Model sinusoidal surfaces for characterizing the influence of topographically-induced deformation on eucaryotic cells – Sinus Surf

By duplicate electrochemical process, we create a sinusoidal surface of 2D and 3D. To set the parameters (number 17), a 3D boundary element simulation allows us to determine the optimum conditions for the amplitude and frequency of the desired surface.

Simulations are made with a predictive model of a cell adhesion on an insulated box with a fixed density functions added (100 microns width, height 12 .mu.m) bump. The cell sends arms in all directions with focal points at the end. The kernel got when the cell extends from due nucléosquelette intermediate filaments and surrounding the core. Development of a biomimetic from standard image model is made. It calculates the forces on the images from the focal adhesions. It tries to add the compressive forces associated with microtubules, in the cytoplasm. The ultimate goal is to optimize the structure of the cell.
However we need static image if possible actin filaments and microtubules intermédiaires.YAP / TAZ markings can be used on fixed cells to see those who were under stress.
It has been shown that by K. Anseth showed a kind of mechanical memory cells. The stem cells were cultured on a long time a rigid substrate lose their ability to respond to the rigidity of the substrate. The LBTO He worked on the vinculin Tensor (available in Addgen bank) to visualize FRET focal points. Attempts to identify clones of cells that express the most. For now, it is only transient transfection. We use replication PDMS electro-eroded surfaces and sinus area. It was tested by pre-coating the surfaces of the silane or not. We showed (publication accepted) that nanoscale defects are replicated by PDMS. When x = y for the nanometric defects, replication is easy, by cons when x y >>>, replication becomes less easy. Optimal treatment of PDMS will be published.

* Final creation of sinusoidal surfaces
* Monitoring freight accession
* DEM modeling of adhesion to sinusoidal area
* Study residual stresses

Patent pending deposits
3 publications accepted

Historically the research developed for understanding how cells and tissue respond to surface topography has been done with the aim to optimize implant surface performance. For several years, we and others have developed research to understand the mechanisms underlying the human bone cell response to materials used in orthopaedics and dental surgery for bone replacement. In several studies, we have demonstrated that the long-term adhesion of primary human bone cells was statistically better correlated with parameters describing organization of topography than with other parameters. This project is a basic research project aiming to elucidate the mechanisms underlying the cell deformation induced by isotropic topography, and notably the intracellular mechano-transduction mechanisms, thanks to the association of experimental and modelling approaches. More specifically, we will focus our attention on peak-and valleys topographies that are the surface morphologies mostly met by cells in vivo contrary to surfaces with geometrical and anisotropic morphologies that have been studied until now in the field. With this objective we will notably develop sinusoidal surfaces presenting peak-and-valleys at the cellular scale. On these sinusoidal and on control surfaces, we will perform original live imaging to visualize and quantify deformation of cytoskeleton and cell membrane, focal adhesion formation and RhoGTPase signalling . Moreover, an original mechanical model based on tensegrity and divided medium mechanics will be adapted to identify the intracellular tensions as well as nucleus deformation on these sinusoidal surface morphologies. Our objective is also to develop new sinusoidal standards with different amplitude and frequencies usable in roughness measurements in biomaterials field but also in other fields not directly related to the project. We propose to fabricate replicas of these surfaces in order to obtain an unlimited number of samples. Then we will develop dynamics studies of intracellular organelles deformation by live imaging under a confocal microscope specifically adapted for cell imaging on materials. This project will bring new input on mechanical intracellular mechanisms underlying the cell response to topography thanks to the association of live imaging approaches and 3D reconstruction of cells and quantification of activities of molecules involved in signal mechanotransduction. Thus, at the end of this project, we will possess a library of sinusoidal model surfaces suitable for replication. This perfectly new library could be reused for future cell-surface interaction studies but also in other fields (ex. fluid mechanics, wear, adhesion, etc.). On a basic point of view, we will have developed a mechanical model of cytoskeleton based on tensegrity and divided medium mechanics. The integration in this model of actin fiber network reconstructed in 3D from images of stained CSK in cells cultured on sinusoidal surfaces will make it a perfectly original model able to manage the cellular deformation on textured surfaces. Such model should have a lot of application for predicting cell deformation on a large variety of surfaces from model surfaces with anisotropic distribution of geometrical motifs to real implant surface presenting isotropic random topography.