Functional gap junction mediated MSC- cardiac myocyte communication in QD labeled MSC. Fluorescence recovery in calcein labeled co-culture with QD labeled MSC (noted by dashed white border and arrow) adjacent to myocytes, a. before photobleach b. immediately after photobleach and c. 5 min. after photobleach. d. Corresponding graph illustrating average fluorescence recovery time (n = 6). Scale bar = 20 μm.