Substrate adhesion determines migration during mesenchymal cell condensation in chondrogenesis

Effective cartilage development relies on the successful formation of mesenchymal cell condensates. Mesenchymal condensation is a prevalent morphogenetic transition, which involves the upregulation of the adhesive extracellular glycoprotein fibronectin (FN). During condensation, there is an active directional migration of cells from the surrounding loose mesenchyme towards regions of increasing matrix adherence (the condensation centers). In this study, we live imaged the first 40 h of mesenchymal condensation during chondrogenesis on nanopatterns of the cell-adhesive peptide arginine-glycine-aspartic acid (RGD), present in FN. Results show cell-substrate adhesions modulate both single-cell and collective cell migration during mesenchymal condensation. Single cell tracking analysis showed that substrate adhesion determines the migration mode, protrusion formation and the directionality of the cell movement. Cells on the more adhesive nanopatterns presented traits among amoeboid and mesenchymal modes of migration facilitating a more directional movement and reducing contact inhibition of locomotion (CIL), which allows merging and condensation. Inhibition experiments demonstrated that neural cadherin (N-Cad) is required in cell-cell interactions, enabling cells to coordinate their movement and directionality in a multicellular environment and to maintain the group cohesiveness during migration. Altogether, this contributes to create a sufficiently dynamic scenario, in which there is a balance between cell-substrate and cell-cell adhesions for condensates to grow. Our results provide a framework for the regulation of single and collective cell migration during mesenchymal condensation, through nanoscale cell-substrate adherence. Summary statementThe fine tuning of substrate adherence through nanopatterning allows control of mesenchymal cell migration and determines condensation during chondrogenesis in vitro.