Yuanliang Wang

Chongqing University, Ch’ung-ch’ing-shih, Chongqing Shi, China

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Publications (56)79.76 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, novel disulfide cross-linked hydrogels were designed and synthesized. First, ethylenediaminetetraacetic dianhydride reacted with butanediamine and amino-terminated polyethylene glycol via N-acylation reaction to give biocompatible poly(amic acid) (PAA) with pendant carboxyl groups; then, the amino groups of cystamine reacted with carboxyl groups of PAA to generate disulfide cross-linked network polymer (PAA-SS). Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance imaging, gel permeation chromatography with multiangle laser light scattering, potentiometric titration, rheology, hydrolytic degradation, morphology, porosity, and in vitro biocompatibility studies were used to qualitatively and quantitatively characterize the obtained polymers. The results indicated that the equilibrium swelling ratio of the PAA-SS decreased with the increase in Rm. The PAA-SS provided good mechanical strength to maintain their integrity, and the storage modules (G′) of the hydrogels can be adjusted by Rm. The PAA-SS presented co-continuum pores, and the pore size correlated with the cross-linking degree. The degradation of PAA-SS could be controlled by regulating the concentration of dithiothreitol. Particularly, the PAA-SS possessed an excellent biocompatibility, as the average proliferating rate of osteoblasts on PAA-SS was appreciably higher than that on PAA and glass coverslips. In conclusion, the above obtained results demonstrate that the performance of the PAA-SS outbalance and facilitate the application in biomedical region, particularly in bone tissue regeneration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40930.
    Journal of Applied Polymer Science 05/2014; · 1.40 Impact Factor
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    ABSTRACT: Mechano growth factor (MGF) and its C-terminal E-peptide with 24 amino acids, MGF-Ct24E, have superiority in resolving the delayed or failed bone repair derived from shortness of suitable biomechanical stimulation. The chitosan/tripolyphosphate microspheres encapsulated with MGF-Ct24E (CS/TPP/MGF-Ct24E) are prepared using emulsion-ionic cross-linking method in order to achieve the sustained release and preserve the bioactivity of MGF-Ct24E. The microspheres are micron-sized and spherical in shape with smooth surface morphology. The TPP component disintegrates in advance of CS matrix and the MGF-Ct24E maintains sustained delivery during in vitro hydrolytic degradation. With the disappearance of TPP, the total weight loss of CS/TPP/MGF-Ct24E is 32% and the release amount of MGF-Ct24E reaches 84.6% after degrading for 2 weeks. In vitro bioactivity assays reveal that the MGF-Ct24E can accelerate MC3T3-E1 cells proliferation and delay their differentiation as well. The encapsulated MGF-Ct24E shows long-term effects after being loaded in the CS/TPP microspheres and the cells exhibit excellent morphology on the surface of microspheres. The continuous delivery of MGF-Ct24E provides a new perspective on resolving the unsatisfactory bone reconstruction associated with microgravity and stress shielding.
    International Journal of Pharmaceutics 04/2014; · 3.99 Impact Factor
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    ABSTRACT: Low fluid shear stress (FSS) is the mechanical environment encountered by osteoblasts in implanted bones or native bones of bed-rest patients. High sensitivity of osteoblasts to low FSS is beneficial to osteogenesis. We hypothesize that this sensitivity might be regulated by chemical microenvironment provided by scaffolds. To confirm this hypothesis, self-assembled monolayers (SAMs) were used to provide various surface chemistries including OH, CH3 , and NH2 while parallel-plate fluid flow system produced low FSS (5 dynes/cm(2) ). Alterations in S-phase cell fraction, alkaline phosphatase (ALP) activity, fibronectin (Fn) and collagen type I (COL I) secretion compared to those without FSS exposure were detected to characterize the sensitivity. Osteoblasts on OH and CH3 SAMs demonstrated obvious sensitivity while on NH2 SAMs negligible sensitivity was observed. Examination of the cell aspect ratio, orientation and focal adhesions before and after FSS exposure indicates that the full spreading and robust focal adhesions on NH2 SAMs should be responsible for the negligible sensitivity through increasing the cell tolerance to low FSS. Despite the higher sensitivity, the Fn and COL I depositions on both OH and CH3 SAMs after FSS exposure were still less than on NH2 SAMs without FSS exposure. These results suggest that elaborate design of surface chemical compositions is essential for orchestration of surface chemistry with low FSS to realize both high sensitivity and high matrix secretion, facilitating formation of functional bone tissues in implanted bone.
