PDGF-Stimulated Corneal Keratocyte Motility and Migration Patterns on Aligned Collagen Fibrils Are Inhibited by Decorin

Decorin, a proteoglycan shown to inhibit transforming growth factor β1 (TGF-β1) signaling, has been increasingly considered as a potential anti-fibrotic agent to aid in therapies addressing corneal scarring and blindness. Decorin is also known to interact with a wide range of other growth factors, such as platelet-derived growth factor (PDGF), which has been shown to stimulate corneal cell migration to repopulate the decellularized region of the wounded cornea. In other tissues, decorin has been shown to inhibit PDGF-mediated migration and prolong wound healing. However, our understanding of the effect of decorin on PDGF signaling in the corneal stroma environment is limited. Specifically, thus far, there have been no studies investigating the interaction between decorin and PDGF in the context of the uniquely organized fibrillar collagen extracellular matrix (ECM), which provides topographic cues that guide cell migration during wound healing. The purpose of this study is to use an in vitro model of decorin-coated aligned collagen fibrils analogous to the corneal stroma ECM to investigate this interaction. With this in vitro model, we demonstrate that decorin inhibits the response of PDGF-BB-stimulated keratocytes to a 2-dimensional (2D) aligned collagen fibril ECM, reducing cell alignment, motility, PDGF receptor β (PDGFRβ) phosphorylation, and wound closure. We observed that when presented with a decellularized wound region, cells on the decorin-coated substrates migrated more randomly and were less aligned with the underlying aligned collagen fibrils than cells on uncoated fibrils, resulting in slower wound closure. Furthermore, PDGF-BB-stimulated cells on the decorin coating had increased branching and reduced solidity, representing a shift from the elongated, bipolar morphology typically resulting from PDGF-BB treatment towards the stellate, branched keratocyte phenotype. While decorin seems to be an effective agent against TGF-β1-mediated fibrosis, its interaction with PDGF-BB appears to present other challenges to wound healing that should be considered in the development of therapies for healthy corneal wound healing.