Biphasic pattern of cell turnover characterizes the progression from fatty streaks to ruptured human atherosclerotic plaques.
OBJECTIVE
To study the amount and phenotype of DNA-synthesizing and apoptotic cells during atherogenesis.


METHODS
Atherosclerotic lesions (n = 76), obtained at autopsy (N = 6) or during vascular surgery (N = 8), were classified [type I-VI; American Heart Association (AHA) classification], immunolabeled with MIB 1 or the TUNEL technique and double stained with cell-type-specific antibodies. Subsequently, the labeled fractions were quantified.


RESULTS
In type II-VI lesions, intimal DNA synthesis was increased compared to that of the non-diseased (ND) arterial wall. DNA synthesis peaked in early type II lesions (2.7 +/- 0.5 vs. 0.02 +/- 0.02% in ND; p < 0.05), and declined to 0.7 +/- 0.2% in type V lesions (p < 0.05). Interestingly, a second peak of DNA synthesis of 1.7 +/- 0.1%, was observed in type VI (ruptured plaque) lesions. Double staining revealed that DNA synthesis was mostly confined to the macrophage-derived foam cell (51.9%). In type II lesions, 100.0% of all DNA-synthesizing cells were present in the intimal foam cell-rich area, while in advanced type III, IV and V lesions, DNA synthesis had shifted to the shoulder region (74.8, 78.5 and 68.1%, respectively). In type VI lesions, DNA synthesis was present in the area underlying the plaque rupture (52.7%). Apoptosis was only elevated in advanced type IV, V and VI lesions (0.8 +/- 0.1, 0.8 +/- 0.1 and 1.1 +/- 0.1%, respectively, vs. 0.0 +/- 0.0% in ND) and was predominant in the lipid core (90.5% in type IV lesions; 54.2% in type V lesions) or equally divided between the lipid core and the region underlying the plaque rupture (31.8 and 34.6% in type VI lesions). In type III-VI lesions, 50.0, 38.9, 42.6 and 42.8% of the TUNEL-positive cells were macrophages.


CONCLUSIONS
In stable atherosclerotic lesions, DNA synthesis is an early event, while apoptosis is a late event. Ruptured plaques show a second peak of cell turnover. Lastly, cell turnover is mostly confined to the macrophage-derived foam cell.
Lutgens
E
E
Department of Cardiology, University of Maastricht, Netherlands.
de Muinck
E D
ED
Kitslaar
P J
PJ
Tordoir
J H
JH
Wellens
H J
HJ
Daemen
M J
MJ
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D017209:Apoptosis; D001161:Arteriosclerosis / Q000473:pathology*; D002455:Cell Division; D004247:DNA / Q000096:biosynthesis; D005260:Female; D005487:Foam Cells / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D013997:Time Factors; D017539:Tunica Intima / Q000473:pathology*
D004247:DNA