    Journal of Biomedical Materials Research Part A 01/2014; · 2.83 Impact Factor
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    ABSTRACT: Piperazine-based polyurethane ureas (P-PUUs) with piperazine (PP) units as the functional ingredients have been designed to explore a novel polymeric biomaterial with the controllable degradation for bone repair in this study. P-PUUs were prepared upon the chain-growth polymerization of poly (D, L -lactic acid) diol (PDLLA diol), 1, 6-hexamethylene diisocyanate (HDI) where PP functioned as the chain extender. The investigation of in vitro degradation of P-PUUs was performed and the mechanical properties of P-PUUs during degradation were calculated. The results revealed that manipulating the ratio of PDLLA diol: HDI: PP could obtain the precise number of PP units (Num(pp)) in P-PUUs which may significantly impact the degradation stability and the degradation rate of P-PUUs. The negative linear correlation between the degradation rate and the Num(pp) of P-PUUs has been proved, suggesting the P-PUUs were endowed with controllable degradation. Such a linear correlation is expected to be applied to bone repair where the specific degradation rate of P-PUUs for the specific bone defect can be precisely predicted once the Num(pp) and the bone repairing period are known. Additionally, P-PUUs with higher Num(pp) exhibited remarkable mechanical properties during degradation which allowed polymers to provide more persistent mechanical support to bone repair.
    Polymer. 01/2014;
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    ABSTRACT: Poly(vinyl alcohol) and hyaluronic acid derived hydrogel was synthesized by a novel synthesis route using click reaction under mild condition. First, we synthesized two kinds of soluble polymers by linking propargylamine and l-cysteine on the poly(vinyl alcohol) and hyaluronic acid, respectively. The polymers were named as PVAPA and HASH, and characterized by 1H NMR and Ellman’s test. The hydrogels were obtained through thiol-yne click reaction in the presence of photoinitiator after 3 min UV light. The swelling ratio in various pH solution and rheology of hydrogels were detected to confirm that the hydrogels process a certain pH-sensitive property and a stable network system. The click reaction of PVAPA and HASH provided a simple and versatile method to get hydrogel network under a mild condition and have a vast potential for biomedical applications.
    Materials Letters. 01/2014; 134:9–12.
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    ABSTRACT: Natural bone tissue receives chemical and mechanical stimuli in physiological environment. The effects of material chemistry alone and mechanical stimuli alone on osteoblasts have been widely investigated. This study reports the synergistic influences of material chemistry and flow shear stress (FSS) on biological functions of osteoblasts. Self-assembled monolayers (SAMs) on glass slides with functional groups of OH, CH3, and NH2 were employed to provide various material chemistries, while FSS (12 dynes/cm(2)) was produced by a parallel-plate fluid flow system. Material chemistry alone had no obvious effects on the expressions of ATP, nitric oxide (NO), and prostaglandin E2 (PGE2), whereas FSS stimuli alone increased the production of those items. When both material chemistry and FSS were loaded, cell proliferation and the expressions of ATP, NO and PGE2 were highly dependent on the material chemistry. Examination of the focal adhesion (FA) formation and F-actin organization of osteoblasts before FSS exposure indicates that the FA formation and F-actin organization followed similar chemistry-dependence. The inhibition of FAs and/or disruption of F-actins eliminated the material dependence of FSS-induced ATP, PGE2 and NO release. A possible mechanism is proposed: material chemistry controls the F-actin organization and FA formation of osteoblasts, which further modulates FSS-induced cellular responses.
