Redox-Responsive Gold Nanoparticles Coated with Hyaluronic Acid and Folic Acid for Application in Targeting Anticancer Therapy

Methotrexate (MTX) has poor water solubility and low bioavailability, and cancer cells can become resistant to it, which limits its safe delivery to tumor sites and reduces its clinical efficacy. Herein, we developed novel redox-responsive hybrid nanoparticles (NPs) from hyaluronic acid (HA) and 3-mercaptopropionic acid (MPA)-coated gold NPs (gold@MPA NPs), which were further conjugated with folic acid (FA). The design of FA-HA-ss-gold NPs aimed at enhancing cellular uptake specifically in cancer cells using an active FA/HA dual targeting strategy for enhanced tumor eradication. MTX was successfully encapsulated into FA-HA-ss-gold NPs, with drug encapsulation efficiency (EE) as high as >98.7%. The physicochemical properties of the NPs were investigated in terms of size, surface charges, wavelength reflectance, and chemical bonds. MTX was released in a sustained manner in glutathione (GSH). The cellular uptake experiments showed effective uptake of FA-HA-ss-gold over HA-ss-gold NPs in the deep tumor. Moreover, the release studies provided strong evidence that FA-HA-ss-gold NPs serve as GSH-responsive carriers. In vitro, anti-tumor activity tests showed that FA-HA-ss-gold/MTX NPs exhibited significantly higher cytotoxic activity against both human cervical cancer (HeLa) cells and breast cancer (BT-20) cells compared to gold only and HA-ss-gold/MTX NPs while being safe for human embryonic kidney (HEK-293) cells. Therefore, this present study suggests that FA-HA-ss-gold NPs are promising active targeting hybrid nanocarriers that are stable, controllable, biocompatible, biodegradable, and with enhanced cancer cell targetability for the safe delivery of hydrophobic anticancer drugs.

Injectable and Multifunctional Hydrogels Based on Poly(N-acryloyl glycinamide) and Alginate Derivatives for Antitumor Drug Delivery

Chemotherapy is a conventional treatment that uses drugs to kill cancer cells; however, it may induce side effects and may be incompletely effective, leading to the risk of tumor recurrence. To address this issue, we developed novel injectable thermal/near-infrared (NIR)-responsive hydrogels to control drug release. The injectable hydrogel formulation was composed of biocompatible alginates, poly(N-acryloyl glycinamide) (PNAGA) copolymers with an upper critical solution temperature, and NIR-responsive cross-linkers containing coumarin groups, which were gelated through bioorthogonal inverse electron demand Diels-Alder reactions. The hydrogels exhibited quick gelation times (120-800 s) and high drug loading efficiencies (>90%). The hydrogels demonstrated a higher percentage of drug release at 37 °C than that at 25 °C due to the enhanced swelling behavior of temperature-responsive PNAGA moieties. Upon NIR irradiation, the hydrogels released most of the entrapped doxorubicin (DOX) (97%) owing to the cleavage of NIR-sensitive coumarin ester groups. The hydrogels displayed biocompatibility with normal cells, while induced antitumor activity toward cancer cells. DOX/hydrogels treated with NIR light inhibited tumor growth in nude mice bearing tumors. In addition, the injected hydrogels emitted red fluorescence upon excitation at a green wavelength, so that the drug delivery and hydrogel degradation in vivo could be tracked in the xenograft model.

NIR-responsive carboxymethyl-cellulose hydrogels containing thioketal-linkages for on-demand drug delivery system

Near-infrared (NIR) light-responsive hydrogels have emerged as a highly promising strategy for effective anticancer therapy owing to the remotely controlled release of chemotherapeutic molecules with minimal invasive manner. In this study, novel NIR-responsive hydrogels were developed from reactive oxygen species (ROS)-cleavable thioketal cross-linkers which possessed terminal tetrazine groups to undergo a bio-orthogonal inverse electron demand Diels Alder click reaction with norbornene modified carboxymethyl cellulose. The hydrogels were rapidly formed under physiological conditions and generated N2 gas as a by-product, which led to the formation of porous structures within the hydrogel networks. A NIR dye, indocyanine green (ICG) and chemotherapeutic doxorubicin (DOX) were co-encapsulated in the porous network of the hydrogels. Upon NIR-irradiation, the hydrogels showed spatiotemporal release of encapsulated DOX (>96 %) owing to the cleavage of thioketal bonds by interacting with ROS generated from ICG, whereas minimal release of encapsulated DOX (<25 %) was observed in the absence of NIR-light. The in vitro cytotoxicity results revealed that the hydrogels were highly cytocompatible and did not induce any toxic effect on the HEK-293 cells. In contrast, the DOX + ICG-encapsulated hydrogels enhanced the chemotherapeutic effect and effectively inhibited the proliferation of Hela cancer cells when irradiated with NIR-light.

