title: Liver regeneration after different degrees of portal vein ligation.
abstract: Selective portal vein ligation (PVL) is followed by ipsilateral atrophy and contralateral hypertrophy of the liver lobes. Although the atrophy-hypertrophy complex induced by PVL is a well-documented phenomenon, the effect of different degrees of extended portal vein occlusion on liver regeneration is not known. The aim of this study was to assess the effects of different degrees of portal occlusion on portal pressure and liver regeneration.
  
  
  
  Male Wistar rats (n = 96; 220-250 g) were randomized into three groups and underwent 70%, 80%, or 90% portal vein ligation, respectively. The portal pressure was measured immediately and 24, 48, 72, 120, and 168 h after PVL (n = 6/group/time point). The hepatic lobes and the spleen were weighed, and liver regeneration ratio was calculated. Changes in liver histology and the mitotic activity were assessed on hematoxylin-eosin stained slides.
  
  
  
  Higher degree of portal occlusion triggered a stronger regenerative response (regeneration ratio of PVL 70%168h = 2.23 ± 0.13, PVL 80%168h = 3.11 ± 0.37, PVL 90%168h = 4.68 ± 0.48) PVL led to an immediate increase in portal pressure, the value of which changed proportionally to the mass of liver tissue deprived of portal perfusion (PVL 70%acute = 17 ± 2 mm Hg, PVL 80%acute = 19 ± 1 mm Hg, PVL 90%acute = 26 ± 4 mm Hg). Findings in histology showed necro-apoptotic lesions in the atrophic liver lobes and increased mitotic cell count in the hypertrophic lobes. The mitotic cell count of PVL 90% peaked earlier and at a significantly higher value than of PVL 70% and PVL 80% (PVL 9024h%: 96.0 ± 3.5 PVL 70%48h: 64.0 ± 2.1, PVL 80%48h: 56.3 ± 4.0). The mitotic index after 24 h showed a strong correlation with the acute portal hypertension.
  
  
  
  A higher degree of portal vein occlusion leads to a greater regenerative response, presumably triggered by the proportional increase in portal pressure, which supports the role of the so-called "blood-flow" theory of PVL-triggered liver regeneration.
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: David Tibor
authors.initials: DT
authors.lastname: Lauber
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: Dóra Krisztina
authors.initials: DK
authors.lastname: Tihanyi
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Czigány
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Kovács
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Budai
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: Dóra
authors.initials: D
authors.lastname: Drozgyik
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Fülöp
authors.affiliation: Hepato-Pancreatico-Biliary (HPB) Surgical Research Center, 1st Department of Surgery, Semmelweis University, Budapest, Hungary. Electronic address: szijartoattila@gmail.com.
authors.forename: Attila
authors.initials: A
authors.lastname: Szijártó
mesh_terms: D000818:Animals; D008026:Ligation; D008099:Liver / Q000254:growth & development*; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D009929:Organ Size; D017082:Portal Pressure; D011169:Portal Vein / Q000502:physiology / Q000601:surgery*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
keywords: Liver regeneration; Portal pressure; Portal vein ligation; Regeneration ratio