Hyaluronan (HA) Immobilized on Surfaces via Self-Assembled Monolayers of HA-Binding Peptide Modulates Endothelial Cell Spreading and Migration through Focal Adhesion

The extracellular matrix (ECM) modulates a multitude of cell functions, and this regulation is provided by key ECM components forming a complex network. Hyaluronic acid (HA) is an abundant component of the ECM that binds to proteins and influences various activities of endothelial cells (ECs). Although the effect of soluble HA on cell spreading has been studied, the impact of peptide-bound HA has not yet been investigated in great detail. We aim to comprehensively study the roles of immobilized HA on the regulation of EC behavior compared to the more conventional use of soluble HA. A 2D model surface formed by self-assembled monolayers (SAMs) of a HA-binding peptide (Pep-1) is used as an anchor for HA immobilization. Mixed SAMs, consisting of thiolated Pep-1 and 1-octanethiol, are prepared and characterized by using ellipsometry and contact angle measurement. Full density Pep-1 SAMs are more hydrophilic and bind more HA than mixed SAMs. Cell spreading and migration are enhanced by immobilized low molecular weight (LMW) HA, which also facilitates cell alignment and elongation under laminar flow conditions and potentially drives directional migration. This effect is not mediated by the expression of CD44, and immobilized LMW HA is found to accelerate the assembly of focal adhesions. Such biomimetic surfaces provide new insights into the role of HA in regulating the spreading and phenotype of endothelial cells.