SMOOTH-MUSCLE CELL-MIGRATION AND PROLIFERATION IS ENHANCED IN ABDOMINAL AORTIC-ANEURYSMS

Background: The aetiology of abdominal aortic aneurysms (AAA) is as ye t undetermined. Smooth muscle cells (SMC) have been implicated in the pathogenesis of AAA as a result of their ability to produce elastin de grading proteases. The present study was undertaken to examine AAA SMC and aortic occlusive disease (AOD) SMC in terms of their respective m igration and proliferation in vitro, in order to identify intrinsic di fferences between these cells. Methods: Five AAA specimens, four AOD a nd five inferior mesenteric artery (IMA) specimens were established in culture. The cultures were examined for the extent and the rate of SM C outgrowth and proliferation. Cells were counted following trypsiniza tion using a haemocytometer. Results: For the AAA explants, the cellul ar outgrowths were first seen at 6.7 days, after culture initiation, w hile the corresponding outgrowth in the AOD group required 8.8 days (P < 0.05) and the IMA group 11.4 days (P < 0.05). AAA cells reached con fluency at a mean of 22.4 days while AOD SMC required 28.6 days (P < 0 .05) and IMA 31 days (P < 0.05). In the first passage, the time for AA A SMC doubling was 5.3 days compared to 6.2 days for AOD (P < 0.05) an d 8.1 days for the IMA group (P < 0.05). Greater than 98% of the cells , in both groups, stained positive to SMC alpha-actin. Conclusion: Fro m these data it is clear that there are intrinsic differences in cellu lar kinetics between SMC from the two disease states, supporting the h ypothesis that AAA are nor the result of atherosclerosis.