A Novel Cell Traction Force Microscopy to Study Multi-Cellular System
Figure 10
Evidence of cell-cell compression in monkey kidney fibroblast (MKF) cluster.
(a) Several MKF cell clusters on 1 kPa PA gel. (b)-(c) The displacement and traction field produced by the clusters on the top surface of the substrate. The traction by the small clusters is negligible compared to those generated by the larger ones. Dashed lines in orange outline the cluster boundaries. (d) Nodal forces computed for the largest cluster. The finite element grid size is about 5 µm. There are regions in the cluster, shown by dashed lines, where repulsive forces appear on the substrate, i.e., cells “push” against each other. (e) To explain the cell-cell compression, a free body diagram is shown to reveal the intercellular force and cell-substrate traction force of 2 neighboring cells on the substrate. As the substrate is soft, the cells have less likelihood of spreading or wetting the substrate, but can adhere to the substrate due to the fibronectin functionalization. As cell proliferation and growth occur within the cluster, the cells push against their neighbors, generating an outward force on the substrate. Scale bar: 50 µm.