Self-assembled nanoparticles of hyaluronic acid/poly(DL-lactide-co-glycolide) block copolymer

Stabilized, ROS-sensitive β-cyclodextrin-grafted hyaluronic supramolecular nanocontainers for CD44-targeted anticancer drug delivery

Hyaluronic acid (HA)-based tumor microenvironment-responsive nanocontainers are attractive candidates for anticancer drug delivery due to HA's excellent biocompatibility, biodegradability, and CD44-targeting properties. Nevertheless, the consecutive synthesis of stabilized, stealthy, responsive HA-based multicomponent nanomedicines generally requires multi-step preparation and purification procedures, leading to batch-to-batch variation and scale-up difficulties. To develop a facile yet robust strategy for promoted translations, a silica monomer containing a cross-linkable diethoxysilyl unit was prepared to enable in situ crosslinking without any additives. Further combined with the host-guest inclusion complexation between β-cyclodextrin-grafted HA (HA-CD) and ferrocene-functionalized polymers, ferrocene-terminated poly(oligo(ethylene glycol) methyl ether methacrylate (Fc-POEGMA) and Fc-terminated poly(ε-caprolactone)-b-poly(3-(diethoxymethylsilyl)propyl(2-(methacryloyloxy)ethyl) carbamate) (Fc-PCL-b-PDESPMA), a reactive oxygen species (ROS)-sensitive supramolecular polymer construct, Fc-POEGMA/Fc-PCL-b-PDESPMA@HA-CD was readily fabricated to integrate stealthy POEGMA, tumor active targeting HA, and an in situ cross-linkable PDESPMA sequence. Supramolecular amphiphilic copolymers with two different POEGMA contents of 25 wt% (P1) and 20 wt% (P2) were prepared via a simple physical mixing process, affording two core-crosslinked (CCL) micelles via an in situ sol-gel process of ethoxysilyl groups. The P1-based CCL micelles show not only desired colloidal stability against high dilution, but also an intracellular ROS-mimicking environment-induced particulate aggregation that is beneficial for promoted intracellular release of the loaded cargoes. Most importantly, P1-based nanomedicines exhibited greater cytotoxicity in CD44 receptor-positive HeLa cells than that in CD44 receptor-negative MCF-7 cells. Overall, this work developed HA-based nanomedicines with sufficient extracellular colloidal stability and efficient intracellular destabilization properties for enhanced anticancer drug delivery via smart integration of in situ crosslinking and supramolecular complexation.

Synergistic Effects of Radiotherapy With JNK Inhibitor-Incorporated Nanoparticle in an Intracranial Lewis Lung Carcinoma Mouse Models

BACKGROUND

Radiosurgery has been recognized as a reasonable treatment for metastatic brain tumors. Increasing the radiosensitivity and synergistic effects are possible ways to improve the therapeutic efficacy of specific regions of tumors. c-Jun-N-terminal kinase (JNK) signaling regulates H2AX phosphorylation to repair radiation-induced DNA breakage. We previously showed that blocking JNK signaling influenced radiosensitivity in vitro and in an in vivo mouse tumor model. Drugs can be incorporated into nanoparticles to produce a slow-release effect. This study assessed JNK radiosensitivity following the slow release of the JNK inhibitor SP600125 from a poly (DL-lactide-co-glycolide) (LGEsese) block copolymer in a brain tumor model.

MATERIALS AND METHODS

A LGEsese block copolymer was synthesized to fabricate SP600125-incorporated nanoparticles by nanoprecipitation and dialysis methods. The chemical structure of the LGEsese block copolymer was confirmed by 1H nuclear magnetic resonance (NMR) spectroscopy. The physicochemical and morphological properties were observed by transmission electron microscopy (TEM) imaging and measured with particle size analyzer. The blood-brain barrier (BBB) permeability to the JNK inhibitor was estimated by BBBflammaTM 440-dye-labeled SP600125. The effects of the JNK inhibitor were investigated using SP600125-incorporated nanoparticles and by optical bioluminescence, magnetic resonance imaging (MRI), and a survival assay in a mouse brain tumor model for Lewis lung cancer (LLC)-Fluc cells. DNA damage was estimated by histone γ H2AX expression and apoptosis was assessed by the immunohistochemical examination of cleaved caspase 3.

