Osteogenic Differentiation of Human Mesenchymal Stem Cells Modulated by Surface Manganese Chemistry in SLA Titanium Implants

The manganese (Mn) ion has recently been probed as a potential candidate element for the surface chemistry modification of titanium (Ti) implants in order to develop a more osteogenic surface with the expectation of taking advantage of its strong binding affinity to the integrins on bone-forming cells. However, the exact mechanism of how Mn enhances osteogenesis when introduced into the surface of Ti implants is not clearly understood. This study investigated the corrosion resistance and potential osteogenic capacity of a Mn-incorporated Ti surface as determined by electrochemical measurement and examining the behaviors of human mesenchymal stem cells (MSCs) in a clinically available sandblasted/acid-etched (SLA) oral implant surface intended for future biomedical applications. The surface that resulted from wet chemical treatment exhibited the formation of a Mn-containing nanostructured TiO2 anatase thin film in the SLA implant and improved corrosion resistance. The Mn-incorporated SLA surface displayed sustained Mn ion release and enhanced osteogenesis-related MSC function, which enhanced early cellular events such as spreading, focal adhesion, and mRNA expression of critical adhesion-related genes and promoted full human MSC differentiation into mature osteoblasts. Our findings indicate that surface Mn modification by wet chemical treatment is an effective approach to produce a Ti implant surface with increased osteogenic capacity through the promotion of the osteogenic differentiation of MSCs. The improved corrosion resistance of the resultant surface is yet another important benefit of being able to provide favorable osseointegration interface stability with an increased barrier effect.