[Show abstract][Hide abstract] ABSTRACT: Recently, we have successfully obtained functional IPCs efficiently from umbilical cord blood-derived mesenchymal stem cells by using hypoxia treatment. In this study, we further elaborated that the improved function and viability of IPCs are the result of the interaction βcell development pathway and c-Met/HGF axis induced by hypoxia. We found that hypoxia induced c-MET elevation is efficiently initiated the early stage differentiation IPCs from MSCs, and HGF improved the fully differentiation of IPCs by inducing the expression of NGN3. This finding may contribute to understanding β cell development and the development of stem cell therapy for diabetes.
Full-text · Article · Sep 2015 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Though nanomaterials are considered as drug carriers or imaging reagents targeting the central nervous system their cytotoxicity effect on neuronal cells has not been well studied. In this study, we treated PC12cells, a model neuronal cell line, with a nanomaterial that is widely accepted for medical use, superparamagnetic iron oxide nanoparticles (SPIONs). Our results suggest that, after treated with SPIONs, the expression pattern of the cellular miRNAs changed widely in PC12 cells. As potential miRNA targets, NMDAR, one of the candidate mRNAs that were selected using GO and KEGG pathway enrichment, was significantly down regulated by SPIONs treatment. We further illustrated that SPIONs may induce cell death through NMDAR suppression. This study revealed a NMDAR neurotoxic effect of SPIONs and provides a reliable approach for assessing the neurocytotoxic effects of nanomaterials based on the comprehensive annotation of miRNA profiling.
[Show abstract][Hide abstract] ABSTRACT: Exosomes are nanoscale membrane vesicles secreted from many types of cells. Carrying functional molecules, exosomes transfer
information between cells and mediate many physiological and pathological processes. In this report, utilizing selective inhibitors,
molecular tools, and specific endocytosis markers, the cellular uptake of PC12 cell-derived exosomes was imaged by high-throughput
microscopy and statistically analyzed. It was found that the uptake was through clathrin-mediated endocytosis and macropinocytosis.
Furthermore, PC12 cell-derived exosomes can enter and deliver microRNAs (miRNAs) into bone marrow-derived mesenchymal stromal
cells (BMSCs), and decrease the expression level of transforming growth factor β receptor II (TGFβRII) and tropomyosin-1 (TPM1)
through miR-21. These results show the pathway of exosome internalization and demonstrate that tumor cell-derived exosomes
regulate target gene expression in normal cells.
Full-text · Article · Jun 2014 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) regulate many biological processes by post-translational gene silencing. Analysis of miRNA expression profiles is a reliable method for investigating particular biological processes due to the stability of miRNA and the development of advanced sequencing methods. However, this approach is limited by the broad specificity of miRNAs, which may target several mRNAs.Result: In this study, we developed a method for comprehensive annotation of miRNA array or deep sequencing data for investigation of cellular biological effects. Using this method, the specific pathways and biological processes involved in Alzheimer's disease were predicted with high correlation in four independent samples. Furthermore, this method was validated for evaluation of cadmium telluride (CdTe) nanomaterial cytotoxicity. As a result, apoptosis pathways were selected as the top pathways associated with CdTe nanoparticle exposure, which is consistent with previous studies.
Our findings contribute to the validation of miRNA microarray or deep sequencing results for early diagnosis of disease and evaluation of the biological safety of new materials and drugs.
[Show abstract][Hide abstract] ABSTRACT: Among a variety of polymers, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a microbial polyester, with biodegradable, nonantigenic, and biocompatible properties, is attracting more and more attention in tissue engineering. Hydroxyapatite (HA), similar to the mineral component of natural bone, is known to be osteoconductive, nontoxic, and noninflammatory. In this study, aligned and random-oriented PHBV nanofibrous scaffolds loaded with HA nanoparticles were fabricated through electrospinning technique. Mesenchymal stem cells (MSCs) derived from rat bone marrow were used to investigate the effects of HA and orientation of fibers on cell proliferation and differentiation in vitro. Cell proliferation tested with CCK-8 assay indicated that the MSCs attached and proliferated more favorably on random-oriented PHBV nanofibrous meshes without HA. After one, two and four weeks of cell seeding, osteogenic markers including alkaline phosphate (ALP), osteocalcin (OCN), and mineralized matrix deposits were detected, respectively. The results indicated that the introduction of HA could induce MSCs to differentiate into osteoblasts. Moreover, 3D PHBV/HA scaffolds made from aligned and random-oriented nanofibers were implanted into critical-sized rabbit radius defects and exhibited significant effects on the repair of critical bone defects, implying their promising applications in bone tissue engineering.
