Abdominal aortic aneurysm rupture is associated with increased medial neovascularization and overexpression of proangiogenic cytokines.
OBJECTIVE
Matrix metalloproteinase (MMP) activity has been linked to abdominal aortic aneurysm (AAA) rupture. Medial neovascularization (MNV), a histopathologic characteristic of AAAs, involves proteolytic degradation of extracellular matrix by MMPs to facilitate endothelial cell migration. The role of MNV in aneurysm rupture is unknown. This study investigated whether MNV is increased in aneurysm rupture.


RESULTS
Biopsy samples from aneurysm rupture edge were compared with control biopsy samples from aneurysm wall at the level of rupture and from anterior sac in 12 ruptured AAAs. Further controls were obtained from anterior sac of 10 nonruptured AAAs. MNV, microvessel diameter, maturity index, and inflammatory infiltrate were quantified using morphometric analyses following immunohistochemistry. Expression of proangiogenic mediators was quantified using quantitative real-time-polymerase chain reaction. Compared with anterior sac and aneurysm wall at level of rupture, MNV was increased (P<0.001) in rupture edge biopsy samples and consisted of smaller diameter (P<0.001) and more immature microvessels (P<0.001). mRNA expression of alpha(v)-integrin, vascular endothelial growth factor, vascular endothelial-cadherin, monocyte chemoattractant protein-1, and vimentin was increased (P<0.05) in rupture edge biopsy samples.


CONCLUSIONS
This study demonstrated increased medial neovascularization and overexpression of proangiogenic cytokines at aneurysm rupture edge. Further investigations into whether this angiogenic response was a causative factor of aneurysm rupture are needed.
Choke
Edward
E
Department of Cardiovascular Science, St George's, University of London, London SW17 0RE, UK.
Thompson
Matthew M
MM
Dawson
Joseph
J
Wilson
W Richard W
WR
Sayed
Saiqa
S
Loftus
Ian M
IM
Cockerill
Gillian W
GW
D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000150:complications*; D017544:Aortic Aneurysm, Abdominal / Q000150:complications*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000473:pathology; D039564:Integrin alphaV / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000209:etiology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D014018:Tissue Distribution; D017540:Tunica Media / Q000473:pathology*
D016207:Cytokines; D039564:Integrin alphaV