    Archives of Biochemistry and Biophysics 09/2013; · 3.37 Impact Factor
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    ABSTRACT: Osteoblasts on implanted biomaterials sense both substrate chemistry and mechanical stimulus. The effects of substrate chemistry alone and mechanical stimulus alone on osteoblasts have been widely studied. This study investigates the optimal combination of substrate chemistry and 12dyn/cm(2) physiological flow shear stress (FSS) by examining their influences on primary rat osteoblasts (ROBs), including the releases of ATP, nitric oxide (NO), and prostaglandin E2 (PGE2). Self-assembled monolayers (SAMs) on glass slides with -OH, -CH3, and -NH2 were employed to provide various substrate chemistries, whereas a parallel-plate fluid flow system produced the physiological FSS. Substrate chemistry alone exerted no observable effects on the releases of ATP, NO, and PGE2. Nevertheless, when ROBs were exposed to both substrate chemistry and FSS, the ATP releases of NH2 were upregulated about 12-fold compared to substrate chemistry alone, while the ATP releases of CH3 and OH was similarly increased 7-fold at the peak. Similar trends were observed for the releases of NO and PGE2. The expressions of ATP, NO, and PGE2 followed the pattern of NH2-FSS>Glass-FSS>CH3-FSS≈OH-FSS. ROBs on NH2 produced the optimal combination of substrate chemistry with the physiological FSS. The F-actin organization and focal adhesion (FA) formation of ROBs on various SAMs without FSS were examined. NH2 produced the best results whereas CH3 and OH produced the worst ones. Inhibition of FAs and/or disruption of F-actin significantly decreased the releases of FSS-induced PGE2, NO, and/or ATP. Consequently, a mechanism was proposed that the best F-actin organization and FA formation of ROBs on NH2 lead to the optimal combination of substrate chemistry with the 12dyn/cm(2) physiological FSS. This mechanism gives guidance for the design of implanted biomaterials and bioreactors for bone tissue engineering.
    Colloids and surfaces B: Biointerfaces 07/2013; 112C:51-60. · 3.55 Impact Factor
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    ABSTRACT: As a growth repair factor, mechano-growth factor (MGF) and its 24 amino acid peptide analogs corresponding to the unique C-terminal E-domain (MGF-Ct24E) positively regulate bone regeneration. MGF-Ct24E was introduced into the poly(D, L-lactic acid) (PDLLA) to improve bone regeneration in our previous study. MGF-Ct24E-grafted PDLLA was chemically characterized and showed potential as a biofunctional polymer. In this study, we evaluated the cytocompatibility of MGF-Ct24E chemically grafted and physically blended with maleic anhydride modified PDLLA, relative to maleic anhydride modified PDLLA (MPLA) as the control. The surface properties of these three polymer films were characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. Rat calvarial osteoblasts were seeded on the three polymer films, and cell adhesion, spreading, and proliferation were assessed with an inverted microscope, laser scanning confocal microscope, and a cell counting kit-8, respectively. The alkaline phosphatase activity and extracellular calcium production were exploited to characterize the differentiation and mineralization of rat calvarial osteoblasts on various polymer films. The results revealed that compared with MPLA, MGF-Ct24E-MPLA, and MGF-Ct24E/MPLA blends promoted adhesion, spreading, proliferation, and the later differentiation and mineralization process of rat calvarial osteoblasts. In addition, the positive effect of MGF-Ct24E-MPLA on rat calvarial osteoblasts was maintained longer than the MGF-Ct24E/MPLA blends. In conclusion, MGF-Ct24E-MPLA synthesized chemically might be a promising biomaterial for bone tissue engineering.
