James Zhenggui Tang

Disulfiram targets cancer stem-like cells and reverses resistance and cross-resistance in acquired paclitaxel-resistant triple-negative breast cancer cells

Background:Triple-negative breast cancer (TNBC) has significantly worse prognosis. Acquired chemoresistance remains the major cause of therapeutic failure of TNBC. In clinic, the relapsed TNBC is commonly pan-resistant to various drugs with completely different resistant mechanisms. Investigation of the mechanisms and development of new drugs to target pan-chemoresistance will potentially improve the therapeutic outcomes of TNBC patients.Methods:In this study, 1-(4,5-Dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT), combination index (CI)–isobologram, western blot, ALDEFLUOR analysis, clonogenic assay and immunocytochemistry were used.Results:The chemoresistant MDA-MB-231PAC10 cells are highly cross-resistant to paclitaxel (PAC), cisplatin (CDDP), docetaxel and doxorubicin. The MDA-MB-231PAC10 cells are quiescent with significantly longer doubling time (64.9 vs 31.7 h). This may be caused by high expression of p21Waf1. The MDA-MB-231PAC10 cells express high aldehyde dehydrogenase (ALDH) activity and a panel of embryonic stem cell-related proteins, for example, Oct4, Sox2, Nanog and nuclealisation of HIF2α and NF-κBp65. We have previously reported that disulfiram (DS), an antialcoholism drug, targets cancer stem cells (CSCs) and enhances cytotoxicity of anticancer drugs. Disulfiram abolished CSC characters and completely reversed PAC and CDDP resistance in MDA-MB-231PAC10 cells.Conclusion:Cancer stem cells may be responsible for acquired pan-chemoresistance. As a drug used in clinic, DS may be repurposed as a CSC inhibitor to reverse the acquired pan-chemoresistance.

Superparamagnetic nano-composite scaffolds for promoting bone cell proliferation and defect reparation without a magnetic field

Apart from chemical molecules, physical regulations also greatly determine the efficiency of healing in regenerating functional tissues. In this study, we fabricated superparamagnetic nano-composite scaffolds for tissue engineering and investigated their effects on different bone cells without an external magnetic field. Poly(lactic-co-glycolic acid) (PLGA) and hydrophobic superparamagnetic magnetite nanoparticles (MNPs) were combined together with different mass ratios in order to construct composite scaffolds using an electrospinning method for the first time. The diameters of the fibers were 400–600 nm with the MNPs uniformly dispersed in them, as shown by transmission (TEM) and scanning (SEM) electron microscopy observations. All composite scaffolds retained superparamagnetism at room temperature, but the saturation magnetization did not increase linearly as the magnetite content increased. The composite scaffolds with different MNP content showed excellent biocompatibility and significantly promoted cell proliferation compared with PLGA nanofibrous scaffold without an external magnetic field. Cell cycle analysis proved that the composite scaffolds decreased cell numbers in G0/G1 phase while increasing those in S phase, which resulted in positive effects on cell proliferation. However, the composite scaffolds had no effect on the differentiation of MC3T3-E1 cells because of the different impact mechanism between proliferation and differentiation. Therefore, the composite scaffolds composed of superparamagnetic MNPs could be considered as an ideal substrate for accelerating osteoblast cell proliferation and tissue repair.

Stabilization of pH-Sensitive mPEG–PH–PLA Nanoparticles by Stereocomplexation Between Enantiomeric Polylactides

Methoxy poly(ethylene glycol)-poly(L-histidine)-poly(lactide) (mPEG(45)-PH(30)-PLA(82)) triblock copolymers self-assemble into nanoparticles by sterocomplexation. The properties of the stereocomplex nanoparticles including morphology, stability, and biocompatibility are investigated. The results reveal that the stereocomplexation between PLLA and PDLA segments could prevent the aggregation of the nanoparticles when the pH value is around 6.8. The mean diameter of the stereocomplex nanoparticles is stabilized at about 100 nm when the pH values are changed from 7.9 to 5.0. The cytotoxicity of the stereocomplex nanoparticles is evaluated, and the results demonstrate that the stereocomplexation could decrease the cytotoxicity of the PDLA segments.

