Dual keratinocyte-attachment and anti-inflammatory coatings for soft tissue sealing around transmucosal oral implants

Abstract

Unlike the attachment of soft epithelial skin tissue to penetrating solid natural structures like fingernails and teeth, sealing around percutaneous/permucosal devices such as dental implants is hindered by inflammation and epidermal down growth. Here, we employed a dual keratinocyte-adhesive peptide and anti-inflammatory biomolecule coating on titanium to promote oral epithelial tissue attachment. For minimizing inflammation-triggered epidermal down growth, we coated pristine and oxygen plasma pre-treated polished titanium (pTi) with conjugated linoleic acid (CLA). Further, in order to aid in soft tissue attachment via the formation of hemidesmosomes, adhesive structures by oral keratinocytes, we coated the anionic linoleic acid (LA) adsorbed titanium with cationic cell adhesive peptides (CAP), LamLG3, a peptide derived from Laminin 332, the major extracellular matrix component of the basement membrane in skin tissue and Net1, derived from Netrin-1, a neural chemoattractant capable of epithelial cell attachment via α6β4 integrins. The dual CLA–CAP coatings on pTi were characterized by X-ray photoelectron spectroscopy and dynamic water contact angle measurements. The proliferation of human oral keratinocytes (TERT-2/OKF6) was accelerated on the peptide coated titanium while also promoting the expression of Col XVII and β-4 integrin, two markers for hemidesmosomes. Simultaneously, CLA coating suppressed the production of inducible nitric oxide synthase (anti-iNOS); a pro-inflammatory M1 marker expressed in lipopolysaccharide (LPS) stimulated murine macrophages (RAW 264.7) and elevated expression of anti-CD206, associated to an anti-inflammatory M2 macrophage phenotype. Taken together, the dual keratinocyte-adhesive peptide and anti-inflammatory biomolecule coating on titanium can help reduce inflammation and promote permucosal/peri-implant soft tissue sealing.