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ABSTRACT: For the purpose of examining the clinical applicability of a newly developed surgical sealant, animal experiments were performed, and clinical trial was followed. In animal experiments, several animal models, including carotid artery anastomosis model and coronary artery bypass grafting model were undertaken. In each model, complete hemostasis of the anastomoses using four simple interrupted sutures, was obtained. In addition, elastomeric property of the sealant prevented thinning of the arterial wall. The clinical trial performed in patients with thoracic aortic surgery showed significantly better hemostasis even under heparinized condition. Based on these excellent results, clinical usage of the sealant was approved.
Kyobu geka. The Japanese journal of thoracic surgery 05/2013; 66(5):395-400.
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ABSTRACT: We have quantitatively determined how the morphology and adhesion strength of myoblast cells can be regulated by photocurable gelatin gels, whose mechanical properties can be fine-tuned by a factor of 103 (0.1 kPa E 140 kPa). The use of such gels allows for the investigation of mechano-sensing of cells not only near the natural mechanical microenvironments (E ~ 10 kPa) but also far below and beyond of the natural condition. Optical microscopy and statistical image analysis revealed that myoblast cells sensitively adopt their morphology in response to the substrate elasticity at E = 1 - 20 kPa, which can be characterized by the significant changes in the contact area and order parameters of actin cytoskeletons. In contrast, the cells in contact with the gels with lower elastic moduli remained almost round, and the increase in the elasticity beyond E ~ 20 kPa caused no distinct change in morphology. In addition to the morphological analysis, the adhesion strength was quantitatively evaluated by measuring the critical detachment pressure with an aid of intensive pressure waves induced by picosecond laser pulses. This non-invasive technique utilizing extremely short pressure waves (pulse time width ~ 100 ns) enables one to determine the critical pressure for cell detachment with reliable statistics while minimizing the artifacts arising from the inelastic deformation of cells. The adhesion strength also exhibited a transition from weak adhesion to strong adhesion within the same elasticity range (E = 1 - 20 kPa). A clear correlation between the cell morphology and adhesion strength suggests the coupling of the strain of the substrate and the mechanosensors near focal adhesion sites.
The Journal of Physical Chemistry B 03/2013; · 3.70 Impact Factor
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ABSTRACT: In situ capture of endothelial progenitor cells (EPCs) in the arterial bloodstream may allow the creation of a functioning endothelium on the luminal surfaces of implanted cardiovascular devices. Our strategy is to use highly biospecific interaction between the cell-surface marker and surface-bound protein. The target-cell marker defined is vascular endothelial growth factor (VEGF) receptor, which is exclusively expressed on endothelial lineage cells. The candidate surface-bound proteins are VEGF and anti-VEGF receptor (VEGF-R1 and VEGF-R2) antibodies, which were covalent-bound on poly(ethylene-co-vinyl alcohol) bearing a high-surface density of hydroxyl groups. Incubating human mononuclear cells on these substrates affected the histochemical expression of cell-surface markers specific for EPCs and endothelial cells (ECs). The VEGF-bound surface significantly increased the number of cells expressing both VEGF receptors after 1 or 2 weeks of culture, whereas both anti-VEGF receptor antibody-bound substrates did not affect the expression of the surface markers, and cells on these surfaces were eventually died. These results indicate that, among the three candidate molecules, VEGF is best able to capture EPCs and induces their differentiation. Additionally, a pilot study of surface architecture of stents and small-diameter artificial grafts was conducted for an ongoing implantation study in a porcine model. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Journal of Biomedical Materials Research Part B Applied Biomaterials 10/2012; · 2.15 Impact Factor
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ABSTRACT: Our ongoing studies show that vascular endothelial cell growth factor (VEGF)-bound surfaces selectively capture endothelial progenitor cells (EPCs) in vitro and in vivo, and that surface-bound VEGF stimulates intracellular signal transduction pathways over prolonged culture periods, resulting in inductive differentiation of EPCs. In this article, we investigated whether simulated arterial shear stress augments the differentiation of EPCs adhered to a VEGF-bound surface. Human peripheral blood-derived mononuclear cells adhered to a VEGF-bound surface were exposed to 1 day of shear stress (15 dynes/cm(2), corresponding to shear load in arteries). Shear stress suppressed the expression of mRNAs encoding CD34 and CD133, which are markers for EPCs, and augmented the expression of mRNAs encoding CD31 and von Willebrand factor (vWF) as well as vWF protein, which are markers for endothelial cells (ECs). Shear stress enhanced expression of ephrinB2 mRNA, a marker for arterial ECs, but did not significantly change expression of EphB4 mRNA, a marker for venous ECs. Focused protein array analysis showed that mechanotransduction by shear stress activated the p38 and MAPK pathways in EPCs. Thus, arterial shear stress, in concert with surface-bound VEGF, augments the differentiation of EPCs. These results strongly support previous observation of rapid differentiation of EPCs captured on VEGF-bound stents in a porcine model.
