Modulation of Stem Cell Adhesion and Morphology via Facile Control over Surface Presentation of Cell Adhesion Molecules

Abstract

To encourage cell adhesion on biomaterial surfaces in a more facile, safe, and low-cost fashion, we have demonstrated a noncovalent approach to spatially conjugate β-cyclodextrin (β-CD) modified peptide sequences onto self-assembled adamantane-terminated polystyrene-b-poly(ethylene oxide) (PS-PEO-Ada) films through inclusion complexing interactions between β-CDs and adamantane. By simply blending various ratios of unmodified PS-PEO with a newly synthesized PS-PEO-Ada, we produced PS polymer films that displayed well-organized adamantine-decorated cylindrical PEO domains with varying average interdomain spacings ranging from 29 to 47 nm. The presence of the adamantane moiety at the terminal end of the PEO chain permitted rapid, and importantly, oriented attachment of β-CD functionalized peptides onto these surfaces. This one-step process not only converted these proven nonadherent PS-PEO surfaces into adherent surfaces, but also permitted precisely controlled presentation and surface distribution of the conjugated peptides. The utility of these surfaces as cell culture substrates was confirmed with human mesenchymal stem cells (hMSCs). We observed that with increasing PS-PEO-Ada content in the PEO cylindrical domains, these novel polymer films displayed improved cell attachment and spreading, with notable differences in hMSC morphology. We further confirmed that this novel PS-PEO-Ada surface provides a flexible platform for facile conjugation of mixtures of β-CDs functionalized with different peptides, specifically RGD and IKVAV peptides. The cell adhesion and spreading assays on these surfaces indicated that the morphologies of hMSCs can be easily manipulated, while no significant changes in cell attachment were observed. The lock-and-key peptide conjugation technique presented in this work is applicable to any substrate that incorporates a moiety capable of forming inclusion complexes with α-, β-, and γ-CDs, providing a facile and flexible method by which to construct peptide-conjugated biomaterial substrates for a multitude of applications in fields ranging from cell bioprocessing and regenerative medicine to cell-based assays.