    Journal of Biomaterials Science Polymer Edition 05/2013; 24(7):849-64. · 1.70 Impact Factor
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    ABSTRACT: Mechano-growth factor (MGF) is an alternative splicing variant of Insulin-like growth factor I. MGF and its 24 amino acid peptide analog corresponding to the unique C-terminal E-domain (MGF-Ct24E) are the positive regulator for tissue regenesis in bone. A novel biomimetic poly(D, L-lactic acid) (PDLLA) modification was designed and synthesized based on MGF-Ct24E grafted maleic anhydride modified PDLLA (MPLA). MGF-Ct24Es were grafted into the side chain of MPLA via a stable covalent amide bond using 1-ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide as the condensing agent to produce biomimetic MPLA materials (MGF-Ct24E-MPLA). Fourier transform infrared spectrometry, amino acid analyzer, and elementary analysis were used to characterize the MGF-Ct24E-MPLA. The hydrophilicity of MGF-Ct24E-MPLA was evaluated by means of the water-uptake ratios and static water contact angle. Data revealed that the grafting efficiency of MGF-Ct24E was about 29.9%. MGF-Ct24E-MPLA had better hydrophilicity than PDLLA and MPLA. The osteoblasts behavior of proliferation, differentiation, and mineralization on PDLLA, MPLA, and MGF-Ct24E-MPLA films was investigated and the results indicated that the introduction of MGF-Ct24E could improve osteoblasts proliferation, mineralization, and delay differentiation. The MGF-Ct24E modified MPLA with higher bioactivity may have potential application for bone tissue engineering. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:3496-3502, 2012.
    Journal of Biomedical Materials Research Part A 08/2012; 100(12):3496-502. · 2.83 Impact Factor
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    ABSTRACT: Folate-conjugated Dol-poly(d,l-lactic acid)-b-poly (ethylene glycol)-folate (Dol-PLA-PEG-FA), was synthesized from dodecanol-poly(d,l-lactic acid), amino-terminated poly(ethylene glycol) and folate. 1H NMR proved the successful synthesis of Dol-PLA-PEG-FA. Nanoparticles (NPs) were further fabricated from Dol-PLA-PEG-FA by using solvent evaporation-induced interfacial self-assembly method. The size, critical micelle concentration (CMC), cytotoxicity and selecting capability to cancer cells in vitro were examined for Dol-PLA-PEG-FA NPs. The size of NPs showed polymer concentration-dependent phenomenon in the fabrication process, and its polydispersity index (PDI) was very narrow. The CMC was determined as 1.995 × 10−4 g/L in aqueous solution, which is much lower than the reported CMC of block copolymer self-assemble micelles. The cytotoxicity evaluation revealed that the obtained NPs2 are non-toxic to either breast cancer cell or normal endothelial cells, and the cell uptake of NPs indicated that the NPs demonstrated much higher selecting capability to breast cancer cells compared to normal fibroblast cells. The possible receptor-mediated endocytosis pathway mechanism was proposed. Based on the above results, it could be concluded that Dol-PLA-PEG-FA polymer and its nanoparticles can be potentially used as a safe drug carrier with strong tumor cells targeting capability for tumor chemotherapy.
    Colloids and surfaces B: Biointerfaces 07/2012; 102:130–135. · 3.55 Impact Factor
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    ABSTRACT: Mechano-growth factor (MGF) has emerged as an important mechanosensitive player in bone repair, but understanding of MGF function is hampered by the fact that MGF receptor and the underlying pathways remain unknown. In this study, fluorescein isothiocyanate (FITC)-labeled MGF-Ct24E (FITC-MGF) was used to determine the subcellular localization of MGF receptor in osteoblasts. After the primary osteoblasts were exposed to stretch with the strain at 10 %, and/or loaded with 50 ng/ml exogenous MGF-Ct24E, cells were incubated with the different concentrations of FITC-MGF (0.01, 0.1, and 1 mg/ml) followed by flow cytometry and laser scanning confocal microscope analysis. Our results showed that the fluorescence intensity and cell population internalizing FITC-MGF increased with the concentration of FITC-MGF. And all the cells were labeled with fluorescence at 1 mg/ml. Notably, FITC-MGF had nuclear localization when osteoblasts were exposed to stretch and/or 50 ng/ml MGF-Ct24E added, compared to the evident cytoplasmic localization in the static culture group. The nuclear localization of FITC-MGF in response to mechanical loading was found to associate with high expression of proliferating cell nuclear antigen, suggesting MGF and its receptor could serve as potential messengers that replay information in nuclei to control cell proliferation.