Biochemical and Biophysical Research Communications 05/2012; 423(1):91-7. · 2.48 Impact Factor
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ABSTRACT: The luminal surfaces of small-diameter artificial vascular grafts must be fully endothelialized to be nonthrombogenic following implantation. To achieve this goal, we have attempted to capture circulating endothelial progenitor cells (EPCs) in situ on the luminal surfaces of implanted grafts. We examined potential receptor-ligand pairs that promote selective and tight adhesion of EPCs using a radial flow chamber comprising three regions, each containing a specific protein-bound substrate: fibronectin (FN) for integrin, and vascular endothelial growth factor (VEGF) and anti-Flk-1 antibody for VEGF receptor. In the presence of shear stress, the greatest retention of endothelial cells and EPCs was observed with FN followed by VEGF and then anti-Flk-1 antibody. Regardless of the bound protein, cell adhesion increased with larger areas of cell adhesion and enhanced cell spreading; the latter was also greatest with FN followed by VEGF and then anti-Flk-1 antibody. The distribution of vinculin-a key protein in focal adhesion plaques-in adherent endothelial cells was examined using total internal reflection fluorescence microscopy; FN-bound surfaces resulted in larger areas of adhesion and more focal adhesion plaques compared with surfaces bound with VEGF. On the other hand, examining these parameters relative to the area of cell adhesion revealed that VEGF-bound surfaces resulted in larger focal adhesion areas and greater fluorescence signals, both of which indicate increased resistance to shear stress. We also discuss in situ capturing of EPCs on surfaces bound with VEGF or anti-Flk-1 antibody, with the goal of creating endothelialized small-diameter vascular grafts.
Journal of Biomedical Materials Research Part B Applied Biomaterials 03/2012; 100(5):1218-28. · 2.15 Impact Factor
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ABSTRACT: If endothelial progenitor cells (EPCs), which circulate in blood flow, are captured on the luminal surface of an implanted artificial graft and sooner or later proliferate to form a fully endothelialized surface, such a small-diameter artificial graft must exhibit a high patency rate. This study aimed at designing a luminal surface of elastomeric electrospun mesh graft, which is capable of selective capture of EPCs under arterial flow and has a high antithrombogenic potential until full endothelization is achieved. The designed luminal surface layer is composed of a photopolymerized gelatin gel layer that enables the release of impregnated heparin and selective adhesion of circulating EPCs via complexation between surface-fixed vascular endothelial growth factor (VEGF) and cellular VEGF receptor. Human mononuclear cells seeded and cultured on such a gel layer expressed endothelial cell surface markers. Confocal laser scanning microscopy observation revealed that VEGF is highly surface-enriched, and heparin is homogeneously distributed in the gel layer. A continuously slow release of heparin was observed. Thus, a prototype luminal surface was fabricated on electrospun segmented polyurethane tubes for in vivo study.
