Comparison of adipogenic differentiation between labeled and unlabeled canine MSCs. UCBMSCs and ATMSCs were cultured in adipogenic differentiation medium for 21 days. Cells were then stained with oil red O. Red lipid droplets were visible in UCBMSCs and ATMSCs, indicating adipogenic differentiation. Adipogenic differentiation was not inhibited by silica nanoparticle labeling as compared with that of unlabeled cells. Magnification, ×200.