RESULTS

The SP600125-incorporated nanoparticles of the LGEsese block copolymer were spherical and released SP600125 continuously for 24h. The use of BBBflammaTM 440-dye-labeled SP600125 demonstrated the ability of SP600125 to cross the BBB. The blockade of JNK signaling with SP600125-incorporated nanoparticles significantly delayed mouse brain tumor growth and prolonged mouse survival after radiotherapy. γ H2AX, which mediates DNA repair protein, was reduced and the apoptotic protein cleaved-caspase 3 was increased by the combination of radiation and SP600125-incorporated nanoparticles.

Hyaluronic Acid within Self-Assembling Nanoparticles: Endless Possibilities for Targeted Cancer Therapy

Self-assembling nanoparticles (SANPs) based on hyaluronic acid (HA) represent unique tools in cancer therapy because they combine the HA targeting activity towards cancer cells with the advantageous features of the self-assembling nanosystems, i.e., chemical versatility and ease of preparation and scalability. This review describes the key outcomes arising from the combination of HA and SANPs, focusing on nanomaterials where HA and/or HA-derivatives are inserted within the self-assembling nanostructure. We elucidate the different HA derivatization strategies proposed for this scope, as well as the preparation methods used for the fabrication of the delivery device. After showing the biological results in the employed in vivo and in vitro models, we discussed the pros and cons of each nanosystem, opening a discussion on which approach represents the most promising strategy for further investigation and effective therapeutic protocol development.

PLGA Nanoparticles Grafted with Hyaluronic Acid to Improve Site-Specificity and Drug Dose Delivery in Osteoarthritis Nanotherapy

Nanoparticles (NPs) have a tremendous potential in medicinal applications, and recent studies have pushed the boundaries in nanotherapy, including in osteoarthritis treatments. The aim of this study was to develop new poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) surfaces decorated with hyaluronic acid (HA) to enhance targeted drug specificity to the osteoarthritic knee joint. HA was selected since it binds to specific receptors expressed in many cells, such as the cluster determinant 44 (CD44), a major receptor of chondrocytes, and because of its function in the synovial fluid (SF), such as maintenance of high fluid viscosity. The PLGA polymer was grafted to sodium hyaluronate using dimethoxy-PEG (PLGA-HA) and compared with control PLGA NPs (not grafted). NPs were characterized by 1H-NMR and IR spectroscopy. Then, near-infrared (NIR) dye and gold (20 nm) were encapsulated in the formulated NPs and used to access NPs’ performance in in vitro, in vivo, and ex vivo experiments. To test the NPs’ CD44 receptor specificity, an antibody assay was performed. All NPs presented a size in the range viable for cell-uptake, no cytotoxicity to chondrocytes was registered. Although all the NPs had a high capacity to be absorbed by the cells, PLGA-HA NPs showed significantly higher affinity towards the chondrocytic C28/I2 cell line. In conclusion, PLGA NPs grafted to sodium hyaluronate showed increased binding to cartilage cells and tissue and enhanced accumulation at the target site. Thus, this study presents a safe drug-delivery system with improved receptor specificity, which may represent an advantageous alternative to current nanotherapies.

Reduction/Oxidation-Responsive Hierarchical Nanoparticles with Self-Driven Degradability for Enhanced Tumor Penetration and Precise Chemotherapy

Deep tumor penetration, long blood circulation, rapid drug release, and sufficient stability are the most concerning dilemmas of nano-drug-delivery systems for efficient chemotherapy. Herein, we develop reduction/oxidation-responsive hierarchical nanoparticles co-encapsulating paclitaxel (PTX) and pH-stimulated hyaluronidase (pSH) to surmount the sequential biological barriers for precise cancer therapy. Poly(ethylene glycol) diamine (PEG-dia) is applied to collaboratively cross-link the shell of nanoparticles self-assembled by a hyaluronic acid-stearic acid conjugate linked via a disulfide bond (HA-SS-SA, HSS) to fabricate the hierarchical nanoparticles (PHSS). The PTX and pSH coloaded hierarchical nanoparticles (PTX/pSH-PHSS) enhance the stability in normal physiological conditions and accelerate drug release at tumorous pH, and highly reductive or oxidative environments. Functionalized with PEG and HA, the hierarchical nanoparticles preferentially prolong the circulation time, accumulate at the tumor site, and enter MDA-MB-231 cells via CD44-mediated endocytosis. Within the acidic tumor micro-environment, pSH would be partially reactivated to decompose the dense tumor extracellular matrix for deep tumor penetration. Interestingly, PTX/pSH-PHSS could be degraded apace by the completely activated pSH within endo/lysosomes and the intracellular redox micro-environment to facilitate drug release to produce the highest tumor inhibition (93.71%) in breast cancer models.

