The Experts below are selected from a list of 1233 Experts worldwide ranked by ideXlab platform
James H C Wang - One of the best experts on this subject based on the ideXlab platform.
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proliferation and collagen production of human patellar tendon fibroblasts in response to cyclic uniaxial stretching in serum free conditions
Journal of Biomechanics, 2004Co-Authors: Guoguang Yang, Richard C Crawford, James H C WangAbstract:We studied the effect of cyclic mechanical stretching on the proliferation and collagen mRNA expression and protein production of human patellar tendon fibroblasts under serum-free conditions. The role of transforming growth factor-beta1 (TGF-beta1) in collagen production by cyclically stretched tendon fibroblasts was also investigated. The tendon fibroblasts were grown in microgrooved silicone dishes, where the cells were highly elongated and aligned with the Microgrooves. Cyclic uniaxial stretching with constant frequency and duration (0.5 Hz, 4 h) but varying magnitude of stretch (no stretch, 4%, and 8%) was applied to the silicone dishes. Following the period of stretching, the cells were rested for 20 h in stretching-conditioned medium to allow for cell proliferation. In separate experiments, the cells were stretched for 4h and then rested for another 4 h. Samples of the medium, total cellular RNA and protein were used for analysis of collagen and TGF-beta1 gene expression and production. It was found that there was a slight increase in fibroblast proliferation at 4% and 8% stretch, compared to that of non-stretched fibroblasts, where at 8% stretch the increase was significant. It was also found that the gene expression and protein production of collagen type I and TGF-beta1 increased in a stretching-magnitude-dependent manner. And, levels of collagen type III were not changed, despite gene expression levels of the protein being slightly increased. Furthermore, the exogenous addition of anti-TGF-beta1 antibody eliminated the increase in collagen type I production under cyclic uniaxial stretching conditions. The results suggest that mechanical stretching can modulate proliferation of human tendon fibroblasts in the absence of serum and increase the cellular production of collagen type I, which is at least in part mediated by TGF-beta1.
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cell orientation determines the alignment of cell produced collagenous matrix
Journal of Biomechanics, 2003Co-Authors: James H C Wang, Thomas W GilbertAbstract:Abstract In healing ligaments and tendons, the cells are not aligned and collagen matrix is not organized as in normal tissues. In addition, the mechanical properties of the tissues are abnormal. We hypothesized that the lack of alignment of the collagen matrix results from random orientation of the cells seen in the healing area. To test this hypothesis, a novel in vitro model was used in which the orientation of cells could be controlled via Microgrooves, and alignment of the collagen matrix formed by these cells could be easily observed. It is known that cells align uniformly along the direction of Microgrooves; therefore MC3T3-E1 cells, which produce large amounts of collagen, were grown on silicone membranes with parallel Microgrooves (10 μm wide×3 μm deep) in the surface. As a control, the same cells were also grown on smooth silicone membranes. Cells on both the microgrooved and smooth silicone surfaces produced a layer of readily visible collagen matrix. Immunohistochemical staining showed that the matrix consisted of abundant type I collagen. Polarized light microscopy of the collagen matrix revealed the collagen fibers to be parallel to the direction of the Microgrooves, whereas the collagen matrix produced by the randomly oriented cells on the smooth membranes was disorganized. Thus, the results of this study suggest that the orientation of cells affects the organization of the collagenous matrix produced by the cells. The results also suggest that orienting cells along the longitudinal direction of healing ligaments and tendons may lead to the production of aligned collagenous matrix that more closely represents the uninjured state. This may enhance the mechanical properties of healing ligaments and tendons.
