Targeting of experimentally induced atherosclerotic lesions by liposome-delivered Zn(II)-phthalocyanine.

Zn(II)-Phthalocyanine (Zn-Pc) is an exogenously administrable dye which is accumulated by tumors and other rapidly proliferating tissues. This property could be used for visualising atherosclerotic plaques. In order to define the feasibility and the optimal conditions for in vivo labelling of atheroma, we evaluated the ability of Zn-PC to be accumulated by experimentally induced atherosclerotic lesions in rabbits. We also performed pharmacokinetic investigations to assess photosensitizer delivery system, difference in phthalocyanine concentration between normal and atherosclerotic vessels, and the time interval after administration, which yields a large difference between normal and diseased vessels. We observed a preferential accumulation of Zn-Pc by atherosclerotic lesions which accumulated about a tenfold larger amount of photosensitizer, and the retention of significant amounts for prolonged periods. Zn-Pc can be considered as a potentially useful fluorescence marker for atheroma. The feasibility of photodiagnosis and phototherapy of atheroma deserves further investigation.