Specific temporal culturing and microgroove depth influence osteoblast differentiation of human periodontal ligament cells grown on titanium substrata

The purpose of this study is two-fold: to compare differences in the development of osteoblast differentiation processes between human bone marrow mesenchymal stem cells (MSCs) and human periodontal ligament cells (PLCs) cultured on microgrooved titanium (Ti) substrata and to investigate the effects of microgroove depth on PLCs' osteoblast differentiation. Using photolithography, 60 mu m-wide and 10 or 20 mu m-deep microgrooves were fabricated on the Ti substrata (NE60/10 or NE60/20). Subsequent acid etching was applied to the fabricated microgrooved Ti to yield the etched microgrooves (E60/10 and E60/20). Smooth and acid-etched Ti were used as the controls (NE0 and E0). Alkaline phosphatase activity and extracellular calcium deposition assays were performed after various timelines of culture on both MSCs and PLCs grown on NE0 and E60/10. For PLCs cultured on NE0, NE60/10, NE60/20, E0, E60/10 and E60/20, cell adhesion, cell proliferation, osteoblast differentiation were determined, followed by the analysis on various osteogenic gene expressions. By comparing the extracellular matrix maturation and mineralization processes on smooth and microgrooved Ti substrata, it was determined that PLCs require more time for osteoblast differentiation than MSCs. Also, E60/10 allowed for the highest levels of adhesion, proliferation, osteoblast differentiation, and osteogenic gene expression by PLCs. PLCs could be an excellent alternative to MSCs for use in future studies investigating cellular processes using microgrooved Ti substrata and other modified surfaces. Optimal Ti microgroove dimensions and osteogenic differentiation timelines are necessary to promote various cellular activities in human PLCs.