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. 2026 Jan 1;16(6):2780–2797. doi: 10.7150/thno.121905

Figure 3.

Figure 3

Dll4-Exo upregulates osteogenic differentiation and mineralization of ST2 cells. (A-B) DiD-labeled GFP-Exo or Dll4-Exo was incubated with ST2 cells and cellular uptake was monitored via fluorescence microscopy every 2 h over a 12-h period. Nuclei and exosomes were stained with DAPI (blue) and DiD (red), respectively. Scale bar = 100 μm. (C-D) ST2 cells were treated with varying concentrations of GFP-Exo or Dll4-Exo (15, 50, 75 µg/mL) or PBS (control) for 3 days, and early osteogenic differentiation was assessed using ALP staining (C) and activity assay (D). (E) qRT-PCR of osteogenic genes (Alpl, Runx2, Osx) in ST2 cells treated with PBS, GFP-Exo, or Dll4-Exo for 3 days. (F-G) ST2 cells were first treated with PBS, GFP-Exo, or Dll4-Exo for 3 days, and analyzed by (F) immunofluorescence staining of osteogenic markers (Alpl, Osx). Scale bar = 200 μm. (G) Western blot of osteogenic markers (Alpl, Osx, Runx2). (H) ARS staining and (I) quantification assay performed on day 14 after osteogenic induction. Scale bar = 200 μm. *p < 0.05, **p < 0.01, ***p < 0.001 vs. PBS control; #p < 0.05, ##p < 0.01, ###p < 0.001 vs. GFP-Exo group.