Enhancing the regeneration of bone defects by alkalizing the peri-implant zone – anin vitroapproach

Abstract

The effects of alkaline pH on the initial adhesion of osteoblasts to titanium surfaces was analyzed by single cell force microscopy (SCFM). In the SCFM measurements, the same cells were used to compare their unspecific adhesion to uncoated titanium with their specific adhesion to collagen coated titanium. When the maximum detachment forces (MDFs) were compared at pH 7.4 and 8.0, only slight differences were found on pure titanium, while the MDFs were significantly increased at collagen coated surfaces at pH 8.0. Effects on the subsequent proliferation and gene expression were investigated in an in vitro model system consisting of an alkalizing polyvinyl alcohol (PVA) matrix and a perforated titanium disc. The sodium hydroxide releasing matrix maintained the medium pH between pH 7.6 and pH 8.4 during the entire experiment. Under these conditions, cell counts were significantly increased with respect to the control system after 7 days in culture. These results were supported by gene expression analyses, which showed an upregulation of proliferation-controlling genes of the EGFR1 and PI3K/AKT pathways after 14 days in culture. The SCFM data were complemented by findings of an intensive regulation of genes known to be associated with focal adhesion such as Itga8 and Tnn.

Surface Coatings Modulate the Differences in the Adhesion Forces of Eukaryotic and Prokaryotic Cells as Detected by Single Cell Force Microscopy

“…It has been used before as an adhesion promoter in SCFM with prokaryotic cells [31, 32]. In previous SCFM experiments, we were also able to attach MC3T3 cells with poly-dopamine to SCFM cantilevers [33]. Here we found that poly-dopamine could also be used to attach PNCs.…”

“…For prokaryotic cells, it is known that electrostatic surface interactions are crucial for the successful formation of colonies [36]. In previous experiments with MC3T3 cells, we found that their MDFs were elevated at alkaline pH, which correlated with increased proliferation in cell culture experiments [33]. Nevertheless, we are not sure about the general strength of the predictive power of initial adhesion for the fate of proliferation of prokaryotic and eukaryotic cells, since many different mechanisms only become effective after the initial phase.…”