by Keyword: Proliferation
Rätze, Max AK., Koorman, Thijs, Sijnesael, Thijmen, Bassey-Archibong, Blessing, van de Ven, Robert, Enserink, Lotte, Visser, Daan, Jaksani, Sridevi, Viciano, Ignacio, Bakker, Elvira RM., Richard, François, Tutt, Andrew, O’Leary, Lynda, Fitzpatrick, Amanda, Roca-Cusachs, Pere, van Diest, Paul J., Desmedt, Christine, Daniel, Juliet M., Isacke, Clare M., Derksen, Patrick WB., (2022). Loss of E-cadherin leads to Id2-dependent inhibition of cell cycle progression in metastatic lobular breast cancer Oncogene 41, 2932-2944
Invasive lobular breast carcinoma (ILC) is characterized by proliferative indolence and long-term latency relapses. This study aimed to identify how disseminating ILC cells control the balance between quiescence and cell cycle re-entry. In the absence of anchorage, ILC cells undergo a sustained cell cycle arrest in G0/G1 while maintaining viability. From the genes that are upregulated in anchorage independent ILC cells, we selected Inhibitor of DNA binding 2 (Id2), a mediator of cell cycle progression. Using loss-of-function experiments, we demonstrate that Id2 is essential for anchorage independent survival (anoikis resistance) in vitro and lung colonization in mice. Importantly, we find that under anchorage independent conditions, E-cadherin loss promotes expression of Id2 in multiple mouse and (organotypic) human models of ILC, an event that is caused by a direct p120-catenin/Kaiso-dependent transcriptional de-repression of the canonical Kaiso binding sequence TCCTGCNA. Conversely, stable inducible restoration of E-cadherin expression in the ILC cell line SUM44PE inhibits Id2 expression and anoikis resistance. We show evidence that Id2 accumulates in the cytosol, where it induces a sustained and CDK4/6-dependent G0/G1 cell cycle arrest through interaction with hypo-phosphorylated Rb. Finally, we find that Id2 is indeed enriched in ILC when compared to other breast cancers, and confirm cytosolic Id2 protein expression in primary ILC samples. In sum, we have linked mutational inactivation of E-cadherin to direct inhibition of cell cycle progression. Our work indicates that loss of E-cadherin and subsequent expression of Id2 drive indolence and dissemination of ILC. As such, E-cadherin and Id2 are promising candidates to stratify low and intermediate grade invasive breast cancers for the use of clinical cell cycle intervention drugs.
Keywords: anoikis resistance, carcinoma, d1, differentiation, gene-expression, growth, id2, proliferation, repression, Mammary epithelial-cells
Pérez-González, Carlos, Ceada, Gerardo, Matejcic, Marija, Trepat, Xavier, (2022). Digesting the mechanobiology of the intestinal epithelium Current Opinion In Genetics & Development 72, 82-90
The dizzying life of the homeostatic intestinal epithelium is governed by a complex interplay between fate, form, force and function. This interplay is beginning to be elucidated thanks to advances in intravital and ex vivo imaging, organoid culture, and biomechanical measurements. Recent discoveries have untangled the intricate organization of the forces that fold the monolayer into crypts and villi, compartmentalize cell types, direct cell migration, and regulate cell identity, proliferation and death. These findings revealed that the dynamic equilibrium of the healthy intestinal epithelium relies on its ability to precisely coordinate tractions and tensions in space and time. In this review, we discuss recent findings in intestinal mechanobiology, and highlight some of the many fascinating questions that remain to be addressed in this emerging field.Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.
