Effect of QD labeling on apoptotic cell death in Control and QD labeled MSCs. Flow cytometry results at 24, 72 and 120 hrs after QD labeling. The percent of annexin positive QD labeled MSCs was similar for HC, LC and Control MSCs at 24 hrs post labeling. Increased apoptosis was observed in HC vs. Control MSCs at 120 hrs (*p < 0.05). No difference in apoptosis was detected in LC vs. Control MSCs.