공동배양에 의한 파골세포 생성에서 티타늄 나노구조의 억제 기전

Abstract

Previously, many studies investigating differentiation of osteoclasts, osteoblasts or mesenchymal stem cells alone on titanium with nanotubular structure were reported. However, there is barely information about the effects of oxidized titanium (TiO₂) nanotubular structure on the formation of osteoclast under coculture condition. In this study, we investigated the differentiation and formation of osteoclast cultured on TiO₂ nanotubular structure under coculture condition. Bone marrow cells were cultured with calvarial osteoblast cells on TiO₂ nanotubes with different diameters (30-100 nm). The formation of mature osteoclasts was apparently increased on 30 nm TiO₂ nanotubes compared to that of electropolished titanium surface (Ti), and then dramatically reduced by increasing nanotube diameters up to 100nm. However, the adhesion of osteoclasts or osteoblasts, and the expression of osteoblast differentiation marker genes were not shown any significant difference at all diameters of TiO₂ nanotubular structures. Rather, the expression of osteoclast differentiation factors (macrophage colony-stimulating factor, M-CSF, osteoprotegerin, OPG and receptor activator of nuclear factor kappa-B ligand, RANKL) produced by osteoblasts was dramatically changed by diameters of TiO₂ nanotubular structure. The expression of M-CSF and OPG in osteoblasts was up-regulated, and the expression of RANKL and RANKL/OPG ratio were down-regulated by increasing diameters of TiO₂ nanotubes, in particular, at 70 and 100 nm. These data suggest that the inhibition of osteoclast formation by TiO₂ nanotube having 70-100 nm diameters may due to diminishing function of osteoblast responsible for osteoclast differentiation under coculture condition. It also indicate that the nano-topography on the Ti surface may affect to successful medical application including dental implantation.