Substrate Effects on the Intrinsic Mechanical Properties of Individual Cells

Cells interact with specific molecular components of the extracellular matrix via cell surface receptors [1]. The principal cell surface receptors that mediate cell-extracellular matrix interactions are termed integrins [2, 3]. Integrins are transmembrane receptors that interact with several intracellular proteins, including elements of the cytoskeleton by cytoplasmic domains. Therefore, integrins serve as a molecular linkage between the extracellular matrix and the cytoskeleton. Some investigators have suggested that many of these vital cellular activities are regulated, at least in part, by intercellular and intracellular forces that are generated by a continuous molecular connection that includes components of the extracellular matrix, integrins, and cytoskeletal elements (i.e., f-actin, microtubules). It is believed that individual cells “sense” and generate forces transmitted through the extracellular environment by these intricate linkages [4]. Furthermore, this linkage, referred to as the “extended cytoskeleton,” could provide a mechanical signaling mechanism that may underlie many vital cellular activities, including gene expression. It is apparent that the physical properties of a cell may also be affected by this mechanism. Thus, cells grown on different extracellular matrix substrates should be expected to vary their cytoskeletal architecture and have concomitant changes in their biomechanical properties. The objectives of this study were 1) to obtain the intrinsic material properties of the individual cell as a function of the type of substrate matrix and therefore, 2) to investigate fundamental aspects of the response mechanism of individual cells to alterations in their biophysical environment.