Keywords: crypt fission, designer matrices, differentiation, growth, gut, migration, model, scaffold, tissue mechanics, Cell migration, Cell proliferation, Ex vivo study, Human tissue, Intestine epithelium, Monolayer culture, Organoid, Review, Stem-cell, Tension, Traction therapy
Konka, J, Espanol, M, Bosch, BM, de Oliveira, E, Ginebra, MP, (2021). Maturation of biomimetic hydroxyapatite in physiological fluids: a physicochemical and proteomic study MATERIALS TODAY BIO 12,
Biomimetic calcium-deficient hydroxyapatite (CDHA) as a bioactive material exhibits exceptional intrinsic osteoinductive and osteogenic properties because of its nanostructure and composition, which promote a favorable microenvironment. Its high reactivity has been hypothesized to play a relevant role in the in vivo performance, mediated by the interaction with the biological fluids, which is amplified by its high specific surface area. Paradoxically, this high reactivity is also behind the in vitro cytotoxicity of this material, especially pro-nounced in static conditions. The present work explores the structural and physicochemical changes that CDHA undergoes in contact with physiological fluids and to investigate its interaction with proteins. Calcium-deficient hydroxyapatite discs with different micro/nanostructures, coarse (C) and fine (F), were exposed to cell-free complete culture medium over extended periods of time: 1, 7, 14, 21, 28, and 50 days. Precipitate formation was not observed in any of the materials in contact with the physiological fluid, which would indicate that the ionic exchanges were linked to incorporation into the crystal structure of CDHA or in the hydrated layer. In fact, CDHA experienced a maturation process, with a progressive increase in crystallinity and the Ca/P ratio, accompanied by an uptake of Mg and a B-type carbonation process, with a gradual propagation into the core of the samples. However, the reactivity of biomimetic hydroxyapatite was highly dependent on the specific surface area and was amplified in nanosized needle-like crystal structures (F), whereas in coarse specimens the ionic exchanges were restricted to the surface, with low penetration in the material bulk. In addition to showing a higher protein adsorption on F substrates, the proteomics study revealed the existence of protein selectivity to-ward F or C microstructures, as well as the capability of CDHA, and more remarkably of F-CDHA, to concentrate specific proteins from the culture medium. Finally, a substantial improvement in the material's ability to support cell proliferation was observed after the CDHA maturation process.
Keywords: calcium phosphates, ion exchange, nanostructure, protein adsorption, Biological-systems, Biomaterials, Biomimetic hydroxyapatites, Biomimetics, Bone-formation, Calcium deficient hydroxyapatite, Calcium phosphate, Calcium phosphates, Cell proliferation, Crystal structure, Crystallinity, Crystals structures, Culture medium, Growth, High reactivity, Hydroxyapatite, In-vitro, Ion exchange, Ionic exchange, Molecular biology, Nanocrystalline apatites, Nanostructure, Nanostructures, Octacalcium phosphate, Physicochemical studies, Physiological fluids, Physiology, Protein adsorption, Proteins, Proteomic studies, Raman spectroscopy, Serum-albumin, Specific surface area
Villasante A, Godier-Furnemont A, Hernandez-Barranco A, Coq JL, Boskovic J, Peinado H, Mora J, Samitier J, Vunjak-Novakovic G, (2021). Horizontal transfer of the stemness-related markers EZH2 and GLI1 by neuroblastoma-derived extracellular vesicles in stromal cells Translational Research 237, 82-97
Neuroblastoma (NB) is the most common extracranial pediatric solid cancer originating from undifferentiated neural crest cells. NB cells express EZH2 and GLI1 genes that are known to maintain the undifferentiated phenotype of cancer stem cells (CSC) in NB. Recent studies suggest that tumor-derived extracellular vesicles (EVs) can regulate the transformation of surrounding cells into CSC by transferring tumor-specific molecules they contain. However, the horizontal transfer of EVs molecules in NB remains largely unknown. We report the analysis of NB-derived EVs in bioengineered models of NB that are based on a collagen 1/hyaluronic acid scaffold designed to mimic the native tumor niche. Using these models, we observed an enrichment of GLI1 and EZH2 mRNAs in NB-derived EVs. As a consequence of the uptake of NB-derived EVs, the host cells increased the expression levels of GLI1 and EZH2. These results suggest the alteration of the expression profile of stromal cells through an EV-based mechanism, and point the GLI1 and EZH2 mRNAs in the EV cargo as diagnostic biomarkers in NB.