    Molecular and Cellular Biochemistry 07/2012; 369(1-2):147-56. · 2.33 Impact Factor
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    ABSTRACT: Angiogenesis is crucial in wound healing. The administration of the C-terminal 24-a.a. peptide of mechano growth factor (MGF24E) has been previously demonstrated to induce more blood vessels in regenerating bone around defective areas compared with the control. Accordingly, this study aims to determine whether MGF24E promotes bone defect healing through MGF24E-increased angiogenesis and whether MGF24E has positive effects on angiogenesis in vitro. The roles of MGF24E on angiogenesis and the underlying mechanisms were investigated. The cell proliferation, migration, and tubulogenesis of the human vascular endothelial EA.hy926 cells co-treated with 2% serum and MGF24E were determined to assess angiogenesis in comparison with 100 ng/ml of vascular endothelial growth factor 165 (VEGF(165))-positive control or vehicle control (phosphate-buffered saline). MGF24E treatment (10 ng/ml) significantly promoted the biological processes of angiogenesis on EA.hy926 cells compared with the vehicle control. The suppression of vascular endothelial growth factor and angiopoietin-I expressions by 2% serum starvation was reversed by the addition of 10 ng/ml of MGF24E in 2% serum medium. This result suggests that MGF24E has a protective effect on angiogenesis. Moreover, the inhibition of ERK due to PD98050 pretreatment completely abolished and mostly blocked MGF24E-induced proliferation and migration, respectively, whereas the MGF24-induced tubulogenesis and the angiogenic factor expression were only partially inhibited. These new findings suggest that MGF24E promotes angiogenesis by enhancing the expression of angiogenic cytokines which involves the MAPK/ERK-signaling pathway.
    Acta Biochimica et Biophysica Sinica 03/2012; 44(4):316-22. · 1.81 Impact Factor
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    ABSTRACT: A novel antibacterial biomaterial (PEB) was prepared with ethylenediaminetetraacetic dianhydride (EDTAD), 1,4-diaminobutane (BDA) and anhydrous piperazine (PP) by a condensation polymerization reaction under simple and mild condition. The obtained material's chemical structure was characterized by Fourier transform infrared spectrometry (FTIR) and 1H nuclear magnetic resonance (1H NMR). Moreover, the antibacterial properties of this material were tested with Staphylococcus aureus by the disc diffusion method and the results revealed that it had an excellent antibacterial activity for S. aureus. Specially, the antibacterial properties of PEB depended on its composition; the greater the content of BDA, the stronger the antibacterial ability.
    Materials Letters. 01/2012;
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    ABSTRACT: The novel {2,4-bis(1,1-dimethylethyl)-6-{[(2-hydroxyethyl)imino]methyl}phenoxy}2 titanium(IV) complex {[(dME)2(HIM)P]2Ti(IV)} had been synthesized and characterized by EA, XRF, IR, and NMR methods. The [(dME)2(HIM)P]2Ti(IV) complex was reactive and promoted ring-opening polymerization (ROP) of d,l-lactide in the presence of benzyl alcohol (BnOH). And the results showed that ROP of d,l-lactide were produced upon addition of an excess (1–8 equiv.) of external BnOH. The complex showed a living and controlled fashion (M w/M n = 1.15–1.32) for ROP of d,l-lactide and could produce the poly(d,l-lactide) with average molecular weight (M n) up to 8.87 × 104 g mol−1. The mechanism study by 1H NMR spectrum of poly(d,l-lactide) with terminal benzyl ester group and [(dME)2(HIM)P]2Ti(IV) complex revealed that the polymerization proceeded through the traditional activated monomer mechanism and the acyl-oxygen bond cleavage mode of monomer. And the 13C NMR spectra and TG/DSC analysis showed that poly(d,l-lactide) was essential atactic and thermal stable polymer.
