Supplementary Material for: Kinetics of Hepatic Volume Evolution and Architectural Changes after Major Resection in a Porcine Model

<b><i>Background:</i></b> The hepatic volume gain following resection is essential for clinical recovery. Previous studies have focused on cellular regeneration. This study aims to explore the rate of hepatic regeneration of the porcine liver following major resection, highlighting estimates of the early microarchitectural changes that occur during the cellular regeneration. <b><i>Methods:</i></b> Nineteen large white pigs had 75% resection with serial measurements of the hepatic volume, density, blood flow, and architectural changes. <b><i>Results:</i></b> The growth rate initially was 45% per day, then rapidly decreased and was accompanied by a similar pattern of hepatic fat deposition. The architectural changes showed a significant increase in the Ki67 expression (<i>p</i> < 0.0001) in the days following resection with a peak on the 2nd day and nearly normalized on day 7. The expression of CD31 increased significantly on the 2nd and 3rd days compared to the pre-resection samples (<i>p</i> = 0.03). Hepatic artery flow per liver volume remained at baseline ranges during regeneration. Portal flow per liver volume increased after liver resection (<i>p</i> < 0.001), was still elevated on the 1st postoperative day, then decreased. Correlations were significantly negative between the hepatic volume increase on day 3 and the hepatic oxygen consumption and the net lactate production at the end of the procedure (<i>r</i> = –0.82, <i>p</i> = 0.01, and <i>r</i> = –0.70, <i>p</i> = 0.03). <b><i>Conclusion:</i></b> The volume increase in the first days – a fast process – is not explained by cellular proliferation alone. The liver/body weight ratio is back to 50% of the preoperative value after 3 days to close to 100% volume regain on days 10–15.