Increased apoptosis and decreased density of medial smooth muscle cells in human abdominal aortic aneurysms

摘要

Objective To determine the increase of apoptosis and the decrease of smooth muscle cells (SMCs) density in human abdominal aortic aneurysms (AAA). Methods In situ terminal transferase-mediated dUTP nick end labeling (TUNEL) was employed to detect apoptosis of SMCs in patients with AAA (n = 25) and normal abdominal aortae (n = 10). Positive cells were identified by specific cell marker in combination with immunohistochemistry. Meanwhile SMC counting was performed by anti-α-actin immunohistostaining to compare the SMC density. Results TUNEL staining revealed that there was significantly increased apoptosis in AAAs (average 8.6%) compared with normal abdominal aortae (average 0.95%, P < 0.01). Double staining showed that most of these cells were SMCs. Counting of α-actin positive SMCs revealed that medial SMC density of AAAs (37.5 +- 7.6 SMCs/HPF) was reduced by 79.1% in comparison with that of normal abdominal aortae (179.2 +- 16.1 SMCs/HPF, P<0.01). Conclusions Significantly increased SMCs of AAA bear apoptotic markers initiating cell death. Elevated apoptosis may result in a decreased density of SMCs in AAA, which may profoundly influence the development of AAA.