title: Controlling integrin specificity and stem cell differentiation in 2D and 3D environments through regulation of fibronectin domain stability.
abstract: The extracellular matrix (ECM) exerts powerful control over many cellular phenomena, including stem cell differentiation. As such, design and modulation of ECM analogs to ligate specific integrin is a promising approach to control cellular processes in vitro and in vivo for regenerative medicine strategies. Although fibronectin (FN), a crucial ECM protein in tissue development and repair, and its RGD peptide are widely used for cell adhesion, the promiscuity with which they engage integrins leads to difficulty in control of receptor-specific interactions. Recent simulations of force-mediated unfolding of FN domains and sequences analysis of human versus mouse FN suggest that the structural stability of the FN's central cell-binding domains (FN III9-10) affects its integrin specificity. Through production of FN III9-10 variants with variable stabilities, we obtained ligands that present different specificities for the integrin alpha(5)beta(1) and that can be covalently linked into fibrin matrices. Here, we demonstrate the capacity of alpha(5)beta(1) integrin-specific engagement to influence human mesenchymal stem cell (MSC) behavior in 2D and 3D environments. Our data indicate that alpha(5)beta(1) has an important role in the control of MSC osteogenic differentiation. FN fragments with increased specificity for alpha(5)beta(1) versus alpha(v)beta(3) results in significantly enhanced osteogenic differentiation of MSCs in 2D and in a clinically relevant 3D fibrin matrix system, although attachment/spreading and proliferation were comparable with that on full-length FN. This work shows how integrin-dependant cellular interactions with the ECM can be engineered to control stem cell fate, within a system appropriate for both 3D cell culture and tissue engineering.
authors.affiliation: Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Mikaël M
authors.initials: MM
authors.lastname: Martino
authors.forename: Mayumi
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Rothenfluh
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Rempel
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hubbell
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Barker
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D005337:Fibrin; D005353:Fibronectins / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects; D010446:Peptide Fragments / Q000494:pharmacology; D055550:Protein Stability / Q000187:drug effects; D017434:Protein Structure, Tertiary
chemical_list: D020099:Coated Materials, Biocompatible; D005353:Fibronectins; D039081:Integrin alpha5beta1; D010446:Peptide Fragments; D005337:Fibrin