Journal of Biomedical Materials Research Part B Applied Biomaterials 07/2010; 94(1):53-63. · 2.15 Impact Factor
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ABSTRACT: Our previous studies showed that a mechano-active scaffold made of poly(L-lactide-co-epsilon-caprolactone) (PLCL) exhibited a high potential to realize the formation of a functional, engineered cartilage in vitro. This animal study therefore was designed to investigate the feasibility of repairing on osteochondral defect with the use of bone marrow-derived mesenchymal stem cells (BMSCs) incorporated with a PLCL scaffold. Rabbit BMSCs, isolated and subsequently cultured in monolayer, were seeded into a porous PLCL scaffold sponge following an implantation onto a full-thickness osteochondral defect (diameter of 4.5 mm, depth of 5 mm) that was artificially created on the medial femoral condyles at a high load-bearing site on a rabbit's knee joint. Time-dependent healing of the defect was evaluated by macroscopic, histological examinations at both 3- and 6-month-implantations, respectively. A PLCL sponge incorporated with BMSCs exhibited sufficient structural support, resulting in new osteochondral tissue regeneration: a physiologically well-integrated subchondral bone formation, a hyaline cartilage-like morphology containing chondrocytes surrounded by abundant cartilaginous matrices. In addition, quantitative biochemical assays also demonstrated high potential for the synthesis of sulfated glycosaminoglycan and collagen, both of which are biomolecules essential to extracelluar matrix in normal cartilage tissue. In contrast, defects filled with cell-free PLCL scaffold or left empty showed a very limited potential for regeneration. Our findings suggest that a composite of PLCL-based sponge scaffold and BMSCs promote the repair of osteochondral defects at high load-bearing sites in adult rabbits.
Journal of Biomedical Materials Research Part B Applied Biomaterials 03/2010; 94(1):80-8. · 2.15 Impact Factor
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Fuyu Ito,
Kengo Usui,
Daigo Kawahara,
Atsushi Suenaga,
Tei Maki,
Satoru Kidoaki,
Harukazu Suzuki,
Makoto Taiji,
Masayoshi Itoh,
Yoshihide Hayashizaki, Takehisa Matsuda
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ABSTRACT: We developed a hydrogel self-assembling method driven by the interaction between recombinant tax-interactive protein-1 (TIP1) with the PDZ domain in a molecule, which is fused to each end of the triangular trimeric CutA protein (CutA-TIP1), and a PDZ domain-recognizable peptide which is covalently bound to each terminus of four-armed poly(ethylene glycol) (PDZ-peptide-PEG). Genetic manipulation based on molecular-dynamic simulation generated a cell-adhesive RGD tripeptidyl sequence in the CutA loop region [CutA(RGD)-TIP1]. Spontaneous viscoelastic hydrogel formation occurred when either CutA-TIP1- or CutA(RGD)-TIP1-containing buffer solution and PDZ-peptide-PEG-containing buffer solutions were stoichiometrically mixed. Dynamic viscoelasticity measurement revealed shear stress-dependent reversible-phase transformation: a spontaneous viscoelastic hydrogel was formed at low shear stress, but it was transformed into a sol at high shear stress. Upon the cessation of shear, hydrogel was restored. When chondrocytes were pre-mixed with one of these two components containing buffer solutions, the stoichiometric mixed solution was also spontaneously gelled. Individual rounded cells and multicellular aggregates were entrapped within both hydrogels without substantial cellular impairment regardless of the presence or absence of RGD motif in the CutA-TIP1 molecule. The potential use of such a shear-sensitive hydrogel for injectable cell delivery into diseased or lost cartilage tissue is discussed.
Biomaterials 01/2010; 31(1):58-66. · 7.40 Impact Factor
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ABSTRACT: Reliable suture line hemostasis should improve the outcome of aortic surgery. We examined the hemostatic effect and the tissue response of a novel elastomeric surgical sealant.
Using porcine internal carotid arteries, we performed 16 end-to-end anastomoses with four stitches of simple interrupted sutures under full heparinization. The anastomoses were divided into two groups (eight anastomoses per group). Either novel sealant or fibrin glue was applied. The amount of bleeding was measured during the 30 s period after removing the vascular clamp. In a separate experiment, we applied the novel sealant around the abdominal aorta of rabbits (n=6) to assess the effect of the elastomeric property of the sealant on arterial wall histology. For comparison, we applied cyanoacrylate, which has no elastomeric property (n=6). A histological study was performed three months after the operation.
