title: Ex situ regeneration of liver remnants hypothermically preserved for 24 hours.
abstract: BACKGROUND
  After partial hepatectomy (PH), the liver remnant (LR) shows a regenerative response, always keeping a percent relationship with the host. This process has been well described in the literature, but several aspects still need to be understood. There are no studies on hepatic LR regeneration during hypothermic preservation. Thus, the objective of the present study was to analyze LR regeneration after PH under conditions of hypothermal preservation.
  
  
  METHODS
  Twenty adult Wistar rats were divided into 4 experimental groups: PHS (70% PH); PHP (70% PH of an organ perfused and preserved for 24 hours); PWL (perfused whole liver preserved for 24 hours); and NPWL (nonperfused whole liver). The liver was perfused with 250 mL Celsior solution with a catheter connected to a 1.30-cm-high liquid column. Hepatic tissue samples were submitted to immunohistochemical analysis for the evaluation of protein Ki67 expression, related to the mechanism of cell proliferation, to analysis of micro-RNA expression (miR-21 and miR-16) by real-time polymerase chain reaction, and to analysis of mitochondrial function. Nonparametric statistical analysis was used (P < .05).
  
  
  RESULTS
  Ki67 analysis revealed that the PHP group showed 17.41% cell proliferation in LR (P < .01) compared to PHS (42.22%), PWL (11.43%), and NPWL (11.98%). miR-16 expression (proapoptotic) was found to be higher in the NPWL group compared to all others (PHS, PHP, and PWL), with a statistically significant difference between the NPWL group and the PHS and PHP groups.
  
  
  CONCLUSIONS
  The animals submitted to PHS and PHP presenting greater Ki67 expression showed low miR-16 expression, indicating a low apoptotic index. In summary, the LR showed ex situ regeneration even under hypothermal conditions. There are no similar data in the literature surveyed.
authors.affiliation: Liver Transplantation Unit, Ribeirão Preto Medical School, University of São Paulo, Brazil.
authors.forename: M R G
authors.initials: MR
authors.lastname: Silveira
authors.affiliation: Illinois Institute of Technology, Illinois, United States.
authors.forename: T
authors.initials: T
authors.lastname: Silva
authors.affiliation: Liver Transplantation Unit, Ribeirão Preto Medical School, University of São Paulo, Brazil.
authors.forename: P C
authors.initials: PC
authors.lastname: Novaes
authors.affiliation: Liver Transplantation Unit, Ribeirão Preto Medical School, University of São Paulo, Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Tirapelli
authors.affiliation: Liver Transplantation Unit, Ribeirão Preto Medical School, University of São Paulo, Brazil.
authors.forename: D P
authors.initials: DP
authors.lastname: Tirapelli
authors.affiliation: Liver Transplantation Unit, Ribeirão Preto Medical School, University of São Paulo, Brazil. Electronic address: orlando@fmrp.usp.br.
authors.forename: O
authors.initials: O
authors.lastname: Castro e Silva
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D006498:Hepatectomy; D007036:Hypothermia, Induced / Q000379:methods*; D008099:Liver / Q000473:pathology* / Q000601:surgery; D008107:Liver Diseases / Q000473:pathology / Q000601:surgery*; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014021:Tissue Preservation / Q000379:methods*