Exosomes released from osteogenically differentiating SHEDs carry miRNAs that promote osteogenic differentiation of osteoblast precursor cells

摘要

Mesenchymal stem cells (MSC)-derived exosomes, or extracellular vesicles are cargo of mRNAs, miRNAs, and signaling proteins that promote osteogenesis and angiogenesis. Exosomes from different sources of MSCs such as bone marrow, placenta, adipose tissue, and dental tissue have differentosteogenic potential. Stem cells from human exfoliated deciduous teeth (SHEDs) are easy to obtain and highly proliferative. This study aimed to develop osteogenically functional exosomes from SHEDs for bone regenerative application. SHEDs were isolated and characterized using the established protocol, and cultured in ± osteogenic medium (OM). Exosomes were isolated from the conditioned medium by ultracentrifugation and characterized by western-blot assay (WB), nanoparticle tracking, (NPT) and transmission electron microscopy (TEM). The effect of exosomes on the osteogenic differentiation of BMSCs was extensively analyzed. The differential expression pattern of miRNAs in exosomes was analyzed by Exos MicroRNA array analysis. Differentially upregulated miRNAs in OM- exosomes were further verified by RT-qPCR. The selected significance level was Pb 0.05. We successfully isolated exosomes with the size 105nm±72nmfromSHEDs,exosomesexpressingsurfacemarkersCD9, CD63, ALIX, and TSG101. PKH26-tagged exosomes were easily uptaken by BMSCs at 4h. Exosomes from OM treatment (OM-exos) enhance BMSCs proliferation, and expression of osteogenic markers, RUNX2, ALP, and OCN at day 4 and 7 compared to exosomes from proliferation medium (PM-exos). Similarly, a higher intensity of ALP staining was observed in OM-Exos treated BMSCs. Total of 200 miRNAs were expressed in OM-Exos. Among them, 9 were upregulated, and 55 were downregulated compared to PM-exos. RT-qPCR results confirmed the higher expression of miR-122-5p (13-fold), miR486-5p (46-fold) and underexpression of miR26a-5p (4-fold), miR199a-3p (4-fold), and miR- 23b-3p (5-fold) in OM-Exos compared to PM-Exos. In conclusion, exosomes released from osteogenically differentiating SHEDs carry miRNAs that promote osteogenic differentiation of BMSCs, indicating the possible use of OM-Exos for bone tissue regeneration application.