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cell orientation determines the alignment of cell produced collagenous matrix
Journal of Biomechanics, 2003Co-Authors: James H C Wang, Thomas W Gilbert, Fengyan Jia, Savio L C WooAbstract:Abstract In healing ligaments and tendons, the cells are not aligned and collagen matrix is not organized as in normal tissues. In addition, the mechanical properties of the tissues are abnormal. We hypothesized that the lack of alignment of the collagen matrix results from random orientation of the cells seen in the healing area. To test this hypothesis, a novel in vitro model was used in which the orientation of cells could be controlled via Microgrooves, and alignment of the collagen matrix formed by these cells could be easily observed. It is known that cells align uniformly along the direction of Microgrooves; therefore MC3T3-E1 cells, which produce large amounts of collagen, were grown on silicone membranes with parallel Microgrooves (10 μm wide×3 μm deep) in the surface. As a control, the same cells were also grown on smooth silicone membranes. Cells on both the microgrooved and smooth silicone surfaces produced a layer of readily visible collagen matrix. Immunohistochemical staining showed that the matrix consisted of abundant type I collagen. Polarized light microscopy of the collagen matrix revealed the collagen fibers to be parallel to the direction of the Microgrooves, whereas the collagen matrix produced by the randomly oriented cells on the smooth membranes was disorganized. Thus, the results of this study suggest that the orientation of cells affects the organization of the collagenous matrix produced by the cells. The results also suggest that orienting cells along the longitudinal direction of healing ligaments and tendons may lead to the production of aligned collagenous matrix that more closely represents the uninjured state. This may enhance the mechanical properties of healing ligaments and tendons.
Arno W Tilles - One of the best experts on this subject based on the ideXlab platform.
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Radial flow hepatocyte bioreactor using stacked microfabricated grooved substrates
'Wiley', 2018Co-Authors: Park J, Li Y, Berthiaume F, Toner M, Ml Yarmush, Arno W TillesAbstract:Bioartificial liver (BAL) devices with fully functioning hepatocytes have the potential to provide temporary hepatic support for patients with liver failure. The goal of this study was to optimize the flow environment for the cultured hepatocytes in a stacked substrate, radial flow bioreactor. Photolithographic techniques were used to microfabricate concentric grooves onto the underlying glass substrates. The Microgrooves served to protect the seeded hepatocytes from the high shear stresses caused by the volumetric flow rates necessary for adequate convective oxygen delivery. Finite element analysis was used to analyze the shear stresses and oxygen concentrations in the bioreactor. By employing high volumetric flow rates, sufficient oxygen supply to the hepatocytes was possible without an integrated oxygen permeable membrane. To implement this concept, 18 microgrooved glass substrates, seeded with rat hepatocytes cocultured with 3T3-J2 fibroblasts, were stacked in the bioreactor, creating a channel height of 100 mu m between each substrate. In this bioreactor configuration, liver-specific functions (i.e., albumin and urea synthesis rates) of the hepatocytes remained stable over 5 days of perfusion, and were significantly increased compared to those in the radial flow bioreactor with stacked substrates without Microgrooves. This study suggests that this radial flow bioreactor with stacked microgrooved substrates is scalable and may have potential as a BAL device in the treatment of liver failure.X115856sciescopu
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Microfabricated grooved substrates as platforms for bioartificial liver reactors
'Wiley', 2018Co-Authors: Park J, Berthiaume F, Toner M, Ml Yarmush, Arno W TillesAbstract:An extracorporeal bioartificial liver device has the potential to provide temporary hepatic support for patients with liver failure. Our goal was to optimize the flow environment for the cultured hepatocytes in a flat-plate bioreactor, specifically focusing on oxygen delivery using high medium flow rates while reducing the detrimental effects of the resulting shear stresses. We used photolithographic techniques to fabricate Microgrooves onto the underlying glass substrate. The Microgrooves, perpendicular to the axial flow direction, protected the hepatocytes from the shear stress induced by the flowing medium. Using finite element analysis, we found that the velocity gradient change near the cell surface (i.e., bottom of the grooves) was smaller than that near the top surface of the flow channel, indicating that the grooves would