Curculigoside Improves Osteogenesis of Human Amniotic Fluid-Derived Stem Cells

Curculigoside, a phenolic glycoside, is the main active compound of Curculigo orchioides (Amaryllidaceae, rhizome). C. orchioides is a traditional Chinese herbal medicine and has been commonly used to treat orthopedic disorders and bone healing in Asia. This study evaluated the effect of curculigoside on osteogenic differentiation of human amniotic fluid-derived stem cells (hAFSCs). The results showed that curculigoside stimulated alkaline phosphatase activity and calcium deposition of hAFSCs during osteogenic differentiation in a dose-dependent manner (1-100 μg/mL), while the effects were reduced at the higher concentration of 200 μg/mL. From reverse transcriptase-polymerase chain reaction analysis, the osteogenic genes osteopontin (OPN) and Collagen I were upregulated with curculigoside treatment (1-100 μg/mL). Concurrently, the ratio of osteoprotegerin (OPG) to receptor activator of nuclear factor kappa-B ligand (RANKL) was increased, indicating the inhibition of osteoclastogenesis by curculigoside. Moreover, the role of Wnt/β-catenin signaling during curculigoside treatment was revealed by the upregulation of β-catenin and Cyclin D1. In summary, curculigoside improved osteogenesis and inhibited osteoclastogenesis of hAFSCs, suggesting its potential use to regulate hAFSC osteogenic differentiation for treating bone disorders.