Facile Fabrication of NIR-Responsive Alginate/CMC Hydrogels Derived through IEDDA Click Chemistry for Photothermal-Photodynamic Anti-Tumor Therapy

Novel chemically cross-linked hydrogels derived from carboxymethyl cellulose (CMC) and alginate (Alg) were prepared through the utilization of the norbornene (Nb)-methyl tetrazine (mTz) click reaction. The hydrogels were designed to generate reactive oxygen species (ROS) from an NIR dye, indocyanine green (ICG), for combined photothermal and photodynamic therapy (PTT/PDT). The cross-linking reaction between Nb and mTz moieties occurred via an inverse electron-demand Diels-Alder chemistry under physiological conditions avoiding the need for a catalyst. The resulting hydrogels exhibited viscoelastic properties (G' ~ 492-270 Pa) and high porosity. The hydrogels were found to be injectable with tunable mechanical characteristics. The ROS production from the ICG-encapsulated hydrogels was confirmed by DPBF assays, indicating a photodynamic effect (with NIR irradiation at 1-2 W for 5-15 min). The temperature of the ICG-loaded hydrogels also increased upon the NIR irradiation to eradicate tumor cells photothermally. In vitro cytocompatibility assessments revealed the non-toxic nature of CMC-Nb and Alg-mTz towards HEK-293 cells. Furthermore, the ICG-loaded hydrogels effectively inhibited the metabolic activity of Hela cells after NIR exposure.

Reduction-Responsive Chitosan-Based Injectable Hydrogels for Enhanced Anticancer Therapy

Selective delivery of anticancer drug molecules to the tumor site enhances local drug dosages, which leads to the death of cancer cells while simultaneously minimizing the negative effects of chemotherapy on other tissues, thereby improving the patient's quality of life. To address this need, we developed reduction-responsive chitosan-based injectable hydrogels via the inverse electron demand Diels-Alder reaction between tetrazine groups of disulfide-based cross-linkers and norbornene groups of chitosan derivatives, which were applied to the controlled delivery of doxorubicin (DOX). The swelling ratio, gelation time (90-500 s), mechanical strength (G'~350-850 Pa), network morphology, and drug-loading efficiency (≥92%) of developed hydrogels were investigated. The in vitro release studies of the DOX-loaded hydrogels were performed at pH 7.4 and 5.0 with and without DTT (10 mM). The biocompatibility of pure hydrogel and the in vitro anticancer activity of DOX-loaded hydrogels were demonstrated via MTT assay on HEK-293 and HT-29 cancer cell lines, respectively.

NIR-degradable and biocompatible hydrogels derived from hyaluronic acid and coumarin for drug delivery and bio-imaging

In this work, bioorthogonal and photodegradable hydrogels derived from norbornene (Nb) functionalized hyaluronic acid and a water soluble coumarin-based cross-linker possessing terminal tetrazine (Tz) groups, were developed for NIR-responsive release of doxorubicin (DOX). The inverse electron demand Diels-Alder cross-linking reaction between Nb and Tz functionalities formed the hydrogels at physiological conditions, whereas N₂ gas liberated during the reaction created pores in the hydrogels. The gelation time ranges (about 5-20 min) and the viscoelastic behavior (G' ~ 346-1380 Pa) demonstrated that the resulting hydrogels were injectable and possessed tunable mechanical properties. Moreover, hydrogels released the encapsulated DOX upon NIR irradiation, owing to the NIR-responsive cleavage of coumarin-ester, and consequently, induced anti-tumor activity in BT-20 cancer cells. Additionally, the hydrogels could be excited at various wavelengths of the visible spectrum and can emit green to red fluorescence, demonstrating their simultaneous photo-responsive drug release and bio-imaging applications.

