Boundary Stiffness Regulates Fibroblast Behavior in Collagen Gels

Recent studies utilizing compliant culture substrates clearly demonstrate that many cell behaviors such as migration and contraction are strongly influenced by the stiffness of the local environment. The goal of this work was to develop a method for studying stiffness-dependent biology within 3D cell-populated gels without altering the biochemical environment of the gel. A device was developed utilizing compliant anchors to tune the boundary stiffness of suspended collagen gels. Human fibroblasts compacted the gels to a greater extent as the stiffness of the anchors was decreased. Further, the force generated by the cells increased with increased boundary stiffness, and the response of the cells to TGF-β1 was accentuated as the stiffness increased. This new method represents a promising tool for the controlled study of stiffness-dependent biology within tissuelike 3D environments.