A potential carrier for anti-tumor targeted delivery-hyaluronic acid nanoparticles

In recent years, biomacromolecules have been widely used in anti-tumor delivery systems due to the biocompatibility and biodegradability. However, their applications are limited due to the lack of specific targeting. Hyaluronic acid (HA) is a natural polysaccharide and presents in extracellular matrix and synovial fluid which can specifically recognize receptors over-expressed by tumor cells. In addition, they can self-assemble into nanoparticles. HA nanoparticles provide new hierarchical targeting strategies: passively targeting tumor tissue by enhanced permeability and retention effect, actively targeting tumor cells by cluster determinant 44 (CD44) receptor, and then entering cells through receptor-mediated endocytosis. In this review, the synthesis of HA nanoparticles is described in detail from several aspects and applications are also discussed for improving the delivery of hydrophobic drugs, nucleic acids and photosensitizers into the tumor cells. In addition, the modification of HA for improving the targeting and drug releasing characteristics are also discussed.

Tumor-targeting core-shell structured nanoparticles for drug procedural controlled release and cancer sonodynamic combined therapy

Combination therapy with multiple drugs or/and multiple assistant treatments has become a hot spot in cancer therapy. In this study, a new type of core-shell structured dual-drug delivery system based on poly (lactic-co-glycolic acid) (PLGA, inner cores) and hyaluronic acid (HA, outer shells) was constructed. Firstly, HA was conjugated to PLGA for preparation of HA-PLGA block copolymer. Secondly, 5-amino levulinic acid (ALA) was connected to PLGA through a pH-sensitive hydrazone bond for synthesization of PLGA-HBA-ALA. Finally, the core-shell structured nanoparticles (HA-PLGA@ART/ALA NPs) were constructed by self-assembled method for artemisinin (ART) loading in PLGA cores. In this co-delivery system, ALA and ART can be released in a manner of procedural controlled release. ALA was released from the NPs at first though the pH sensitive hydrazone bond cleavage in order to generate protoporphyrin IX (PpIX) for heme formation. And the increase of heme can effectively improve the curative effect of the subsequent released ART. Furthermore, this system has also shown obvious sonodynaimc activity which can be used for cancer sonodynamic combination therapy. The in vitro and in vivo anticancer results demonstrate that HA-PLGA@ART/ALA delivery system could provide a prospective comprehensive treatment strategy for cancer therapy.

Biodegradable Polymeric Nanoparticles for Therapeutic Cancer Treatments

Polymeric nanoparticles have tremendous potential to improve the efficacy of therapeutic cancer treatments by facilitating targeted delivery to a desired site. The physical and chemical properties of polymers can be tuned to accomplish delivery across the multiple biological barriers required to reach diverse subsets of cells. The use of biodegradable polymers as nanocarriers is especially attractive, as these materials can be designed to break down in physiological conditions and engineered to exhibit triggered functionality when at a particular location or activated by an external source. We present how biodegradable polymers can be engineered as drug delivery systems to target the tumor microenvironment in multiple ways. These nanomedicines can target cancer cells directly, the blood vessels that supply the nutrients and oxygen that support tumor growth, and immune cells to promote anticancer immunotherapy.

Hybrid nanoparticles based on chlorin e6-conjugated hyaluronic acid/poly(l-histidine) copolymer for theranostic application to tumors