Keywords: exosomes, genes, lines, maintenance, pathway, proliferation, rna, stemness, tumor, Cancer
Velasco-Mallorqui, F, Rodriguez-Comas, J, Ramon-Azcon, J, (2021). Cellulose-based scaffolds enhance pseudoislets formation and functionality Biofabrication 13,
In vitro research for the study of type 2 diabetes (T2D) is frequently limited by the availability of a functional model for islets of Langerhans. To overcome the limitations of obtaining pancreatic islets from different sources, such as animal models or human donors, immortalized cell lines as the insulin-producing INS1E beta-cells have appeared as a valid alternative to model insulin-related diseases. However, immortalized cell lines are mainly used in flat surfaces or monolayer distributions, not resembling the spheroid-like architecture of the pancreatic islets. To generate islet-like structures, the use of scaffolds appeared as a valid tool to promote cell aggregations. Traditionally-used hydrogel encapsulation methods do not accomplish all the requisites for pancreatic tissue engineering, as its poor nutrient and oxygen diffusion induces cell death. Here, we use cryogelation technology to develop a more resemblance scaffold with the mechanical and physical properties needed to engineer pancreatic tissue. This study shows that carboxymethyl cellulose (CMC) cryogels prompted cells to generate beta-cell clusters in comparison to gelatin-based scaffolds, that did not induce this cell organization. Moreover, the high porosity achieved with CMC cryogels allowed us to create specific range pseudoislets. Pseudoislets formed within CMC-scaffolds showed cell viability for up to 7 d and a better response to glucose over conventional monolayer cultures. Overall, our results demonstrate that CMC-scaffolds can be used to control the organization and function of insulin-producing beta-cells, representing a suitable technique to generate beta-cell clusters to study pancreatic islet function.
Keywords: biomaterial, cryogel, pancreatic islets, scaffold, tissue engineering, ?-cell, Architecture, Beta-cell, Beta-cell heterogeneity, Biomaterial, Carboxymethyl cellulose, Cell culture, Cell death, Cell engineering, Cell organization, Cells, Cellulose, Cryogel, Cryogels, Cytoarchitecture, Delivery, Encapsulation methods, Gelation, Gene-expression, Immortalized cells, Insulin, Insulin secretory responses, Islets of langerhans, Mechanical and physical properties, Monolayer culture, Monolayers, Pancreatic islets, Pancreatic tissue, Pancreatic-islets, Proliferation, Scaffold, Scaffolds, Scaffolds (biology), Size, Tissue, Tissue engineering
Olmo C, Franco L, Vidal A, Del Valle LJ, Puiggalí J, (2021). Ultrasound micromolding of porous polylactide/hydroxyapatite scaffolds Express Polymer Letters 15, 389-403
© BME-PT. Ultrasound micromolding (USM) preparation of hybrid scaffolds based on polylactide (PLA) and hydroxyapatite (HAp) particles has been evaluated. PLA was stable under the applied ultrasound source since a minimum degradation was detected. Porous materials were achieved using polyethylene glycol (PEG) and NaCl salts to the initial PLA and the subsequent leaching of the micromolded specimens. To avoid cavitation and decomposition problems during micromolding, it was necessary to use HAp free of typical synthesis impurities like carbonate and nitrate compounds. Compact PLA/HAp pieces allowed a maximum HAp load of 60 wt%, while porous specimens could be obtained with a maximum load of 38 wt%. Physical characterization of new scaffolds was performed by X-ray diffraction, spectroscopic and calorimetric techniques, stress-strain tests and contact angle measurements. Results indicated that a degree of porosity of 35% and relatively good mechanical properties could be achieved (i.e., 580 MPa, 4%, and 15.6 MPa for the Young modulus, elongation at break, and tensile strength, respectively). Scaffolds showed the positive effect of HAp and porosity on cell proliferation; this latter was 40% higher than that detected for non-porous PLA specimens.
