66 research outputs found
Computational model combined with in vitro experiments to analyse mechanotransduction during mesenchymal stem cell adhesion.
The shape that stem cells reach at the end of adhesion
process influences their differentiation. Rearrangement of
cytoskeleton and modification of intracellular tension may
activate mechanotransduction pathways controlling cell
commitment. In the present study, the mechanical signals
involved in cell adhesion were computed in in vitro stem
cells of different shapes using a single cell model, the
so-called Cytoskeleton Divided Medium (CDM) model.
In the CDM model, the filamentous cytoskeleton and
nucleoskeleton networks were represented as a mechanical
system of multiple tensile and compressive interactions
between the nodes of a divided medium. The results showed
that intracellular tonus, focal adhesion forces as well as
nuclear deformation increased with cell spreading. The
cell model was also implemented to simulate the adhesion
process of a cell that spreads on protein-coated substrate by
emitting filopodia and creating new distant focal adhesion
points. As a result, the cell model predicted cytoskeleton
reorganisation and reinforcement during cell spreading.
The present model quantitatively computed the evolution
of certain elements of mechanotransduction and may be a
powerful tool for understanding cell mechanobiology and
designing biomaterials with specific surface properties to
control cell adhesion and differentiation
Cell interaction with nanopatterned surface of implants
International audienceMetals such as titanium and alloys are commonly used for manufacturing orthopedic and dental implants because their surface properties provide a biocompatible interface with peri-implant tissues. Strategies for modifying the nature of this interface frequently involve changes to the surface at the nanometer level, thereby affecting protein adsorption, cell-substrate interactions and tissue development. Recent methods to control these biological interactions at the nanometer scale on the surface of implants are reviewed. Future strategies to control peri-implant tissue healing are also discussed
Early adhesion of human mesenchymal stem cells on TiO2 surfaces studied by single-cell force spectroscopy measurements
International audienceUnderstanding the interactions involved in the adhesion of living cells on surfaces is essential in the field of tissue engineering and biomaterials. In this study, we investigate the early adhesion of living human mesenchymal stem cells (hMSCs) on flat titanium dioxide (TiO2) and on nanoporous crystallized TiO2 surfaces with the use of atomic force microscopy-based single-cell force spectroscopy measurements. The choice of the substrate surfaces was motivated by the fact that implants widely used in orthopaedic and dental surgery are made in Ti and its alloys. Nanoporous TiO2 surfaces were produced by anodization of Ti surfaces. In a typical force spectroscopy experiment, one living hMSC, immobilized onto a fibronectine-functionalized tipless lever is brought in contact with the surface of interest for 30 s before being detached while recording force-distance curves. Adhesion of hMSCs on nanoporous TiO2 substrates having inner pore diameter of 45 nm was lower by approximately 25% than on TiO2 flat surfaces. Force-distance curves exhibited also force steps that can be related to the pulling of membrane tethers from the cell membrane. The mean force step was equal to 35 pN for a given speed independently of the substrate surface probed. The number of tethers observed was substrate dependent. Our results suggest that the strength of the initial adhesion between hMSCs and flat or nanoporous TiO2 surfaces is driven by the adsorption of proteins deposited from serum in the culture media
Lateral root development in Arabidopsis : fifty shades of auxin
The developmental plasticity of the root system represents a key adaptive trait enabling plants to cope with abiotic stresses such as drought and is therefore important in the current context of global changes. Root branching through lateral root formation is an important component of the adaptability of the root system to its environment. Our understanding of the mechanisms controlling lateral root development has progressed tremendously in recent years through research in the model plant Arabidopsis thaliana (Arabidopsis). These studies have revealed that the phytohormone auxin acts as a common integrator to many endogenous and environmental signals regulating lateral root formation. Here, we review what has been learnt about the myriad roles of auxin during lateral root formation in Arabidopsis
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