The aim of this study is to synthesize multifunctional hybrid nanoparticles composed of hyaluronic acid (HA) and poly(l-histidine) (PHS) with a disulfide linkage and chlorin e6 (HAPHSce6ss) for diagnostic and therapeutic application against breast tumor cells. The reductive end of HA was conjugated with cystamine to make a disulfide linkage (HA-cystamine). PHS was conjugated with Ce6 with the aid of carbodiimide chemistry (PHS-ce6). Then, HA-cystamine was conjugated with the carboxyl group of Ce6 to make an HAPHSce6ss copolymer. Nanoparticles of HAPHSce6ss copolymer have small particle sizes of less than 100 nm and their diameters increased with acidic pH, indicating that HAPHSce6ss nanoparticles have pH-sensitivity. Furthermore, ce6 was activated in the acidic environment and had redox-status in a fluorescence study. In a cell culture study, the nanoparticles were specifically targeted at the CD44 receptor of MDA-MB231 cells while CD44-negative MCF7 cells had no CD44-specificity. The nanoparticles exhibited an enhanced association with cells and were more fluorescent at acidic pH or in the presence of GSH. They inhibited the growth of tumor cells in a CD44 receptor specific or pH-sensitive manner. In an in vivo animal tumor xenograft study using mice, HAPHSce6ss nanoparticles predominantly targeted an MDA-MB231 tumor rather than an MCF7 tumor and effectively inhibited tumor growth. HAPHSce6ss nanoparticles have CD44 specificity, pH/redox dual sensitivity and a fluorescence diagnostic function against tumor cells. We suggest that HAPHSce6ss nanoparticles are a promising candidate for theranostic application to tumors.

Functionalizing PLGA and PLGA Derivatives for Drug Delivery and Tissue Regeneration Applications

Poly(lactic-co-glycolic) acid (PLGA) is one of the most versatile biomedical polymers, already approved by regulatory authorities to be used in human research and clinics. Due to its valuable characteristics, PLGA can be tailored to acquire desirable features for control bioactive payload or scaffold matrix. Moreover, its chemical modification with other polymers or bioconjugation with molecules may render PLGA with functional properties that make it the Holy Grail among the synthetic polymers to be applied in the biomedical field. In this review, the physical-chemical properties of PLGA, its synthesis, degradation, and conjugation with other polymers or molecules are revised in detail, as well as its applications in drug delivery and regeneration fields. A particular focus is given to successful examples of products already on the market or at the late stages of trials, reinforcing the potential of this polymer in the biomedical field.

Co-administration of biocompatible self-assembled polylactic acid–hyaluronic acid block copolymer nanoparticles with tumor-penetrating peptide-iRGD for metastatic breast cancer therapy

The safe and efficient targeted delivery of chemotherapeutic drugs has remained a challenge in metastatic breast cancer therapy.

Functionalized diterpene parvifloron D-loaded hybrid nanoparticles for targeted delivery in melanoma therapy

AIM

Parvifloron D is a natural diterpene with a broad and not selective cytotoxicity toward human tumor cells. In order to develop a targeted antimelanoma drug delivery platform for Parvifloron D, hybrid nanoparticles were prepared with biopolymers and functionalized with α-melanocyte stimulating hormone. Results/methodology: Nanoparticles were produced according to a solvent displacement method and the physicochemical properties were assessed. It was shown that Parvifloron D is cytotoxic and can induce, both as free and as encapsulated drug, cell death in melanoma cells (human A375 and mouse B16V5). Parvifloron D-loaded nanoparticles showed a high encapsulation efficiency (87%) and a sustained release profile. In vitro experiments showed the nanoparticles' uptake and cell internalization.

CONCLUSION

Hybrid nanoparticles appear to be a promising platform for long-term drug release, presenting the desired structure and a robust performance for targeted anticancer therapy.

Applications of deuterium oxide in human health

The main aim goal of this review was to gather information about recent publications related to deuterium oxide (D₂O), and its use as a scientific tool related to human health. Searches were made in electronic databases Pubmed, Scielo, Lilacs, Medline and Cochrane. Moreover, the following patent databases were consulted: EPO (Espacenet patent search), USPTO (United States Patent and Trademark Office) and Google Patents, which cover researches worldwide related to innovations using D₂O.

Near-infrared light triggered drug delivery system for higher efficacy of combined chemo-photothermal treatment

The combination of chemotherapy and photothermal therapy is a promising strategy for cancer treatment. In the present study, indocyanine green (ICG), a widely used near-infrared (NIR) dye in photothermal therapy, and chemotherapeutic drug-doxorubicin (DOX) were loaded within the nanoparticles of novel designed arylboronic ester and cholesterol modified hyaluronic acid (PPE-Chol₁-HA), denoted as PCH-DI. We take advantage of reactive oxygen species (ROS) production capability of ICG and ROS-sensitivity of arylboronic ester to realize controllable drug release. It was confirmed that PCH-DI exhibited remarkable photothermal effect and light-triggered faster release of DOX with NIR laser irradiation. DOX in PCH-DI/Laser group exhibited the most efficient nucleus binding toward HCT-116 colon cells in vitro. Furthermore, enhanced cytotoxicity and promoted tumor growth suppression effect of PCH-DI on HCT-116 tumor xenograft nude mice and AOM-induced murine orthotopic colorectal cancer model was achieved under NIR laser irradiation. Thus, the co-delivery system based on PCH appears to be a promising platform for the combined chemo-photothermal therapy in tumor treatment.

