Background. The purpose of this study was to determine the correlation
between progression and regression of myointimal hyperplasia (MH) and
cytokine production in experimental vein grafts. Although the autolog
ous vein is the best suitable bypass conduit for reconstruction of per
ipheral arteries, at the end of the first year thrombosis in the coron
ary and lower extremity circulation ranges from 20% to 50%. Many of th
ese failures are caused by MH. Methods. In 76 inbred Lewis rats, a 1 c
m long segment of inferior vena cava was inserted at the level of the
abdominal aorta. The segments of inferior vena cava were obtained from
syngeneic Lewis rats. In 56 animals the arterial vein graft was expla
nted 3 days (n = 10), 7 days (n = 10), 4 weeks (n = 26), and 12 weeks
(n = 10) after operation. In 20 animals the vein graft was explanted 4
weeks after being in the arterial system and reimplanted as iliac ven
ovenous bypass in syngeneic Lewis rats. These grafts were explanted 2
weeks (n = 10) and 8 weeks (n = 10) later Grafts were analyzed by ligh
t and electron microscopy, morphometric study, and histochemical analy
sis an were put in an organ culture to assess cytokine production. Res
ults. We observed MH formation in arterial vein grafts and MH regressi
on in reimplanted vein grafts (p < 0.001). MH formation was correlated
with production of platelet-derived growth factor; basic fibroblast g
rowth factor interleukin-1, and tumor necrosis factor-alpha. MH regres
sion was correlated with transforming growth factor-beta(1) production
. Conclusions. On the basis of the results of our study, we conclude t
hat MH formation in experimental vein grafts depends on production of
platelet-derived growth factor basic fibroblast growth factor, interle
ukin-1, and tumor necrosis factor-alpha, and MH regression depends on
transforming growth factor-beta(1) production. Cytokine therapy may re
present a valuable new treatment to prevent vein bypass failures cause
d by MH.