ANALYSIS OF MECHANICAL RESPONSES IN CELLS USING ATOMIC FORCE MICROSCOPY

Guillaume Charras and Michael Horton

Department of Medicine, University College London, London WC1E 6JJ, UK

Bone adapts its structure to its mechanical usage. The detection of the strain applied to the skeleton is carried out by cells of the osteoblast lineage which lie on, or within, bone. Atomic Force Microscopy (AFM) was used to examine cellular responses following application of forces to cells (an increase in intracellular calcium concentration is one of the earliest events in the detection of mechanical stimuli by cells), as well as to determine their material properties and strains. Forces were applied using a ThermoMicroscopes Explorer AFM and cantilever tips modified by the addition of a glass sphere of known size; calcium levels monitored with the calcium sensitive dye, Fluo 3, via an integrated Bio-Rad Radiance 2000 confocal microscope. The material properties of the cells were calculated and the strains applied derived post hoc. The strain dose response, and the effect of regulators of intracellular signal transduction and modification of the cell cytoskeleton structure upon cellular reactions were examined. Our data show that AFM can be used to examine the behaviour of osteoblasts in response to strain, a process of key import for our understanding of the regulation of adaptation of the skeleton to mechanical forces.