Keywords: apatite, conformation, fabrication, hydroxyapatite, micropieces, polymers, porous scaffolds, proliferation, tissue, ultrasound micromolding, vibration, Composite scaffolds, Hydroxyapatite, Micropieces, Porous scaffolds, Processing technologies, Ultrasound micromolding
Puiggalí-Jou A, Ordoño J, del Valle LJ, Pérez-Amodio S, Engel E, Alemán C, (2021). Tuning multilayered polymeric self-standing films for controlled release of L-lactate by electrical stimulation Journal Of Controlled Release 330, 669-683
© 2020 Elsevier B.V. We examine different approaches for the controlled release of L-lactate, which is a signaling molecule that participates in tissue remodeling and regeneration, such as cardiac and muscle tissue. Robust, flexible, and self-supported 3-layers films made of two spin-coated poly(lactic acid) (PLA) layers separated by an electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) layer, are used as loading and delivery systems. Films with outer layers prepared using homochiral PLA and with nanoperforations of diameter 146 ± 70 experience more bulk erosion, which also contributes to the release of L-lactic acid, than those obtained using heterochiral PLA and with nanoperforations of diameter 66 ± 24. Moreover, the release of L-lactic acid as degradation product is accelerated by applying biphasic electrical pulses. The four approaches used for loading extra L-lactate in the 3-layered films were: incorporation of L-lactate at the intermediate PEDOT layer as primary dopant agent using (1) organic or (2) basic water solutions as reaction media; (3) substitution at the PEDOT layer of the ClO4− dopant by L-lactate using de-doping and re-doping processes; and (4) loading of L-lactate at the outer PLA layers during the spin-coating process. Electrical stimuli were applied considering biphasic voltage pulses and constant voltages (both negative and positive). Results indicate that the approach used to load the L-lactate has a very significant influence in the release regulation process, affecting the concentration of released L-lactate up to two orders of magnitude. Among the tested approaches, the one based on the utilization of the outer layers for loading, approach (4), can be proposed for situations requiring prolonged and sustained L-lactate release over time. The biocompatibility and suitability of the engineered films for cardiac tissue engineering has also been confirmed using cardiac cells.
Keywords: biphasic voltage pulse, cardiac tissue regeneration, cardiomyocytes proliferation, conducting polymer, nanoperforated films, sustained delivery, Biphasic voltage pulse, Cardiac tissue regeneration, Cardiomyocytes proliferation, Conducting polymer, Nanoperforated films, Sustained delivery
Castellanos, M. I., Mas-Moruno, C., Grau, A., Serra-Picamal, X., Trepat, X., Albericio, F., Joner, M., Gil, F. J., Ginebra, M. P., Manero, J. M., Pegueroles, M., (2017). Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation Applied Surface Science , 393, 82-92
Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.
Keywords: Cell adhesive peptides, CoCr alloy, Endothelialization, HUVEC proliferation, SMCs adhesion, Surface functionalization
Won, J. E., Mateos-Timoneda, M. A., Castaño, O., Planell, J. A., Seo, S. J., Lee, E. J., Han, C. M., Kim, H. W., (2015). Fibronectin immobilization on to robotic-dispensed nanobioactive glass/polycaprolactone scaffolds for bone tissue engineering Biotechnology Letters , 37, (4), 935-342
Bioactive nanocomposite scaffolds with cell-adhesive surface have excellent bone regeneration capacities. Fibronectin (FN)-immobilized nanobioactive glass (nBG)/polycaprolactone (PCL) (FN-nBG/PCL) scaffolds with an open pore architecture were generated by a robotic-dispensing technique. The surface immobilization level of FN was significantly higher on the nBG/PCL scaffolds than on the PCL scaffolds, mainly due to the incorporated nBG that provided hydrophilic chemical-linking sites. FN-nBG/PCL scaffolds significantly improved cell responses, including initial anchorage and subsequent cell proliferation. Although further in-depth studies on cell differentiation and the in vivo animal responses are required, bioactive nanocomposite scaffolds with cell-favoring surface are considered to provide promising three-dimensional substrate for bone regeneration.
Keywords: Bone scaffolds, Cell response, Fibronectin, Nanobioactive glass, Nanocomposites, Polycaprolactone, Bone, Cell proliferation, Cells, Cytology, Glass, Nanocomposites, Polycaprolactone, Robotics, Bone scaffolds, Bone tissue engineering, Cell response, Fibronectin, Fibronectin immobilizations, Nano bioactive glass, Nanocomposite scaffolds, Three-dimensional substrates, Scaffolds (biology)
Llorens, F., Carulla, P., Villa, A., Torres, J. M., Fortes, P., Ferrer, Isidro, Del Río, J. A., (2013). PrPC regulates epidermal growth factor receptor function and cell shape dynamics in Neuro2a cells Journal of Neurochemistry , 127, (1), 124-138
The prion protein (PrP) plays a key role in prion disease pathogenesis. Although the misfolded and pathologic variant of this protein (PrPSC) has been studied in depth, the physiological role of PrPC remains elusive and controversial. PrPC is a cell-surface glycoprotein involved in multiple cellular functions at the plasma membrane, where it interacts with a myriad of partners and regulates several intracellular signal transduction cascades. However, little is known about the gene expression changes modulated by PrPC in animals and in cellular models. In this article, we present PrPC-dependent gene expression signature in N2a cells and its implication in the most overrepresented functions: cell cycle, cell growth and proliferation, and maintenance of cell shape. PrPC over-expression enhances cell proliferation and cell cycle re-entrance after serum stimulation, while PrPC silencing slows down cell cycle progression. In addition, MAP kinase and protein kinase B (AKT) pathway activation are under the regulation of PrPC in asynchronous cells and following mitogenic stimulation. These effects are due in part to the modulation of epidermal growth factor receptor (EGFR) by PrPC in the plasma membrane, where the two proteins interact in a multimeric complex. We also describe how PrPC over-expression modulates filopodia formation by Rho GTPase regulation mainly in an AKT-Cdc42-N-WASP-dependent pathway.
