title: Repair of gamma-irradiation-induced DNA single-strand breaks in human bone marrow cells: analysis of unfractionated and CD34+ cells using single-cell gel electrophoresis.
abstract: Human bone marrow mononuclear cells (BMMNCs) were separated by density gradient centrifugation, and a subpopulation of progenitor cells was further isolated using anti-CD34-coated magnetic beads. The cells were irradiated with gamma-rays (0.93-5.43 Gy) from a 137Cs source. The extent of DNA damage, i.e., single-strand breaks (SSBs) and alkali-labile lesions of individual cells, was investigated using the alkaline single-cell gel electrophoresis technique. The irradiation resulted in a dose-dependent increase in DNA migration, reflecting the number of detectable DNA lesions. An approximately similar extent of SSB formation was observed in BMMNCs and CD34 + cells. Damage was repaired when the cells were incubated at 37 degrees C: a fast initial repair phase was followed by a slower rejoining of SSBs in both BMMNC and CD34 + cell populations. A significantly longer time was required to repair the lesions caused by 5.43 Gy than those caused by 0.93 Gy. In the present work we report, for the first time, the induction and repair of DNA SSBs at the level of single human bone marrow cells when exposed to ionizing radiation at clinically relevant doses. These data, together with our previous results with human blood granulocytes and lymphocytes, indicate an approximately similar extent of formation and repair of gamma-irradiation-induced DNA SSBs in immature and mature human hematopoietic cells.
authors.affiliation: Department of Clinical Chemistry, Tampere University Hospital, Finland.
authors.forename: M H
authors.initials: MH
authors.lastname: Lankinen
authors.forename: J A
authors.initials: JA
authors.lastname: Vilpo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000528:radiation effects*; D001853:Bone Marrow / Q000502:physiology / Q000528:radiation effects*; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004586:Electrophoresis / Q000379:methods*; D005720:Gamma Rays; D006098:Granulocytes / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D008214:Lymphocytes / Q000502:physiology / Q000528:radiation effects; D008875:Middle Aged; D013234:Stem Cells / Q000502:physiology / Q000528:radiation effects
chemical_list: D018952:Antigens, CD34; D004277:DNA, Single-Stranded