Analysis of the Active Response of Cells to Cyclic Loading Using a Modified AFM System

Dynamic mechanical loading is essential for cell function and tissue maintenance. In an effort to characterize the response of cells to cyclic deformation several in vitro studies have relied on the testing of large populations of cells seeded on 2D substrates or in 3D scaffolds and gels. However, such studies do not allow for the measurement of forces actively generated at a single cell level. In the present study deformation controlled cyclic loading experiments are performed on single osteoblasts at the whole cell level using a modified AFM system ^[1,2]. In addition to untreated cells, experiments are also performed on passive cells in which the actin cytoskeleton has been disrupted. A computational analysis of experimentally measured single cell forces reveals that passive cell behaviour is characterized by a non-linear visco-hyperelastic formulation and active forces generated by the actin cytoskeleton are accurately predicted by the a Hill-type contractility framework with tension dependent remodeling ^[3,4].