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Cell Behavior (cell + behavior)
Selected AbstractsTailoring Cell Behavior on Polymers by the Incorporation of Titanium Doped Phosphate Glass Filler,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Wojciech Chrzanowski Abstract Understanding tissue response to materials, to enable modulation and guided tissue regeneration is one of the main challenges in biomaterials science. Nowadays polymers, glasses, and metals dominate as biomaterials. Often native properties of those materials are not sufficient and there is a need to combine them, so as to modify and adjust their properties to the application. The primary aim of this study was to improve cell response to polymer (PLDL) using phosphate glass as filler (titanium doped phosphate glass). As a control ,-tricalcium phosphate (TCP) filler was used. Various concentrations of the filler were used (10,40 vol%). Wetting behavior, , -potentials, mechanical and thermal properties, and human cells response to the materials were evaluated. Results showed that with increase in glass filler loading wettability improved, , -potentials dropped, and increase in stiffness of materials was observed. Importantly cell culture experiments showed more developed and well spread cells on the samples with glass content up to 20 vol%. Cells responded much more positively to the glass filled samples than to TCP filled. However, expression of osteocalcin and osteopontin, proteins that indicate formation of the mineralized structures was positive for all the samples including pure PLDL. It was concluded that due to improved wetting behavior, lower , -potentials, and specific chemistry of the glass filler it was possible to alter cells response, improve bioactivity of the polymer, and vary mechanical properties. [source] A Method for the Real-Time Observation of Endodermal Cell Behavior on Micropatterned Surfaces,ADVANCED ENGINEERING MATERIALS, Issue 8 2009David C. Trimbach Surface chemistry and geometry have a strong influence on adhesion and proliferation of various cell types, including human embryonic stem cells (ES). Visceral endoderm like cells (END-2) is an important cell line which induces ES cells to differentiate into cardiomyocytes. In this study, we have investigated the effect of surface chemistry and geometry on the END-2 cell adhesion and proliferation on gold surface. [source] Mechanical Gradient Cues for Guided Cell Motility and Control of Cell Behavior on Uniform SubstratesADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Barbara Cortese Abstract A novel method for the fabrication and the use of simple uniform poly(dimethylsiloxane) PDMS substrates for controlling cell motility by a mechanical gradient is reported. The substrate is fabricated in PDMS using soft lithography and consists of a soft membrane suspended on top of a patterned PDMS substrate. The difference in the gradient stiffness is related to the underlying pattern. It is shown experimentally that these uniform substrates can modulate the response of cell motility, thus enabling patterning on the surfaces with precise cell motility. Because of the uniformity of the substrate, cells can spread equally and a directional movement to stiffer regions is clearly observed. Varying the geometry underlying the membrane, cell patterning and movement can be quantitatively characterized. This procedure is capable of controlling cell motility with high fidelity over large substrate areas. The most significant advance embodied in this method is that it offers the use of mechanical features to control cell adhesion and not topographical or chemical variations, which has not been reported so far. This modulation of the response of cell motility will be useful for the design and fabrication of advanced planar and 3D biological assemblies suitable for applications in the field of biotechnology and for tissue-engineering purposes. [source] Directional change produced by perpendicularly-oriented microgrooves is microtubule-dependent for fibroblasts and epitheliumCYTOSKELETON, Issue 5 2009Douglas W. Hamilton Abstract Anisotropic substrata such as micromachined grooves can control cell shape, orientation, and the direction of cell movement, a phenomena termed topographic guidance. Although many types of cells exhibit topographic guidance, little is known regarding cell responses to conflicting topographic cues. We employed a substratum with intersecting grooves in order to present fibroblasts and epithelial cells with conflicting topographic cues. Using time-lapse and confocal microscopy, we examined cell behavior at groove intersections. Migrating fibroblasts and epithelial cells typically extended a cell process into the intersection ahead of the cell body. After travelling along the "X" groove to enter the intersection, the leading lamellipodia of the cell body encountered the perpendicular "Y" groove, and spread latterly along the "Y" groove. The formation of lateral lamellipodia resulted in cells forming "T" or "L" morphologies, which were characterized by the formation of phosphotyrosine-rich focal adhesions at the leading edges. The "Y" groove did not prove an absolute barrier to cell migration, particularly for epithelial cells. Analysis of cytoskeletal distribution revealed that F-actin bundles did not adapt closely to the groove patterns, but typically did align to either the "X" or "Y" grooves. In contrast microtubules (MT) adapted closely to the walls. Inhibition of microtubule nucleation attenuated fibroblast and epithelial cell orientation within the intersection of the perpendicular grooves. We conclude that MT may be the prime determinant of fibroblast and epithelial cell conformation to conflicting topographies. