Fig. 2.
The effect of spheroid size on exosome secretion from hBM-MSCs. A Schematic illustration of the experimental groups. hBM-MSCs were cultured at four different densities. 3D-HD (1 × 104, 2.5 × 104, 1 × 104, and 2.5 × 104 per drop) or 3D-PH (1.4 × 104, 3.5 × 104, 1.4 × 104, and 3.5 × 104 per 96-well). B Gross morphology of 3D-HD-MSCs and 3D-PH-MSCs at 3 days after culture. Scale bar: 500 μm. C Size of spheroids was shown for 3D-HD-MSCs and 3D-PH-MSCs at 3 days. The area of the spheroids’ cross-sections was quantified using image J analysis from the bright-field images. D The production efficiency of exosomes derived from 3D-HD and 3D-PH culture. The amounts of exosomes obtained from 1 × 105 cells are presented for each group. Data are presented as the mean and SD from three independent experiments in C and D. *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 by one-way ANOVA. ***** 3D: three-dimensional, hBM-MSCs: human bone marrow-mesenchymal stem cells, 3D-HD: 3D spheroids formed by the hanging drop method, 3DPH: 3D spheroids formed by the poly-HEMA coating method, ANOVA: analysis of variance