Extraction and characterization of polysaccharides from Semen Cassiae by microwave-assisted aqueous two-phase extraction coupled with spectroscopy and HPLC.

A novel and rapid method for simultaneous extraction and separation of the different polysaccharides from Semen Cassiae (SC) was developed by microwave-assisted aqueous two-phase extraction (MAATPE) in a one-step procedure. Using ethanol/ammonium sulfate system as a multiphase solvent, the effects of MAATPE on the extraction of polysaccharides from SC such as the composition of the ATPS, extraction time, temperature and solvent-to-material ratio were investigated by UV-vis analysis. Under the optimum conditions, the yields of polysaccharides were 4.49% for the top phase, 8.80% for the bottom phase and 13.29% for total polysaccharides, respectively. Compared with heating solvent extraction and ultrasonic assisted extraction, MAATPE exhibited the higher extraction yields in shorter time. Fourier-transform infrared spectra showed that two polysaccharides extracted from SC to the top and bottom phases by MAATPE were different from each other in their chemical structures. Through acid hydrolysis and PMP derivatization prior to HPLC, analytical results by indicated that a polysaccharide of the top phases was a relatively homogeneous homepolysaccharide composed of dominant gucose glucose while that of the bottom phase was a water-soluble heteropolysaccharide with multiple components of glucose, xylose, arabinose, galactose, mannose and glucuronic acid. Molar ratios of monosaccharides were 95.13:4.27:0.60 of glucose: arabinose: galactose for the polysaccharide from the top phase and 62.96:14.07:6.67: 6.67:5.19:4.44 of glucose: xylose: arabinose: galactose: mannose: glucuronic acid for that from the bottom phase, respectively. The mechanism for MAATPE process was also discussed in detail. MAATPE with the aid of microwave and the selectivity of the ATPS not only improved yields of the extraction, but also obtained a variety of polysaccharides. Hence, it was proved as a green, efficient and promising alternative to simultaneous extraction of polysaccharides from SC.

Oral delivery of camptothecin using cyclodextrin/poly(anhydride) nanoparticles.

Camptothecin (CPT), a molecule that shows powerful anticancer activity, is still not used in clinic due to its high hydrophobicity and poor active forms stability. In order to solve these drawbacks, the combination between poly(anhydride) nanoparticles and cyclodextrins was evaluated. CPT-loaded nanoparticles, prepared in the presence of 2-hydroxypropyl-β-cyclodextrin, (HPCD-NP) displayed a mean size close to 170nm and a payload of 50μg per mg (25 times higher than the one of the control nanoparticles). CPT was not released from nanoparticles under gastric conditions. However, under intestinal conditions, about 50% of the drug content was released as a burst, whereas the remained drug was released following a zero-order kinetic. Pharmacokinetic studies revealed that the CPT plasma levels, from orally administered nanoparticles, were high and sustained up to 48h. The CPT oral bioavailability was 7-fold higher than the value obtained with the control, whereas its clearance was significantly lower than for the aqueous suspension. These observations may be directly related to a prolonged residence time of nanoparticles in close contact with the intestinal epithelium, the presence of the cyclodextrin that decreases the CPT transformation into its inactive form and the generation of an acidic microenvironment during the degradation of the poly(anhydride) that would prevent the transformation of the active lactone into the inactive carboxylate conformation.

