Fig. 2

Effects of recombinant Apelin-13 on osteogenic differentiation of hBMSCs. a Relative mRNA expression of osteo-specific genes (COL1A1, RUNX2, and OCN) on days 1, 3, and 5 of osteogenesis. The mRNA expression levels were normalized to that of 18S ribosomal RNA. b Relative expression of osteo-specific proteins (RUNX2 and COL1A1) on days 1, 3, and 5 of osteogenesis. Protein expression levels were normalized to that of GAPDH. c Apelin-13 promoted hBMSC mineralization. The cells were incubated with different concentrations of Apelin-13 for 9 and 11 days. Calcium deposits were identified by Alizarin Red S staining. Compared with the control group, Apelin-13 enhanced mineralization dramatically. Scale bar, 500 μm. Alizarin Red S-stained area was determined by measuring the absorbance at 560 nm. d ALP staining on day 3 of osteogenesis and ALP activity detection on day 3 of osteogenic differentiation. Scale bars, 500 μm. Data are expressed as mean ± SD. Assays were performed in triplicates. *P < 0.05, ^#P < 0.05, **P < 0.01, and ***P < 0.001 compared with the control group