Biophysical Society Thematic Meeting - November 16-20, 2015

Biophysics in the Understanding, Diagnosis, and Treatment of Infectious Diseases Poster Abstracts

1-POS Board 1 Computational Simulation of Mechanical Interactions between a Cell and its Environment Considering Focal Adhesions and Substrate Stiffness Tamer Abdalrahman 1 , Laura Dubuis 1,2 , Neil Davies 2 , Jason Green 2 , Thomas Franz 1 . 1 Division of Biomedical Engineering, University of Cape Town, Observatory, Western Cape, South Africa, 2 Cardiovascular Research Unit, University of Cape Town, Observatory, Western Cape, South Africa. Introduction Cell and viral mechanics including cell-environment, cell-cell and cell-virion interactions may play important roles in aetiology of infectious diseases. Exploring these interactions experimentally is often challenging, and computational modelling offers a complementary approach of inquiry. Methods The three-dimensional geometry of a fibroblast, distinguishing cytosol and nucleus, was reconstructed from confocal micrographs (ScanIP, Simpleware Ltd, Exeter, UK) of a cell cultured two-dimensionally and stained with phalloidin (for actin fibres) and Hoechst (for nucleus). The geometry was imported in ABAQUS 6.12 (Dassault Systèmes, Providence, USA) and complemented with a 0.01 μm thick membrane enveloping the cytosol and a flat substrate (thickness: 10 μm). Focal adhesions (FA) were represented with estimated sizes and locations using cohesive elements. Mechanical properties of the cell components from literature were used, and the elastic modulus of the substrate was varied (E Sub = 0.01, 0.14, 1, and 10 MPa). The substrate was stretched to λ = 1.1 (equivalent to a strain of 9.5e -2 ) and the resulting deformation of the cell was assessed for different substrate moduli. Results The largest maximum principal strain predicted for E Sub = 0.01, 0.14, 1, and 10 MPa, respectively, was 4.58e -4 , 5.27e -4 , 5.33e -4 and 5.34e -4 in the membrane, 1.18e -3 , 1.33e -3 , 1.34e - 3 and 1.34e -3 in the cytosol, 6.88e -6 , 8.17e -6 , 8.27e -6 and 8.29e -6 in the nucleus, and 1.87, 1.96, 1.97 and 1.97 in the FA. Discussion The maximum FA strains are likely to be overestimated due to absence of a detachment criterion in the FA formulation. Nevertheless, the results indicate increased cell deformation with increased substrate modulus for a simple case and present a point of departure for the advancement of the models and methods towards the assessment of more complex in cell and virion mechanics.

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