EFFECTS OF ULTRAVIOLET-LIGHT IN VASCULAR CELLS IN-VITRO AND IN INTACTATHEROSCLEROTIC EXPLANTS - POTENTIAL ROLE OF APOPTOSIS IN VASCULAR BIOLOGY

Complex cell-to-cell interactions are known to participate during vasc ular injury and remodeling, resulting in smooth muscle cell proliferat ion. Mechanical interventions have yielded little benefit in limiting this process and several site-specific genetic therapies are not yet c linically available. The aim of this study was to delineate the effect of very short wavelength ultraviolet (UVC) light therapy on the viabi lity of macrophage and smooth muscle cells. Vascular cells were both t reated in vitro and in intact explanted atherosclerotic aortic segment s ex vivo with WC light. Brief exposure to short wavelength WC light i n the absence of photosensitizers elicited a differential temporal and functional response among treated cells. However, dramatic reduction in both cellular viability and proliferative capacity with eventual ce ll demise was observed in all WC-treated cells. Flow cytometry and imm unohistochemical analyses revealed the presence of extensive DNA fragm entation, suggestive of apoptosis as a predominant pathway of cell dea th in these cells exposed to UVC light. We hypothesize that selective induction of apoptosis, in contrast to necrosis, with WC light may rep resent a beneficial approach to interdict the complex biologic cascade of messengers that participate in the restenotic response to vascular injury.