물리적 자극에 의한 조골세포의 뼈 재형성 과정의 조절

Bone consists of three types of mechanosensitive cells, namely osteoblast, osteocytes, and osteoclast. Osteoblasts and osteoclasts are specialized cells responsible for bone formation and resorption, respectively. Osteoblasts get trapped into bone matrix to form osteocytes. These cells functionally adapt to external physical forces in concert to maintain homeostasis and mechanical integrity of the bone. Especially, osteroblasts playa central role in bone remodeling by regulating neighboring osteoclasts and differentiating themselves into osteocytes. In this research, we employ two different types of physical stimulations, tensile stress (TS) and electric field (EF), on osteoblasts to investigate the effects of these forces on factors influencing bone remodeling. Our results indicate that osteoblasts are responsive to both TS and EF, showing noticeable upregulation of ALP, BSP, osteopontin (OP), OPG as well as downregulation of RANKL. Since high expression of RANKL is known to promote osteoclast activity for accelerated resorption, TS and EF induced downregulation of RANKL and upregulation of ALP, BSP, OP, and OPG will likely to activate bone formation. Furthermore, TS and EF have shown to up-regulate the expression of DMP-1, promoting the differentiation of osteoblast to osteocyte. Our study confirms that proper external stimulation can strengthen bone remodeling process through ostoeblast activation and osteoclast de-activation.