    Polymer Bulletin 01/2012; 69(5). · 1.33 Impact Factor
  • Jiaoxia Sun, Yuanliang Wang, Zhiyong Qian, Chenbo Hu
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    ABSTRACT: The angiogenesis of 3D scaffold is one of the major current limitations in clinical practice tissue engineering. The new strategy of construction 3D scaffold with microchannel circulation network may improve angiogenesis. In this study, 3D poly(D: ,L: -lactic acid) scaffolds with controllable microchannel structures were fabricated using sacrificial sugar structures. Melt drawing sugar-fiber network produced by a modified filament spiral winding method was used to form the microchannel with adjustable diameters and porosity. This fabrication process was rapid, inexpensive, and highly scalable. The porosity, microchannel diameter, interconnectivity and surface topographies of the scaffold were characterized by scanning electron microscopy. Mechanical properties were evaluated by compression tests. The mean porosity values of the scaffolds were in the 65-78% and the scaffold exhibited microchannel structure with diameter in the 100-200 μm range. The results showed that the scaffolds exhibited an adequate porosity, interconnective microchannel network, and mechanical properties. The cell culture studies with endothelial cells (ECs) demonstrated that the scaffold allowed cells to proliferate and penetrate into the volume of the entire scaffold. Overall, these findings suggest that the fabrication process offers significant advantages and flexibility in generating a variety of non-cytotoxic tissue engineering scaffolds with controllable distributions of porosity and physical properties that could provide the necessary physical cues for ECs and further improve angiogenesis for tissue engineering.
    Journal of Materials Science Materials in Medicine 08/2011; 22(11):2565-71. · 2.14 Impact Factor
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    ABSTRACT: The main objective of this study was to observe the adhesion, proliferation and differentiation of mouse osteblast-like MC3T3-E1 cells cultured on maleic anhydride-modified poly(D,L-lactic acid) (MPLA) and poly(D,L-lactic acid) (PDLLA) polymers, and to evaluate the cytocompatibility of MPLA polymer. The effects of MPLA and PDLLA polymers on the morphology, adhesion, proliferation, the content of total cellular protein, alkaline phosphatase (ALP) activity and the content of Ca of MC3T3-E1 cells were explored. These results indicated that MC3T3-E1 cells on MPLA polymer adhered and spread more fully. On MPLA polymer, the proliferation, total protein content, ALP activity, Ca content of the cells were significantly higher than those of the cells on PDLLA polymer (P < 0.01). It was concluded that MPLA polymer could promote the adhesion, spreading, proliferation and the synthesis of protein of osteoblasts, and also induced the differentiation and mineralization of osteoblasts, suggesting that MPLA polymer might have the better cytocompatibility than PDLLA.
    Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi 08/2011; 28(4):753-7.
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    ABSTRACT: Mechano-growth factor (MGF), an insulin-like growth factor-I (IGF-I) splice variant, often serves as an important local tissue repair factor in response to the mechanical environment. However, there is no model for exhibiting the MGF expression in a series of strain distribution up to now. In this study, a novel mechanical loading model containing different stresses and strains simultaneously was developed to examine the MGF expression. The strain distributions were predicted by finite element modeling. The MC3T3-E1 cells on a silicone membrane with a central circular hole were exposed to a variable strain environment through stretching. The finite element analysis showed that, when the strain reached the magnitude of 10%, the strain concentration near the circular hole displayed along with the vertical stretch direction, while the minimum strain appeared in the parallel stretch direction. Furthermore, the results showed that MGF expression decreased gradually from high to low strain regions by immunocytochemistry. Meanwhile, the proliferation of osteoblasts increased significantly in the high strain region. In conclusion, this mechanical loading model can present the different distributions of the strain of osteoblasts in vitro. MGF expression and osteoblast proliferation have a high correlation with the levels of strain.
    Archives of Biochemistry and Biophysics 07/2011; 511(1-2):8-13. · 3.37 Impact Factor
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    ABSTRACT: In this work, long serial analysis of gene expression (LongSAGE) technology was used to investigate the molecular mechanism of the interaction between cells and poly(D,L-lactic acid)-modified biomaterials. After mouse osteoblast-like MC3T3-E1 cells were cultured on poly(D,L-lactic acid) (PDLLA) and a novel maleic anhydride-modified poly(D,L-lactic acid) (MPLA) films, the morphology, proliferation activity and alkaline phosphatase (ALP) activity of MC3T3-E1 cells were assessed by laser confocal microscope, cell counting assay and ALP assay, and the gene expression profiles of the cells were detected and compared at the transcript levels, respectively. 202 tags were found differentially expressed (p<0.05, and fold change >2) between PDLLA and MPLA LongSAGE libraries. Gene ontology functional analysis of the differentially expressed genes indicates that surface modification of MPLA biomaterial has an extensive influence on cells by regulating expression of genes related to cell proliferation, cell cycle, cytoskeleton organization, ossification, bone remodeling, metabolism, and eventually induces osteoblast proliferation and differentiation. The approach presented here provides a new insight in the molecular biocompatibility evaluation of biomaterials, contributing to the development of biomaterials in tissue engineering field.
