Imaging of lysophosphatidylcholine in human coronary plaques by color fluorescence angioscopy

Lysophosphatidylcholine (LPC) is a proinflammatory and proatherogenic substance, and it plays an important role in the initiation, progression, and destabilization of atherosclerotic plaques. If LPC in the vascular wall is visualized in vivo, the mechanisms of atherosclerosis and the effects of medical and interventional therapies on atherosclerosis can be objectively evaluated. Therefore, this study was carried out to visualize LPC in human coronary plaques using a color fluorescence angioscopy (CFA) system. (1) The fluorescence characteristics of LPC were investigated by color fluorescence microscopy (CFM) using Trypan blue dye (TB) as an indicator. For fluorescence imaging, a combination of a band-pass filter (345 nm) and a band-absorption filter of 420 nm (A imaging), or a combination of a band-pass filter (470 nm) and a band-absorption filter of 520 nm (B imaging) was employed. (2) The fluorescence of LPC in the excised human coronary plaques was investigated by CFA and CFM scanning using the same filters as those in CFM. In the presence of TB, LPC exhibited a red fluorescence in both A and B imaging. This red fluorescence color in both A and B imaging was not observed for the other known major substances that constitute the atherosclerotic plaques. This red fluorescence color in both A and B imaging was detected by CFA in both white and yellow plaques that were classified by conventional angioscopy. This fluorescence color was found to be distributed in a web-like or diffuse configuration by CFM scanning. LPC in the human coronary plaques was successfully visualized by CFA using TB as an indicator.