STATEMENT OF SIGNIFICANCE

In case of chemo-photothermal combination therapy, the synchronism of treatments plays an important role in achieving expected antitumor efficiency. In this study, a light triggered ROS mediated drug delivery system was developed with the help of ROS-sensitive moieties of arylboronic ester and ROS producer of ICG. We innovatively make use of the ROS production capability of ICG under NIR laser irradiation to promote a faster release of DOX resulting from swelling of PCH-DI due to the presence of arylboronic ester. Intracellular ROS detection demonstrated that ROS level of PCH-I increased under irradiation. Moreover, the faster release behavior of DOX from PCH-DI with NIR laser irradiation was confirmed by the in vitro drug release and cellular uptake study. Meanwhile, local hyperthermia was verified by photothermal effect tests. Therefore, the synchronism of the combination therapy was achieved via light triggered faster release of DOX (chemo-therapy) and local hyperthermia (thermal-therapy) using PCH-DI under irradiation. It was reasonable to attribute the efficient anti-tumor efficiency of PCH-DI both in vitro and in vivo to the enhanced synergistic effect of chemo-photothermal combination therapy with realization of synchronism. To this end, this novel co-delivery system has provided a promising solution for achieving the synchronism of treatment to strengthen the efficiency of combination therapy.

Hyaluronic acid and its derivatives in drug delivery and imaging: Recent advances and challenges

Hyaluronic acid (HA) is a biodegradable, biocompatible, nontoxic, and non-immunogenic glycosaminoglycan used for various biomedical applications. The interaction of HA with the CD44 receptor, whose expression is elevated on the surface of many types of tumor cells, makes this polymer a promising candidate for intracellular delivery of imaging and anticancer agents exploiting a receptor-mediated active targeting strategy. Therefore, HA and its derivatives have been most investigated for the development of several carrier systems intended for cancer diagnosis and therapy. Nonetheless, different and important delivery applications of the polysaccharide have also been described, including gene and peptide/protein drugs delivery. The aim of this review was to provide an overview of the existing recent literature on the use of HA and its derivatives for drug delivery and imaging. Notable attention is given to nanotheranostic systems obtained after conjugation of HA to nanocarriers as quantum dots, carbon nanotubes and graphene. Meanwhile, attention is also paid to some challenging aspects that need to be addressed in order to allow translation of preclinical models based on HA and its derivatives for drug delivery and imaging purposes to clinical testing and further their development.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

Folic-acid-conjugated pullulan/poly(DL-lactide-co-glycolide) graft copolymer nanoparticles for folate-receptor-mediated drug delivery

BACKGROUND

Nanoparticles have been extensively investigated for targeted delivery of anticancer drugs. Since the folate receptor is universally over-expressed on the tumor cell membrane, folic acid is often used to modify the fate of nanoparticles in biologicals.

METHODS

To fabricate targetable nanoparticles, folic acid was conjugated to a pullulan backbone and poly(DL-lactide-co-glycolide) (PLGA) (abbreviated as FAPuLG) was conjugated. KB cells and NIH3T3-cell-bearing mice were prepared to prove folate receptor targeting of FAPuLG nanoparticles.

RESULTS AND DISCUSSION

Nanoparticles of FAPuLG copolymer that self-assembled in water were small with diameters <200 nm. Doxorubicin (DOX) as a model drug was incorporated into the FAPuLG nanoparticles that were used to treat folate receptor over-expressing KB human carcinoma cells. Fluorescence microscopy revealed that DOX-incorporated FAPuLG nanoparticles induced strong red fluorescence in the KB cells in the absence of folic acid. However, fluorescence intensity was decreased by blocking folate receptors. Antitumor activity of FAPuLG nanoparticles against KB cells in vitro was also decreased by blocking folate receptors. In animal study using near-infrared dye-conjugated FAPuLG nanoparticles, fluorescence intensity was significantly higher at KB solid tumor than that of NIH3T3.

