The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Tsuyoshi Miyake - One of the best experts on this subject based on the ideXlab platform.
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change in enzyme production by gradually drying Culture Substrate during solid state fermentation
Journal of Bioscience and Bioengineering, 2015Co-Authors: Kazunari Ito, Katsuya Gomi, Masahiro Kariyama, Tsuyoshi MiyakeAbstract:The influence of drying the Culture Substrate during solid-state fermentation on enzyme production was investigated using a non-airflow box. The drying caused a significant increase in enzyme production, while the mycelium content decreased slightly. This suggests that changes in the water content in the Substrate during Culture affect enzyme production in fungi.
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uniform Culture in solid state fermentation with fungi and its efficient enzyme production
Journal of Bioscience and Bioengineering, 2011Co-Authors: Kazunari Ito, Katsuya Gomi, Masahiro Kariyama, Tomoka Kawase, Hiroyuki Sammoto, Tsuyoshi MiyakeAbstract:Solid-state fermentation (SSF) has attracted a lot of interest for carrying out high-level protein production in filamentous fungi. However, it has problems such as the fermentation heat generated during the Culture in addition to the reduced mobility of substances. These conditions lead to a nonuniform state in the Culture Substrate and result in low reproducibility. We constructed a non-airflow box (NAB) with a moisture permeable fluoropolymer membrane, thereby making it possible to control and maintain uniform and optimal conditions in the Substrate. For the NAB Culture in Aspergillus oryzae, temperature and water content on/in the whole Substrate were more consistent than for a traditional tray box (TB) Culture. Total weight after the Culture remained constant and dry conditions could be achieved during the Culture. These data demonstrate the possibility of growing a uniform Culture of the whole Substrate for SSF. The NAB is advantageous because it allows for the control of exact temperature and water content in the Substrate during the Culture by allowing vapor with latent heat to dissipate out of the box. In addition, several enzymes in the NAB Culture exhibited higher production levels than in the TB Culture. We believe that culturing in the constructed NAB could become a standard technique for commercial SSF.
Kazunari Ito - One of the best experts on this subject based on the ideXlab platform.
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change in enzyme production by gradually drying Culture Substrate during solid state fermentation
Journal of Bioscience and Bioengineering, 2015Co-Authors: Kazunari Ito, Katsuya Gomi, Masahiro Kariyama, Tsuyoshi MiyakeAbstract:The influence of drying the Culture Substrate during solid-state fermentation on enzyme production was investigated using a non-airflow box. The drying caused a significant increase in enzyme production, while the mycelium content decreased slightly. This suggests that changes in the water content in the Substrate during Culture affect enzyme production in fungi.
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uniform Culture in solid state fermentation with fungi and its efficient enzyme production
Journal of Bioscience and Bioengineering, 2011Co-Authors: Kazunari Ito, Katsuya Gomi, Masahiro Kariyama, Tomoka Kawase, Hiroyuki Sammoto, Tsuyoshi MiyakeAbstract:Solid-state fermentation (SSF) has attracted a lot of interest for carrying out high-level protein production in filamentous fungi. However, it has problems such as the fermentation heat generated during the Culture in addition to the reduced mobility of substances. These conditions lead to a nonuniform state in the Culture Substrate and result in low reproducibility. We constructed a non-airflow box (NAB) with a moisture permeable fluoropolymer membrane, thereby making it possible to control and maintain uniform and optimal conditions in the Substrate. For the NAB Culture in Aspergillus oryzae, temperature and water content on/in the whole Substrate were more consistent than for a traditional tray box (TB) Culture. Total weight after the Culture remained constant and dry conditions could be achieved during the Culture. These data demonstrate the possibility of growing a uniform Culture of the whole Substrate for SSF. The NAB is advantageous because it allows for the control of exact temperature and water content in the Substrate during the Culture by allowing vapor with latent heat to dissipate out of the box. In addition, several enzymes in the NAB Culture exhibited higher production levels than in the TB Culture. We believe that culturing in the constructed NAB could become a standard technique for commercial SSF.
Matthias P Lutolf - One of the best experts on this subject based on the ideXlab platform.
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artificial niche microarrays for probing single stem cell fate in high throughput
Nature Methods, 2011Co-Authors: Samy Gobaa, Sylke Hoehnel, Marta Roccio, Andrea Negro, Stefan Kobel, Matthias P LutolfAbstract:To understand the regulatory role of niches in maintaining stem-cell fate, multifactorial in vitro models are required. These systems should enable analysis of biochemical and biophysical niche effectors in a combinatorial fashion and in the context of a physiologically relevant cell-Culture Substrate. We report a microengineered platform comprised of soft hydrogel microwell arrays with modular stiffness (shear moduli of 1-50 kPa) in which individual microwells can be functionalized with combinations of proteins spotted by robotic technology. To validate the platform, we tested the effect of cell-cell interactions on adipogenic differentiation of adherent human mesenchymal stem cells (MSCs) and the effect of Substrate stiffness on osteogenic MSC differentiation. We also identified artificial niches supporting extensive self-renewal of nonadherent mouse neural stem cells (NSCs). Using this method, it is possible to probe the effect of key microenvironmental perturbations on the fate of any stem cell type in single cells and in high throughput.
Shanhui Hsu - One of the best experts on this subject based on the ideXlab platform.
