Conclusions
Adhesion is an important determinant of cellular bioenergetics, (99m)Tc-pertechnetate uptake, and BLI signal. BLI and sodium-iodide symporter imaging may be useful for in vivo optimization of bioenergetics in transplanted cells.
Objective
The effects of cell dissociation/suspension on cellular bioenergetics and the signal obtained by firefly luciferase and human sodium-iodide symporter labeling of cardiosphere-derived cells were investigated.
Results
(18)Fluorodeoxyglucose uptake, ATP levels, (99m)Tc-pertechnetate uptake, and bioluminescence were measured in vitro in adherent and suspended cardiosphere-derived cells. In vivo dual-isotope single-photon emission computed tomography/computed tomography imaging or bioluminescence imaging (BLI) was performed 1 hour and 24 hours after cardiosphere-derived cell transplantation. Single-photon emission computed tomography quantification was performed using a phantom for signal calibration. Cell loss between 1 hour and 24 hours after transplantation was quantified by quantitative polymerase chain reaction and ex vivo luciferase assay. Cell dissociation followed by suspension for 1 hour resulted in decreased glucose uptake, cellular ATP, (99m)Tc uptake, and BLI signal by 82%, 43%, 42%, and 44%, respectively, compared with adherent cells, in vitro. In vivo (99m)Tc uptake was significantly lower at 1 hour compared with 24 hours after cell transplantation in the noninfarct (P<0.001; n=3) and infarct (P<0.001; n=4) models, despite significant cell loss during this period. The in vivo BLI signal was significantly higher at 1 hour than at 24 hours (P<0.01), with the BLI signal being higher when cardiosphere-derived cells were suspended in glucose-containing medium compared with saline (PBS). Conclusions: Adhesion is an important determinant of cellular bioenergetics, (99m)Tc-pertechnetate uptake, and BLI signal. BLI and sodium-iodide symporter imaging may be useful for in vivo optimization of bioenergetics in transplanted cells.