Silica nanoparticles are internalized without affecting cell morphology. Silica nanoparticles were internalized after 4 h of incubation with canine ATMSCs and UCBMSCs (c, h). Labeled canine MSCs (c, d) spread well on the dish, and showed fibroblastoid and spindle shapes. No notable differences in morphology were observed compared with that of unlabeled canine MSCs (a, b). Magnification, ×400.