Early changes of ECM-related gene expression in fibroblasts cultured on TiO2, ZrO2 and PEEK: The beneficial effects of UVC photofunctionalization

Abstract

Abstract Background The importance of an efficient seal created by soft (connective) tissues around newly inserted dental implants has become increasingly clear. This study was aimed to compare the compatibility of fibroblasts – the main cell type in connective tissues – with three dental materials commonly employed for the manufacture of implant abutments, i.e. zirconia (ZrO2), titanium oxide (TiO2) and polyether-ether-ketone (PEEK), as well as the effects of UVC photofunctionalization of the materials prior to the contact with cells. Materials and methods Human fibroblasts (MRC-5 cell line) were allowed to attach and grow up to 72\xa0h on disks of each material, in absence or after UVC photofunctionalization. Cell viability as well as the expression of five genes related to extracellular matrix (ECM) homeostasis (fibronectin, collagen 1A1, vinculin, metalloproteases 2 and 9) were assessed at various times after cell seeding. Results The viability of fibroblasts was higher when cultured on zirconia disks, in the order ZrO2 > TiO2 > PEEK. The lower viability observed with untreated PEEK could be however recovered after UVC photofunctionalization. Early upregulation was observed of genes involved in cell adhesion and migration (FN1, VCL) as well as in ECM remodeling (MMP9). UVC photofunctionalization significantly enhanced these effects with all three materials tested. At variance, the expression of Col1A1 gene – coding for collagen type I-alpha 1 – was precociously downregulated, but UVC photofunctionalization could largely reverse this phenomenon. Conclusions Our observations suggest that fibroblasts cultured on UVC treated surfaces present an increased/accelerated activation of factors involved in the formation of new connective tissue. UVC photofunctionalization of dental implant abutments could thus enhance/accelerate the formation of soft tissue seals capable of preventing bacterial invasion.