Fluorescent lifetime imaging microscopy using Europium complexes improves atherosclerotic plaques discrimination

Area of Science:

• Biomedical Optics
• Atherosclerosis Research
• Fluorescence Microscopy

Background:

• Atherosclerosis is a complex arterial disease.
• Accurate characterization of atherosclerotic plaque is crucial for diagnosis and treatment.
• Novel imaging techniques are needed to improve plaque analysis.

Purpose of the Study:

• To characterize arterial tissue with and without atherosclerosis using fluorescence lifetime imaging microscopy (FLIM).
• To evaluate the efficacy of Europium Chlortetracycline complex (EuCTc) as a fluorescent marker for plaque detection.
• To investigate the interaction of EuCTc with arterial tissue components.

Main Methods:

• Twelve rabbits were divided into control and experimental groups, fed different diets for 60 days.
• Aortic arch cryosections were stained with Europium (Eu), Chlortetracycline (CTc), EuCTc, and EuCTcMg.
• FLIM images were acquired using 405 nm excitation.

Main Results:

• Average autofluorescence lifetime in plaque depositions was ~1.36 ns.
• Incubation with EuCTc and EuCTcMg reduced plaque autofluorescence lifetimes to 0.23 ns and 0.31 ns, respectively.
• EuCTc quenched collagen, cholesterol, and triglyceride emission spectra, attributed to resonant energy transfer.

Conclusions:

• Europium Chlortetracycline complex (EuCTc) shows potential as a fluorescent marker for atherosclerosis detection.
• FLIM combined with EuCTc can effectively characterize arterial plaque by reducing autofluorescence.
• The observed quenching mechanism provides insights into plaque composition analysis.