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] Primary mesenchyme cell-ring pattern formation in 2D-embryos of the sea urchinDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2000Hideki Katow Primary mesenchyme cell (PMC) migration during PMC-ring pattern formation was analyzed using computer-assisted time-lapse video microscopy in spread embryos (2D-embryo) of the sea urchin, Mespilia globulus, and a computer simulation. The PMC formed a near normal ring pattern in the 2D-embryos, which were shown to be an excellent model for the examination of cell behavior in vivo by time-lapse computer analysis. The average migration distance of the ventro-lateral PMC aggregate-forming cells (AFC) and that of the dorso-ventral PMC cable-forming cells (CFC) showed no significant difference. All PMC took a rather straightforward migration path to their destinations with little lag time after ingression. This in vivo cell behavior fitted well to a computer simulation with a non-diffusable chemotaxis factor in the cyber-cell migration field. This simulation suggests that PMC recognize their destination from a very early moment of cell migration from the vegetal plate, and implicates that a chemoattractive region is necessary for making the PMC migration pattern. The left- and right-lateral AFC and dorso and ventral CFC were each derived from an unequally divided one-quarter segment of the vegetal plate. This suggests that AFC and CFC have a distinctive ancestor in the vegetal plate, and the PMC are a heterogeneous population at least in terms of their destination in the PMC-ring pattern. [source] Cellular dynamics of epithelial clefting during branching morphogenesis of the mouse submandibular glandDEVELOPMENTAL DYNAMICS, Issue 6 2010Yuichi Kadoya Abstract We cultured the rudimental submandibular gland (SMG) of mice with a non,cell-permeable fluorescent tracer, and observed cell behavior during epithelial branching morphogenesis using confocal time-lapse microscopy. We traced movements of individual cells as shadowgraph movies. Individual epithelial cells migrated dynamically but erratically. The epithelial cleft extended by wiggling and separated a cluster of cells into two buds during branching. We examined the ultrastructure of the clefts in SMG rudiments treated with the laminin peptide A5G77f, which induces epithelial clefting. A short cytoplasmic shelf with a core of microfilaments was found at the deep end of the cleft. We propose that epithelial clefting involves a dynamic movement of cells at the base of the cleft, and the formation of a shelf within a cleft cell. The shelf might form a matrix attachment point at the base of the cleft with a core of microfilaments driving cleft elongation. Developmental Dynamics 239:1739,1747, 2010. © 2010 Wiley-Liss, Inc. [source] Analysis of conserved residues in the ,pat-3 cytoplasmic tail reveals important functions of integrin in multiple tissuesDEVELOPMENTAL DYNAMICS, Issue 3 2010Xiaojian Xu Abstract Integrin cytoplasmic tails contain motifs that link extracellular information to cell behavior such as cell migration and contraction. To investigate the cell functions mediated by the conserved motifs, we created mutations in the Caenorhabditis elegans ,pat-3 cytoplasmic tail. The ,1D (799FK800), NPXY, tryptophan (784W), and threonine (797TT798) motifs were disrupted to identify their functions in vivo. Animals expressing integrins with disrupted NPXY motifs were viable, but displayed distal tip cell migration and ovulation defects. The conserved threonines were required for gonad migration and contraction as well as tail morphogenesis, whereas disruption of the ,1D and tryptophan motifs produced only mild defects. To abolish multiple conserved motifs, a ,1C-like variant, which results in a frameshift, was constructed. The ,pat-3(,1C) transgenic animals showed cold-sensitive larval arrests and defective muscle structure and gonad migration and contraction. Our study suggests that the conserved NPXY and TT motifs play important roles in the tissue-specific function of integrin. Developmental Dynamics 239:763,772, 2010. © 2010 Wiley-Liss, Inc. [source] Expression patterns and cell cycle profiles of PCNA, MCM6, cyclin D1, cyclin A2, cyclin B1, and phosphorylated histone H3 in the developing mouse retinaDEVELOPMENTAL DYNAMICS, Issue 3 2008Kirston M. Barton Abstract A challenge in studying organogenesis is the ability to identify progenitor cell populations. To address this problem, we characterized the expression patterns of cell cycle proteins during mouse retinal development and used flow cytometry to determine the expression profiles in the cell cycle. We found that MCM6 and PCNA are expressed in essentially all retinal progenitor cells throughout the proliferative period and these proteins are readily detectable in all cell cycle phases. Furthermore, their expression levels are downregulated as cells exit the cell cycle and differentiate. We also analyzed the expression of Cyclins D1, A2, and B1, and phosphorylated Histone H3 and found unexpected expression patterns and cell cycle profiles. The combined utilization of the markers tested and the use of flow cytometry should further facilitate the study of stem and progenitor cell behavior during development and in adult tissues. Developmental Dynamics 237:672,682, 2008. © 2008 Wiley-Liss, Inc. [source] Effect of elevated homocysteine on cardiac neural crest migration in vitroDEVELOPMENTAL DYNAMICS, Issue 2 2002Philip R. Brauer Abstract A positive correlation between elevated maternal homocysteine (Hcys) and an increased risk of neural tube, craniofacial, and cardiac defects is well known. Studies suggest Hcys perturbs neural crest (NC) development and may involve N-methyl-D-aspartate (NMDA) receptors (Rosenquist et al., 