Structural features of cell death in atherosclerotic lesions affecting long-term aortocoronary saphenous vein bypass grafts.
Aortocoronary saphenous vein bypass grafts fail because of structural pathologies (thrombosis, intimal hyperplasia and atherosclerosis) within the 'arterialized' vein leading to graft stenosis. This study examined structural characteristics of atherosclerotic alterations in long-term aortocoronary artery saphenous vein bypass grafts with particular attention to the features of cell death in atherosclerotic lesions. Stenotic vein grafts were obtained from 10 patients at redo coronary artery bypass grafting operations. All the grafts were affected by histological abnormalities, with eight out of ten grafts showing evidence of atherosclerotic alterations in the intimal hyperplastic layer. Areas containing foam cells were examined by electron microscopy. Cells with cytoplasmic lipid accumulations were characterized by varying degrees of chromatin condensation, fragmentation or dispersion, by focal areas of oedema and vacuolisation of their cytoplasm, and by plasmalemmal destruction. Some lipid-filled cells exhibiting signs of destruction contained myofilaments and basal membrane fragments, allowing them to be identified as smooth muscle cells. Macrophage foam cells were found to have undergone similar destruction. No cells showing nuclear degeneration were observed to have intact cytoplasmic organelles. Neither were apoptotic bodies identified, but necrotic remnants were frequently seen. The results suggest that cell death in atherosclerotic lesions affecting aortocoronary artery saphenous vein bypass grafts occurs through oncosis rather than by apoptosis.
Wang
A Y
AY
Surgical Professorial Unit, St. Vincent's Hospital, Darlinghurst, NSW, Australia.
Bobryshev
Y V
YV
Cherian
S M
SM
Liang
H
H
Inder
S J
SJ
Lord
R S
RS
Ashwell
K W
KW
Farnsworth
A E
AE
D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000473:pathology*; D016923:Cell Death; D001026:Coronary Artery Bypass / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D012501:Saphenous Vein / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D013997:Time Factors