11 - Summary

Summary

The primary objective of this book was to bring together various points of view regarding cell mechanics, contrasting and comparing these diverse perspectives. This final short chapter summarizes the various models discussed in an attempt to identify commonalities as well as any irreconcilable differences.

A wide range of computational and phenomenological models were described for cytoskeletal mechanics, ranging from continuum models for cell deformation and mechanical stress to actin-filament-based models for cell motility. A concise review was also presented (Chapter 2) of numerous experimental techniques, which typically aim to quantify cytoskeletal mechanics by exerting some sort of perturbation on the cell and examining its static and dynamic responses. These experimental observations along with computational approaches have given rise to several often contradictory theories for describing the mechanics of living cells, modeling the cytoskeleton as a simple mechanical elastic, viscoelastic, or poroviscoelastic continuum, a porous gel, a soft glassy material, or a tensegrity (tension integrity) network incorporating discrete structural elements that bear compression.

With such remarkable disparity among these models, largely due to the diversity of scales and biomechanical issues of interest, it may appear to the uninitiated that various authors are describing entirely different cells. Yet depending on the test conditions or length scales of interest, identical cells may be viewed so differently as either a continuum or as a discrete collection of structural elements.

Experimental data are accumulating, and promising methods have been proposed to describe cell rheology. While there has been some convergence toward a range of values for the cytoskeletal shear modulus, the range remains large, spanning several orders of magnitude.