Fig. 4

Indirect effects of HAPs on the expression of osteogenic differentiation-related genes. a RUNX-2, b Col I, c OCN, d ALP, e NANOG, f OCT3/4, and g SOX2 gene levels in hWJ-MSCs cultured with CM for the indicated time. *P < 0.05; **P < 0.01; ***P < 0.001 versus control group; ^&P < 0.05; ^&&P < 0.01; ^&&&P < 0.001 versus the m-HAP group; ^#P < 0.05; ^##P < 0.01 versus the np20 group. Cells incubated in osteogenic medium without HAPs treatment were used as the control group. Abbreviations: HAPs hydroxyapatite particles, m-HAP micro-sized HAP particles, hWJ-MSCs human umbilical cord Wharton’s jelly-derived mesenchymal stem cells, RUNX-2 runt-related transcription factor 2, Col I type I collagen, OCN osteocalcin, ALP alkaline phosphatase, SOX 2 SRY-related HMG-box 2