title: Effects of single and fractionated low-dose irradiation on vascular endothelial cells.
abstract: OBJECTIVE
  An increasing number of epidemiological studies suggest that chronic low-dose irradiation increases the risk of atherosclerosis. We evaluated and compared the in vitro biological effects of both single and fractionated low-doses of X-ray irradiation on endothelial cells.
  
  
  METHODS
  Human umbilical vein endothelial cells (HUVECs) were irradiated with X-rays, with single doses of 0.125, 0.25 and 0.5 Gy or fractionated doses of 2 × 0.125 Gy and 2 × 0.25 Gy, with 24 h interfraction interval. Survival, apoptosis, reactive oxygen species (ROS) production, nuclear factor-κB (NF-κB) activation, intercellular adhesion molecule-1 (ICAM-1) expression, HUVEC adhesiveness and DNA damage were investigated.
  
  
  RESULTS
  We did not observe any effect on viability and apoptosis. Both single and fractionated doses induced ROS generation, NF-κB activation, ICAM-1 protein expression and HUVEC adhesiveness, but only fractionated doses increase significantly ICAM-1 mRNA. The effects measured after fractionated dose result always higher than those induced by the single dose. Moreover, we observed that DNA double strand break (DSB), visualized with γ-H2AX foci, is dose-dependent and that the kinetics of γ-H2AX foci is not affected by fractionated doses.
  
  
  CONCLUSIONS
  We showed that single and fractionated low-dose irradiations with low energy X-rays do not affect cell viability and DNA repair. Interestingly, the greater increase of ICAM-1 surface exposure and endothelial adhesiveness observed after fractionated irradiation, suggests that fractionated low-doses may accelerate chronic vascular inflammation, from which the atherosclerotic process can arise.
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy. Electronic address: tizicerv@ifc.cnr.it.
authors: Tiziana
authors: T
authors: Cervelli
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Daniele
authors: D
authors: Panetta
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Teresa
authors: T
authors: Navarra
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Maria Grazia
authors: MG
authors: Andreassi
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Giuseppina
authors: G
authors: Basta
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Alvaro
authors: A
authors: Galli
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Piero A
authors: PA
authors: Salvadori
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Eugenio
authors: E
authors: Picano
authors: CNR, Institute of Clinical Physiology, San Cataldo Research Area, Via Moruzzi, 1, 56124 Pisa, Italy.
authors: Serena
authors: S
authors: Del Turco
mesh_terms: D002448:Cell Adhesion / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair; D019583:Dose Fractionation, Radiation; D042783:Endothelial Cells / Q000528:radiation effects*; D004730:Endothelium, Vascular / Q000528:radiation effects*; D061307:Human Umbilical Vein Endothelial Cells / Q000528:radiation effects; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014965:X-Rays
chemical_list: D016328:NF-kappa B; D017382:Reactive Oxygen Species; D018799:Intercellular Adhesion Molecule-1
keywords: DNA double strand break; HUVECs; ICAM-1; Inflammation; Low-dose irradiation