after therapy as determined by ultrasonography of selected tumours. Histological examination revealed a reduction of tumour-like structures and the absence of KS spindle cells in involved areas after therapy. In vitro experiments with KS-derived cell cultures, which most likely represent the KS spindle cells, suggested that liposomal doxorubicin may cause regression of KS via two different mechanisms: (i) by highly specific inhibition of KS spindle cell proliferation and (ii) by induction of monocyte chemoattractant protein-1 expression in KS spindle cells, which may result in increased recruitment of phagocytic cells (monocytes/macrophages) into the lesions. A cooperative action of both mechanisms may explain the high efficacy of liposomal doxorubicin in the treatment of AIDS-KS.

Phase I and pharmacokinetic trial of liposome-encapsulated doxorubicin

A total of 21 patients with advanced cancer were entered into a phase I study to determine the maximum tolerable dose (MTD) of liposome-encapsulated doxorubicin (LED) given weekly for 3 consecutive weeks at doses of 20, 30, or 37.5 mg/m2 per week. For a comparison of the pharmacokinetic behavior of LED with that of standard-formulation doxorubicin, 13 patients received a dose of standard-formulation doxorubicin 2 weeks prior to the first dose of LED. All doses were given by 1-h infusion through a central vein. Toxicity was evaluated in 22 courses delivered to 17 patients. The MTD with this schedule was 30 mg/m2 per week x 3. The single patient treated at 37.5 mg/m2 weekly could not complete the entire course due to myelosuppression. At the dose of 30 mg/m2 per week, three of eight patients had grade > or = 3 leukopenia. Other toxicities included mild to moderate thrombocytopenia, nausea, vomiting, fever, alopecia, diarrhea, fatigue, stomatitis, and infection. At the dose of 30 mg/m2 per week, the total doxorubicin AUC and peak total doxorubicin concentrations in plasma were 8.75 +/- 8.80 microM h (mean +/- SD) and 3.07 +/- 1.45 microM, respectively, after LED administration. The total doxorubicin AUC and peak total doxorubicin concentrations in plasma were 3.92 +/- 2.47 microM h and 2.75 +/- 2.70 microM, respectively, after the infusion of standard-formulation doxorubicin. The total body clearance of doxorubicin was 18.42 +/- 11.23 l/h after the infusion of LED and 31.21 +/- 15.48 l/h after the infusion of standard-formulation doxorubicin. The mean elimination half-lives of doxorubicin were similar: 8.65 +/- 5.16 h for LED and 7.46 +/- 5.16 h for standard-formulation doxorubicin. Interpatient variability in pharmacokinetic parameters as demonstrated by the percentage of coefficients of variation was 33%-105%. There was no relationship between the percentage of WBC decrease or the duration of WBC suppression and the total doxorubicin or doxorubicinol AUC. There was no correlation between the duration of leukopenia and drug exposure as reflected by the AUC of liposome-associated doxorubicin. LED can be given in doses similar to those of standard-formulation doxorubicin and produces acute toxicities similar to those caused by standard doxorubicin.