The novel sealant prevented arterial bleeding. The amount of bleeding from the anastomoses applied with novel sealant and fibrin glue was 0.12+/-0.03 g vs. 91.8+/-16.5 g, respectively (P<0.001). Thinning of the rabbit aortic wall was observed in the cyanoacrylate-treated abdominal aorta, whereas no thinning was observed in the novel sealant group. Histological examination revealed neither cell death nor necrosis in the novel sealant group.
The novel sealant effectively prevented arterial bleeding from the anastomosis under full heparinization. In addition, the elastomeric property of the sealant prevented thinning of the aortic wall. The novel sealant may be a promising hemostatic agent for arterial anastomosis.
Interactive cardiovascular and thoracic surgery 11/2009; 10(2):258-61.
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Protein Science 06/2009; · 2.80 Impact Factor
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ABSTRACT: To characterize the effects of adherent macrophages and biomaterial surface chemistries on lymphocyte adhesion and activation, lymphocytes were co-cultured with monocytes alone and together, directly and separated by a porous membrane transwell on hydrophobic, hydrophilic/neutral, hydrophilic/anionic, and hydrophilic/cationic biomaterial surfaces. Surface adherent cells were quantitatively analyzed after 3 days utilizing immunofluorescence and phase contrast imaging. After periods of 3, 7, and 10 days, secreted interferon-gamma (IFN-gamma) was quantified by ELISA. Limited direct biomaterial-adherent lymphocytes were identified regardless of the presence of macrophages or foreign body giant cells (FBGC). The majority of adherent lymphocytes, which were T cells (>95%) rather than natural killer cells, predominantly interacted with adherent macrophages and FBGCs; greater than 90% were interacting on surfaces with higher levels of adherent macrophages and FBGCs and greater than 55% were interacting on surfaces with lower levels of macrophages and FBGCs. The hydrophilic/anionic surface promoted higher levels of macrophage- and FBGC-adherent lymphocytes but was nonselective for lymphocyte subtype interactions. The hydrophilic/neutral surface was selective for CD4+ T lymphocyte interactions while the hydrophobic surface was selective for CD8+ T lymphocyte interactions. IFN-gamma was produced in direct and indirect co-cultures but not in lymphocyte- and monocyte-only cultures suggesting that lymphocytes are activated via macrophage-derived cytokines rather than direct biomaterial contact. Direct lymphocyte interactions with adherent macrophages/FBGCs enhanced IFN-gamma production relative to indirect co-cultures. These results suggest that lymphocytes prefer interactions with adherent macrophages and FBGCs, resulting in lymphocyte activation, and these interactions can be influenced by biomaterial surface chemistries.
Journal of Biomedical Materials Research Part A 01/2009; 91(4):1210-20. · 2.63 Impact Factor
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ABSTRACT: Novel self-assembled monolayers (SAMs) designed to present homogenous surface chemistries were utilized to further investigate the material surface chemistry dependent macrophage and foreign-body giant cell (FBGC) behaviors, including macrophage adhesion, fusion, and apoptosis. Contact angle analysis revealed instabilities in the --CH(3) and --COOH terminated SAM surfaces upon incubation in serum-free media (SFM) at 37 degrees C or under dry, room temperature conditions. Further analysis indicated that the --CH(3) terminated SAM surface degraded rapidly within 2 h and loss of sufficient SAM units to be comparable to the gold (Au) control surface, within 24 h of incubation in SFM at 37 degrees C. After 5 days of incubation in SFM at 37 degrees C, the contact angles for the --COOH terminated SAM surfaces increased markedly. AFM analysis confirmed the desorption of --CH(3) terminated SAM molecules from the surface with increased roughness and marked appearance of peaks and valleys within 2 h. A decrease in the thickness of the --COOH terminated SAM surface also suggests molecular desorption over time. No significant changes in contact angle or AFM analyses were observed on the --OH terminated SAM surfaces. Cellular adhesion decreased more rapidly on the Au control and --CH(3) terminated SAM surfaces in comparison to the other surfaces. However by day 10, cellular adhesion, fusion, and apoptosis were comparable on all SAM surfaces and the Au control. These studies suggest that SAM surfaces may not be suitable for long-term studies where material dependent properties are investigated.