provide protection to the attached cells from the mechanical effects of the flowing medium. We also determined that the shear stress at the cell surface could be reduced by as Much as 30 times (channel 2 height of 100 gm) in the grooved-substrate (0.5 dyn/cm(2)) bioreactor compared to the flat-substrate (15 dyn/cm(2)) bioreactor for a medium flow rate of 4.0 mL/min. Albumin and urea synthesis rates of hepatocytes cocultured with 3T3-J2 fibroblasts remained stable over 5 days of perfusion in the grooved-substrate bioreactor, whereas in the flat-substrate bioreactor they decreased over the same time period. These studies indicate that under "high" flow conditions the microgrooved-substrate in the bioreactor can decrease the detrimental effects of shear stress on the hepatocytes while providing adequate oxygenation, thereby resulting in stable liver-specific function. (c) 2005 Wiley Periodicals, Inc.X1199104sciescopu
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radial flow hepatocyte bioreactor using stacked microfabricated grooved substrates
Biotechnology and Bioengineering, 2008Co-Authors: Jaesung Park, Francois Berthiaume, Mehmet Toner, Martin L Yarmush, Arno W TillesAbstract:Bioartificial liver (BAL) devices with fully functioning hepatocytes have the potential to provide temporary hepatic support for patients with liver failure. The goal of this study was to optimize the flow environment for the cultured hepatocytes in a stacked substrate, radial flow bioreactor. Photolithographic techniques were used to microfabricate concentric grooves onto the underlying glass substrates. The Microgrooves served to protect the seeded hepatocytes from the high shear stresses caused by the volumetric flow rates necessary for adequate convective oxygen delivery. Finite element analysis was used to analyze the shear stresses and oxygen concentrations in the bioreactor. By employing high volumetric flow rates, sufficient oxygen supply to the hepatocytes was possible without an integrated oxygen permeable membrane. To implement this concept, 18 microgrooved glass substrates, seeded with rat hepatocytes cocultured with 3T3-J2 fibroblasts, were stacked in the bioreactor, creating a channel height of 100 µm between each substrate. In this bioreactor configuration, liver-specific functions (i.e., albumin and urea synthesis rates) of the hepatocytes remained stable over 5 days of perfusion, and were significantly increased compared to those in the radial flow bioreactor with stacked substrates without Microgrooves. This study suggests that this radial flow bioreactor with stacked microgrooved substrates is scalable and may have potential as a BAL device in the treatment of liver failure. Biotechnol. Bioeng. 2008;99: 455–467. © 2007 Wiley Periodicals, Inc.
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microfabricated grooved substrates as platforms for bioartificial liver reactors
Biotechnology and Bioengineering, 2005Co-Authors: Jaesung Park, Francois Berthiaume, Mehmet Toner, Martin L Yarmush, Arno W TillesAbstract:An extracorporeal bioartificial liver device has the potential to provide temporary hepatic support for patients with liver failure. Our goal was to optimize the flow environment for the cultured hepatocytes in a flat- plate bioreactor, specifically focusing on oxygen delivery using high medium flow rates while reducing the detri- mental effects of the resulting shear stresses. We used photolithographic techniques to fabricate Microgrooves onto the underlying glass substrate. The Microgrooves, perpendicular to the axial flow direction, protected the hepatocytes from the shear stress induced by the flowing medium. Using finite element analysis, we found that the velocity gradient change near the cell surface (i.e., bottom of the grooves) was smaller than that near the top surface of the flow channel, indicating that the grooves would provide protection to the attached cells from the mechan- ical effects of the flowing medium. We also determined that the shear stress at the cell surface could be reduced by as much as 30 times (channel height of 100 Am) in the grooved-substrate (0.5 dyn/cm 2 ) bioreactor compared to the flat-substrate (15 dyn/cm 2 ) bioreactor for a medi- um flow rate of 4.0 mL/min. Albumin and urea synthesis rates of hepatocytes cocultured with 3T3-J2 fibroblasts remained stable over 5 days of perfusion in the grooved- substrate bioreactor, whereas in the flat-substrate bio- reactor they decreased over the same time period. These studies indicate that under ''high'' flow conditions the microgrooved-substrate in the bioreactor can decrease the detrimental effects of shear stress on the hepatocytes while providing adequate oxygenation, thereby resulting in stable liver-specific function. B 2005 Wiley Periodicals, Inc.
Toshinori Fujie - One of the best experts on this subject based on the ideXlab platform.
