title: In vitro effects of 0 to 120 Grays of irradiation on bone viability and release of growth factors.
abstract: BACKGROUND
  High dose radiation therapy is commonly used in maxillofacial surgeries to treat a number of head and neck tumors. Despite its widespread use, little information is available regarding the effects of irradiation on bone cell viability and release of growth factors following dose-dependent irradiation.
  
  
  METHODS
  Bone samples were collected from porcine mandibular cortical bone and irradiated at doses of 0, 7.5, 15, 30, 60 and 120 Grays. Thereafter, cell viability was quantified, and the release of growth factors including TGFβ1, BMP2, VEGF, IL1β and RANKL were investigated over time.
  
  
  RESULTS
  It was observed that at only 7.5Gy of irradiation, over 85 % of cells were non-vital and by 60 Gy, all cells underwent apoptosis. Furthermore, over a 7-fold decrease in VEGF and a 2-fold decrease in TGFβ1 were observed following irradiation at all tested doses. Little change was observed for BMP2 and IL1β whereas RANKL was significantly increased for all irradiated samples.
  
  
  CONCLUSIONS
  These results demonstrate the pronounced effects of irradiation on bone-cell vitality and subsequent release of growth factors. Interestingly, the largest observed change in gene expression was the 7-fold decrease in VEGF protein following irradiation. Future research aimed at improving our understanding of bone following irradiation is necessary to further improve future clinical treatments.
authors.affiliation: Department of Cranio Maxillofacial Surgery, Inselspital, University of Bern, Bern, Switzerland.|The Nippon Dental University, School of Life Dentistry at Niigata, Advanced Research Center, Niigata, Japan.
authors.forename: Kosaku
authors.initials: K
authors.lastname: Sawada
authors.affiliation: Department of Cranio Maxillofacial Surgery, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Masako
authors.initials: M
authors.lastname: Fujioka-Kobayashi
authors.affiliation: Department of Cranio Maxillofacial Surgery, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Eizaburo
authors.initials: E
authors.lastname: Kobayashi
authors.affiliation: Department of Radiation Oncology, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Jens O
authors.initials: JO
authors.lastname: Brömme
authors.affiliation: Department of Cranio Maxillofacial Surgery, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Benoit
authors.initials: B
authors.lastname: Schaller
authors.affiliation: Department of Oral Surgery and Stomatology, Department of Periodontology, University of Bern, Bern, Switzerland. rmiron@nova.edu.|Department of Periodontology, College of Dental Medicine, Nova Southeastern University, 3200 South University Drive, Fort Lauderdale, Florida, 33328, USA. rmiron@nova.edu.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Miron
mesh_terms: D000818:Animals; D002470:Cell Survival; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D053583:Interleukin-1beta; D008334:Mandible / Q000166:cytology* / Q000378:metabolism; D013552:Swine
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D053583:Interleukin-1beta
keywords: Bone cell death; Bone chips; Grays; Growth factor release; Irradiation