Cyclic Stretch Enhances Osteogenic Differentiation of Human Periodontal Ligament Cells via YAP Activation

Figure 2

Cyclic stretch enhances osteoblastic differentiation of HPDLCs. (a) Cyclic stretch increased the alkaline phosphatase activity of HPDLCs. The positive cells for the ALP were stained with NBT-formazan (dark blue) and the representative image of positive ALP staining is shown in (a). (b) The ALP activity of HPDLCs was quantified using an ALP reagent kit. The activities were normalized to the protein concentration. , p < 0.05. (c) Increased expression of osteogenic marker genes in HPDLCs after cyclic stretch. The mRNA expression of YAP, osteopontin (OPN), RUNX2, collagen type 1 (COL1), alkaline phosphatase (ALP), osterix (OSX), and osteocalcin (OCN) was analyzed using qRT-PCR. The relative expression level was calculated after normalization to the GAPDH level. , p < 0.001; , p < 0.01. (d) The expression of OPN and OCN in HPDLCs was analyzed using immunoblots. (e) Relative grey values of each band in (d) were normalized to the level of GAPDH. , p < 0.01; , p < 0.05. All data was based on three independent experiments.

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