Fig 2: ALP staining of differentiated BM-MSCs after 14 days. (A) Representative light micrographs of cells exposed to (i) BMP-2-loaded PSiO2 carriers via physical adsorption, (ii) Empty PSiO2 carriers, (iii) BMP-2-loaded PSiO2 carriers via covalent conjugation, (iv) Empty chemically-modified PSiO2 carriers, (v) Free BMP-2 solution (100 ng mL−1) and (vi) no treatment (control, cells only). Scale bar = 100 µm. (B) Quantitative analysis of ALP activity, expressed as the average positively stained areas for each condition tested, *** indicates p ≤ 0.005.

Fig 3: Representative images of ALP staining, performed after 19 or 23 days of culture, on untreated NHOst cells and on cells exposed to HA+AA.

Fig 4: ALP activity assay. The reported data represent the means of three independent experiments. The HA+AA group is significantly different from the supplemented medium group after 19 and 23 days of culture (* p < 0.05).

Fig 5: Knockdown of Sfrp1 promotes osteogenic differentiation of BMSCs in vitro. (a) BMSCs were isolated from wild‐type (WT) mice and cultured in vitro. The expression of Sfrp1 was analysed by qPCR at the indicated time points. (b–e) BMSCs were transfected with empty vector pcDNA3.1, or Sfp1‐expressing vector pcDNA3.1‐Sfrp1 alone or followed by TNF‐α treatment (10 ng/mL). (b) The expression of Sfrp1 was analysed by qPCR 48 h later. (c–e) Transfected BMSCs were cultured in vitro for 7 days. (c) The expression of ALP and formation of mineralized nodule were subsequently analysed by ALP staining and Alizarin Red‐S staining, respectively. (d) The mRNA expression of Runx2 and Osterix was analysed by qPCR. (e) The protein expression of Runx2 and Osterix was analysed by western blot. *P < 0.05, **P < 0.01, ***P < 0.001, between the indicated groups.