AORTIC VASCULAR SMOOTH MUCLE CELL APOPTOSIS IN PATIENTS WITH TYPE-A AORTIC DISSECTION

Methods: Between November/2002 and January/2005, full-thickness aortic wall specimens were obtained from 10 patients undergoing elective surgical repair of TypeA-AD (age:53.3±13.1, 7M/3F, duration of dissection: 18.1_16.8 days) and 10 patients undergoing coronary artery bypass grafting (CABG) used as a control preparations (mean age: 64.3±6.6, 7M/3F). All tissue samples collected at the time of operation were submitted to analysis of VSMC apoptosis by using in situ end-labelling of DNAfragments (TUNEL). Furthermore the expression of Bak, Bax, Bcl-2, and Bcl- XL proteins which are responsible from the regulation of apoptosis were also investigated by using immunohistochemical staining.

Results: Segments from TypeA-AD patients exhibited the onset of apoptosis s which were identified by specific in situ endlabelling of DNA-fragments (TUNEL). Proapoptotic Bak protein expression was significantly increased in type A-AD patients when compared to that of aortic segments from the patients undergoing CABG whereas antiapoptotic Bcl-2 protein expression was predominantly observed in the CABG group.

Conclusions: Increased Bak protein expression observed in patients with Type-A AD may suggest that these VSMCs are more vulnerable to apoptosis due to the proapoptotic effects of circumferential overload. Therefore, the regulation of Bcl-2 gene family member proteins may have a therapeutic and prognostic role in TypeA-AD. (Turkish J Vasc Surg 2005;14(2): 25-30).