    Colloids and surfaces B: Biointerfaces 03/2011; 85(2):248-61. · 3.55 Impact Factor
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    ABSTRACT: Novel amphoteric pH-sensitive hydrogels with pendant carboxyl and backbone tertiary amine groups were designed and synthesized. First, ethylenediaminetetraacetic dianhydride (EDTAD) reacted with butanediamine (BDA) via N-acylation reaction to give a polyamide prepolymer with pendant carboxyl groups (PEB–COOH); then amino-terminated poly(ethylene glycol) 500 (ATPEG500) was added as a cross-linking agent to produce the desired network polymer (PEB–ATPEG500–COOH). The obtained hydrogels are potentially degradable and non-toxic since its backbone and cross-linking sections are both linked by amide bonds and all monomers have been proved as safe. FTIR, 1H NMR, 13C NMR and ninhydrin reaction method were employed to qualitatively and quantitatively characterize the obtained polymers. The effect of cross-linking agent amount, characterized by the molar ratios (Rm) of NH2 groups in ATPEG500 to pendant COOH groups in PEB–COOH, on the swelling behavior of the proposed hydrogel was examined. The results indicate that the equilibrium swelling ratio decreases and the pH-sensitivity becomes retarded with the increase of Rm. For PEB–ATPEG500–COOH hydrogels with Rm no more than 0.42, they exhibited three SRe variation zones at pH 2–4, pH 6–7 and pH 9–11, respectively, suggesting obvious and interesting amphoteric pH-sensitivity. In addition, the swelling kinetics tests on PEB–ATPEG500–COOH with Rm=0.32 reveal that the swelling kinetics of proposed hydrogel follows a Fickian diffusion process in media of pH 7, and an anomalous diffusion process in media of pH 2 and 11. The above obtained results will facilitate the application of this proposed hydrogel in biomedical fields, particularly in the drug controlled release.
    European Polymer Journal - EUR POLYM J. 01/2011; 47(1):40-47.
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    ABSTRACT: To assess the potential efficacy of mechano growth factor (MGF) for bone injury, we firstly investigated the effects of growth factors, including MGF, its E peptide (a short 24-amino acid C-terminal peptide, MGF-Ct24E), and insulin-like growth factor 1(IGF-1) on MC3T3-E1 osteoblast-like cell proliferation. MGF-Ct24E had the highest pro-proliferation activity among three growth factors, which was 1.4 times greater than that of IGF-1. Moreover, MGF-Ct24E promoted cell proliferation by inducing cell cycle arrest in the S and G(2)/M phase of the cell cycle, but also mainly by the activation of the MAPK-Erk1/2 pathway. In vivo, a 5-mm segmental bone defect in the radius of 27 rabbits was treated with MGF-Ct24E by two doses (28.5 and 57 μg /kg body weight) vs. non-growth factor injection for five consecutive days postoperatively. The cumulative rate of radiographically healed defects and histological scores of bone defect-healing revealed a statistical difference between high-dose treatment and non treatment (p < 0.01), which showed the treatment promoted defect healing. This report is the first to demonstrate that MGF-Ct24E possesses positive effects on osteoblast proliferation and bone-defect healing, suggesting a new strategy in fracture healing.
    International Orthopaedics 11/2010; 35(7):1099-106. · 2.32 Impact Factor

Publication Stats

120 Citations
79.76 Total Impact Points

Institutions

  • 2003–2014
    • Chongqing University
      • • Department of Biorheological Science and Technology
      • • School of Bioengineering
      • • Key Laboratory for Biomechanics and Tissue Engineering under the State Ministry of Education
      Ch’ung-ch’ing-shih, Chongqing Shi, China
  • 2010
    • Chongqing University of Science & Technology
      Ch’ung-ch’ing-shih, Chongqing Shi, China