In vitro photodynamic diagnosis of atherosclerotic wall changes with the use of mono-l-aspartyl chlorin e6. A preliminary report.

BACKGROUND

Although several methods for atherosclerosis detection are available, none of them seems to be accurate enough to identify the vulnerable atheromatous plaque. Photodynamic diagnosis (PDD) and therapy (PDT) - a new method evaluated for neoplasm treatment, is a modern approach for detecting and treating atherosclerosis.

AIM

To asses in vitro the capability of PDD with the use of chlorin e6 to detect atherosclerotic plaque and the usefulness of this method as a feedback system for photoangioplasty treatment.

METHODS

30 specimens of human aorta and 15 specimens of human coronary arteries were examined. The samples were soaked with chlorin e6 and then washed out. The luminescence spectra were then collected. All samples were examined with light microscopy.

RESULTS

Tissue fluorescence is seen as green light. We noted a very strong red fluorescence of chlorin e6 originating from lipid-rich plaque. We established a quantitative factor (R) which is the ratio of chlorin e6 red intensity in its 660 nm maximum to the area of green luminescence centred at 515 nm. The highest value of R was reached at the atheromatous samples, followed by calcified and normal ones R(2)=3.51+/-0.62, R(3)=1.63+/-0.31, and R(1)=1.51+/-0.15, respectively. A statistically significant difference was noted between groups two and one, and between groups two and three (R(2)=3.51+/-0.62 vs. R(3)=1.63+/-0.31, p<0.05; and R(2)=3.51+/-0.62 vs. R(1)=1.51+/-0.15, p<0.05, respectively).

CONCLUSIONS

This in vitro study confirms that photosensitiser chlorin e6 accumulates within atheromatous plaque. It may be a specific tool for atheromatous and normal or calcified segments discrimination. The advantage of the above method is the possibility of a real-time imaging followed by targeted therapy of various forms and stages of atherosclerosis.