The effect of molecular weight and chemical structure of cross-linkers on the properties of redox-responsive hyaluronic acid hydrogels

In this work, we investigated the effect of the size and the chemical structure of crosslinkers on the properties of hyaluronic acid-based hydrogels prepared via an inverse electron demand Diels-Alder reaction. Hydrogels having loose and dense networks were designed by cross-linkers with and without polyethylene glycol (PEG) spacers of different molecular weights (1000 and 4000 g/mol). The study showed that the properties of hydrogels such as swelling ratios (20-55 times), morphology, stability, mechanical strength (storage modulus in the range 175-858 Pa), and drug loading efficiency (87 % ~ 90 %) were greatly influenced by the addition of PEG and changing its molecular weight in the cross-linker. Particularly, the presence of PEG chains in redox- responsive crosslinkers increased the doxorubicin release (85 %, after 168 h) and the degradation rate (96 %, after 10 d) of hydrogels in the simulated reducing medium (10 mM DTT). The in vitro cytotoxicity experiments conducted for HEK-293 cells revealed that the formulated hydrogels were biocompatible, which could be a promising candidate for drug delivery applications.

Fast Absorbent and Highly Bioorthogonal Hydrogels Developed by IEDDA Click Reaction for Drug Delivery Application

In this work, we engineered highly biocompatible and fast absorbent injectable hydrogels derived from norbornene (Nb)-functionalized hyaluronic acid (HA-Nb) and a water-soluble cross-linker possessing tetrazine (Tz) functional groups on both ends of polyethylene glycol (PEG-DTz). The by-product (nitrogen gas) of the inverse electron demand Diels−Alder (IEDDA) cross-linking reaction carved porosity in the resulting hydrogels. By varying the molar ratio of HA-Nb and PEG-DTz (Nb:Tz = 10:10, 10:5, 10:2.5), we were able to formulate hydrogels with tunable porosity, gelation time, mechanical strength, and swelling ratios. The hydrogels formed quickly (gelation time < 100 s), offering a possibility to use them as an injectable drug delivery system. The experimental data showed rapid swelling and a high swelling ratio thanks to the existence of PEG chains and highly porous architectures of the hydrogels. The hydrogels were able to encapsulate a high amount of curcumin (~99%) and released the encapsulated curcumin in a temporal pattern. The PEG-DTz cross-linker, HA-Nb, and the resulting hydrogels showed no cytotoxicity in HEK-293 cells. These fast absorbent hydrogels with excellent biocompatibility fabricated from HA-Nb and the IEDDA click-able cross-linker could be promising drug carriers for injectable drug delivery applications.

Injectable and biocompatible alginate-derived porous hydrogels cross-linked by IEDDA click chemistry for reduction-responsive drug release application

In this work, novel injectable and reduction-responsive hydrogels were successfully prepared via inverse electron demand Diels-Alder reaction between alginate-norbornene and a water-soluble PEG based disulfide cross-linker. The reduction-responsive cross-linker was designed to contain a PEG chain within two disulfide linkages, and two terminal tetrazine groups. The resulting hydrogels possessed high swelling ratios, porous morphology, excellent drug loading efficiency (~92%), and suitable mechanical properties. The drug release experiments demonstrated that the hydrogels released more than 90% of the encapsulated doxorubicin (DOX) in the presence of 10 mM glutathione while a minimal DOX release (<25%) was measured in physiological buffer (PBS, pH = 7.4) after 11 d. The cross-linker and hydrogels did not exhibit any apparent cytotoxicity to fibroblast cells. In contrast, DOX-loaded hydrogels induced anti-tumor activity against cancer cells. The injectable and reduction-responsive hydrogels hold great potential as a biomaterial for stimuli responsive drug delivery applications.

Effect of organoclay on morphology and properties of linear low density polyethylene and Vietnamese cassava starch biobased blend

Linear low density polyethylene (LLDPE)/thermal plastic starch (TPS) blend was studied to prepare the biobased nanocomposite material using organoclay nanofil15 (N15) modified by alkilammonium as the reinforced phase. The LLDPE/TPS blend and its nanocomposites were elaborated by melt mixing method at 160 °C for 7 min. And the compounded sample was filmed by blowing method at three different zones of temperature profile which are 160-170-165 °C. The good dispersion of clay in the polymer blend matrix is showed by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), and a semi-exfoliated structure was obtained. The thermal and mechanical properties of materials are enhanced when N15 is added to the mixture. The effect of N15 on morphology and particles size of TPS phase is also investigated. The biodegradation test shows that more than 60% in weight of LLDPE/TPS film is degraded into CO2, H2O, methane and biomass after 5 months in compost soil.

