Changes in human mesenchymal stem cell behaviors on dendrimer-immobilized surfaces due to mediation of fibronectin adsorption and assembly.

Dynamic changes of morphologies in human mesenchymal stem cells (hMSCs) were investigated on dendrimer surfaces with different capacities for fibronectin adsorption by changing the polymeric generation numbers of first (G1), third (G3), and fifth (G5) generations. The amount of adsorbed fibronectin on dendrimer surfaces increased with the generation number. Time-lapse observations revealed that cells on the G1 surface maintained their shape with formation of fibronectin fibrils in the bodies, introducing to the stabilization of focal adhesion with enriched stress fibers. Cells on the G3 surface showed partial contraction with degradation of fibril structures in the trailing edge. Cells on the G5 surface changed the shape by active extension and strong contracting without stabilization of focal adhesion through the formation of fibronectin aggregates and immature stress fibers. In addition, the paxillin which is a focal adhesion protein at lamellipodia was phosphorylated, leading to active lamellipodium protrusions. These results indicate that the amount and structure of fibronectin affects dynamic hMSC behaviors through the formation of cytoskeletons and focal adhesions.