title: Adipose mesenchymal stromal cells response to ionizing radiation.
abstract: OBJECTIVE
  This study evaluates the biological response of adipose tissue-derived mesenchymal stromal cells (aMSCs) to ionizing radiation (IR).
  
  
  METHODS
  Irradiated BALB/c mice aMSCs were characterized for functionality and phenotype. The clonogenic capacity of irradiated aMSCs was assessed and compared with those of metastatic breast cancer cell line (4T1) and normal mouse fibroblasts (NIH3T3-wt). We investigated the IR-induced DNA damage response, apoptosis, changes in cell cycle (CC) dynamics and protein and gene expression.
  
  
  RESULTS
  Irradiated and non-irradiated aMSCs were able to differentiate into adipocytes, chondrocytes and osteocytes with no significant difference. Irradiated aMSCs maintained the expression of mesenchymal stromal cells (MSCs) surface antigens and, as expected, were negative for hematopoietic stem cells (HSCs) surface antigens when tested up to 7 days after IR for all irradiation doses with no significant difference. Clonogenically, irradiated aMSCs had higher relative survival fraction and plating efficiency than 4T1 and NIH3T3-wt. Irradiated aMSCs expressed higher □H2AX and significantly showed faster and more time-efficient IR-induced DNA damage response evident by up-regulated DNA-PKcs and RAD51. Two hours after IR, most of aMSCs DNA damage/repair-related genes showed up-regulation that disappeared within 6 h after IR. Irradiated aMSCs showed a significant rise and an earlier peak of p-ATM-dependent and -independent (p84/5E10-mediated) G2/M CC arrest compared with 4T1 and NIH3T3-wt.
  
  
  CONCLUSIONS
  After IR exposure, aMSCs showed a robust and time-efficient radiation-induced DNA damage repair response, stable phenotypical characteristics and multi-lineage differentiation potential, suggesting they may be reliable candidates for cell therapy in radiation oncology regenerative medicine.
authors.affiliation: Experimental Medicine Department, Jewish General Hospital, Montreal, Canada; Surgery Department, Faculty of Medicine, Jewish General Hospital, Montreal, Canada; Radiation Oncology Department, Jewish General Hospital, Montreal, Canada.
authors.forename: Osama Muhammad
authors.initials: OM
authors.lastname: Maria
authors.affiliation: Radiation Oncology Department, Jewish General Hospital, Montreal, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Canada; Oncology Department, McGill University, Montreal, Canada.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Kumala
authors.affiliation: Radiation Oncology Department, Jewish General Hospital, Montreal, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Canada; Human Genetics Department, McGill University, Montreal, Canada.
authors.forename: Mitra
authors.initials: M
authors.lastname: Heravi
authors.affiliation: Radiation Oncology Department, Jewish General Hospital, Montreal, Canada; Oncology Department, McGill University, Montreal, Canada; Medical Physics Unit, Jewish General Hospital, Montreal, Canada.
authors.forename: Alasdair
authors.initials: A
authors.lastname: Syme
authors.affiliation: Surgery Department, Faculty of Medicine, Jewish General Hospital, Montreal, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Canada.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Eliopoulos
authors.affiliation: Experimental Medicine Department, Jewish General Hospital, Montreal, Canada; Radiation Oncology Department, Jewish General Hospital, Montreal, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Canada; Oncology Department, McGill University, Montreal, Canada. Electronic address: tmuanza@yahoo.com.
authors.forename: Thierry
authors.initials: T
authors.lastname: Muanza
mesh_terms: D017667:Adipocytes / Q000502:physiology / Q000528:radiation effects; D000273:Adipose Tissue / Q000166:cytology* / Q000528:radiation effects; D000818:Animals; D002453:Cell Cycle / Q000528:radiation effects; D002454:Cell Differentiation / Q000502:physiology / Q000528:radiation effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000502:physiology / Q000528:radiation effects; D005260:Female; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000528:radiation effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D041681:NIH 3T3 Cells; D011839:Radiation, Ionizing; D015854:Up-Regulation / Q000528:radiation effects
keywords: DNA damage repair; G2/M arrest; adipose; cell cycle; gene expression; ionizing radiation; mesenchymal stromal cells; radiation resistance