Platelets Promote Liver Regeneration under Conditions of Kupffer Cell Depletion after Hepatectomy in Mice

Abstract

Platelets have been proven to promote liver regeneration after hepatectomy. Kupffer cells produce inflammatory cytokines and also promote liver regeneration. In the present study, we examined whether platelets promote liver regeneration after hepatectomy under conditions of Kupffer cell depletion. Seventy percent hepatectomy was carried out in mice, which were subsequently divided into four groups: (1) a normal group without any treatment, (2) a Kupffer cell depleted (KD) group, (3) a thrombocytotic group, and (4) a combined thrombocytotic and Kupffer cell depleted (TKD) group. Growth kinetics in the liver regeneration, growth factors, inflammatory cytokines, and signal transduction relating to hepatocyte proliferation were analyzed. In the KD group, liver regeneration was significantly delayed compared to the normal group 48 h after hepatectomy. On the other hand, liver regeneration of the TKD group increased significantly compared to KD group, to a level that was the same as that recorded in the normal group. In the thrombocytotic group, liver regeneration increased significantly compared to the normal group. Tumor necrosis factor alpha (TNF-alpha) expression was lower in the KD and TKD groups than in the normal group after hepatectomy, but, in the TKD group, hepatocyte growth factor and Akt phosphorylation were higher than in the normal and KD groups. After hepatectomy, liver regeneration in the Kupffer cell depleted group was delayed because of lower TNF-alpha expression. Platelets promote liver regeneration even under condition of Kupffer cell depletion by stimulating hepatocyte growth factor and insulin-like growth factor-1 expression, and they activate Akt.