Journal of Biomedical Materials Research Part A 08/2008; 86(1):261-8. · 2.63 Impact Factor
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ABSTRACT: Antibody-based cell microarrays may serve as a high-throughput diagnostic tool that requires precise surface design providing high biological specificity, high reliability, and high validity. A fundamental study on the quantitative evaluation of immunophenotyping using a cell microarray on which antibodies specific to cluster of differentiation (CD) antigens of blood cells are fixed was performed. The microarray, which was prepared by photomicropatterning self-assembled monolayers of alkanethiols, consisted of carboxyl group (3-mercaptopropionic acid)-packed domains regularly distributed in the methyl group (1-dodecanethiol)-packed matrix phase. This was verified by X-ray photoelectron spectroscopy and water wettability measurements. The patterned carboxylated domains of 1.0 mm or 0.2 mm diameter were covalently fixed with the anti-CD4 or anti-CD8 antibody by coupling reaction using a water-soluble carbodiimide and hydroxysuccinimide. Precision antibody fixation at almost complete conversion was verified by confocal laser scanning microscopy coupled with a specific dye staining technique. Peripheral blood mononuclear cells expressing CD4 or CD8 antigen, respectively, adhered on the anti-CD4 or anti-CD8 antibody-fixed domains of the microarray at a very high specificity, which was verified with flow cytometric analysis and an antibody-coated magnetic-bead-based cell isolation technique. The CD4/CD8 subset ratios determined using the antibody-fixed microarrays were very close to those obtained by flow cytometric analysis. These results indicate that microarrays, on which antibodies specific to cell surface antigens are covalently fixed, provide a solid basis of the high-throughput quantitative evaluation of immunophenotyping in medical diagnosis.
Journal of Biomedical Materials Research Part B Applied Biomaterials 07/2008; 87(2):525-37. · 2.15 Impact Factor
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ABSTRACT: Increasing demand for a flexible catheter tip exists in the rapidly growing fields of vascular and interventional radiology. This article describes a fabrication technology producing a catheter tip with gradually graded or gradient flexibility. Based on deflection mechanics of a tubular construct, three models were incorporated into structural designs. The models included graded wall thickness, tapered shape, or graded Young's moduli. Electrospinning using elastomeric polymer [poly(L-lactide-co-epsilon-caprolactone), polyurethane] solutions on a transversely and rotationally moving mandrel enabled preparation of three prototype tubular tips by either regio-specific control of wall thickness, tapered mandrel, or regiospecific deposition of polyurethanes with different Young's moduli. All prototype tips exhibited high flexibility at tip ends, as verified using a bifurcated vessel model.
Journal of Biomedical Materials Research Part B Applied Biomaterials 05/2008; 87(1):35-41. · 2.15 Impact Factor
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ABSTRACT: A novel technique and instrumented device were developed to harvest target cells from multicellular mixture of different cell types under a microscope. The principle of the technique is that cells cultured on a thermoresponsive-substance-coated dish were detached by a region-specific cooling device and simultaneously harvested using a micropipette, both of which were assembled in an inverted microscope. Thermoresponsive coating consists of the mixture of poly(N-isopropylacrylamide) (PNIPAAm) and PNIPAAm-grafted gelatin. The former non-cell-adhesive polymer dissolves below at 32.1 degrees C in water and precipitates over that temperature (called lower critical solution temperature, LCST), and the latter cell-adhesive polymer has LCST of 34.1 degrees C. The appropriate mixing ratio of these thermoresponsive polymers exhibited high cell adhesion at physiological temperature and complete cell detachment at room temperature. A device developed as to cool at only a tiny area of the bottom of the dish, beneath which a cell that was targeted under a microscope, was assembled in a microscope. It was demonstrated that single cell or two cells that adhered to each other was detached from the surface and harvested by a micropipette within approximately 30s.
