Increased medial TUNEL-positive staining associated with apoptotic bodies is linked to smooth muscle cell diminution during evolution of abdominal aortic aneurysms.

Apoptosis has recently been identified as an important process in large vessel structural integrity. We examined whether the size of the abdominal aortic aneurysm might be associated with programmed cell death. We performed in situ labeling of the 3' ends of DNA fragments by apoptosis-associated endonucleases in 20 aneurysms, 10 controls with aortoiliac occlusive disease, and 4 controls with healthy aortas. Antibodies against a-smooth muscle actin were used to quantify smooth muscle cell alterations in the medial layer. Inflammatory cell characterization was made by using four monoclonal mouse antibodies (UCHL1, L26, PG-M1, and KP1). The results confirm the assumption that an apoptotic process may be of consequence for the loss of medial smooth muscle cells in the early evolution of an abdominal aortic aneurysm process.