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Biohybrid Actuators Based on Skeletal Muscle-Powered Microgrooved Ultrathin Films Consisting of Poly(styrene-block-butadiene-block-styrene)
2019Co-Authors: Arihiro Hasebe, Yoshitaka Suematsu, Shinji Takeoka, Tommaso Mazzocchi, Lorenzo Vannozzi, Leonardo Ricotti, Toshinori FujieAbstract:This paper describes a biohybrid actuator consisting of a microgrooved thin film, powered by contractile, aligned skeletal muscle cells. The system was made of a thermoplastic elastomer [SBS, poly(styrene-block-butadiene-block-styrene)]. We prepared SBS thin films with different thicknesses (0.5–11.7 μm) and Young’s moduli (46.7–68.6 MPa) to vary their flexural rigidity. The Microgrooves on the SBS thin film resembled the microstructure of the extracellular matrix of muscle and facilitated the alignment and differentiation of skeletal muscle cells. Electrical stimulation was applied to self-standing biohybrid thin films to trigger their contraction, enabled by the low flexural rigidity of the SBS thin film. Finite element model simulations were also examined to predict their contractile behavior. We achieved the prediction of displacements, which were rather close to the actual values of the SBS thin film: the discrepancy was
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periosteum mimetic structures made from freestanding microgrooved nanosheets
Advanced Materials, 2014Co-Authors: Xuetao Shi, Shinji Takeoka, Toshinori Fujie, Akihiro Saito, Ying Hou, Yiwei Shu, Mingwei Che, Ali KhademhosseiniAbstract:: A "sticker-like" PLGA nanosheet with microgrooved patterns is developed through a facile combination of spin coating and micropatterning techniques. The resulting microgrooved PLGA nanosheets can be physically adhered on flat or porous surfaces with excellent stability in aqueous environments and can harness the spatial arrangements of cells, which make it a promising candidate for generating biomimic periosteum for bone regenerative applications.
Thomas W Gilbert - One of the best experts on this subject based on the ideXlab platform.
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cell orientation determines the alignment of cell produced collagenous matrix
Journal of Biomechanics, 2003Co-Authors: James H C Wang, Thomas W GilbertAbstract:Abstract In healing ligaments and tendons, the cells are not aligned and collagen matrix is not organized as in normal tissues. In addition, the mechanical properties of the tissues are abnormal. We hypothesized that the lack of alignment of the collagen matrix results from random orientation of the cells seen in the healing area. To test this hypothesis, a novel in vitro model was used in which the orientation of cells could be controlled via Microgrooves, and alignment of the collagen matrix formed by these cells could be easily observed. It is known that cells align uniformly along the direction of Microgrooves; therefore MC3T3-E1 cells, which produce large amounts of collagen, were grown on silicone membranes with parallel Microgrooves (10 μm wide×3 μm deep) in the surface. As a control, the same cells were also grown on smooth silicone membranes. Cells on both the microgrooved and smooth silicone surfaces produced a layer of readily visible collagen matrix. Immunohistochemical staining showed that the matrix consisted of abundant type I collagen. Polarized light microscopy of the collagen matrix revealed the collagen fibers to be parallel to the direction of the Microgrooves, whereas the collagen matrix produced by the randomly oriented cells on the smooth membranes was disorganized. Thus, the results of this study suggest that the orientation of cells affects the organization of the collagenous matrix produced by the cells. The results also suggest that orienting cells along the longitudinal direction of healing ligaments and tendons may lead to the production of aligned collagenous matrix that more closely represents the uninjured state. This may enhance the mechanical properties of healing ligaments and tendons.
