Fig. 4

miR-26a-CD34⁺-Exos promote osteogenic activity of BMSCs in vitro. a Uptake of CD34⁺-Exos and miR-26a- CD34⁺-Exos shown by fluorescence microscopy. The PKH26 red-labeled Exos were localized in the perinuclear region of BMSCs. Scale bar: 200 μm. b The proliferative effects of different treatments on BMSCs were measured using a CCK-8 kit. c Expression of ALP was determined by ALP staining in different groups. Scale bar: 100 μm. d Quantitative analysis of ALP activity. The ratio of the area of ALP staining to total area was measured. e Formation of calcium nodules was analyzed by Alizarin red staining in the different groups. Scale bar: 100 μm. f Quantitative analysis of Alizarin red staining. The ratio of the area of Alizarin red staining to total area was measured. g The expression levels of osteogenesis-related genes including ALP, RUNX2, and COL I were evaluated by qPCR in the different groups. *P < 0.05, **P < 0.01