Bringing cell death alive.
The role of apoptosis in ischemia and reperfusion of the heart has been widely debated. This controversy has been continued because of the lack of an apoptosis detection method that allowed obtaining detailed kinetic and quantitative information on apoptosis. Here we focus on recent findings that look into the detection of apoptosis following ischemia and reperfusion in the heart in animal models and in patients using Annexin-A5 based image technology. Following cardiac cell damage, one major characteristic finding is that apoptotic cells express phosphatidylserines (PS) on the outer leaflet of their cell membrane, serving as a "remove me" signal for the immune system. Annexin-A5, a native plasma protein with a high affinity for PS, can be used to measure this mode of cell death. Several Annexin-A5 based imaging systems have been developed to measure apoptosis from cell culture up to patients. In this review, implications, limitations, and clinical relevance of cell death imaging will be discussed.