Cell behaviour on micropatterned substrata: limits of extracellular matrix geometry for spreading and adhesion

Abstract

Cell adhesion, spreading and migration require the dynamic formation and dispersal of contacts with the extracellular matrix (ECM). In vivo, the number, availability and distribution of ECM binding sites dictate the shape of a cell and determine its mobility. To analyse the geometrical limits of ECM binding sites required for cell attachment and spreading, we used microcontact printing to produce regular patterns of ECM protein dots of defined size separated by nonadhesive regions. Cells cultured on these substrata adhere to and spread on ECM regions as small as 0.1 microm2, when spacing between dots is less than 5 microm. Spacing of 5-25 microm induces a cell to adapt its shape to the ECM pattern. The ability to spread and migrate on dots > or =1 microm2 ceases when the dot separation is > or =30 microm. The extent of cell spreading is directly correlated to the total substratum coverage with ECM-proteins, but irrespective of the geometrical pattern. An optimal spreading extent is reached at a surface coating above 15%. Knowledge of these geometrical limits is essential for an understanding of cell adhesion and migration, and for the design of artificial surfaces that optimally interact with cells in a living tissue

Band-like Stress Fiber Propagation in a Continuum and Implications for Myosin Contractile Stresses

“…On the other hand, actin-stained images of cells contracting under micro-patterned constraints or micro-needles placed at the corners of square and triangular geometries show distinct actin bundles or stress fibers forming at the edges of the geometry instead of diagonal. 39,51,74 …”

“…It can be argued that the actin staining along the edges of contracting cells 39,51,74 is due to the cortical actin network and not stress fibers. However, the existence of edge or peripheral stress fibers in fibroblasts on rigid surfaces have been documented.…”

“…18 Experimental observations indicate otherwise: they show the stress fibers forming along the edges in cells under comparable constraints. 39,51,74 The central focus of this paper is to explore, from a continuum mechanics viewpoint, the nature of cytoskeletal actin-myosin interaction and myosin contractility that could lead to band-like stress fiber propagations in cells. We show that the description of myosin contractility in Deshpande et al 18,19 omits a component of the myosin contractile force that is lateral or perpendicular to the direction of cytoskeletal resistance.…”

Cellular and multicellular form and function☆

“…For example, it has been shown that when cells are organized into square shapes with asymmetric adhesive patterns, cells polarize their mitotic axis in a specific direction based on the matrix pattern [21], suggesting that spindle orientation is largely dependent on spatial distribution of ECM ( Figure 3B). Using subcellular, adhesion-sized ECM islands, investigators have also revealed that controlling adhesion size, shape and density can itself feed back to control the degree of cell spreading and shape ( Figure 3C) [22]. Thus there are multiple scales at which one can use patterning to control cell function.…”

Two-photon fluorescent microlithography for live-cell imaging

“…Custom protein distributions created by microcontact printing (lCP) (Chen et al, 1997;Singhvi et al, 1994) have been shown to be useful for studying the mechanisms of cell signaling, adhesion, migration, and neurite outgrowth (Lehnert et al, 2004;Thomas et al, 2002). In lCP, these stamps are first ''inked'' with a solution of molecules (often proteins or thiols), and then brought into contact with a substrate.…”