Fig. 5
Sfrp2 deficiency leads to a reduced osteogenic differentiation capacity of BMSCs/SSCs in vitro. a After 3 days of osteogenic differentiation with dexamethasone, β-glycerol phosphate and L-ascorbic acid 2-phosphate (D/P/A), Sfrp2 KO BMSCs/SSCs showed less expression of Runx2 and Osterix (vs. Gapdh) than WT BMSCs/SSCs. Addition of exogenous rm-Sfrp2 (1 μg·mL−1) normalized Runx2 expression, and increased Osterix expression above WT levels. b After 21 days of osteogenic differentiation (D/P/A), Sfrp2 KO BMSC/SSC cultures were less mineralized than WT cultures, as measured by alizarin red S staining and absorptiometry at 405 nm. *P < 0.05; **P < 0.01; ***P < 0.01 vs. WT BMSCs/SSCs; #P < 0.05; ##P < 0.01; ###P < 0.01 vs. Sfrp2 KO BMSCs/SSCs. c–f DM-5, an immortalized BMSC/SSC line that retains the ability to form an ectopic ossicle upon transplantation, was transfected with scrambled (Con-siRNA) or Sfrp2-siRNA. After 3 days of osteogenic differentiation with either D/P/A in (c), or BMP-2, β-glycerol phosphate and L-ascorbic acid 2-phosphate (B/P/A) in (e), cells silenced for Sfrp2 expression showed decreased expression of Runx2 and Osterix (vs. Gapdh). After 7 days of osteogenic differentiation with D/P/A or B/P/A, cells silenced for Sfrp2 expression showed decreased calcium accumulation as shown in alizarin red S stains in (d, f). Data represent mean ± SD. *P < 0.05; **P < 0.01 vs. Con-siRNA-treated cells
