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 (F_ad) 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 F_ad through regulating cell adhesion and force balance between the cell traction force and F_ad. Furthermore, protein utilization has an F_ad-dependent temporal sequence. On low F_ad surface, FN endocytosis might happen prior to FN desorption and aggregation. This work confirms the importance of F_ad 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.