Effect of thrombopoietin on platelet counts and liver regeneration after partial hepatectomy in a rat model

Purpose We investigated the effects of thrombopoietin (TPO) on platelet counts and liver regeneration after partial hepatectomy in rats. Methods We performed 70% partial hepatectomy on 60 rats given either TPO or a vehicle (controls). The rats were killed 6 h, 24 h, 72 h, or 168 h after the procedure, and we examined the platelet counts, weight of the regenerated liver, hepatocyte proliferation by bromodeoxyuridine (BrdU) labeling index, and expression of hepatocyte growth factor (HGF) mRNA by reverse transcription-polymerase chain reaction. Results In the controls, the platelet counts were significantly lower than the basal levels, by about 20%, at 6, 24, and 72 h; then recovered to the basal level at 168 h. Conversely, in the TPO-treated rats, the platelet counts increased significantly by 17%, 35%, and 60%, at 24, 72, and 168 h, respectively. The regenerated liver regained 80% of the pre-hepatectomy weight by 72 h in the controls, whereas reconstitution of the liver was accomplished by 72 h in the TPO-treated rats. Thrombopoietin significantly enhanced the BrdU labeling index of hepatocytes and expression of HGF mRNA 24 h post hepatectomy in TPO-treated rats versus controls. Conclusion Thrombopoietin increased platelet counts; thereby accelerating liver regeneration after partial hepatectomy with enhanced induction of HGF.