CONCLUSIONS

The results indicate that FAPuLG nanoparticles can target the folate receptor of tumor cells. FAPuLG nanoparticles are a promising candidate for active targeting of anticancer agents.

Preparation, in vitro and in vivo evaluation of polymeric nanoparticles based on hyaluronic acid-poly(butyl cyanoacrylate) and D-alpha-tocopheryl polyethylene glycol 1000 succinate for tumor-targeted delivery of morin hydrate

Herein, we describe the preparation of a targeted cellular delivery system for morin hydrate (MH), based on a low-molecular-weight hyaluronic acid-poly(butyl cyanoacrylate) (HA-PBCA) block copolymer. In order to enhance the therapeutic effect of MH, D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) was mixed with HA-PBCA during the preparation process. The MH-loaded HA-PBCA “plain” nanoparticle (MH-PNs) and HA-PBCA/TPGS “mixed” nanoparticles (MH-MNs) were concomitantly characterized in terms of loading efficiency, particle size, zeta potential, critical aggregation concentration, and morphology. The obtained MH-PNs and MH-MNs exhibited a spherical morphology with a negative zeta potential and a particle size less than 200 nm, favorable for drug targeting. Remarkably, the addition of TPGS resulted in about 1.6-fold increase in drug-loading. The in vitro cell viability experiment revealed that MH-MNs enhanced the cytotoxicity of MH in A549 cells compared with MH solution and MH-PNs. Furthermore, blank MNs containing TPGS exhibited selective cytotoxic effects against cancer cells without diminishing the viability of normal cells. In addition, the cellular uptake study indicated that MNs resulted in 2.28-fold higher cellular uptake than that of PNs, in A549 cells. The CD44 receptor competitive inhibition and the internalization pathway studies suggested that the internalization mechanism of the nanoparticles was mediated mainly by the CD44 receptors through a clathrin-dependent endocytic pathway. More importantly, MH-MNs exhibited a higher in vivo antitumor potency and induced more tumor cell apoptosis than did MH-PNs, following intravenous administration to S180 tumor-bearing mice. Overall, the results imply that the developed nanoparticles are promising vehicles for the targeted delivery of lipophilic anticancer drugs.

Hyaluronic acid conjugates as vectors for the active targeting of drugs, genes and nanocomposites in cancer treatment

Hyaluronic acid (HA) is a naturally-occurring glycosaminoglycan and a major component of the extracellular matrix. Low levels of the hyaluronic acid receptor CD44 are found on the surface of epithelial, hematopoietic, and neuronal cells; it is overexpressed in many cancer cells, and in particular in tumor-initiating cells. HA has recently attracted considerable interest in the field of developing drug delivery systems, having been used, as such or encapsulated in different types of nanoassembly, as ligand to prepare nano-platforms for actively targeting drugs, genes, and diagnostic agents. This review describes recent progress made with the several chemical strategies adopted to synthesize conjugates and prepare novel delivery systems with improved behaviors.

The eradication of breast cancer cells and stem cells by 8-hydroxyquinoline-loaded hyaluronan modified mesoporous silica nanoparticle-supported lipid bilayers containing docetaxel

Breast cancer stem cells (BCSCs), which can fully recapitulate the tumor origin and are often resistant to chemotherapy and radiotherapy, are currently considered as a major obstacle for breast cancer treatment. To achieve the goal of both targeting BCSCs and bulk breast cancer cells, we developed 8-hydroxyquinoline-loaded hyaluronan modified mesoporous silica nanoparticles (MSN)-supported lipid bilayers (HA-MSS) and docetaxel-loaded MSS. The results showed that the size of all the nanoparticles was smaller than 200 nm. BCSCs were enriched from MCF-7 cells by a sphere formation method and identified with the CD44(+)/CD24(-) phenotype. Quantitative and qualitative analysis demonstrated that HA promotes the uptake of HA-MSS in CD44-overexpressing MCF-7 mammospheres, revealing the mechanism of receptor-mediated endocytosis. DTX or DTX-loaded MSS showed much enhanced cytotoxicity against MCF-7 cells compared with MCF-7 mammospheres, whereas 8-HQ or 8-HQ-loaded HA-MSS showed much enhanced cytotoxicity against MCF-7 mammospheres compared with MCF-7 cells. In the MCF-7 xenografts in mice, the combination therapy with DTX-loaded MSS plus 8-HQ-loaded HA-MSS produced the strongest antitumor efficacy, with little systemic toxicity (reflecting by loss of body weight) in mice. Thus, this combination therapy may provide a potential strategy to improve the therapy of breast cancer by eradication of breast cancer cells together with BCSCs.