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spheroid formation of mesenchymal stem cells on chitosan and chitosan hyaluronan membranes
Biomaterials, 2011Co-Authors: Guoshiang Huang, Lienguo Dai, Betty Linju Yen, Shanhui HsuAbstract:Stem cells can lose their primitive properties during in vitro Culture. The Culture Substrate may affect the behavior of stem cells as a result of cell-Substrate interaction. The maintenance of self-renewal for adult human mesenchymal stem cells (MSCs) by a biomaterial Substrate, however, has not been reported in literature. In this study, MSCs isolated from human adipose (hADAS) and placenta (hPDMC) were Cultured on chitosan membranes and those further modified by hyaluronan (chitosan-HA). It was observed that the MSCs of either origin formed three-dimensional spheroids that kept attached on the membranes. Spheroid formation was associated with the increased MMP-2 expression. Cells on chitosan-HA formed spheroids more quickly and the size of spheroids were larger than on chitosan alone. The expression of stemness marker genes (Oct4, Sox2, and Nanog) for MSCs on the materials was analyzed by the real-time RT-PCR. It was found that formation of spheroids on chitosan and chitosan-HA membranes helped to maintain the expression of stemness marker genes of MSCs compared to culturing cells on polystyrene dish. The maintenance of stemness marker gene expression was especially remarkable in hPDMC spheroids (vs. hADAS spheroids). Blocking CD44 by antibodies prevented the spheroid formation and decreased the stemness gene expression moderately; while treatment by Y-27632 compound inhibited the spheroid formation and significantly decreased the stemness gene expression. Upon chondrogenic induction, the MSC spheroids showed higher levels of Sox9, aggrecan, and collagen type II gene expression and were stained positive for glycosaminoglycan and collagen type II. hPDMC had better chondrogenic differentiation potential than hADAS upon induction. Our study suggested that the formation of adhered spheroids on chitosan and chitosan-HA membranes may sustain the expression of stemness marker genes of MSCs and increase their chondrogenic differentiation capacity. The Rho/Rho-associated kinase (ROCK) signaling pathway may be involved in spheroid formation.
Robert Langer - One of the best experts on this subject based on the ideXlab platform.
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tissue engineering of functional cardiac muscle molecular structural and electrophysiological studies
American Journal of Physiology-heart and Circulatory Physiology, 2001Co-Authors: Maria Papadaki, J Merok, Nenad Bursac, Gordana Vunjaknovakovic, Robert Langer, Lisa E FreedAbstract:The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed cardiac muscle with its electrophysiological function using an in vitro model system based on neonatal rat cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered cardiac muscle contained a 120- to 160-μm-thick peripheral region with cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue Culture Substrate, bioreactor, and Culture medium. Native tissue and the best experimental group (engineered cardiac muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered cardiac muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.
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biodegradable polymer scaffolds for tissue engineering
Nature Biotechnology, 1994Co-Authors: Lisa E Freed, Gordana Vunjaknovakovic, Robert J Biron, Dana Burton Eagles, Daniel Lesnoy, Sandra K Barlow, Robert LangerAbstract:Synthetic polymer scaffolds designed for cell transplantation were reproducibly made on a large scale and studied with respect to biocompatibility, structure and biodegradation rate. Polyglycolic acid (PGA) was extruded and oriented to form 13 μm diameter fibers with desired tenacity. Textile processing techniques were used to produce fibrous scaffolds with a porosity of 97% and sufficient structural integrity to maintain their dimensions when seeded with isolated cartilage cells (chondrocytes) and Cultured in vitro at 37°C for 8 weeks. Cartilaginous tissue consisting of glycosaminoglycan and collagen was regenerated in the shape of the original PGA scaffold. The resulting cell-polymer constructs were the largest grown in vitro to date (1 cm diameter × 0.35 cm thick). Construct mass was accurately predicted by accounting for accumulation of tissue components and scaffold degradation. The scaffold induced chondrocyte differentiation with respect to morphology and phenotype and represents a model cell Culture Substrate that may be useful for a variety of tissue engineering applications.
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electrically conducting polymers can noninvasively control the shape and growth of mammalian cells
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Joyce Y. Wong, Robert Langer, Donald E. IngberAbstract:Abstract Electrically conducting polymers are novel in that their surface properties, including charge density and wettability, can be reversibly changed with an applied electrical potential. Such properties might render conducting polymers unique for biological applications. However, the majority of research on conducting polymers has been carried out under nonbiological conditions. We synthesized optically transparent polypyrrole thin films and studied them in environments suitable for protein adsorption and mammalian cell Culture. In vitro studies demonstrated that extracellular matrix molecules, such as fibronectin, adsorb efficiently onto polypyrrole thin films and support cell attachment under serum-free conditions. When aortic endothelial cells were Cultured on fibronectin-coated polypyrrole (oxidized) in either chemically defined medium or the presence of serum, cells spread normally and synthesized DNA. In contrast, when the polymer was switched to its neutral state by applying an electrical potential, both cell extension and DNA synthesis were inhibited without affecting cell viability. Application of a similar electrical potential to cells Cultured on indium tin oxide surfaces had no effect on cell shape or function. These data suggest that electrically conducting polymers may represent a type of Culture Substrate which could provide a noninvasive means to control the shape and function of adherent cells, independent of any medium alteration.
