Fibronectin functionalized hydroxyapatite coatings: improving dermal fibroblast adhesion in vitro and in vivo

Skin-penetrating devices including intraosseous transcutaneous amputation prostheses (ITAP) and external fixator pins rely on a skin-implant seal to prevent infection. In this study, we assess the effectiveness of fibronectin (Fn) functionalized hydroxyapatite (HA) coatings for promoting dermal fibroblast and dermal tissue attachment and ingrowth in vitro and in vivo. By measuring the number of focal adhesions per unit cell area we have demonstrated that HA significantly promotes dermal fibroblast attachment compared with titanium alloy. Dermal fibroblast attachment is promoted further using Fn functionalized HA coatings incorporated into an implant design with 700mm pores, which significantly increased dermal tissue ingrowth and attachment compared with non-functionalized HA and titanium alloy controls incorporating 500 or 1000mm pores. We postulate that Fn functionalized HA coatings applied to transdermal implants may promote and sustain the skin-implant interface and assist in preventing infection long term.