Keywords: Cell signaling, Cellular prion protein, Filopodia, Gene expression, Microarray, Proliferation
Gustavsson, J., Ginebra, M. P., Planell, J., Engel, E., (2012). Osteoblast-like cellular response to dynamic changes in the ionic extracellular environment produced by calcium-deficient hydroxyapatite Journal of Materials Science-Materials in Medicine , 23, (10), 2509-2520
Solution-mediated reactions due to ionic substitutions are increasingly explored as a strategy to improve the biological performance of calcium phosphate-based materials. Yet, cellular response to well-defined dynamic changes of the ionic extracellular environment has so far not been carefully studied in a biomaterials context. In this work, we present kinetic data on how osteoblast-like SAOS-2 cellular activity and calcium-deficient hydroxyapatite (CDHA) influenced extracellular pH as well as extracellular concentrations of calcium and phosphate in standard in vitro conditions. Since cells were grown on membranes permeable to ions and proteins, they could share the same aqueous environment with CDHA, but still be physically separated from the material. In such culture conditions, it was observed that gradual material-induced adsorption of calcium and phosphate from the medium had only minor influence on cellular proliferation and alkaline phosphatase activity, but that competition for calcium and phosphate between cells and the biomaterial delayed and reduced significantly the cellular capacity to deposit calcium in the extracellular matrix. The presented work thus gives insights into how and to what extent solution-mediated reactions can influence cellular response, and this will be necessary to take into account when interpreting CDHA performance both in vitro and in vivo.
Keywords: Alkaline-phosphatase activity, Saos-2 cells, In-vitro, bone mineralization, Biological basis, Differentiation, Culture, Matrix, Proliferation, Topography
Trepat, X., Fredberg, J. J., (2011). Plithotaxis and emergent dynamics in collective cellular migration Trends in Cell Biology 21, (11), 638-646
For a monolayer sheet to migrate cohesively, it has long been suspected that each constituent cell must exert physical forces not only upon its extracellular matrix but also upon neighboring cells. The first comprehensive maps of these distinct force components reveal an unexpected physical picture. Rather than showing smooth and systematic variation within the monolayer, the distribution of physical forces is dominated by heterogeneity, both in space and in time, which emerges spontaneously, propagates over great distances, and cooperates over the span of many cell bodies. To explain the severe ruggedness of this force landscape and its role in collective cell guidance, the well known mechanisms of chemotaxis, durotaxis, haptotaxis are clearly insufficient. In a broad range of epithelial and endothelial cell sheets, collective cell migration is governed instead by a newly discovered emergent mechanism of innately collective cell guidance - plithotaxis.
Keywords: Positional information, Drosophila embryo, Sheet migration, Dpp gradient, Cells, Force, Morphogenesis, Transition, Identification, Proliferation
Byrne, Damien P., Lacroix, Damien, Prendergast, Patrick J., (2011). Simulation of fracture healing in the tibia: Mechanoregulation of cell activity using a lattice modeling approach Journal of Orthopaedic Research , 29, (10), 1496-1503
In this study, a three-dimensional (3D) computational simulation of bone regeneration was performed in a human tibia under realistic muscle loading. The simulation was achieved using a discrete lattice modeling approach combined with a mechanoregulation algorithm to describe the cellular processes involved in the healing process namely proliferation, migration, apoptosis, and differentiation of cells. The main phases of fracture healing were predicted by the simulation, including the bone resorption phase, and there was a qualitative agreement between the temporal changes in interfragmentary strain and bending stiffness by comparison to experimental data and clinical results. Bone healing was simulated beyond the reparative phase by modeling the transition of woven bone into lamellar bone. Because the simulation has been shown to work with realistic anatomical 3D geometry and muscle loading, it demonstrates the potential of simulation tools for patient-specific pre-operative treatment planning.