Reduced turn-around time for Mycobacterium tuberculosis drug susceptibility testing with a proportional agar microplate assay

Multidrug-resistant tuberculosis is a major issue worldwide; however, accessibility to drug susceptibility testing (DST) is still limited in developing countries, owing to high costs and complexity. We developed a proportion method on 12-well microplates for DST. The assay reduced the time to results to <12 days and <10 days when bacterial growth was checked with the naked eye or a microscope, respectively. Comparison with the Canetti-Grosset method showed that the results of the two assays almost overlapped (kappa index 0.98 (95% CI 0.91-1.00) for isoniazid, rifampicin, streptomycin; and kappa index 0.92 (95% CI 0.85-0.99) for ethambutol). The sequencing of genes involved in drug resistance showed similar level of phenotype-genotype agreement between techniques. Finally, measurement of the MICs of rifampicin and ethambutol suggests that the currently used critical ethambutol concentration should be revised, and that the current molecular drug susceptibility tests for rifampicin need to be re-evaluated, as in vitro rifampicin-sensitive isolates could harbour drug resistance-associated mutation(s).

Abstract P5-08-02: New target in the resistant mechanism to trastuzumab

Her2 positive (Her2+) breast cancer (BC) accounts for 18-20% of all breast cancer subtypes and is associated with high risk of death. Trastuzumab, the first Food and Drug Administration-approved targeted therapy for BC, represents a key milestone in the personalized treatment of Her2+ metastatic disease (Her2+ MBC). However, the median duration of response is less than a year, due to either primary or acquired resistance to the therapy. In addition, there is currently no conclusive biomarker for the response of patients to trastuzumab. Therefore, understanding the development of resistance to trastuzumab is of our interest. Recent studies have proposed various potential mechanisms leading to the resistance, including p27 rapid degradation. Previously, our study and other research demonstrated that Jab1 degrades p27 in breast cancer. These findings suggest that Jab1 over-expression contributes to trastuzumab resistance by facilitating p27 degradation.

Jab1/CSN5 (c-Jun activation domain-binding protein 1) is over-expressed in 50% of primary and 90% of metastatic breast cancers, while its expression is low or absent in normal adult breast tissues. We previously identified that high expression of Jab1 is associated with shorter progression-free survival in breast cancer patients. In this study, our preliminary data showed that the knockdown of Jab1 sensitizes the breast cancer cells to trastuzumab treatment in a dose-dependent manner. Mechanistically, we found that Jab1 over-expression is significantly correlated with the activation of Akt pathway in Her2+ breast cancer cells and xenograft model. Interestingly, activated Akt, due to PTEN loss or PI3K activating mutation has been widely implicated in the potential mechanism to trastuzumab resistance. Therefore, our results suggest that targeting Jab1 overcomes the resistance to trastuzumab via interfering with PI3K/Akt pathway.

In general, our study identifies Jab1 as a novel contributor to trastuzumab resistance and elucidates its potential mechanisms of actions. The successful completion of the study can potentially be translated to the clinic for the benefit of patients refractory to the therapy. Also our study suggests Jab1 expression level can be used as a predictive marker for trastuzumab treatment.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-02.

Effects of endophytic Fusarium oxysporum towards Radopholus similis activity in absence of banana

Four endophytic fungi (Fusarium spp.) isolated from the cortical tissue of surface-sterilised banana as well as from tomato roots were tested for their capacity of biological control towards the burrowing nematode Radopholus similis on banana. The pathogenic and parasitic capacities of endophytic fungi towards R. similis were tested in in vitro experiments. No parasitism of fungi on R. similis was observed. However, nematode activity decreased significantly in the presence of all endophytic fungi in vitro when compared to nematodes in the absence of fungi. The effects of fungi on R. similis activities in the soil were tested in the absence of plants. Nematode activities were reduced significantly by 16-30% by endophytic fungi when compared to untreated soil.

Oxidative stress as a mechanism of chronic cadmium-induced hepatotoxicity and renal toxicity and protection by antioxidants

The role of oxidative stress in chronic cadmium (Cd) toxicity and its prevention by cotreatment with antioxidants was investigated. Adult female Sprague-Dawley rats were injected sc with 5 micromol CdCl2/kg/day, 5 times a week, for up to 22 weeks. Serum alanine amino transferase and lactate dehydrogenase activities were elevated after 9 weeks of Cd administration, indicating hepatic damage. Renal toxicity, indicated by elevation in urinary lactate dehydrogenase activity and protein, was also observed around this time. Chronic Cd administration resulted in a gradual rise in hepatic as well as renal cortex glutathione levels. In spite of this, lipid peroxidation increased in both tissues, particularly during the second half of the Cd exposure period. Depletion of glutathione following buthionine sulfoximine administration at the end of Week 5, or inhibition of catalase by aminotriazole at the end of Week 7, resulted in the development of acute nephrotoxicity within 6 h. Coadministration of antioxidants, N-acetylcysteine (50-100 mg/kg, sc), or vitamin E (100-150 mg/kg, sc) with Cd, starting from the early phases of Cd exposure, controlled Cd-induced lipid peroxidation and protected the animals against hepatic as well as renal toxicity. A Japanese hepatoprotective drug, Stronger Neo-Minophagen C, containing glycyrrhizin, glycine, and cysteine, was also effective in reducing the chronic Cd nephrotoxicity. In conclusion, oxidative stress appears to play a major role in chronic Cd-induced hepatic and renal toxicity since inhibition of components of the antioxidant defense system accelerated and administration of antioxidants protected against Cd toxicity.