Effects of pH-sensitive chain length on release of doxorubicin from mPEG-b-PH-b-PLLA nanoparticles

Background Two methoxyl poly(ethylene glycol)-poly(L-histidine)-poly(L-lactide) (mPEG-PH-PLLA) triblock copolymers with different poly(L-histidine) chain lengths were synthesized. The morphology and biocompatibility of these self-assembled nanoparticles was investigated. Methods Doxorubicin, an antitumor drug, was trapped in the nanoparticles to explore their drug-release behavior. The drug-loaded nanoparticles were incubated with HepG2 cells to evaluate their antitumor efficacy in vitro. The effects of poly(L-histidine) chain length on the properties, drug-release behavior, and antitumor efficiency of the nanoparticles were investigated. Results The nanoparticles were pH-sensitive. The mean diameters of the two types of mPEG-PH- PLLA nanoparticle were less than 200 nm when the pH values were 5.0 and 7.4. The nanoparticles were nontoxic to NIH 3T3 fibroblasts and HepG2 cells. The release of doxorubicin at pH 5.0 was much faster than that at pH 7.4. The release rate of mPEG45-PH15-PLLA82 nanoparticles was much faster than that of mPEG45-PH30-PLLA82 nanoparticles at pH 5.0. Conclusion The inhibition effect of mPEG45-PH15-PLLA82 nanoparticles on the growth of HepG2 cells was greater than that of mPEG45-PH30-PLLA82 nanoparticles when the concentration of encapsulated doxorubicin was less than 15 μg/mL.

Sustained PDGF-BB release from PHBHHx loaded nanoparticles in 3D hydrogel/stem cell model

This study aimed to design a growth factor loaded copolyester of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBHHx) nanoparticles containing 3D collagen matrix to achieve growth factor sustained release for long-term stimulation of human mesenchymal stem cells (hMSCs) proliferation/differentiation for tissue engineer application. Platelet-derived growth factor-BB (PDGF-BB), which is known to enhance hMSCs proliferation in human serum, was selected as a model growth factor, and biodegradable copolyester of PHBHHx was chosen to be the sustained release vehicle. PDGF-BB phospholipid complex encapsulated PHBHHx nanoparticles were fabricated, and their effect on hMSCs proliferation was investigated via assays of CCK-8 and live-dead staining to cells inoculated in 2D tissue culture plates and 3D collagen gel scaffolds, respectively. The resulting spherical PHBHHx nanoparticles were stable in terms of their mean particle size, polydispersity index and zeta potential before and after lyophilization. In vitro study revealed a sustained release of PDGF-BB with a low burst release. Furthermore, sustained released PDGF-BB was revealed to significantly promote hMSCs proliferation in both cell monolayer and cell seeded 3D collagen scaffolds inoculated in serum-free media. Therefore, the 3D collagen matrices with locally sustained release growth factor nanoparticles hold promise to be used for stem cell tissue engineering.

Self-assembly of pH-sensitive fluorinated peptide dendron functionalized dextran nanoparticles for on-demand intracellular drug delivery.

Abstract In this study, the amphiphilic fluorinated peptide dendrons functionalized dextran (FPD-HZN-Dex) via an acid-sensitive hydrazone linkage was successfully designed and prepared for the first time. We demonstrated a spontaneous self-assembly of amphiphilic FPD-HZN-Dex into the well-defined nanoparticles with the core-shell architecture in aqueous media, which is attributed to the efficient amphiphilic functionalization of dextran by the hydrophobic fluorinated peptide dendrons. The spherical morphology, uniform particle size and good storage stability of the prepared FPD-HZN-Dex nanoparticles were characterized by dynamic light scattering and transmission electron microscopy, respectively. In vitro drug release studies showed a controlled and pH dependent hydrophobic drug release profile. The cell viability assays show excellent biocompatibility of the FPD-HZN-Dex nanoparticles for both normal cells and tumor cells. Moreover, the FPD-HZN-Dex self-assembled systems based on pH-sensitive hydrazone linkage also can serve as stimulus bioresponsive carriers for on-demand intracellular drug delivery. These self-assembled nanoparticles exhibit a stimulus-induced response to endo/lysosome pH (pH 5.0) that causes their disassembly over time, enabling controlled release of encapsulated DOX. This work has unveiled a unique non-covalent interaction useful for engineering amphiphilic dendrons or dendrimers self-assembled systems.Graphical Abstract

