Zn(II)-bis(cyclen) complexes and the imaging of apoptosis/necrosis.

In vivo cell-death imaging is still a challenging issue. Until now, only (99m)Tc-labeled HYNIC-rh-annexin A5 has been extensively studied in clinical trials. In the ongoing search for an alternative imaging agent, we synthesized a series of fluorescent zinc-cyclen complexes as annexin A5 mimics and studied structural variations on the uptake behavior of cells undergoing apoptosis/necrosis.

131I-labeled peptides as caspase substrates for apoptosis imaging.

Unlabelled: Nonivasive assessment of programmed cell death is currently an attractive research topic for the follow-up of tumor therapy and myocardial infarction. Apoptosis imaging with (99m)Tc-HYNIC-annexin V (HYNIC is hydrazinonicotinamide) is based on the binding of the tracer to externalized phosphatidylserine residues. Concurrently with the externalization of phosphatidylserine, a series of caspases are activated after the onset of apoptosis.