P. Dufourcq et al., PHENOTYPIC MODIFICATION OF ARTERIAL SMOOTH-MUSCLE CELLS IN RESPONSE TO MEDIAL DISSECTION, Coronary artery disease, 8(3-4), 1997, pp. 163-170
Background In the treatment of peripheral arteries, percutaneous trans
luminal angioplasty is commonly associated with intimal tears and diss
ections. Objective To investigate the influence of medial dissection o
n the remodelling of the vessel wall after balloon injury. Methods Aor
tae were obtained from 14 Fauve de Bourgogne rabbits that had been fed
a normal diet. Seven days after the initial pull-back injury, the aor
tae were examined using morphometric and immunocytochemical methods. R
esults Eight rabbits (57%) had a tear that extended into the media. Mo
rphometric measurements showed that the intima was significantly thinn
er when there was a medial dissection [(18.3 +/- 6.9) x 10(-3) versus
(39.1 +/- 3.5) x 10(-3) mm without dissection, P < 0.001]. In the medi
a of injured vessels, medial dissection was associated with a greater
accumulation of extracellular matrix proteins (50.5 +/- 9.7 versus 12.
4 +/- 2.2% of the surface area), a marked reduction in alpha-smooth mu
scle actin content (36.6 +/- 5.4 versus 47.4 +/- 7.5% of the surface a
rea), a higher expression of a smooth muscle activation antigen (21.2
+/- 5.7 versus 8.9 +/- 1.5% of the 2P1A2-immunostained surface area) a
nd an increase in the number of medial proliferating cell nuclear anti
gen-positive nuclei (8.2 versus 1.2% of labelled nuclei). Conclusion T
hese observations indicated that mechanical injury of the arterial wal
l induces a phenotypic activation of medial smooth muscle cells. In th
e case of acute distension, the response of the smooth muscle cells in
the media was mainly responsible for wound healing in the presence of
medial dissection; moreover, acute distension induced a significant h
igher state of activation and a medial repairing that could prevent mi
gration towards the intimal space. (C) Rapid Science Publishers.