Figure 1.

The “Triangle” of material/surface interface. The “triangle” of materials refers to variations in chemistry, stiffness, and nanotopography to control the interactions with MSC focal adhesions. The three cartoon panels show MSC adhesion to chemical, stiffness, and topographically modified surfaces and how this influences stem cell tension and signaling and, hence, subsequent differentiation and phenotype (as will be discussed). The cells are shown to extend filopodia to “find” adhesion ligands (shown in red). Binding of the cell through focal adhesions to these ligands creates tension and activates signaling. Chemical functionality can be used to fabricate areas of high adhesion (red) or low adhesion (capped in green) for the cells to respond to (the cell is shown in a 3D scaffold). Stiffness will affect the cells ability to produce tension through focal adhesions formation (the cell is shown on a planar surface). Topography will present the adhesion ligands to the cells in either a favorable or unfavorable manner, again affecting adhesion and subsequent tension and signaling (the cell is shown on a 2D surface).