Enantioseparation of Racemic Flurbiprofen by Aqueous Two-Phase Extraction With Binary Chiral Selectors of L-dioctyl Tartrate and L-tryptophan

A novel method for chiral separation of flurbiprofen enantiomers was developed using aqueous two-phase extraction (ATPE) coupled with biphasic recognition chiral extraction (BRCE). An aqueous two-phase system (ATPS) was used as an extracting solvent which was composed of ethanol (35.0% w/w) and ammonium sulfate (18.0% w/w). The chiral selectors in ATPS for BRCE consideration were L-dioctyl tartrate and L-tryptophan, which were screened from amino acids, β-cyclodextrin derivatives, and L-tartrate esters. Factors such as the amounts of L-dioctyl tartrate and L-tryptophan, pH, flurbiprofen concentration, and the operation temperature were investigated in terms of chiral separation of flurbiprofen enantiomers. The optimum conditions were as follows: L-dioctyl tartrate, 80 mg; L-tryptophan, 40 mg; pH, 4.0; flurbiprofen concentration, 0.10 mmol/L; and temperature, 25 °C. The maximum separation factor α for flurbiprofen enantiomers could reach 2.34. The mechanism of chiral separation of flurbiprofen enantiomers is discussed and studied. The results showed that synergistic extraction has been established by L-dioctyl tartrate and L-tryptophan, which enantioselectively recognized R- and S-enantiomers in top and bottom phases, respectively. Compared to conventional liquid-liquid extraction, ATPE coupled with BRCE possessed higher separation efficiency and enantioselectivity without the use of any other organic solvents. The proposed method is a potential and powerful alternative to conventional extraction for separation of various enantiomers.

Synthesis, characterization, and drug delivery of amphiphilic poly{(lactic acid)-co-[(glycolic acid)-alt-(L-glutamic acid)]}-g-poly(ethylene glycol)

AbstractThis paper discusses the use of a novel amphiphilic graft polymer poly{(lactic acid)-co-[(glycolic acid)-alt-(Lglutamic acid)]}-g-monomethyl poly(ethylene glycol) (PLGG-g-mPEG) as a drug carrier. PLGG was synthesized through the ring-opening polymerization of L-lactide (LLA) and (3s)-benzoxylcarbonylethyl-morpholine-2,5-dione (BEMD) using Sn(Oct)2 as a catalyst and it was subsequently deprotected via hydrogenolysis in the presence of Pd/C. A series of monomethyl poly(ethylene glycol) (PEG) with the molecular weights of 2,000, 1,100, and 500 were immobilized on the carboxyl groups of PLGG. These PEGylated graft derivatives were characterized using proton nuclear magnetic resonance spectra (1H NMR), Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The critical micelle concentrations (CMCs) of the amphiphilic copolymers were tested by the fluorescence probe technique and the CMCs were 2.3, 1.0, and 0.32 μg/mL, respectively. Transmission electronic microscopy (TEM) and dynamic light scattering (DLS) images revealed that the micelles were homogeneous spherical nanoparticles and the sizes of the micelles were distributed across a range of 80 to 22 nm. Anticancer drug doxorubicin (DOX) was loaded into the micelles. The in vitro release profiles showed that the sustaining release of the drugloaded micelles could last over 7 days. The in vitro cytotoxicity assay of the DOX-loaded micelles against HepG2 cells was assessed by methyl thiazolyl tetrazolium (MTT) assays. The results demonstrated that the drug-loaded micelles exhibited a high level of inhibition activity on cancer cells. The confocal microscopy images of HepG2 cells showed that DOX released from the micelles could be delivered into cell nuclei. PLGG-g-mPEG micelles are promising potential carriers for delivering anticancer drugs.