Low-dose irradiation stimulates TNF-alpha-induced ICAM-1 mRNA expression in human coronary vascular cells.
BACKGROUND
Low-dose irradiation (LDI) is employed to extend the irradiation area in vascular brachytherapy to minimize the edge effect. Stimulation of adhesion molecule 1 (ICAM-1) is one of many mechanisms important in the early stages of atherosclerosis and restenosis. This study investigates the effect of gamma-irradiation on mRNA expression of ICAM-1 in human coronary vascular cells.


METHODS
Human coronary endothelial cells (HCAECs), human umbilical endothelial cells (HUVECs), and human coronary smooth muscle cells (HCMSMCs) were cultured and identified. Twenty-four hours after seeding, gamma-irradiation at doses of 0.5 Gy, 1 Gy, 10 Gy, 20 Gy, and 30 Gy (Linac Philips FL 75/20) was carried out. Twenty hours after irradiation, ICAM-1 expression was stimulated for 6 h with TNF-alpha (20 ng/ml). In Northern blot assays, 10 microg of RNA were used. The relative band density of ICAM-1 mRNA of irradiated and stimulated cells were compared with that of non-irradiated cells after TNF-alpha stimulus only.


RESULTS
In HCAECs and HCMSMCs, stimulation of ICAM-1 mRNA was detected after irradiation, no matter which dose was applied. After low-dose irradiation (0.5 Gy and 1 Gy) the stimulating effect was pronounced, significant differences being found in HCAECs after irradiation with 1 Gy.


CONCLUSIONS
Stimulation of ICAM-1 mRNA expression after LDI of human coronary vascular cells may be one of the many mechanisms that trigger the edge effect in vivo. If these results are confirmed by further studies and if anti-inflammatory treatment strategies cannot inhibit the stimulatory effects, a major problem exists for the future of vascular brachytherapy.
Voisard
Rainer
R
Department of Internal Medicine II - Cardiology, University of Ulm, Ulm, Germany. rainer.voisard@uni-ulm.de
Wiegmann
Dirk
D
Baur
Regine
R
Hombach
Vinzenz
V
Kamenz
Joachim
J
D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D005720:Gamma Rays; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D012333:RNA, Messenger / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1