Keywords: Tissue differentiation, Computational analysis, Mechanical conditions, Bone regeneration, Weight-bearing, Proliferation, Osteoblast, Stiffness, Ingrowth, Scaffold
Madronal, Noelia, Lopez-Aracil, Cristina, Rangel, Alejandra, del Rio, Jose A., Delgado-Garcia, Jose M., Gruart, Agnes, (2010). Effects of Enriched Physical and Social Environments on Motor Performance, Associative Learning, and Hippocampal Neurogenesis in Mice PLoS ONE 5, (6), e11130
We have studied the motor abilities and associative learning capabilities of adult mice placed in different enriched environments. Three-month-old animals were maintained for a month alone (AL), alone in a physically enriched environment (PHY), and, finally, in groups in the absence (SO) or presence (SOPHY) of an enriched environment. The animals' capabilities were subsequently checked in the rotarod test, and for classical and instrumental learning. The PHY and SOPHY groups presented better performances in the rotarod test and in the acquisition of the instrumental learning task. In contrast, no significant differences between groups were observed for classical eyeblink conditioning. The four groups presented similar increases in the strength of field EPSPs (fEPSPs) evoked at the hippocampal CA3-CA1 synapse across classical conditioning sessions, with no significant differences between groups. These trained animals were pulse-injected with bromodeoxyuridine (BrdU) to determine hippocampal neurogenesis. No significant differences were found in the number of NeuN/BrdU double-labeled neurons. We repeated the same BrdU study in one-month-old mice raised for an additional month in the above-mentioned four different environments. These animals were not submitted to rotarod or conditioned tests. Non-trained PHY and SOPHY groups presented more neurogenesis than the other two groups. Thus, neurogenesis seems to be related to physical enrichment at early ages, but not to learning acquisition in adult mice.
Keywords: Long-term potentiation, Adult neurogenesis, Synaptic transmission, Cell proliferation, CA3-CA1 synapse, Granule cells
Nicolas, O., Gavin, R., Del Rio, J. A., (2009). New insights into cellular prion protein (PrPc) functions: The "ying and yang" of a relevant protein Brain Research Reviews , 61, (2), 170-184
The conversion of cellular prion protein (PrPc) a GPI-anchored protein, into a protease-K-resistant and infective form (generally termed PrPsc) is mainly responsible for Transmissible Spongiform Encephalopathies (TSEs), characterized by neuronal degeneration and progressive loss of basic brain functions. Although PrPc is expressed by a wide range of tissues throughout the body, the complete repertoire of its functions has not been fully deter-mined. Recent studies have confirmed its participation in basic physiological processes such as cell proliferation and the regulation of cellular homeostasis. Other studies indicate that PrPc interacts with several molecules to activate signaling cascades with a high number of cellular effects. To deter-mine PrPc functions, transgenic mouse models have been generated in the last decade. In particular, mice lacking specific domains of the PrPc protein have revealed the contribution of these domains to neurodegenerative processes. A dual role of PrPc has been shown, since most authors report protective roles for this protein while others describe pro-apoptotic functions. in this review, we summarize new findings on PrPc functions, especially those related to neural degeneration and cell signaling.
Keywords: Prion, Doppel, Shadoo, Cell death, Cell proliferation, Cell differentiation
Fernandez, Javier G., Mills, C. A., Samitier, J., (2009). Complex microstructured 3D surfaces using chitosan biopolymer Small 5, (5), 614-620
A technique for producing micrometer-scale structures over large, nonplanar chitosan surfaces is described. The technique makes use of the rheological characteristics (deformability) of the chitosan to create freestanding, three-dimensional scaffolds with controlled shapes, incorporating defined microtopography. The results of an investigation into the technical limits of molding different combinations of shapes and microtopographies are presented, highlighting the versatility of the technique when used irrespectively with inorganic or delicate organic moulds. The final, replicated scaffolds presented here are patterned with arrays of one-micrometer-tall microstructures over large areas. Structural integrity is characterized by the measurement of structural degradation. Human umbilical vein endothelial cells cultured on a tubular scaffold show that early cell growth is conditioned by the microtopography and indicate possible uses for the structures in biomedical applications. For those applications requiring improved chemical and mechanical resistance, the structures can be replicated in poly(dimethyl siloxane).
