Epidermal growth factor: layered silicate nanocomposites for tissue regeneration.

Wound healing is a complex, multistep process that can be summarized into three stages, namely, hemostasis and inflammation, proliferation, and finally, tissue remodeling. Battlefield wound healing demands rapid hemostasis using clotting or cauterizing agents to immediately limit blood loss, but this occurs at the expense of proper tissue repair beyond hemostasis. Layered silicate clays such as kaolin and montmorillonite (MMT) have been previously shown to induce blood clotting due to their ability to form charged interactions with clotting factors. The charge characteristics of sodium MMT (Na-MMT) also enable functionalization with active biomolecules. Herein we functionalized Na-MMT with epidermal growth factor (EGF) via ion exchange reaction to create a nanocomposite (MMT-EGF) with approximately 0.004 EGF molecules per Na(+) exchange site and conduct biochemical analyses of keratinocytes after treatment with MMT-EGF. Our results demonstrate that EGF immobilized on MMT retains the ability to activate the epidermal growth factor receptor (EGRF), causing phosphorylation of the AKT and MEK1 pathways, as well as upregulation of its downstream target gene expression involved in cell growth and migration. This study also shows that like EGF, MMT-EGF treatment can stimulate cell migration in vitro, which is dependent on ERK1/2 phosphorylation.