1999). However, there is no direct evidence that Hcys alters NC cell behavior. Here, we evaluated the effect of Hcys on cardiac NC cell migratory behavior in vitro. Neural tube segments from chick embryos treated in ovo with or without Hcys were placed in culture and the migratory behavior of emigrating NC cells was monitored. Hcys significantly increased in vitro NC cell motility at all embryonic stages examined. NC cell surface area and perimeter were also increased. However, the relative distance NC cells migrated from their original starting point only increased in NC cells treated in ovo at stage 6 or at the time neural tube segments were cultured. Cysteine had no effect. NMDA mimicked Hcys' effect on NC motility and migration distance but had no effect on cell area or perimeter. The noncompetitive inhibitor of NMDA receptors, MK801+, significantly inhibited NC cell motility, reduced migration distance, and also blocked the effects of NMDA and Hcys on NC motility and migratory distance in vitro. A monoclonal antibody directed against the NMDA receptor immunostained NC cells in vitro and, in western blots, bound a single protein with the appropriate molecular weight for the NMDA receptor in NC cell lysates. These data are consistent with the hypothesis that a Hcys-sensitive NMDA-like receptor is expressed by early emigrating NC cells or their precursors, which is important in mediating their migratory behavior. Perturbation of this receptor may be related to some of the teratogenic effects observed with elevated Hcys. © 2002 Wiley-Liss, Inc. [source] Inside Front Cover (Adv. Eng.ADVANCED ENGINEERING MATERIALS, Issue 5 2010Mater. Surface roughness is another important factor impacting cell behavior and AFM is utilized to determine the surface morphology. The Cover shows the surface morphology measured by AFM obtained from O2 PIII PTFE. More details can be found in the article of Paul K. Chu on p. B163. [source] Embryo of an annual fish (Austrolebias charrua) in the last dormancy stage, diapause IIIGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2009Article first published online: 22 JAN 200 Embryo of an annual fish (Austrolebias charrua) in the last dormancy stage, diapause III. The embryo, surrounded by a transparent vitelline envelope, is in the pre-hatching stage. A prominent eye and part of the pigmented body and tail are apparent. Why annual fishes? Annual fishes (Order Cyprinodontiformes) are a special kind of teleost, found in Africa and South America, with developmental strategies closely related to their life cycle. These fishes inhabit temporary pools that undergo drying during summer, when all adults die. The embryos remain buried in the bottom mud and are resistant to desiccation. In the subsequent rainy season they hatch a few hours after the pool is flooded and a new reproductive cycle begins. This developmental pattern is characterized by the presence of a unique stage between cleavage and embryogenesis, dispersion-aggregation of blastomeres and because the embryos show reversible developmental arrests (diapauses) at different stages. Annual fish embryos are transparent, large, hardy and easy to maintain in the laboratory. Adults show continuous production of eggs and juveniles reach sexual maturity a few weeks after hatching (an unusual condition in fishes). Their particular developmental features confer unique opportunities for research on cell behavior during early development, the effect of environmental factors on development, the regulation of diapauses and the mechanisms involved in sex determination, among others topics. Image provided by Nibia Berois, Universidad de la República, Montevideo, Uruguay. [source] Potential and Bottlenecks of Bioreactors in 3D Cell Culture and Tissue ManufacturingADVANCED MATERIALS, Issue 32-33 2009David Wendt Abstract Over the last decade, we have witnessed an increased recognition of the importance of 3D culture models to study various aspects of cell physiology and pathology, as well as to engineer implantable tissues. As compared to well-established 2D cell-culture systems, cell/tissue culture within 3D porous biomaterials has introduced new scientific and technical challenges associated with complex transport phenomena, physical forces, and cell,microenvironment interactions. While bioreactor-based 3D model systems have begun to play a crucial role in addressing fundamental scientific questions, numerous hurdles currently impede the most efficient utilization of these systems. We describe how computational modeling and innovative sensor technologies, in conjunction with well-defined and controlled bioreactor-based 3D culture systems, will be key to gain further insight into cell behavior and the complexity of tissue development. These model systems will lay a solid foundation to further develop, optimize, and effectively streamline the essential bioprocesses to safely and reproducibly produce appropriately scaled tissue grafts for clinical studies. [source] Bioceramic Bone Graft Substitutes: Influence of Porosity and ChemistryINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2005Karin A. Hing Bioceramics have been considered for use as synthetic bone graft substitutes (BGSs) for over 30 years, throughout which there have been two primary areas of research: (i) optimization of the physical pore structure and (ii) formulation of an appropriate bioceramic chemistry. While it is well recognized that both the rate of integration and the final volume of regenerated bone are primarily dependent on the macroporosity, there still seems to be some dispute regarding the optimum "type" of porosity. The rate and quality of bone integration have, in turn, been related to a dependence on pore size, porosity volume fraction, and