Keywords: Biocompatible Materials/ chemistry, Cell Adhesion, Cell Culture Techniques/ methods, Cell Proliferation, Cells, Cultured, Chitosan/ chemistry, Crystallization/methods, Endothelial Cells/ cytology/ physiology, Humans, Materials Testing, Nanostructures/ chemistry/ ultrastructure, Nanotechnology/methods, Particle Size, Surface Properties, Tissue Engineering/methods
Engel, E., Del Valle, S., Aparicio, C., Altankov, G., Asin, L., Planell, J. A., Ginebra, M. P., (2008). Discerning the role of topography and ion exchange in cell response of bioactive tissue engineering scaffolds Tissue Engineering Part A , 14, (8), 1341-1351
Surface topography is known to have an influence on osteoblast activity. However, in the case of bioactive materials, topographical changes can affect also ion exchange properties. This makes the problem more complex, since it is often difficult to separate the strictly topographical effects from the effects of ionic fluctuations in the medium. The scope of this paper is to analyze the simultaneous effect of topography and topography-mediated ion exchange on the initial cellular behavior of osteoblastic-like cells cultured on bioactive tissue engineering substrates. Two apatitic substrates with identical chemical composition but different micro/nanostructural features were obtained by low-temperature setting of a calcium phosphate cement. MG63 osteoblastic-like cells were cultured either in direct contact with the substrates or with their extracts. A strong and permanent decrease of calcium concentration in the culture medium, dependent on substrate topography, was detected. A major effect of the substrate microstructure on cell proliferation was observed, explained in part by the topography-mediated ion exchange, but not specifically by the ionic Ca(2+) fluctuations. Cell differentiation was strongly enhanced when cells were cultured on the finer substrate. This effect was not explained by the chemical modification of the medium, but rather suggested a strictly topographical effect.
Keywords: Alkaline Phosphatase/metabolism, Bone Cements/pharmacology, Calcium/metabolism, Calcium Phosphates/pharmacology, Cell Adhesion/drug effects, Cell Differentiation/drug effects, Cell Proliferation/drug effects, Cell Shape/drug effects, Cells, Cultured, Culture Media, Durapatite/pharmacology, Humans, Interferometry, Ion Exchange, Materials Testing, Osteoblasts/ cytology/drug effects/enzymology/ultrastructure, Phosphorus/metabolism, Powders, Tissue Engineering, Tissue Scaffolds
Roca-Cusachs, P., Alcaraz, J., Sunyer, R., Samitier, J., Farre, R., Navajas, D., (2008). Micropatterning of single endothelial cell shape reveals a tight coupling between nuclear volume in G1 and proliferation Biophysical Journal , 94, (12), 4984-4995
Shape-dependent local differentials in cell proliferation are considered to be a major driving mechanism of structuring processes in vivo, such as embryogenesis, wound healing, and angiogenesis. However, the specific biophysical signaling by which changes in cell shape contribute to cell cycle regulation remains poorly understood. Here, we describe our study of the roles of nuclear volume and cytoskeletal mechanics in mediating shape control of proliferation in single endothelial cells. Micropatterned adhesive islands were used to independently control cell spreading and elongation. We show that, irrespective of elongation, nuclear volume and apparent chromatin decondensation of cells in G1 systematically increased with cell spreading and highly correlated with DNA synthesis (percent of cells in the S phase). In contrast, cell elongation dramatically affected the organization of the actin cytoskeleton, markedly reduced both cytoskeletal stiffness (measured dorsally with atomic force microscopy) and contractility (measured ventrally with traction microscopy), and increased mechanical anisotropy, without affecting either DNA synthesis or nuclear volume. Our results reveal that the nuclear volume in G1 is predictive of the proliferative status of single endothelial cells within a population, whereas cell stiffness and contractility are not. These findings show that the effects of cell mechanics in shape control of proliferation are far more complex than a linear or straightforward relationship. Our data are consistent with a mechanism by which spreading of cells in G1 partially enhances proliferation by inducing nuclear swelling and decreasing chromatin condensation, thereby rendering DNA more accessible to the replication machinery.
