Evidence for serotonin as a relevant inducer of liver regeneration after liver resection in humans.

Unlabelled: Liver regeneration (LR) involves a complex interplay of growth factors and antagonists. In this context, platelet-derived serotonin (5-HT) has been identified as a critical inducer of LR in mice. Clinical evidence for a role of 5-HT in LR in humans is lacking. Accordingly, serum and plasma 5-HT was monitored perioperatively in 60 patients undergoing liver resection, of which 35 served as exploration and 25 as validation sets. Intraplatelet (IP) levels of 5-HT were calculated by subtraction of plasma 5-HT from serum values. Serum markers of liver function were used to evaluate LR and liver dysfunction (LD). In the exploration setting, IP 5-HT levels significantly decreased after liver resection (P < 0.001) and gradually recovered during the first week. IP 5-HT measured before surgery specifically predicted LD in the subsequent 7 days (area under the curve: 0.721; P = 0.029). Patients suffering from postoperative LD and morbidity were found to have reduced IP 5-HT levels during the entire perioperative period. Furthermore, we validated that reduced preoperative IP 5-HT (<73 ng/mL) was associated with an increased incidence of postoperative LD and morbidity (P = 0.045 and P = 0.021) and were able to demonstrate that IP 5-HT levels were an independent predictor of poor clinical outcome.

Conclusions: These findings provide evidence that IP 5-HT correlates with LR in humans: Patients with low IP 5-HT before liver resection suffered from delayed hepatic regeneration. Therefore, IP 5-HT levels may prove a helpful clinical marker to predict postoperative LD and clinical outcome before hepatic resection and initiate suitable interventions.