title: 99m-Technetium binding site in bone marrow mononuclear cells.
abstract: BACKGROUND
  The increasing interest in 99m-technetium ((99m)Tc)-labeled stem cells encouraged us to study the (99m)Tc binding sites in stem cell compartments.
  
  
  METHODS
  Bone marrow mononuclear cells were collected from femurs and tibia of rats. Cells were labeled with (99m)Tc by a direct method, in which reduced molecules react with (99m)Tc with the use of chelating agents, and lysed carefully in an ultrasonic apparatus. The organelles were separated by means of differential centrifugation. At the end of this procedure, supernatants and pellets were counted, and the percentages of radioactivity (in megabecquerels) bound to the different cellular fractions were determined. Percentages were calculated by dividing the radioactivity in each fraction by total radioactivity in the sample. The pellets were separated and characterized by their morphology on electron microscopy.
  
  
  RESULTS
  The labeling procedure did not affect viability of bone marrow mononuclear cells. Radioactivity distributions in bone marrow mononuclear cell organelles, obtained in five independent experiments, were approximately 38.5 % in the nuclei-rich fraction, 5.3 % in the mitochondria-rich fraction, 2.2 % in microsomes, and 54 % in the cytosol. Our results showed that most of the radioactivity remained in the cytosol; therefore, this is an intracellular labeling procedure that has ribosomes unbound to membrane and soluble molecules as targets. However, approximately 39 % of the radioactivity remained bound to the nuclei-rich fraction. To confirm that cell disruption and organelle separation were efficient, transmission electron microscopy assays of all pellets were performed.
  
  
  CONCLUSIONS
  Our results showed that most of the radioactivity was present in the cytosol fraction. More studies to elucidate the mechanisms involved in the cellular uptake of (99m)Tc in bone marrow cells are ongoing.
authors.affiliation: Laboratório de Cardiologia Celular e Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Av. Carlos Chagas Filho, 373, Bloco G. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-902, Brasil. grazisuhett@gmail.com.
authors.forename: Grazielle Dias
authors.initials: GD
authors.lastname: Suhett
authors.affiliation: Departamento de Radiologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rua Prof. Rodolpho Paulo Rocco, 255. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-913, Brasil. sergioalsouza@gmail.com.
authors.forename: Sergio Augusto Lopes
authors.initials: SA
authors.lastname: de Souza
authors.affiliation: Laboratório de Cardiologia Celular e Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Av. Carlos Chagas Filho, 373, Bloco G. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-902, Brasil. carvalhoab@gmail.com.
authors.forename: Adriana Bastos
authors.initials: AB
authors.lastname: Carvalho
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Av. Carlos Chagas Filho, 373, Bloco G. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-902, Brasil. narcisacunha@gmail.com.
authors.forename: Rachel
authors.initials: R
authors.lastname: de Pinho Rachid
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Av. Carlos Chagas Filho, 373, Bloco G. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-902, Brasil. rachel.rachid@yahoo.com.br.
authors.forename: Narcisa Leal
authors.initials: NL
authors.lastname: da Cunha-E-Silva
authors.affiliation: Laboratório de Cardiologia Celular e Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Av. Carlos Chagas Filho, 373, Bloco G. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-902, Brasil. camposcarvalho@me.com.
authors.forename: Antonio Carlos Campos
authors.initials: AC
authors.lastname: de Carvalho
authors.affiliation: Departamento de Radiologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rua Prof. Rodolpho Paulo Rocco, 255. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-913, Brasil. leamirianbf@gmail.com.
authors.forename: Lea Mirian Barbosa
authors.initials: LM
authors.lastname: da Fonseca
authors.affiliation: Laboratório de Cardiologia Celular e Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Av. Carlos Chagas Filho, 373, Bloco G. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-902, Brasil. rcsgoldenberg@hotmail.com.
authors.forename: Regina Coeli
authors.initials: RC
authors.lastname: dos Santos Goldenberg
authors.affiliation: Departamento de Radiologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rua Prof. Rodolpho Paulo Rocco, 255. Ilha do Fundão, Cidade Universitária, Rio de Janeiro, 21941-913, Brasil. bianca.gutfilen@gmail.com.
authors.forename: Bianca
authors.initials: B
authors.lastname: Gutfilen
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D002469:Cell Separation; D002478:Cells, Cultured; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D005269:Femur / Q000166:cytology; D046529:Microscopy, Electron, Transmission; D051381:Rats; D017208:Rats, Wistar; D013670:Sodium Pertechnetate Tc 99m / Q000737:chemistry* / Q000378:metabolism; D013977:Tibia / Q000166:cytology
chemical_list: D013670:Sodium Pertechnetate Tc 99m