title: Oxidative stress as a component of chromium-induced cytotoxicity in rat calvarial osteoblasts.
abstract: It has been documented that medical prosthetic alloys release metal ions into surrounding tissues and cause cytotoxicity, but the mechanisms remain undefined. In that regard the cellular oxidative stress may be a common pathway in cellular responses to metal ions. The objective of this study was to approach the hypothesis that oxidative stress mediates chromium-induced cytotoxicity in rat calvarial osteoblasts. Osteoblasts were exposed to different concentrations of Cr6+ or Cr3+ (5-20 microM) in the presence or absence of the antioxidant N-acetyl-cysteine (NAC; 1-5 mM). Cellular viability, differentiation, and intracellular ultrastructural alterations were evaluated by MTT assay, alkaline phosphatase (ALP) activity assay, and transmission electron microscopy. Cellular oxidative stress was evaluated by intracellular reactive oxygen species (ROS) production. ROS production was monitored by the oxidation-sensitive fluorescent probe 2'7'-dichlorofluorescin diacetate (DCFH-DA). A time- and concentration- dependent increased cytotoxicity, time-dependent increased intracellular ROS production were indicated on exposure to Cr6+. Pretreatment of osteoblasts with 1-5 mM NAC afforded dose-dependent cytoprotective effects against Cr6+-induced cytotoxicity in osteoblasts. NAC decreased the level of intracellular ROS induced by Cr6+, too. While Cr3+ and NAC did not have any significant effects on osteoblasts (5-20 microM). These results suggest that oxidative stress is involved in Cr6+-induced cytotoxicity in osteoblasts, and NAC can provide protection for osteoblasts against Cr6+-induced oxidative stress. Cr3+ (5-20 microM) have no significant cytotoxicity in osteoblasts based on the results of this study.
authors.affiliation: Key Laboratory of Oral Biomedical Engineering of Chinese Ministry of Education, West China College of Stomatology, Sichuan University, Chengdu, Sichuan 610041, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fu
authors.forename: Xing
authors.initials: X
authors.lastname: Liang
authors.forename: Yue
authors.initials: Y
authors.lastname: Chen
authors.forename: Li
authors.initials: L
authors.lastname: Tang
authors.forename: Qing-hong
authors.initials: QH
authors.lastname: Zhang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Dong
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002857:Chromium / Q000633:toxicity*; D008297:Male; D046529:Microscopy, Electron, Transmission; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D002857:Chromium; D000469:Alkaline Phosphatase; D000111:Acetylcysteine