Adsorption Force of Fibronectin Regulates Protein Reorganization, Desorption, and Endocytosis

Protein adsorption on biomaterials occurs before cell adhesion. To adapt the properties of biomaterials, adhered cells may utilize and modify adsorbed proteins for survival and function. In this process, the protein–material interfacial force (Fad) is supposed to play vital roles, which, however, has received little attention. Here, we found that rat mesenchymal stem cells (rMSCs) can utilize the adsorbed fibronectin (FN) via reorganization, desorption, or endocytosis, and these utilization processes are regulated by Fad through regulating cell adhesion and force balance between the cell traction force and Fad. Furthermore, protein utilization has an Fad-dependent temporal sequence. On low Fad surface, FN endocytosis might happen prior to FN desorption and aggregation. This work confirms the importance of Fad in protein utilization and provides new insight into the mechanism by which cells process their surrounding ECM proteins, which may help to guide the design of better biomaterials.