Comparative effects of N-cadherin protein and peptide fragments on mesenchymal stem cell mechanotransduction and paracrine function.

The recent interest in exploiting cadherin-derived fragments to mimic intercellular adhesion in engineered hybrid biomaterials raises questions about which cadherin constructs effectively mimic cadherin interactions. This study compared the biophysical properties of and signaling initiated by three different, immobilized N-cadherin-derived fragments, in order to identify a minimal construct that mimics intercellular adhesion in biomaterials. Specifically, we compared: i) the full N-cadherin extracellular region with all five ectodomains (EC1-5), ii) the first two ectodomains (EC1-2) of N-cadherin, and iii) a peptide containing the histidine-alanine-valine-aspartic acid-valine (HAVDI) sequence in the first extracellular domain. Comparisons of the binding kinetics and affinities between each of these ligands and N-cadherin expressed on mesenchymal stem cells (MSCs) revealed quantitative differences. Nevertheless, MSCs exhibited similar, rigidity-dependent spreading and traction forces when cultured on gels displaying any of these N-cadherin ligands. There were, however, differences in cell signaling and secretory activities. MSCs cultured on the full N-cadherin extracellular domain (EC1-5) exhibited stiffness-dependent changes in nuclear YAP/TAZ localization and significantly higher secretion of vascular endothelial growth factor and insulin growth factor 1, compared to cells cultured on hydrogels displaying either EC1-2 or the HAVDI peptide. The increased paracrine secretion also enhanced myogenic differentiation. These findings reveal functional differences between N-cadherin derived ligands important for the design of biomaterials that mimic intercellular adhesion.