interconnection size and interconnection density, both as a function of structural permeability and mechano-transduction. Moreover, the role of strut microstructure and pore geometry have been considered with respect to their influence on entrapment and recruitment of growth factors (GFs) in addition to its influence on scaffold mechanics. Deconvoluting the relative affects of these parameters is complicated by the use of both resorbable and nonresorbable bioactive bioceramics, which are believed to mediate bioactivity in the osseous environment through two principal mechanisms: (i) directly through dissolution and release of ionic products in vivo, elevating local concentrations of soluble species that interact directly with local cells or influence cell behavior by their effect on local pH, (ii) indirectly through the influence that surface chemistry will have on protein adsorption, GF entrapment, and subsequent cell attachment and function. This article aims to review some of the recent developments in bioceramic BGSs, with a view to understanding how the various physiochemical parameters may be optimized to promote bone healing. [source] Biological indicators of prognosis in Ewing's sarcoma: An emerging role for lectin galactoside-binding soluble 3 binding protein (LGALS3BP)INTERNATIONAL JOURNAL OF CANCER, Issue 1 2010Diana Zambelli Abstract Starting from an experimental model that accounts for the 2 most important adverse processes to successful therapy of Ewing's sarcoma (EWS), chemoresistance and the presence of metastasis at the time of diagnosis, we defined a molecular signature of potential prognostic value. Functional annotation of differentially regulated genes revealed 3 major networks related to cell cycle, cell-to-cell interactions and cellular development. The prognostic impact of 8 genes, representative of these 3 networks, was validated in 56 EWS patients. High mRNA expression levels of HINT1, IFITM2, LGALS3BP, STOML2 and c-MYC were associated with reduced risk to death and lower risk to develop metastasis. At multivariate analysis, LGALS3BP, a matricellular protein with a role in tumor progression and metastasis, was the most important predictor of event-free survival and overall survival. The association between LGALS3BP and prognosis was confirmed at protein level, when expression of the molecule was determined in tumor tissues but not in serum, indicating a role for the protein at local tumor microenvironment. Engineered enhancement of LGALS3BP expression in EWS cells resulted in inhibition of anchorage independent cell growth and reduction of cell migration and metastasis. Silencing of LGALS3BP expression reverted cell behavior with respect to in vitro parameters, thus providing further functional validation of genetic data obtained in clinical samples. Thus, we propose LGALS3BP as a novel reliable indicator of prognosis, and we offer genetic signatures to the scientific communities for cross-validation and meta-analysis, which are indispensable tools for a rare tumor such as EWS. [source] BRCA1 modulates malignant cell behavior, the expression of survivin and chemosensitivity in human breast cancer cells,INTERNATIONAL JOURNAL OF CANCER, Issue 12 2009Moltira Promkan Abstract BRCA1 is a multifunctional tumor-suppressive protein. Many functional aspects of BRCA1 are not fully understood. We used a shRNA approach to probe the function of BRCA1 in human breast cancer cells. Knocking down BRCA1 expression by shRNA in the wild-type BRCA1 human breast cancer MCF-7 and MDA-MB-231 cells resulted in an increase in cell proliferation, anchorage-independent growth, cell migration, invasion and a loss of p21/Waf1 and p27Kip1 expression. In BRCA1 knocked-down cells, the expression of survivin was significantly up regulated with a concurrent decrease in cellular sensitivity to paclitaxel. We also found that cells harboring endogenous mutant or defective BRCA1 (MDA-MB-436 and HCC1937) were highly proliferative and expressed a relatively low level of p21/Waf1 and p27Kip1 by comparison to wild-type BRCA1 cells. Cells harboring mutated BRCA1 also expressed a high level of survivin and were relatively resistant to paclitaxel by comparison to wild-type cells. Increase resistance to paclitaxel was due to an increase in the expression of survivin in both the BRCA1 knocked-down and mutant BRCA1 cells because knocking down survivin expression by siRNA restored sensitivity to paclitaxel. We conclude that BRCA1 down-modulates the malignant behavior of breast cancer cells, promotes the expression of p21/Waf1, p27Kip1 and inhibits the expression of survivin. Moreover, loss of BRCA1 expression or function leads to an increase in survivin expression and a reduction in chemosensitivity to paclitaxel. © 2009 UICC [source] Aberrant p53 alters DNA damage checkpoints in response to cisplatin: Downregulation of CDK expression and activityINTERNATIONAL JOURNAL OF CANCER, Issue 5 2004Katharine H. Wrighton Abstract The p53 tumor suppressor protein is a critical mediator of cell cycle arrest and apoptosis in response to genotoxic stress. Abrogation of p53 function is a major feature of tumor development and may result in a compromised DNA-damage response. In our study, we examined the effect of expressing a human p53 cDNA, encoding a histidine to leucine amino acid substitution at codon 179 (H179L), on the ability of wild-type p53-containing NIH3T3 cells to respond to treatment with the chemotherapeutic cisplatin. After 72 hr of cisplatin treatment control cells underwent apoptosis preceded by a combination of S- and G2 arrest, as judged by flow cytometry of propidium iodide-stained cells, and TUNEL and caspase-3 assays. This correlated with increased expression of the pro-apoptotic protein Bax. In contrast, cells