Osteoblast derived extracellular vesicles induced by dexamethasone: A novel biomimetic tool for enhancing osteogenesis in vitro

Xing Zhang; Qun Zhao; Nan Zhou; Yu Liu; Kang Qin; Eva Miriam Buhl; Xinhong Wang; Frank Hildebrand; Elizabeth R Balmayor; Johannes Greven

doi:10.3389/fbioe.2023.1160703

Osteoblast derived extracellular vesicles induced by dexamethasone: A novel biomimetic tool for enhancing osteogenesis in vitro

Front Bioeng Biotechnol. 2023 Mar 10:11:1160703. doi: 10.3389/fbioe.2023.1160703. eCollection 2023.

Authors

Affiliations

¹ Department of Orthopedics, Trauma and Reconstructive Surgery, University Hospital RWTH Aachen, Aachen, Germany.
² Electron Microscopy Facility, Institute of Pathology and Medical Clinic II, University Hospital RWTH Aachen, Aachen, Germany.
³ Department of Orthopedics, The Affliated Huai'an Hospital of Xuzhou Medical University, Huai'an Second People's Hospital, Huai'an, Jiangsu, China.

Abstract

Extracellular vesicles (EVs) are newly appreciated communicators involved in intercellular crosstalk, and have emerged as a promising biomimetic tool for bone tissue regeneration, overcoming many of the limitations associated with cell-based therapies. However, the significance of osteoblast-derived extracellular vesicles on osteogenesis has not been fully established. In this present study, we aim to investigate the therapeutic potential of extracellular vesicles secreted from consecutive 14 days of dexamethasone-stimulated osteoblasts (OB-EV_Dex) to act as a biomimetic tool for regulating osteogenesis, and to elucidate the underlying mechanisms. OB-EV_dex treated groups are compared to the clinically used osteo-inductor of BMP-2 as control. Our findings revealed that OB-EV_Dex have a typical bilayer membrane nanostructure of, with an average diameter of 178 ± 21 nm, and that fluorescently labeled OB-EV_Dex were engulfed by osteoblasts in a time-dependent manner. The proliferation, attachment, and viability capacities of OB-EV_Dex-treated osteoblasts were significantly improved when compared to untreated cells, with the highest proliferative rate observed in the OB-EV_Dex + BMP-2 group. Notably, combinations of OB-EV_Dex and BMP-2 markedly promoted osteogenic differentiation by positively upregulating osteogenesis-related gene expression levels of RUNX2, BGLAP, SPP1, SPARC, Col 1A1, and ALPL relative to BMP-2 or OB-EV_Dex treatment alone. Mineralization assays also showed greater pro-osteogenic potency after combined applications of OB-EV_Dex and BMP-2, as evidenced by a notable increase in mineralized nodules (calcium deposition) revealed by Alkaline Phosphatase (ALP), Alizarin Red Alizarin Red staining (ARS), and von Kossa staining. Therefore, our findings shed light on the potential of OB-EV_Dex as a new therapeutic option for enhancing osteogenesis.

Keywords: bone regeneration; dexamethasone stimulation; extracellular vesicles; intercellular crosstalk; osteoblastic differentiation; osteogenesis.

Grants and funding

The project was partially funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project Number 429837092. The author, XZ, is finically funded and supervised by China Scholarship Council (CSC) under Grant 202008080053.