[Show abstract][Hide abstract] ABSTRACT: Microenvironments in which cells live play an important role in the attachment, growth and interactions of cells. To mimic the natural structure of extracellular matrices, electrospinning was applied to fabricate biomaterials into ultrafine fibers. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biocompatible and biodegradable polyester, has been shown to be an excellent biomaterial candidate for tissue engineering. In this study, five types of PHBV fibrous scaffolds with different diameters and orientations were obtained by changing solvents, concentration of electrospun solution and collector. Three kinds of scaffolds with good continuity and suitable mechanical properties, selected according to the morphology and mechanical properties of the scaffolds, were used for studying the influence of fiber diameter and orientation on growth behavior of bone-marrow-derived mesenchymal stem cells (MSCs). The results indicated that the random-oriented nanofibrous scaffold is most favorable for cell growth compared to other scaffolds, while the microfibrous scaffold resulted in the lowest viability of MSCs. The orientation of nanofibers showed a distinct effect on cell morphology by guiding cell skeleton extension. Both the random-oriented and aligned PHBV nanofibrous scaffolds showed to be good candidates for applications in tissue engineering.
No preview · Article · Feb 2012 · Biomedical Materials
[Show abstract][Hide abstract] ABSTRACT: Sodium butyrate (NaBu) is regarded as a potential reagent for cancer therapy. In this study, a specific breast cancer cell population that is resistant NaBu treatment was identified. These cells possess cancer stem cell characters, such as the capability of sphere formation in vitro and high tumor incident rate (85%) in mouse model. Forty percent of the NaBu resistant cells express the cancer stem cells marker, the CD133, whereas only 10% intact cells present the CD133 antigen. Furthermore, the endogenous expressing c-MET contributes to the survival of cancer stem cell population from the treatment of NaBu. The CD133+ group also presents a higher level of c-MET. A combination treatment of MET siRNA and NaBu efficiently prohibited the breast cancer progression, and the incident rate of the tumor decrease to 18%. This study may help to develop a new and alternative strategy for breast cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: The folding dynamics of a completely stretched dexoxyribonucleic acid (DNA) molecule chain is an important feature of single DNA mechanics. By constructing a fully parameterized bead-spring chain model and applying a highly efficient second order semi-implicit predictor-corrector algorithm, we studied the influence of three nonlinear interactions including the excluded volume interaction, the finite extensible nonlinear elastic interaction, and the fluctuating hydrodynamic interaction on the folding process. Simulation results show that the excluded volume interaction decreases the relative radius of gyration of the DNA chain obviously but has no influence on the relaxation time. Instead, the hydrodynamic interaction clearly decreases the relaxation time but it does not change the relative radius of gyration. In addition, the finite extensible elastic interaction was found to decrease the relative radius of gyration of the short chain clearly and increase the relaxation time of the long chain obviously. Furthermore, we obtained a smooth change for the relative radius of gyration with time. The scaling exponent of the relaxation time with the length of chain has two different values under all three nonlinear interactions. These results complete our understanding about single DNA molecule chain mechanics in solution.
Preview · Article · Nov 2011 · ACTA PHYSICO-CHIMICA SINICA
[Show abstract][Hide abstract] ABSTRACT: As a non-invasive technique applied for the functional mapping of human brain, Magnetoencephalography (MEG) can acquire the neural activity with high temporal resolution and moderate spatial resolution. However, when reading a MEG record, for research or clinical reference, the investigator face the signals from non-cerebral sources like eye movements, heart beat and muscle activity always appear mixed with brain signals. In this article, we proposed a procedure including the independent component analysis(ICA) followed by an automatic independent component(IC) detection module mainly based on the analysis of statistical and spectral characteristics of each IC to remove the artifacts from MEG signals. The whole process was tested with both simulated data and real MEG signal, the results showed that the proposed technique was able to differentiate artfactual ICs successfully.