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cell orientation determines the alignment of cell produced collagenous matrix
Journal of Biomechanics, 2003Co-Authors: James H C Wang, Thomas W Gilbert, Fengyan Jia, Savio L C WooAbstract:Abstract In healing ligaments and tendons, the cells are not aligned and collagen matrix is not organized as in normal tissues. In addition, the mechanical properties of the tissues are abnormal. We hypothesized that the lack of alignment of the collagen matrix results from random orientation of the cells seen in the healing area. To test this hypothesis, a novel in vitro model was used in which the orientation of cells could be controlled via Microgrooves, and alignment of the collagen matrix formed by these cells could be easily observed. It is known that cells align uniformly along the direction of Microgrooves; therefore MC3T3-E1 cells, which produce large amounts of collagen, were grown on silicone membranes with parallel Microgrooves (10 μm wide×3 μm deep) in the surface. As a control, the same cells were also grown on smooth silicone membranes. Cells on both the microgrooved and smooth silicone surfaces produced a layer of readily visible collagen matrix. Immunohistochemical staining showed that the matrix consisted of abundant type I collagen. Polarized light microscopy of the collagen matrix revealed the collagen fibers to be parallel to the direction of the Microgrooves, whereas the collagen matrix produced by the randomly oriented cells on the smooth membranes was disorganized. Thus, the results of this study suggest that the orientation of cells affects the organization of the collagenous matrix produced by the cells. The results also suggest that orienting cells along the longitudinal direction of healing ligaments and tendons may lead to the production of aligned collagenous matrix that more closely represents the uninjured state. This may enhance the mechanical properties of healing ligaments and tendons.
Surya K Mallapragada - One of the best experts on this subject based on the ideXlab platform.
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oriented growth and transdifferentiation of mesenchymal stem cells towards a schwann cell fate on micropatterned substrates
Journal of Bioscience and Bioengineering, 2016Co-Authors: Anup D Sharma, Surya K Mallapragada, Svitlana Zbarska, Emma M Petersen, Mustafa Esen Marti, Donald S SakaguchiAbstract:While Schwann cells (SCs) have a significant role in peripheral nerve regeneration, their use in treatments has been limited because of lack of a readily available source. To address this issue, this study focused on the effect of guidance cues by employing micropatterned polymeric films to influence the alignment, morphology and transdifferentiation of bone marrow-derived rat mesenchymal stem cells (MSCs) towards a Schwann cell-like fate. Two different types of polymers, biocompatible polystyrene (PS) and biodegradable poly(lactic acid) (PLA) were used to fabricate patterned films. Percentages of transdifferentiated MSCs (tMSCs) immunolabeled with SC markers (α-S100β and α-p75(NTR)) were found to be similar on patterned versus smooth PS and PLA substrates. However, patterning had a significant effect on the alignment and elongation of the tMSCs. More than 80% of the tMSCs were oriented in the direction of Microgrooves (0°-20°), while cells on the smooth substrates were randomly oriented. The aspect ratio [AR, ratio of length (in direction of Microgrooves) and breadth (in direction perpendicular to Microgrooves)] of the tMSCs on patterned substrates had a value of approximately five, as compared to cells on smooth substrates where the AR was one. Understanding responses to these cues in vitro helps us in understanding the behavior and interaction of the cells with the 3D environment of the scaffolds, facilitating the application of these concepts to designing effective nerve guidance conduits for peripheral nerve regeneration.
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oriented schwann cell growth on micropatterned biodegradable polymer substrates
Biomaterials, 2001Co-Authors: Cheryl Miller, Anthony Witt, Gregory E Rutkowski, H. R. Shanks, Surya K MallapragadaAbstract:Abstract This paper investigates the influence of substrate-mediated chemical and physical guidance on the growth and alignment of Schwann cells in vitro. Novel techniques were developed to fabricate Microgrooves with adsorbed proteins on biodegradable polymer substrates made of poly( d , l -lactic acid). Compression molding and solvent-casting were used to transfer micropatterns from quartz and silicon substrates onto biodegradable polymer films. Laminin was selectively adsorbed onto the grooves and rat sciatic Schwann cells were seeded on the substrates. Laminin was found to improve adhesion of Schwann cells on the substrates. The Microgrooves were found to cause the Schwann cells to align along the direction of the grooves. The groove width influenced Schwann cell alignment the most, while groove depth did not seem to play a significant role. The degradation of the grooves in the solvent cast films was much slower than those in the compression-molded films, making them the preferred substrates for Schwann cell culture.