stably expressing H179L-p53 arrested in S-phase following cisplatin treatment, which correlated with a marked decrease in the expression of cdc2, cyclin B1 and cyclin A, and a decrease in CDK2 and cyclin A-associated kinase activity. Interestingly, H179L p53 expressing cells underwent apoptosis earlier than control cells, indicating that this aberrant p53 may enhance cisplatin chemosensitivity. These data suggest that dominant-negative p53 can influence the expression and activity of CDK complexes, thereby modifying cell behavior following cisplatin-induced genotoxicity. © 2004 Wiley-Liss, Inc. [source] Calcium phosphate-based coatings on titanium and its alloysJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008R. Narayanan Abstract Use of titanium as biomaterial is possible because of its very favorable biocompatibility with living tissue. Titanium implants having calcium phosphate coatings on their surface show good fixation to the bone. This review covers briefly the requirements of typical biomaterials and narrowly focuses on the works on titanium. Calcium phosphate ceramics for use in implants are introduced and various methods of producing calcium phosphate coating on titanium substrates are elaborated. Advantages and disadvantages of each type of coating from the view point of process simplicity, cost-effectiveness, stability of the coatings, coating integration with the bone, cell behavior, and so forth are highlighted. Taking into account all these factors, the efficient method(s) of producing these coatings are indicated finally. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Local regulation of human breast xenograft models,,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2010Jodie M. Fleming Breast cancer studies implant human cancer cells under the renal capsule, subcutaneously, or orthotopically and often use estrogen supplementation and immune suppressants (etoposide) in xenograft mouse models. However, cell behavior is significantly impacted by signals from the local microenvironment. Therefore, we investigated how the combinatorial effect of the location of injection and procedural differences affected xenograft characteristics. Patient-derived breast cancer cells were injected into mouse abdominal or thoracic mammary glands,±,estrogen and/or etoposide pretreatment. Abdominal xenografts had increased tumor incidence and volume, and decreased latency (P,<,0.001) compared to thoracic tumors. No statistically significant difference in tumor volume was found in abdominal xenografts treated,±,estrogen or etoposide; however, etoposide suppressed tumor volume in thoracic xenografts (P,<,0.02). The combination of estrogen and etoposide significantly decreased tumor incidence in both sites. In addition, mice treated,±,estradiol were injected orthotopically or subcutaneously with well-characterized breast cancer cell lines (MCF7, ZR75-1, MDA MB-231, or MCF10Ca1h). Orthotopic injection increased tumor volume; growth varied with estrogen supplementation. Location also altered methylation status of several breast cancer-related gene promoters. Lastly, vascularization of orthotopic tumors was significantly enhanced compared to subcutaneous tumors. These data suggest that optimal xenograft success occurs with orthotopic abdominal injections and illustrate molecular details of the compelling influence of the local microenvironment on in vivo models. J. Cell. Physiol. 224: 795,806, 2010. Published 2010 Wiley-Liss, Inc. [source] Cancer stem cells in leukemia, recent advancesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2007Gang-Ming Zou The history of stem cell research was started in the early 1900s in Europe where the researcher realized that various types of blood cells came from a particular "stem cells." However, it was not until 1963 that the first quantitative description of the self-renewal activities of transplanted mouse bone marrow cells were documented by Canadian scientist Ernest A McCulloch and James E Till in Toronto. The concept of cancer stem cells has been used over 50 years ago; whereas the strong evidence for the existence of a Cancer Stem Cells was obtained recently. Consequently, there is increasing attention in recent year about cancer stem cells. The findings from recent studies support the concept that stem cells are integral to the development of several forms of human cancer. Changes in stem cell behavior can contribute to tumor formation. Leukemia is a cancer of blood-forming tissue, including the bone marrow and lymphatic system. Leukemic stem cells represent the cancer stem cells in the leukemia. In this review, we summarize the recent advance in the study of leukemic stem cells. J. Cell. Physiol. 213: 440,444, 2007. © 2007 Wiley-Liss, Inc. [source] The regulation of osteogenesis by ECM rigidity in MC3T3-E1 cells requires MAPK activationJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2007Chirag B. Khatiwala Once thought to provide only structural support to tissues by acting as a scaffold to which cells bind, it is now widely recognized that the extracellular matrix (ECM) provides instructive signals that dictate cell behavior. Recently we demonstrated that mechanical cues intrinsic to the ECM directly regulate the behavior of pre-osteoblastic MC3T3-E1 cells. We hypothesized that one possible mechanism by which ECM compliance exerts its influence on osteogenesis is by modulating the mitogen-activated protein kinase (MAPK) pathway. To address this hypothesis, the differentiation of MC3T3-E1 cells cultured on poly(ethylene glycol) (PEG)-based model substrates with tunable mechanical properties was assessed. Alkaline phosphatase (ALP) levels at days 7 and 14 were found to be significantly higher in cells grown on stiffer substrates (423.9 kPa hydrogels and rigid tissue culture polystyrene (TCPS) control) than on a soft hydrogel (13.7 kPa). Osteocalcin (OCN) and bone sialoprotein (BSP) gene expression levels followed a similar trend. In parallel, MAPK activity was significantly higher in cells cultured on stiffer substrates at both time points. Inhibiting this activation pharmacologically, using PD98059, resulted in significantly lower ALP levels, OCN, and BSP gene expression levels on the hydrogels. Interestingly, the effectiveness of PD98059 was itself dependent on substrate stiffness, with marked inhibition of MAPK phosphorylation in cells grown on compliant hydrogels but insignificant reduction in cells grown on TCPS. Together, these data confirm a role for MAPK in the regulation of osteogenic differentiation by ECM compliance. J. Cell. Physiol. 