Exosomes derived from human adipose-derived stem cells ameliorate osteoporosis through miR-335-3p/Aplnr axis

Treatment of osteoporosis is still a challenge in clinic,which leads to an increasing social burden as the aging of population.Exosomes originated from human adipose-derived stem cells(hASCs)hold promise to promote osteogenic differentiation,thus may ameliorate osteoporosis.The main purpose of this study was to investigate the novel usage of hASC-derived exosomes in the treatment of osteoporosis and their underlying mechanism.Two types of exosomes,i.e.,exosomes derived from hASCs cultured in proliferation medium(P-Exos)and osteogenic induction medium(O-Exos),were obtained.As compared with P-Exos,O-Exos could promote the osteogenic differentiation of mouse bone marrow-derived stem cells(mBMSCs)from osteoporotic mice in vitro and ameliorated osteoporosis in vivo.Then,microRNA(miRNA)-335-3p was identified to be the key differentially expressed microRNA between the two exosomes by small RNA sequencing,gene overexpression and knock-down,qRT-PCR,and dual-luciferase reporter assay,and Aplnr was confirmed to be the potential target gene of miRNA-335-3p.In addition,miR335-3p inhibitor-optimized O-Exos were established by transfection of miR-335-3p inhibitor,which significantly enhanced the osteogenic differentiation of mBMSCs in vitro,and bone density and number of trabecular bones in vivo compared with unoptimized O-Exos.Our results indicated that the ASC-exosome-based therapy brings new possibilities for osteoporosis treatment.Besides,engineered exosomes based on transfection of miRNA are a promising strategy to optimize the therapeutic effect of exosomes on osteoporosis.