title: Hyperplasiavshypertrophy in tissue regeneration after extensive liver resection.
abstract: OBJECTIVE
  To address to what extent hypertrophy and hyperplasia contribute to liver mass restoration after major tissue loss.
  
  
  METHODS
  The ability of the liver to regenerate is remarkable on both clinical and biological grounds. Basic mechanisms underlying this process have been intensively investigated. However, it is still debated to what extent hypertrophy and hyperplasia contribute to liver mass restoration after major tissue loss. We addressed this issue using a genetically tagged system. We were able to follow the fate of single transplanted hepatocytes during the regenerative response elicited by 2/3 partial surgical hepatectomy (PH) in rats. Clusters of transplanted cells were 3D reconstructed and their size distribution was evaluated over time after PH.
  
  
  RESULTS
  Liver size and liver DNA content were largely recovered 10 d post-PH, as expected (e.g., total DNA/liver/100 g b.w. was 6.37 ± 0.21 before PH and returned to 6.10 ± 0.36 10 d after PH). Data indicated that about 2/3 of the original residual hepatocytes entered S-phase in response to PH. Analysis of cluster size distribution at 24, 48, 96 h and 10 d after PH revealed that about half of the remnant hepatocytes completed at least 2 cell cycles. Average size of hepatocytes increased at 24 h (248.50 μm2± 7.82 μm2,P= 0.0015), but returned to control values throughout the regenerative process (up to 10 d post-PH, 197.9 μm2± 6.44 μm2,P= 0.11). A sizeable fraction of the remnant hepatocyte population does not participate actively in tissue mass restoration.
  
  
  CONCLUSIONS
  Hyperplasia stands as the major mechanism contributing to liver mass restoration after PH, with hypertrophy playing a transient role in the process.
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Marongiu
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Marongiu
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Contini
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Serra
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Erika
authors.initials: E
authors.lastname: Cadoni
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Murgia
authors.affiliation: Fabio Marongiu, Michela Marongiu, Antonella Contini, Monica Serra, Erika Cadoni, Riccardo Murgia, Ezio Laconi, Experimental Medicine Unit, Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy.
authors.forename: Ezio
authors.initials: E
authors.lastname: Laconi
mesh_terms: D000818:Animals; D002453:Cell Cycle; D048429:Cell Size; D006498:Hepatectomy; D022781:Hepatocytes / Q000502:physiology*; D006965:Hyperplasia / Q000235:genetics / Q000503:physiopathology*; D006984:Hypertrophy / Q000235:genetics / Q000503:physiopathology*; D008099:Liver / Q000166:cytology / Q000502:physiology* / Q000601:surgery; D008115:Liver Regeneration / Q000235:genetics / Q000502:physiology*; D023421:Models, Animal; D051381:Rats; D011916:Rats, Inbred F344
keywords: Hyperplasia; Hypertrophy; Liver regeneration