Role of integrins on the osteoblast differentiation of mesenchymal stem cells induced by titanium surfaces with micro and nanotopography

Abstract

Integrins are a family of membrane receptors that primarily mediate adhesion of cells to extracellular matrix proteins and some members are involved in the process of osteoblast differentiation and bone formation, key events of titanium (Ti) implant osseointegration. It is well known that Ti surfaces with micro and nanotopography favor matrix mineralization but the cellular mechanisms implicated in this process are not entirely understood. In this context, we hypothesized that integrins may have important role in the osteoblast differentiation induced by micro and nanostructured Ti surfaces. To test this hypothesis rat bone marrow mesenchymal stem cells will be cultured on Ti discs with three different surfaces, (1) nanostructured, (2) microstructured and (3) machined (untreated - control) and the following aspects will be evaluated: (1) presence of focal adhesions by vinculin immunolabeling, (2) gene expression of members of the integrin signaling pathway by PCR array, (3) gene expression of bone markers by real-time PCR, (4) protein expression of members of the integrin signaling pathway and bone markers by Western blot and (5) effect of gene silencing using siRNA of integrin signaling pathway members on osteoblast differentiation induced by different Ti surface topographies by real-time PCR and western blot. The outcomes of this study could contribute to clarify the intracellular mechanisms involved in osteoblast responses to Ti and consequently novel strategies using integrins and surface topography could be developed in order to favor the process of osseointegration. (AU)