Polysaccharide-based micelles for drug delivery

Delivery of hydrophobic molecules and proteins has been an issue due to poor bioavailability following administration. Thus, micelle carrier systems are being investigated to improve drug solubility and stability. Due to problems with toxicity and immunogenicity, natural polysaccharides are being explored as substitutes for synthetic polymers in the development of new micelle systems. By grafting hydrophobic moieties to the polysaccharide backbone, self-assembled micelles can be readily formed in aqueous solution. Many polysaccharides also possess inherent bioactivity that can facilitate mucoadhesion, enhanced targeting of specific tissues, and a reduction in the inflammatory response. Furthermore, the hydrophilic nature of some polysaccharides can be exploited to enhance circulatory stability. This review will highlight the advantages of polysaccharide use in the development of drug delivery systems and will provide an overview of the polysaccharide-based micelles that have been developed to date.

Synthesis of Dextran/Methoxy Poly(ethylene glycol) Block Copolymer

We synthesized a block copolymer composed of dextran and methoxy poly(ethylene glycol) (mPEG). To accomplish this, the end group of dextran was modified by reductive amination. The aminated dextran (Dextran-NH2) showed the intrinsic peaks of both dextran at 3~5.5 ppm and hexamethylene diamine at 1~2.6 ppm at1H nuclear magnetic resonance (NMR) spectrum. The amino end group of dextran was conjugated with mPEG to make the block copolymer consisting of dextran/mPEG (abbreviated as DexPEG). The synthesized aminated dextran and DexPEG were characterized using1H NMR and gel permeation chromatography (GPC). The molecular weight and conjugation yield were estimated by comparing the intensity ratio of the proton peaks of the glucose molecule (4.9 ppm and 3.3~4.0 ppm) to that of the ethylene group of mPEG (3.7 ppm). Abundant hydroxyl group in the dextran chain can be used as a source of bioactive agent conjugation.

Polysaccharide-covered nanoparticles with improved shell stability using click-chemistry strategies

Dextran-covered PLA nanoparticles have been formulated by two strategies. On one hand, dextran-g-PLA copolymers have been synthesized by click-chemistry between azide-multifunctionalized dextran (DexN3) and alkyne end-functionalized PLA chains (α-alkyne PLA); then nanoprecipitated without any additional surfactants. On the other hand, DexN3 exhibiting surfactant properties have been emulsified with unfunctionalized or α-alkyne PLA, which are dissolved in organic phase with or without CuBr. Depending on the o/w emulsion/evaporation process experimental conditions, dextran-g-PLA copolymers have been produced in situ, by click chemistry at the liquid/liquid interface during the emulsification step. Whatever the process, biodegradable core/shell polymeric nanoparticles have been obtained, then characterized. Colloidal stability of these nanoparticles in the presence of NaCl or SDS has been studied. While the physically adsorbed polysaccharide based shell has been displaced by SDS, the covalently-linked polysaccharide based shell ensures a permanent stability, even in the presence of SDS.

CD44: a validated target for improved delivery of cancer therapeutics

INTRODUCTION

Advances in cancer therapeutics, namely more effective and less toxic treatments, will occur with targeting strategies that enhance the tumor biodistribution and thwart normal tissue exposure of the drug. This review focuses on cancer drug targeting approaches that exploit the expression of the cell-surface proteoglycan family, CD44, on the tumor cell surface followed by some form of ligand binding and induced CD44 internalization and intracellular drug release: in effect using this as a 'Trojan Horse' to more selectively access tumor cells.

AREAS COVERED

This review defines the origins of evidence for a linkage between CD44 expression and malignancy, and invokes contemporary views of the importance of putative CD44(+) cancer stem cells in disease resistance. Although the primary emphasis is on the most advanced and developed paths, those that have either made it to the clinic or are well-poised to get there, a wide scope of additional approaches at various preclinical stages is also briefly reviewed.

EXPERT OPINION

The future should see development of drug targeting approaches that exploit CD44 expression on CSCs/TICs, including applications to cytotoxic agents currently in the clinic.