211: 661,672, 2007. © 2007 Wiley-Liss, Inc. [source] The integrin family of cell adhesion molecules has multiple functions within the CNSJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2002Richard Milner Abstract Integrins comprise a large family of cell adhesion molecules that mediate interactions between the extracellular environment and the cytoplasm. During the last decade, analysis of the expression and function of these molecules has revealed that integrins regulate many aspects of cell behavior including cell death, proliferation, migration, and differentiation. Within the central nervous system (CNS), most of the early studies focused on the role of integrins in mediating adhesive and migratory events in two distinct processes: neural development and CNS inflammation. Interestingly, recent analysis of transgenic mice has provided some surprising results regarding the role of integrins in neural development. Furthermore, a large body of evidence now supports the idea that in addition to these well-described functions, integrins play multiple roles in the CNS, both during development and in the adult in areas as diverse as synaptogenesis, activation of microglia, and stabilization of the endothelium and blood-brain barrier. Many excellent reviews have addressed the contribution of integrins in mediating leukocyte extravasation during CNS inflammation. This review will focus on recently emerging evidence of novel and diverse roles of integrins and their ligands in the CNS during development and in the adult, in health and disease. © 2002 Wiley-Liss, Inc. [source] Microtopography of metal surfaces influence fibroblast growth by modifying cell shape, cytoskeleton, and adhesionJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 11 2007David O. Meredith Abstract Stainless Steel (SS), titanium (cpTi), and Ti-6Al-7Nb (TAN) are frequently used metals in fracture fixation, which contact not only bone, but also soft tissue. In previous soft tissue cytocompatibility studies, TAN was demonstrated to inhibit cell growth in its "standard" micro-roughened state. To elucidate a possible mechanism for this inhibition, cell area, shape, adhesion, and cytoskeletal integrity was studied. Only minor changes in spreading were observed for cells on electropolished SS, cpTi, and TAN. Cells on "standard" cpTi were similarly spread in comparison with electropolished cpTi and TAN, although the topography influenced the cell periphery and also resulted in lower numbers and shorter length of focal adhesions. On "standard" microrough TAN, cell spreading was significantly lower than all other surfaces, and cell morphology differed by being more elongated. In addition, focal adhesion numbers and mean length were significantly lower on standard TAN than on all other surfaces, with 80% of the measured adhesions below a 2-µm threshold. Focal adhesion site location and maturation and microtubule integrity were compromised by the presence of protruding ,-phase microspikes found solely on the surface of standard TAN. This led us to propose that the impairment of focal adhesion numbers, maturation (length), and cell spreading to a possibly sufficient threshold observed on standard TAN blocks cell cycle progress and eventually cell growth on the surface. We believe, as demonstrated with standard cpTi and TAN, that a difference in surface morphology is influential for controlling cell behavior on implant surfaces. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1523,1533, 2007 [source] Expression and release of IL-29 by mast cells and modulation of mast cell behavior by IL-29ALLERGY, Issue 10 2010S. He To cite this article: He S, Zhang H, Chen H, Yang H, Huang T, Chen Y, Lin J, Wang F, Chen X, Li T-L, Yang P. Expression and release of IL-29 by mast cells and modulation of mast cell behavior by IL-29. Allergy 2010; 65: 1234,1241. Abstract Background:, The role of interleukin (IL)-29 in innate immunity has been recognized recently, and it is regarded as a potent bioactive molecule. However, little is known about its role in the pathogenesis of allergy. Because mast cells are recognized as primary effector cells of allergy, we investigated the potential relationship between IL-29 and mast cells in this study. Objective:, To examine the expression of IL-29 in mast cells and the influence of IL-29 on mast cell mediator release and accumulation. Methods:, Expression of IL-29 in mast cells was determined by double-labeling immunohistochemistry and flow cytometry analysis. Mast cell cell-line was cultured to examine the mediator release, and mouse peritoneal model was employed to observe the mast cell accumulation. Results:, Large proportions of mast cells expressing IL-29 were localized in human tissue including the colon, tonsil and lung. Mast cells can release substantial quantity of IL-29 upon challenge with proteolytic allergens. Extrinsic IL-29 provoked IL-4 and IL-13 release from mast cell line