Oleanolic Acid Enhances Mesenchymal Stromal Cell Osteogenic Potential by Inhibition of Notch Signaling

Bing Shu,Guangxi Wang,Marjorie Chelly,Yongjian Zhao,Margaret Olmedo,Massimo Max Morandi,Xifu Shang,Shane Barton,Michael Britt,Yufeng Dong,Yongjun Wang

doi:10.1038/s41598-017-07633-7

Abstract

Oleanolic acid (OA), a pentacyclic triterpenoid, has been shown to modulate multiple signaling pathways in a variety of cell linages. But the mechanisms underlying OA-mediated mesenchymal stromal cell (MSC) osteogenic differentiation are not known. In this study, we examined effects of OA on cell viability, osteogenic differentiation in MSCs, and the involvement of Notch and BMP signaling. OA induced bone marrow derived MSC differentiation towards osteoprogenitor cells and inhibited Notch signaling in a dose dependent manner. Constitutive activation of Notch signaling fully blocked OA induced MSC osteogenic differentiation. The expression level of early osteogenic marker genes, ALP, Runx2, and type I collagen, which play a critical role in MSC to osteoblast transition and servers as a downstream target of BMP signaling, was significantly induced by OA. Furthermore, BMP2 mediated MSC osteogenic differentiation was significantly enhance by OA treatment, indicating a synergistic effect between BMP2 and OA. Our results suggest that OA is a promising bioactive agent for bone tissue regeneration, and inhibition of Notch signaling is required for its osteogenic effects on MSCs.

Highlights

As a natural pentacyclic triterpenoid, oleanolic acid [(3β)-3-hydroxyolean-12-en-28-oic acid] (OA) is an aglycone of many saponins, and one of the most important compounds with bioactivity in medicinal herbs[9]
Oleanolic acid (OA) induces osteogenic differentiation of mesenchymal stromal cell (MSC) while inhibits Notch signaling in a dose-dependent manner
alkaline phosphatase (ALP) staining in cultures indicated a dose dependent increase of MSC osteogenic differentiation in OA treated MSCs by showing a stronger staining (Fig. 1C) further confirmed this enhanced osteogenic differentiation in OA treated MSCs

Summary

Introduction

As a natural pentacyclic triterpenoid, oleanolic acid [(3β)-3-hydroxyolean-12-en-28-oic acid] (OA) is an aglycone of many saponins, and one of the most important compounds with bioactivity in medicinal herbs[9]. Studies by Bian, et al.[18] showed that oleanolic acid exerts an osteoprotective effect in ovariectomy-induced www.nature.com/scientificreports/. Other studies indicate that osteoprotective effect of oleanolic acid is due to inhibited RANKL-mediated osteoclastogenesis via PLCγ2-Ca2+ -NFATc1 signaling[19]. The effects of OA on stem cell osteogenic differentiation have not been investigated in detail, and the underlying mechanisms responsible for bone forming effect of OA are still unknown. Our group along with others have identified the Notch pathway as an important inducer of MSC proliferation, and as an inhibitor of MSC differentiation during mouse limb-bud and postnatal bone development[20]. We first studied the effect of OA on Notch signaling-mediated MSC osteogenic differentiation, and determined the effect of OA on BMP-induced osteogenesis

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Discussion

Conclusion