Implants Hyperhydrophilicity Affects on Murine Osteoblasts Adhesion and Macrophages Activation

Objectives: The aim of this study was to investigate the response of murine osteoblastic cells to microstructured titanium surfaces with normal or increased hydrophilicity, obtained by thermal treatment. The study investigated protein adsorption, the morphology and adhesion of murine osteoblasts using Scanning Electron Microscopy (SEM) with a Focused Ion Beam (FIB) and murine macrophage activation.
Methods: Sandblasted and acid etched titanium discs with normal or hyperhydrophilicity were characterized by Raman spectroscopy. Protein adsorption on surfaces was studied through Bradford assay, SDS-Page and Western Blot. Murine osteoblastic cells (MC3T3-E1) were then seeded on discs. Cell adhesion and morphology were investigated by SEM, while sectioning cells in real time with a gallium focused ion beam (FIB) and by fluorescenze through actin, vinculin and cell nuclei staining. Murine RAW macrophages were plated on titanium and stained with Calcein, while their activity was assesed by measuring NO synthesis.
Results: Hyperhydrophilic surfaces promoted protein adsorption, cell proliferation and firmer cell adhesion. FIB analysis showed that cells on microstructured surfaces adhere preferentially to the surface peaks. Moreover, hyperhydrophilic surfaces promoted a tighter adhesion of the cell body to the whole titanium. Cells appeared thinner and spread on the entire surface of the sample and with a higher number of focal adhesion stained. Macrophage adhesion was enhanced but NO synthesis was not stimulated by hydrophilic surfaces.
Conclusions: In conclusion, our study supports the hypothesis that a hyperhydrophilic surface affects protein adsorption and osteoblasts behavior, improving cell adhesion and morphology.