Fig. 5

Knockdown of GDF5 inhibited osteogenic differentiation of PDLSCs and partially blocked the pro-osteogenic function of miR-7 inhibitor. a Images of alkaline phosphatase (ALP) staining (top row) in the small interfering RNA normal control (si-NC) and three small interfering RNAs targeting growth differentiation factor 5 (si-GDF5) groups. Cells were cultured in growth medium (GM) or osteogenic medium (OM) for 7 days. Images of alizarin red S (ARS) staining (bottom row) for mineralized matrix in the si-NC and three si-GDF5 groups. Cells were cultured in GM or OM for 14 days. Histograms show ALP activity and quantification of ARS staining by spectrophotometry (normalized to the si-NC groups). b The efficiency of transient transduction of si-GDF5 (left panel) and relative mRNA expression of ALP (middle panel) and RUNX2 (right panel) measured by qRT-PCR at day 3 of osteogenic induction. GAPDH was used for normalization relative to si-NC groups. c Images of ALP staining (top row) in the normal control (NC), miR-7 inhibitor, si-GDF5, and miR-7 inhibitor + si-GDF5 groups. Cells were cultured in GM or OM for 7 days. Images of ARS staining (bottom row) for mineralized matrix in the NC, miR-7 inhibitor, si-GDF5, and miR-7 inhibitor + si-GDF5 groups. Cells were cultured in GM or OM for 14 days. Histograms show ALP activity and quantification of ARS staining by spectrophotometry normalized to the si-NC groups. *p < 0.05, **p < 0.001. RUNX2 Runt-related transcription factor 2