Hyaluronic acid induces osteogenesis in periosteal cell

Objectives: The maxilla and mandible bone formation mainly depends on membranous ossification. In this process, mesenchymal stromal cells of periosteum differentiate into chondro-osteoprogenitor cells and form bone tissue. The coordinated actions of numerous growth factors and cytokines from extracellular matrix (ECM) stimulate these cells. Hyaluronic acid (HA) is a major component of the ECM and is used as scaffold in the case of reconstruction for bone defects. Previous studies demonstrated that HA up-regulated bone mineralization, but detailed mechanisms of HA on osteogenesis were not fully elucidated. The aim of this study was to demonstrate the effects of HA on osteoblastic differentiation in periosteal cell. Methods: Periosteal cells were isolated from calvariae of 4-week-old C57BL/6N mice. Phenotype of periosteal cells were determined by measurement of alkaline phosphatase (ALP) activity and real time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Periosteal cells were cultured with high molecular weight of HA for indicated time to demonstrate the effect of HA on osteogenesis. mRNA purified from cultured cells were subjected to real-time RT-PCR. Results: Periosteal cells had less activity of ALP and less mRNA expression of osteoblastic differentiation markers, such as Runx2, ALP, collagen type I, osteocalcin, and osterix, compared with osteoblastic lineage cells. On the other hand, the expression of periosteum marker, periostin was higher in periosteal cell. HA up-regulated the mRNA expression of Runx2, ALP, collagen type I, osteocalcin and especially osterix. Oppositely, HA down-regulated the mRNA expression of markers, such as collagen type II, collagen type X, sox9, and aggrecan. Conclusion: These results indicated that HA stimulates osteogenesis of periosteal cell through the up-regulation of Runx2.