A reliable scoring system after major liver resection in mice

Posthepatectomy liver failure and its transplant counterpart, small-for-size syndrome, remain significant limitations for liver resections and segmental liver transplantation. Partial hepatectomy in mice is one of the most commonly used models to study liver regeneration, but blood and tissue sampling necessary to collect data can affect outcomes or even require euthanasia. We therefore developed a quantitative observational system to predict death from hepatectomy during the first 24 postoperative hours.

A total of 100 female, 10 to 12-week-old C57BL/6 mice underwent two-thirds hepatectomy and were monitored for up to 7 d. Our scoring system was based on five categories, each assigned 0-2 points: activity level, body posture, fur condition, respiratory status, and eye appearance. Seventy-five mice were scored 6 h, 12 h, 24 h, 2 d, 3 d, 5 d, and 7 d after surgery. The remaining 25 mice were scored similarly, but underwent, in addition, blood sampling for serum alanine aminotransferase, total bilirubin, interleukin-6, tumor necrosis factor-alpha, or euthanasia with liver sampling for conventional hematoxylin-eosin and Ki-67 staining.

Retrospective analysis indicated that body condition scores ≤5 on two consecutive time points within the first 24 postoperative hours accurately predicted eventual death. Animals in the low scoring group also had significantly higher serum alanine aminotransferase, total bilirubin, interleukin-6, tumor necrosis factor-alpha, more hepatocyte necrosis in hematoxylin-eosin, and fewer Ki-67 positive hepatocytes.

Our scoring system accurately predicts survival, hepatocyte damage, liver regeneration, and systemic inflammation in a mouse hepatectomy model, within the first 24 hours of surgery. This could be useful in evaluating posthepatectomy interventions for their effect on survival and liver regeneration.