P815 cells through PI3K/Akt and (JAK)/STAT3 signaling pathways, but failed to induce mast cell histamine release from human mast cells. Extrinsic IL-29 also induced mast cell infiltration in mouse peritoneum by a CD18- and ICAM1-dependent mechanism. Conclusion:, Mast cell-derived IL-29 has the potential to be involved in the pathogenesis of allergic inflammation. [source] Cellular interactions in the vascular niche: implications in the regulation of tumor dormancy,APMIS, Issue 7-8 2008ELENA FAVARO Angiogenesis plays an established role in the promotion of growth of dormant micrometastasis, because blood vessels deliver oxygen and nutrients to the tumor microenvironment. In addition to this feeding function, however, there is accumulating evidence suggesting that endothelial cells,and perhaps other cellular components of the microenvironment,could communicate both positive and negative signals to tumor cells. This cross-talk between heterogeneous cell types could turn out to be important in the regulation of cancer cell behavior. Normal cells recruited during the angiogenic process, or attracted to future sites of metastasis by soluble products released by cancer cells, have been shown to create a niche favorable to tumor cell proliferation and survival. In addition, following an exogenous angiogenic spike, as may occur during inflammation, the same mechanisms could lead to re-activation of poorly angiogenic tumor cells seeded into tissues. In this review, we discuss the possible implications of this hypothesis for our understanding of the phenomenon of tumor dormancy. [source] Haematopoietic stem cell niche in DrosophilaBIOESSAYS, Issue 8 2007Ute Koch Development and homeostasis of the haematopoietic system is dependent upon stem cells that have the unique ability to both self-renew and to differentiate in all cell lineages of the blood. The crucial decision between haematopoietic stem cell (HSC) self-renewal and differentiation must be tightly controlled. Ultimately, this choice is regulated by the integration of intrinsic signals together with extrinsic cues provided by an exclusive microenvironment, the so-called haematopoietic niche. Although the haematopoietic system of vertebrates has been studied extensively for many decades, the specification of the HSC niche and its signals involved are poorly understood. Much of our current knowledge of how niches regulate long-term maintenance of stem cells is derived from studies on Drosophila germ cells. Now, two recently published studies by Mandal et al.1 and Krezmien et al.2 describe the Drosophila haematopoietic niche and signal transduction pathways that are involved in the maintenance of haematopoietic precursors. Both reports emphasize several features that are important for controlling stem cell behavior and show parallels to both the vertebrate haematopoietic niche as well as the Drosophila germline stem cell niches in ovary and testis. The findings of both papers shed new light on the specific interactions between haematopoietic progenitors and their microenvironment. BioEssays 29:713,716, 2007. © 2007 Wiley Periodicals, Inc. [source] Kinetic characterization of vero cell metabolism in a serum-free batch culture processBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Emma Petiot Abstract A global kinetic study of the central metabolism of Vero cells cultivated in a serum-free medium is proposed in the present work. Central metabolism including glycolysis, glutaminolysis, and tricarboxylic acid cycle (TCA) was demonstrated to be saturated by high flow rates of consumption of the two major substrates, glucose, and glutamine. Saturation was reavealed by an accumulation of metabolic intermediates and amino acids, by a high production of lactate needed to balance the redox pathway, and by a low participation of the carbon flow to the TCA cycle supply. Different culture conditions were set up to reduce the central metabolism saturation and to better balance the metabolic flow rates between lactate production and energetic pathways. From these culture conditions, substitutions of glutamine by other carbon sources, which have lower transport rates such as asparagine, or pyruvate in order to shunt the glycolysis pathway, were successful to better balance the central metabolism. As a result, an increase of the cell growth with a concomitant decrease of cell death and a better distribution of the carbon flow between TCA cycle and lactate production occurred. We also demonstrated that glutamine was a major carbon source to supply the TCA cycle in Vero cells and that a reduction of lactate production did not necessary improve the efficiency of the Vero cell metabolism. Thus, to adapt the formulation of the medium to the Vero cell needs, it is important to provide carbon substrates inducing a regulated supply of carbon in the TCA cycle either through the glycolysis or through other pathways such as glutaminolysis. Finally, this study allowed to better understand the Vero cell behavior in serum-free medium which is a valuable help for the implementation of this cell line in serum-free industrial production processes. Biotechnol. Bioeng. 