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

Abstract

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.

Migration-driven aggregate behaviors of human mesenchymal stem cells on a dendrimer-immobilized surface direct differentiation toward a cardiomyogenic fate commitment

“…These mechanisms are dependent on the synthesis and degradation of the extracellular matrix (7). Our previous reports indicated that the dynamic cellular behaviors on the G5 surface were changed due to the adsorption and assembly of fibronectin (16). On the G5 surface, adsorption of fibronectin induces the extension of cells, and that fibronectin assembly affected by matrix metalloproteinases plays important roles in the stabilization of focal adhesions associated with cytoskeletal formations.…”

“…On the G5 surface, adsorption of fibronectin induces the extension of cells, and that fibronectin assembly affected by matrix metalloproteinases plays important roles in the stabilization of focal adhesions associated with cytoskeletal formations. Because paxillin phosphorylation enhances the turnover of focal adhesion with lamellipodium protrusion, focal adhesion turnover is thought to be promoted by active cell migration through paxillin phosphorylation (16). In addition, cadherins at cellecell adhesion sites may show responses to mechanical signals similar to paxillin at focal adhesions, which is supported by the similarity of interactions in cellecell and cell-substrate adhesion structures with the actin cytoskeleton (16,18).…”

“…Because paxillin phosphorylation enhances the turnover of focal adhesion with lamellipodium protrusion, focal adhesion turnover is thought to be promoted by active cell migration through paxillin phosphorylation (16). In addition, cadherins at cellecell adhesion sites may show responses to mechanical signals similar to paxillin at focal adhesions, which is supported by the similarity of interactions in cellecell and cell-substrate adhesion structures with the actin cytoskeleton (16,18). These results suggest that extracellular signals can be locally integrated by the endogenous Rho family GTPases to coordinate the dynamic cytoskeletal rearrangements and cellecell communication necessary for directing stem cell fates.…”

“…0000183402; Lonza, Walkersville, MD, USA) were used in the following experiments. Routine subcultures were conducted as described previously (16). For all experiments, hMSCs were harvested in Dulbecco's modified Eagle's medium (DMEM; SigmaeAldrich, St. Louis, MO, USA) supplemented with 10% fetal bovine serum and antibiotics (Life Technologies, Carlsbad, CA, USA).…”

“…The fifth-generation dendrimer surface (G5 surface) was prepared on the tissue-cultured polystyrene (PS) surface of a square 8-well plate (Nunc, Roskilde, Denmark) and 35 mm culture dish (Ibidi GmbH, Martinsried, Germany) as described previously (16). Briefly, hydroxyl groups on the starting materials were displayed by addition of potassium tert-butoxide.…”