EFFECT OF A NANO-SCALE FINE HOLE PATTERN ON THE DIFFERENTIATION OF RAW264.7 CELLS INTO OSTEOCLASTS

Osteoclasts are associated with certain diseases such as osteopetrosis. The development and functions of osteoclasts are controlled by the micro-and nano-surface roughness of biomaterials. However, the effect of fine micro/nano-patterns on osteoclastic differentiation remains poorly understood. In the present study, we investigated the effect of fine shape patterns at the nano-scale on osteoclastic differentiation. A hole pattern of 500 nm in diameter and 500 nm in height was prepared using nanoimprinting of a glycol-modified polyethylene terephthalate (G-PET) film for a basic topological study. RAW264.7 cells were used as an alternative basic model to primary cells. The result of a cell attachment assay showed that the average number of attached cells on the hole patterned-film was 1.5 times higher than that on the planar film. A cell differentiation assay showed that the average number of multinucleated osteoclasts on the hole patterned-film was approximately 1.9 times higher than that on the planar film. However, the patterning effects in this study were quite small (p>0.05). Although the morphology of the cells was basically similar when observed under an optical microscope, the morphologies of the attached and differentiated cells were slightly different in terms of their cell shape and filopodia shape between the holed and planar films when observed under a scanning electron microscope. Differences in cell attachment and differentiation behaviors between holed and planar films would affect the functions of the osteoclasts. We suggest that fine nano-patterning of the substrate could be one factor to control osteoclastic differentiation and cell function.