The role of the spleen, platelets, and plasma hepatocyte growth factor activity on hepatic regeneration in rats

BACKGROUND: Hepatocyte growth factor (HGF) is a humoral factor that may act as a trigger for hepatic regeneration. In this study, changes in the plasma HGF activity on hepatic regeneration in a splenectomized condition were measured for the first time, while the role of the spleen and platelets on hepatic regeneration were also carefully evaluated. STUDY DESIGN: Seventy- five male Wister rats were classified into three groups: group A consisted of rats who underwent a sham operation and a partial hepatectomy; group B consisted of those who underwent a splenectomy and partial hepatectomy; and group C consisted of those who underwent a splenectomy, partial hepatectomy, and were administered an antiplatelet agent. RESULTS: At 24 hours after partial hepatectomy, the weights of the livers of the rats in groups B and C were significantly greater than those of group A, while the labeling index of group C was significantly higher than that of group A and also tended to be higher than that of group B. Regarding the number of platelets, the transient increase in group A occurred earlier than that of either group B or C. The plasma HGF activities also showed a transient increase and the maximum levels were reached at 24 hours in group A, six hours in group B, and 12 hours in group C. CONCLUSIONS: It is suggested that the spleen plays an inhibitory role in hepatic regeneration. In the early stage of hepatic regeneration, platelets possibly control HGF induction, while in the following stage, a possible feedback mechanism is also postulated to exist.