Expression of MicroRNAs in the Extracellular Microvesicles of Murine Osteoclasts

142 INTRODUCTION Bone is one of the most important oral tissues. It is maintained by the balance between bone formation and resorption . It is remodeled continuously by two specialized cell types: bone-forming osteoblasts and bone-resorbing osteoclasts . Osteoclasts are tartrate-resistant acid phosphatase (TRAP)-positive, multinucleated giant cells that originate from the monocyte/macrophage lineage of hematopoietic stem cells . Stromal cells and osteoblasts express macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL), which are essential for the induction of osteoclasts. In terms of tissue engineering, osteoclasts and macrophages resorb scaffolds, making space for bone matrix formation . Consequently, osteoclasts play an important role in bone regeneration. We reported previously microRNAs (miRNAs) expression profiles during osteoclastogenesis using microarrays . miRNAs are small, endogenous, noncoding RNAs of approximately 22 nuExpression of MicroRNAs in the Extracellular Microvesicles of Murine Osteoclasts