Keywords: Cell Line, Cell Nucleus/ physiology, Cell Proliferation, Cell Size, Computer Simulation, Endothelial Cells/ cytology/ physiology, G1 Phase/ physiology, Humans, Mechanotransduction, Cellular/ physiology, Models, Biological, Statistics as Topic
Charles-Harris, M., Koch, M. A., Navarro, M., Lacroix, D., Engel, E., Planell, J. A., (2008). A PLA/calcium phosphate degradable composite material for bone tissue engineering: an in vitro study Journal of Materials Science-Materials in Medicine , 19, (4), 1503-1513
Biodegradable polymers reinforced with an inorganic phase such as calcium phosphate glasses may be a promising approach to fulfil the challenging requirements presented by 3D porous scaffolds for tissue engineering. Scaffolds' success depends mainly on their biological behaviour. This work is aimed to the in vitro study of polylactic acid (PLA)/CaP glass 3D porous constructs for bone regeneration. The scaffolds were elaborated using two different techniques, namely solvent-casting and phase-separation. The effect of scaffolds' micro and macrostructure on the biological response of these scaffolds was assayed. Cell proliferation, differentiation and morphology within the scaffolds were studied. Furthermore, polymer/glass scaffolds were seeded under dynamic conditions in a custom-made perfusion bioreactor. Results indicate that the final architecture of the solvent-cast or phase separated scaffolds have a significant effect on cells' behaviour. Solvent-cast scaffolds seem to be the best candidates for bone tissue engineering. Besides, dynamic seeding yielded a higher seeding efficiency in comparison with the static method.
Keywords: Biocompatible Materials/ chemistry, Bone and Bones/ metabolism, Calcium Phosphates/ chemistry, Cell Differentiation, Cell Proliferation, Humans, Lactic Acid/ chemistry, Microscopy, Confocal, Microscopy, Electron, Scanning, Osteoblasts/metabolism, Permeability, Polymers/ chemistry, Porosity, Solvents/chemistry, Tissue Engineering/ methods
Gustavsson, J., Altankov, G., Errachid, A., Samitier, J., Planell, J. A., Engel, E., (2008). Surface modifications of silicon nitride for cellular biosensor applications Journal of Materials Science-Materials in Medicine , 19, (4), 1839-1850
Thin films of silicon nitride (Si3N4) can be used in several kinds of micro-sized biosensors as a material to monitor fine environmental changes related to the process of bone formation in vitro. We found however that Si3N4 does not provide optimal conditions for osseointegration as osteoblast-like MG-63 cells tend to detach from the surface when cultured over confluence. Therefore Si3N4 was modified with self-assembled monolayers bearing functional end groups of primary amine (NH2) and carboxyl (COOH) respectively. Both these modifications enhanced the interaction with confluent cell layers and thus improve osseointegration over Si3N4. Furthermore it was observed that the NH2 functionality increased the adsorption of fibronectin (FN), promoted cell proliferation, but delayed the differentiation. We also studied the fate of pre-adsorbed and secreted FN from cells to learn more about the impact of above functionalities for the development of provisional extracellular matrix on materials interface. Taken together our data supports that Si3N4 has low tissue integration but good cellular biocompatibility and thus is appropriate in cellular biosensor applications such as the ion-sensitive field effect transistor (ISFET). COOH and NH2 chemistries generally improve the interfacial tissue interaction with the sensor and they are therefore suitable substrates for monitoring cellular growth or matrix deposition using electrical impedance spectroscopy.
Keywords: Adsorption, Amines/chemistry, Biocompatible Materials/ chemistry, Biosensing Techniques, Cell Differentiation, Cell Line, Cell Proliferation, Electric Impedance, Extracellular Matrix/metabolism, Fibronectins/chemistry, Humans, Materials Testing, Osteoblasts/ cytology, Silicon Compounds/ chemistry, Surface Properties