[Show abstract][Hide abstract] ABSTRACT: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biodegradable polyester, has been a good candidate of biomaterial employed in tissue engineering. However, the PHBV film is hydrophobic and has no recognition sites for cell attachment. In this study, PHBV films are activated by ammonia plasma treatment to produce amino groups on the surface, followed by sequential reactions with a heterobifunctional cross-linker containing a segment of poly(ethylene glycol) (PEG) and further with RGD-containing peptides. XPS analyses of modified surfaces after each reaction step reveal that the RGD-containing peptides have been covalently grafted onto PHBV films. The result of cell viability assay indicates that the RGD-modified PHBV films exhibit a distinctly improved cellular compatibility. Moreover, according to the results of serum adsorption tests by optical waveguide lightmode spectroscopy (OWLS) and fibrinogen adsorption tests by enzyme-linked immunosorbent assay (ELISA) on unmodified and modified PHBV surfaces, the introduced PEG chains can significantly decrease the nonspecific adsorption of proteins from serum and fibrinogen from plasma, thus decreasing the risk of thrombus formation and improving the blood compatibility of implanted materials.
[Show abstract][Hide abstract] ABSTRACT: Aligned and randomly oriented chitosan nanofibers were prepared by electrospinning. The fibers were modified with the RGD cell-adhesive peptide through a heterobifunctional crosslinker containing a segment of poly(ethylene glycol) (PEG). PEG rendered the surface hydrophilic and provided flexible spacers, allowing the preservation of the bioactivity of further captured RGD peptides. NIH 3T3 cells were used to test the cellular compatibility of these chitosan nanofibrous scaffolds. Cell morphology and viability were investigated by SEM, fluorescent staining and cell counting. The results indicate that RGD-modified surfaces significantly improve the cellular compatibility of chitosan nanofibers and suggest a good candidate as a scaffold employed in tissue engineering.
No preview · Article · Sep 2010 · Biomedical Materials
[Show abstract][Hide abstract] ABSTRACT: Metal-mediated assembly for the hybrid multilayers of multiporphyrin arrays of zinc 5,10,15,20-tetrapyridylporphyrin (ZnTPyP) with three kinds of pyridyl derivatives, poly(4-vinylpyridine) (PVP), 4,4′-bipyridyl (Bpy) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPyTa), have been constructed directly on solid surfaces. The assembly process was characterized with the use of X-ray photoelectron spectroscopy (XPS) and absorption spectroscopy. The Soret absorption intensity of ZnTPyP was proportional to the layer numbers, indicating a similar amount of ZnTPyP was assembled for each layer. The average surface density of ZnTPyP molecules per layer was estimated to be in the range of 3.5–4.0 × 10− 10 mol/cm2. Orientation angle for the porphyrin macrocycles relative to the substrate surface was about 50–60° for the multilayers of Pd–ZnTPyP, Pd–ZnTPyP–Bpy, Pd–ZnTPyP–TPyTa, and about 80° for the Pd–ZnTPyP–PVP, respectively. Atomic force microscopic images showed that the domain sizes and shapes of the hybrid multilayer arrays closely related to the inserted layers (PVP, BPy or TPyTa).
No preview · Article · May 2007 · Materials Science and Engineering C
[Show abstract][Hide abstract] ABSTRACT: Porous silicon (PS) was incubated in an organic solution of metal acetylacetonates of Mn(acac)(3), Fe(acac)(3), Co(acac)(3), and Ni(acac)(2) (acac = MeCOCHCOMe) at room temperature. Crystal-like domains were found to be spontaneously self-assembled on PS surfaces by atomic force microscopy (AFM). Spectroscopic studies with attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that the domains were grown from metal acetylacetonates. Current sensing atomic force microscopy (CSAFM) was used to measure the I-V curves of domains in nanoscale and specific step-jump currents on the manganese and cobalt acetylacetonate domains were surprisingly detected.
Full-text · Article · Jan 2007 · The Journal of Physical Chemistry B