Journal of Biotechnology 05/2008; 134(3-4):297-304. · 3.05 Impact Factor
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ABSTRACT: In vitro "simultaneous processing" was investigated in which fibril formation of collagen and cross-linking occur simultaneously in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) as a cross-linking reagent. Fibril formation in simultaneous processing was monitored using turbidity. The EDC in simultaneous processing increased T(1/2) (time required for half of the plateau value in turbidity) and decreased the degree of the fibril formation dose dependently. The reduced fibril formation rate (T(1/2) > 60 s) suggests the introduction of intrafibrillar cross-linking during fibril formation. The collagen gels prepared using simultaneous processing had a compressive modulus that was 6-fold higher than that using sequential processing, which is an advantage of simultaneous processing. Atomic force microscopy images acquired under water on the wet gels demonstrated that the simultaneous processing provided a unique double-network structure: intrafibrillarly cross-linked collagen fibrils among which nonfibrous collagens act as interfibrillar cross-linkages.
Biomacromolecules 03/2008; 9(3):879-85. · 5.48 Impact Factor
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ABSTRACT: The understanding and realization of directional cell movement towards a harder region of a cell culture substrate surface, so-called mechanotaxis, might provide a solid basis for a functional artificial extracellular matrix, enabling manipulation and elucidation of cell motility. The photolithographic surface microelasticity patterning method was developed for fabricating a cell-adhesive hydrogel with a microelasticity gradient (MEG) surface using photocurable styrenated gelatin to investigate the condition of surface elasticity to induce mechanotaxis as a basis for such substrate-elasticity-dependent control of cell motility. Patterned MEG gels consisting of different absolute surface elasticities and elasticity jumps were prepared. Surface elasticity and its two-dimensional distribution were characterized by microindentation tests using atomic force microscopy (AFM). From analyses of trajectories of 3T3 cell movement on each prepared MEG gel, two critical criteria of the elasticity jump and the absolute elasticity to induce mechanotaxis were identified: (1) a high elasticity ratio between the hard region and the soft one, and (2) elasticity of the softer region to provide medium motility. Design of these conditions was found to be necessary for fabricating an artificial extracellular matrix to control or manipulate cell motility.
Journal of Biotechnology 02/2008; 133(2):225-30. · 3.05 Impact Factor
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ABSTRACT: Matrix metalloproteinases (MMPs) can degrade structural components within the extracellular matrix and at the cellular surface producing changes in cellular behavior (i.e., adhesion and migration) and subsequent pathological responses (i.e., the foreign body reaction and wound healing). We continue to study the foreign body reaction that occurs following biomaterial implantation by investigating secretory responses of biomaterial-adherent macrophages and foreign body giant cells (FBGCs) as directed by material surface chemistry and further this research by determining whether secreted MMPs play a role in macrophage adhesion and fusion. We have identified numerous MMPs and their tissue inhibitors (TIMPs) in in vitro cell-culture supernatants using antibody arrays and quantified select MMP/TIMPs with ELISAs. MMP-9 concentrations were significantly greater than both TIMP-1 and TIMP-2 on all materials. The ratios of MMP-9/TIMP-1 and MMP-9/TIMP-2 increased with time because of an increase in MMP-9 concentrations over time, while the TIMP concentrations remained constant. Total MMP-9 concentrations in the supernatants were comparable on all materials at each timepoint, while TIMP-1 and TIMP-2 concentrations tended to be greater on hydrophilic/anionic surfaces. Analysis of the MMP/TIMP quantities produced per cell revealed that the hydrophilic/neutral surfaces, which inhibited macrophage adhesion, activated the adherent macrophages/FBGCs to produce a greater quantity of MMP-9, TIMP-1, and TIMP-2 per cell. Pharmacological inhibition of MMP-1,-8,-13, and -18 reduced macrophage fusion without affecting adhesion, while inhibitors of MMP-2,-3,-9, and -12 did not affect adhesion or fusion. These findings demonstrate that material surface chemistry does modulate macrophage/FBGC-derived MMP/TIMP secretion and implicates MMP involvement in macrophage fusion.
