Abstract
Human mesenchymal stem cell (hMSC)-derived exosomes have shown regenerative effects, but their role in osteogenesis and the underlying mechanism are yet to be determined. In this study, we examined the time-course secretion of exosomes by hMSCs during the entire process of osteogenic differentiation. Exosomes derived from hMSCs in various stages of osteogenic differentiation committed homotypic cells to differentiate towards osteogenic lineage, but only exosomes from late stages of osteogenic differentiation induced extracellular matrix mineralisation. Exosomes from expansion and early and late stages of osteogenic differentiation were internalised by a subpopulation of hMSCs. MicroRNA profiling revealed a set of differentially expressed exosomal microRNAs from the late stage of osteogenic differentiation, which were osteogenesis related. Target prediction demonstrated that these microRNAs enriched pathways involved in regulation of osteogenic differentiation and general mechanisms how exosomes exert their functions, such as “Wnt signalling pathway” and “endocytosis”. Taken together, the results show that MSCs secrete exosomes with different biological properties depending on differentiation stage of their parent cells. The exosomal cargo transferred from MSCs in the late stage of differentiation induces osteogenic differentiation and mineralisation. Moreover, it is suggested that the regulatory effect on osteogenesis by exosomes is at least partly exerted by exosomal microRNA.
Highlights
Exosomes, with a diameter of 30–150 nm [1], are the only subgroup of extracellular vesicles (EVs) known to be derived from endosomes and released into the extracellular milieu upon the fusion of multivesicular bodies with the plasma membrane [2, 3]
HMSCs were seeded at 18,000 cells/cm2 in osteogenic differentiation media (ODM, including exosome-free media supplemented with 100 nM dexamethasone, 45 μM ascorbic acid and mM β-glycerophosphate) in 2 μg/cm2 human fibronectin coated tissue culture flasks (BD Biosciences) for d
Exosomes were isolated from conditioned media of Human mesenchymal stem cell (hMSC) expansion and different time points (D3, D6, D9, D12, D15, D18 and D21) of osteogenic differentiation through a series of ultrafiltration and ultracentrifugation
Summary
With a diameter of 30–150 nm [1], are the only subgroup of extracellular vesicles (EVs) known to be derived from endosomes and released into the extracellular milieu upon the fusion of multivesicular bodies with the plasma membrane [2, 3]. Exosomes are secreted by different cell types and exist in most body fluids. Mesenchymal stem cell-derived exosomes, microRNA and osteogenic differentiation for treatment of transfemoral amputees” (http:// www.researchweb.org/is/alfgbg), ALFGBG-448851 (PT), the IngaBritt and Arne Lundberg Foundation (http://www.lundbergsstiftelsen.se), 2014-0049 (PT), Stiftelsen Hjalmar Svenssons Forskningsfond (https://stiftelsemedel.se, HJSV2014073 (XW), HJSV2013030 (XW), HJSV201341 (KE), HJSV2014059 (KE) Adlerbertska forskningsstiftelsen (www.adlerbertska.se) E 2015/ 78 (KE)), Magnus Bergvalls stiftelse The grant providers were not involved in the study design, data acquisition, interpretation, writing and submission of the article. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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