title: Protective Effects of Cerium Oxide Nanoparticles on MC3T3-E1 Osteoblastic Cells Exposed to X-Ray Irradiation.
abstract: OBJECTIVE
  Exposure to ionizing radiation can result in bone damage, including decreased osteocyte number and suppressed osteoblastic activity. However, molecular mechanisms remain to be elucidated, and effective prevention strategies are still limited. This study was to investigate whether cerium oxide nanoparticles (CeO2 NP) can protect MC3T3-E1 osteoblast-like cells from damaging effects of X-ray irradiation, and to study the underpinning mechanism(s).
  
  
  METHODS
  MC3T3-E1, a osteoblast-like cell line, was exposed to X-ray irradiation and treated with different concentration of CeO2 nanoparticles. The micronucleus frequency was counted under a fluorescence microscope. Cell viability was evaluated using MTT assay. The effects of irradiation and CeO2 nanoparticles on alkaline phosphatase activity and MC3T3-E1 mineralization were further assayed.
  
  
  RESULTS
  We found that the ratio of micronuclei to binuclei was dose-dependently increased with X-ray irradiation (from 2 to 6 Gy), but diminished with the increased concentration of CeO2 NP treatment (from 50 to 100 nM). Exposure to X-rays (6 Gy) decreased cell viability, differentiation and the mineralization, but CeO2 NP treatment (100 nM) attenuated the deteriorative effects of irradiation. Both intracellular reactive oxygen species (ROS) production and extracellular H2O2 concentration were increased after X-ray irradiation, but reduced following CeO2 NP treatment. Similar to irradiation, exposure to H2O2 (10 µM) elevated the frequency of micronuclei and diminished cell viability and mineralization, while these changes were ameliorated following CeO2 NP treatment.
  
  
  CONCLUSIONS
  Taken together, our findings suggest that CeO2 nanoparticles exhibit astonishing protective effects on irradiation-induced osteoradionecrosis in MC3T3-E1 cells, and the protective effects appear to be mediated, at least partially, by reducing oxidative stress.
authors.forename: Cuifen
authors.initials: C
authors.lastname: Wang
authors.forename: Eric
authors.initials: E
authors.lastname: Blough
authors.forename: Xiaoniu
authors.initials: X
authors.lastname: Dai
authors.forename: Omolola
authors.initials: O
authors.lastname: Olajide
authors.forename: Henry
authors.initials: H
authors.lastname: Driscoll
authors.forename: John W
authors.initials: JW
authors.lastname: Leidy
authors.forename: Mose
authors.initials: M
authors.lastname: July
authors.forename: William E
authors.initials: WE
authors.lastname: Triest
authors.forename: Miaozong
authors.initials: M
authors.lastname: Wu
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects* / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002563:Cerium / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020011:Protective Agents / Q000737:chemistry / Q000494:pharmacology*; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D020011:Protective Agents; D017382:Reactive Oxygen Species; D002563:Cerium; C030583:ceric oxide; D006861:Hydrogen Peroxide; D000469:Alkaline Phosphatase