Imaging of acute heart-transplant rejection using 99m-Technetium labelled oligonucleotides against interleukin-2 mRNA in rats☆

Objectives: Today, acute cardiac rejection is detected by endomyocardial biopsy, which harbours many risks. Thus, there is a necessity for less invasive methods. Since interleukin-2 (IL2) is over-expressed in acute graft rejection, we use radioactive DNA-fragments complementary to the mRNA of IL2 to detect graft rejection scintigraphically. Methods: In a rat model of acute graft rejection, the oligonucleotide sequence complementary to the mRNA of IL2 is labelled with 99m-Technetium and injected intravenously. Scintigraphic and Geiger-counter activity of the transplants are evaluated and correlated with the current rejection classification of the International Society for Heart and Lung Transplantation (ISHLT). Results: From the fourth postoperative day onwards, the scintigraphic images show a significant increase of radioactivity (p < 0.05) in the rejectedorgans thanin theacceptedgrafts. Whilescintigraphyis not significantlycorrelated with thestandardrejectionsclassification ofthe ISHLT,thereissignificantcorrelationbetweentheISHLTclassificationandradioactivityintheGeiger-counteranalysis.Conclusions:Radioactively labelled anti-sense-oligonucleotides against mRNA of IL2 may be a promising approach for the detection of acute transplant rejection in vivo. # 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.