2010;107: 143,153. © 2010 Wiley Periodicals, Inc. [source] Dynamic culture of droplet-confined cell arraysBIOTECHNOLOGY PROGRESS, Issue 1 2010Elisa Cimetta Abstract Responding to the need of creating an accurate and controlled microenvironment surrounding the cell while meeting the requirements for biological processes or pharmacological screening tests, we aimed at designing and developing a microscaled culture system suitable for analyzing the synergic effects of extracellular matrix proteins and soluble environments on cell phenotype in a high-throughput fashion. We produced cell arrays deposing micrometer-scale protein islands on hydrogels using a robotic DNA microarrayer, constrained the culture media in a droplet-like volume and developed a suitable perfusion system. The droplet-confined cell arrays were used either with conventional culture methods (batch operating system) or with automated stable and constant perfusion (steady-state operating system). Mathematical modeling assisted the experimental design and assessed efficient mass transport and proper fluidodynamic regimes. Cells cultured on arrayed islands (500 ,m diameter) maintained the correct phenotype both after static and perfused conditions, confirmed by immunostaining and gene expression analyses through total RNA extraction. The mathematical model, validated using a particle tracking experiment, predicted the constant value of velocities over the cell arrays (less than 10% variation) ensuring the same mass transport regime. BrdU analysis on an average of 96 cell spots for each experimental condition showed uniform expression inside each cell island and low variability in the data (average of 13%). Perfused arrays showed longer doubling times when compared with static cultures. In addition, perfused cultures showed a reduced variability in the collected data, allowing to detect statistically significant differences in cell behavior depending on the spotted ECM protein. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Bioassembly of three-dimensional embryonic stem cell-scaffold complexes using compressed gasesBIOTECHNOLOGY PROGRESS, Issue 2 2009Yubing Xie Abstract Tissues are composed of multiple cell types in a well-organized three-dimensional (3D) microenvironment. To faithfully mimic the tissue in vivo, tissue-engineered constructs should have well-defined 3D chemical and spatial control over cell behavior to recapitulate developmental processes in tissue- and organ-specific differentiation and morphogenesis. It is a challenge to build a 3D complex from two-dimensional (2D) patterned structures with the presence of cells. In this study, embryonic stem (ES) cells grown on polymeric scaffolds with well-defined microstructure were constructed into a multilayer cell-scaffold complex using low pressure carbon dioxide (CO2) and nitrogen (N2). The mouse ES cells in the assembled constructs were viable, retained the ES cell-specific gene expression of Oct-4, and maintained the formation of embryoid bodies (EBs). In particular, cell viability was increased from 80% to 90% when CO2 was replaced with N2. The compressed gas-assisted bioassembly of stem cell-polymer constructs opens up a new avenue for tissue engineering and cell therapy. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Fed-Batch Cultivation of Saccharomyces cerevisiae in a Hyperbaric BioreactorBIOTECHNOLOGY PROGRESS, Issue 2 2003I. Belo Fed-batch is the dominating mode of operation in high-cell-density cultures of Saccharomyces cerevisaein processes such as the production of bakerapos;s yeast and recombinant proteins, where the high oxygen demand of these cultures makes its supply an important and difficult task. The aim of this work was to study the use of hyperbaric air for oxygen mass transfer improvement on S. cerevisiaefed-batch cultivation. The effects of increased air pressure up to 1.5 MPa on cell behavior were investigated. The effects of oxygen and carbon dioxide were dissociated from the effects of total pressure by the use of pure oxygen and gas mixtures enriched with CO2. Fed-batch experiments were performed in a stirred tank reactor with a 600 mL stainless steel vessel. An exponential feeding profile at dilution rates up to 0.1 h,1 was used in order to ensure a subcritical flux of substrate and, consequently, to prevent ethanol formation due to glucose excess. The ethanol production observed at atmospheric pressure was reduced by the bioreactor pressurization up to 1.0 MPa. The maximum biomass yield, 0.5 g g,1 (cell mass produced per mass of glucose consumed) was attained whenever pressure was increased gradually through time. This demonstrates the adaptive behavior of the cells to the hyperbaric conditions. This work proved that hyperbaric air up to 1.0 MPa (0.2 MPa of oxygen partial pressure) could be applied to S. cerevisiaecultivation under low glucose flux. Above that critical oxygen partial pressure value, i.e., for oxygen pressures of 0.32 and 0.5 MPa, a drastic cell growth inhibition and viability loss were observed. The increase of carbon dioxide partial pressure in the gas mixture up to 48 kPa slightly decreased the overall cell mass yield but had negligible effects on cell viability. [source] Estimating the spatiotemporal pattern of volumetric growth rate from fate maps in chick limb developmentDEVELOPMENTAL DYNAMICS, Issue 2 2009Yoshihiro Morishita Abstract Morphogenesis is achieved through volumetric growth of tissue at a rate varying over space and time. The volumetric growth rate of each piece of tissue reflects the behaviors of constituent cells such as cell proliferation and death. Hence, clarifying its spatiotemporal pattern accurately is a key to bridge between cell behaviors and organ morphogenesis. We here propose a new method to estimate the spatiotemporal pattern of volumetric growth rate from fate map data with limited resolution on space and time by using a mathematical model. We apply the method to chick wing data along the proximodistal axis, and find that the volumetric growth pattern is biphasic: it is spatially uniform in earlier stages (until stage 23), but in later stages the volumetric growth occurs approximately 4.5 times as fast as in the distal region (within approximately 100 ,m from the limb tip) than in the proximal region. Developmental Dynamics 238:415,422, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||