[Ca++ ion transport blockers as reversants of the drug resistance of malarial parasites. 1. The effect of verapamil on the resistance to chloroquine in vivo of Plasmodium berghei and in vitro of Plasmodium falciparum]

The reversing action of verapamil on the effect of chloroquine was found in in vivo experiments by using a model P. berghei resistant to chloroquine, an LNK65 isolate having a naturally lower resistance to the agent, and its polyresistant strain with the acquired resistance to chloroquine and fansidar, as well as by employing the chlorine-resistant P. falciparum isolates from the south of the Socialist Republic of Vietnam. The magnitude of this effect was related to the dose of verapamil, the frequency of administration of a combination of the agents in vivo, while that was associated to the concentration of verapamil and the level of isolate resistance to chloroquine in vitro which was the most pronounced. Taking into account the dose-dependent effect of verapamil, it can be suggested that increasing its concentration in combination with chloroquine can provide a more marked reversing action with lower chloroquine concentrations. The parameters accepted by the authors in evaluating the combined effect enable the effect of the verapamil/chloroquine concentration to be regarded as potentiation.

Screening donor blood for malaria by polymerase chain reaction

In countries where malaria is endemic, its transmission is a hazard of blood transfusion. The microscopical and immunological methods in current use for malaria diagnosis are unsatisfactory for low levels of parasitaemia in blood donations. The polymerase chain reaction (PCR) can be 100-fold more sensitive than thick blood film examination when appropriate primers are used and can detect and distinguish Plasmodium falciparum and P. vivax in a single tube. A study of 1506 blood donations in Ho Chi Minh City (3 of which were positive) suggests that PCR can provide an effective screen for P. falciparum under local conditions. Studies in a region of Viet Nam where malaria is common showed that PCR detects many more cases of low-level parasitaemia (19/30) than thick blood films (4/30).

Long-term evaluation of immune status in leprosy patients undergoing multiple drug therapy

A long-term survey of leprosy patients of all clinical types, starting at the time of diagnosis, was carried out to monitor clinical, bacteriological and immunological parameters at regular intervals during multiple drug therapy (MDT). The patients were assigned to two groups for treatment following WHO guidelines: paucibacillary (PB) and multibacillary (MB). Immunoglobulin levels, specific antibodies, skin-test responses to different soluble mycobacterial antigens (new tuberculins), and in vitro proliferative responses to mitogens and to antigens were measured during treatment, as were clinical changes, the bacterial index, and clinical improvement. No exact relations between disease activity and IgM antibody levels, both IgM immunoglobulin and specific IgM antibody to a species-specific antigen (ND-O-BSA), could be seen for MB patients. Changes in in vitro cell-mediated immunity and skin-test response seemed to be more directly related to the bacterial load and could reflect the improvement of bacteriological and clinical parameters during MDT.

[The clinical efficacy of and tolerance for lariam (mefloquine) in tropical malaria in the south of the Socialist Republic of Vietnam]

The study was performed in the area of distribution of tropical malaria resistant to 4-aminoquinolines (Vietnam) on 30 patients receiving lariam (mefloquine). The results were compared to the standard therapy with quinine and fansidar. They indicate a high efficacy of and a good tolerance to the drug tested. The use of lariam leads to a more rapid (as compared to the standard treatment) elimination of parasitemia and complete eradication of the disease relapses. The findings make it possible to recommend lariam for the prevention and treatment of tropical malaria.

[The efficacy of and tolerance for fansimef in the treatment of tropical malaria in the south of the Socialist Republic of Vietnam]

The efficacy of and tolerance to fancimef in 49 patients was compared to the efficacy of and tolerance to quinine in combination with fansidar in 33 patients with moderate P. falciparum malaria. A good tolerance to and a high efficacy of fancimef have been shown, which was manifested in rapid fever arrest, disappearance of parasitemia, absence of the disease relapses, which were observed in 2 patients on quinine combined with fansidar. The advantage of fansimef is one-time administration of the total course dose.