Osteogenic effects of exosomes derived from human chorion membrane extracts

Abstract

Objective: Human chorion membrane extracts (CME) are known to exhibit osteogenic effects when used for treating human osteoblast-like cells (MG63 cells), but the active compound in CME remains unknown. The aim of this study was to identify the presence of exosomes in CME and to determine the osteogenic effect of CME exosomes on MG63 cells. Methods: Exosomes were isolated from human placenta CME using the ExoQuick-TC solution and were characterized. The activity and deposition of alkaline phosphatase (ALP) on MG63 cells cultured with or without exosomes in osteogenic induction medium (OIM) were determined. Human amniotic membrane extracts (AME) were used as controls as they had not affected the osteogenic differentiation of MG63 cells in our previous study. Results: Transmission electron microscopy (TEM) revealed that exosomes isolated from CME and AME (CME-Exo and AME-Exo, respectively) had a cup-shaped structure. NanoSight™ particle tracking analysis (NTA) confirmed that the size of these exosomes was 100–150 nm. In vitro osteogenic experiments demonstrated that the exosomes from CME, but not those from AME, presented increased alkaline phosphatase (ALP) activity and resulted in the mineralization of MG63 cells in a dose-dependent manner. Conclusion: Exosomes were identified in CME and AME from the human placenta. Further, the exosomes from CME were found to be capable of promoting osteogenic differentiation, suggesting that exosomes are a key component of CME that stimulate the osteogenesis of human osteoblast-like cells. CME exosomes can be developed as promising therapeutic candidates for bone regeneration.