Adhesion and friction contributions to cell motility

One challenge in biotribology is a complete explanation of cell motility. As the basic unit of life, cells are complex biological systems. Cells must express genetic information to perform their specialized functions: synthesize, modify, sort, store and transport biomolecule, covert different forms of energy, transduce signals, maintain internal structures and respond to external environments. All of these processes involve mechanical, chemical and physical processes. Mechanical forces play a fundamental role in cell migration, where contractile forces are generated within the cell and pull the cell body forward. On the other side, mechanical forces and deformations induce biological response in cells, and many normal and diseased conditions of cells are dependent upon or regulated by their mechanical environment. The effects of applied forces depend on the type of cells and how the forces are applied on, transmitted into, and distributed within cells. Traction forces exerted by cells on substrates can now be determined with a good degree of accuracy, but the intimate relation between cell shape and traction mechanics requires further qualitative investigation. In this chapter, we overview measurements strategies and the models for quantifying adhesion forces and friction developed during cell-cell and cell-substrate interaction during migration.