Fig. 4

SMFs promote osteogenic differentiation of BMSCs. a Representative images of alkaline phosphatase (ALP) staining of BMSCs cultured in osteogenic medium and treated with gradient SMF for 3 days. Scale bar, 100 μm. b Detection of ALP activity. *P < 0.05, **P < 0.01 vs control or 0 T group. n = 4 per group. c, d Representative images of alizarin red S (ALS) staining (c) and quantification of matrix mineralization by ALS absorption (d) in BMSCs grown in osteogenesis induction medium and stimulated with gradient SMF for 21 days. Scale bar, 100 μm. *P < 0.05, **P < 0.01, as indicated. n = 4 per group. e–j Expression of key osteogenic transcription factors (Runx2 and Ost) (e and f) and osteoblast marker genes (Col1α1, Col1α2, Alp, and Spp1) (g–j) in BMSCs grown in osteogenesis induction medium and treated with gradient SMF. *P < 0.05, **P < 0.01, as indicated. n = 8–10 per group. ns=not significant