INFLUENCES OF SR, ZN AND MG DOPANTS ON OSTEOCLAST DIFFERENTIATION AND RESORPTION

摘要

Osteoclasts, the bone resorbing cells, are specialized macrophages generating from differentiation of mononuclear cells. In this research strontium (Sr), magnesium (Mg) and zinc (Zn) substituted beta-tricalcium phosphate (β-TCP) on differentiation of mononuclear cells into osteoclasts and its resorptive activity were studied. 1.0 wt% Sr, 1.0 wt% Mg, and 0.25 wt% Zn doped β-TCP were prepared by sintering at 1250 ℃. Osteoclast differentiation and resorption was studied in vitro using RAW 264.7 precursor cell, supplemented with receptor activator of nuclear factor kβ ligand (RANKL). Formation of osteoclast cells were monitored by field emission scanning electron microscope (FESEM) and immunohistochemical analysis. Formation of osteoclasts were noticed on pure, Sr doped and Zn doped β-TCP samples after 8 days of culture. However, no such osteoclast formation was found on Mg doped β-TCP samples. Cells on the substrates surface expressed specific osteoclast markers such as; actin ring, multiple nucleus, and vitronectin receptor. Immunohistochemical analysis indicated that matured osteoclasts were formed on β-TCP, Sr, and Zn doped samples after 14 days of culture whereas it took 21 days to form matured osteoclasts on Mg doped samples. Differentiated osteoclasts successfully resorbed β-TCP samples which increased for Zn doped samples and decreased for Sr doped samples. Mg doped β-TCP samples initially restricted osteoclast differentiation, however, once formed showed prominent resorption lacunae formation.