Journal of Biomedical Materials Research Part A 02/2008; 84(1):158-66. · 2.63 Impact Factor
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ABSTRACT: It is known that complex loading is involved in the development and maintenance of articular cartilage in the body. It means the compressive mechanical stimulation is a very important factor for formation of articular cartilage using a tissue-engineering technique. The objective of this study is to engineer cartilaginous constructs with mechano-active scaffolds and to evaluate the effect of dynamic compression for regeneration of cartilage. The mechano-active scaffolds were prepared from a very elastic poly(L-lactide-co-epsilon-caprolactone) (PLCL) with 85% porosity and 300-500 mum pore size using a gel-pressing method. The scaffold was seeded with 2 x 10(6) chondrocytes and the continuous compressive deformation of 5% strain was applied with 0.1 Hz for 10 days and 24 days, respectively. Then, the chondrocytes-seeded constructs were implanted subcutaneously into nude mice. Mechano-active scaffolds with complete rubber-like elasticity showed almost complete (over 97%) recovery at an applied strain of up to 500%. The amount of chondral extracellular matrix was increased significantly by mechanical stimulation on the highly elastic mechano-active scaffolds. Histological analysis showed the mechanically stimulated implants formed mature and well-developed cartilaginous tissue, as evidenced by the chondrocytes within lacunae and the abundant accumulation of sulfated GAGs. However, unhealthy lacunae shapes and hypertrophy forms were observed in the implants stimulated mechanically for 24 days, compared with those stimulated for 10 days. In conclusion, the proper periodical application of dynamic compression can encourage chondrocytes to maintain their phenotypes and enhance the production of GAGs, which would improve the quality of cartilaginous tissue formed both in vitro and in vivo.
Journal of Biomaterials Science Polymer Edition 02/2008; 19(1):61-74. · 1.69 Impact Factor
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ABSTRACT: The role of lymphocytes in the biological response to synthetic polymers is poorly understood despite the transient appearance of lymphocytes at the biomaterial implant site. To investigate cytokines, chemokines, and extracellular matrix (ECM) proteins produced by lymphocytes and macrophages in response to biomaterial surfaces, human peripheral blood monocytes and lymphocytes were co-cultured on polyethylene terephthalate (PET)-based material surfaces displaying distinct hydrophobic, hydrophilic/neutral, hydrophilic/anionic, and hydrophilic/cationic chemistries. Antibody array screening showed the majority of detected proteins are inflammatory mediators that guide the early inflammatory phases of wound healing. Proteomic ELISA quantification and adherent cell analysis were performed after 3, 7, and 10 days of culture. IL-2 and IFN-gamma were not detected in any co-cultures suggesting lack of lymphocyte activation. The hydrophilic/neutral surfaces increased IL-8 relative to the hydrophobic PET surface (p < 0.05). The hydrophilic/anionic surfaces promoted increased TNF-alpha over hydrophobic and cationic surfaces and increased MIP-1beta compared to hydrophobic surfaces (p < 0.05). Since enhanced macrophage fusion was observed on hydrophilic/anionic surfaces, the production of these cytokines likely plays an important role in the fusion process. The hydrophilic/cationic surface promoted IL-10 production and increased matrix metalloproteinase (MMP)-9/tissue inhibitor of MMP (TIMP) relative to hydrophilic/neutral and anionic surfaces (p < 0.05). These results suggest hydrophilic/neutral and anionic surfaces promote pro-inflammatory responses and reduced degradation of the ECM, whereas the hydrophilic/cationic surfaces induce an anti-inflammatory response and greater MMP-9/TIMP with an enhanced potential for ECM breakdown. The study also underscores the usefulness of protein arrays in assessing the role of soluble mediators in the inflammatory response to biomaterials.
Journal of Biomedical Materials Research Part A 01/2008; 87(3):676-87. · 2.63 Impact Factor
