Cellular liver regeneration after extended hepatic resection in pigs

Abstract

Background: The liver has an enormous capacity to regenerate itself. The aim of this study was to evaluate whether the regeneration is due to hypertrophy or hyperplasia of the remnant liver after extended resection and whether a portosystemic shunt is beneficial.

Material and methods: An extended left hemihepatectomy was performed in 25 pigs, and in 14 after performing a portosystemic shunt. During follow up, liver regeneration was estimated by macroscopic markers such as liver volume and size of the portal fields [mm(2)] as well as the amount of hepatocytes per portal field and the amount of hepatocytes per mm(2).

Results: Regardless of the operation procedure, the volume of the remnant liver increased about 2.5 fold at the end of the first week after resection. The size of the portal fields increased significantly as well as the number of hepatocytes in the portal fields. Interestingly, the number of hepatocytes per mm(2) remained the same.

Conclusion: After extended resection, liver regeneration was achieved by an extensive and significant hyperplasia of hepatocytes within the preexisting portal fields and not by de novo synthesis of new portal fields. However, there was no difference in liver regeneration regarding the operation procedure performed with or without portosystemic shunt.

Figure 1

The areal increase of the pre-existing portal fields is expressed in Figure 1 in animals operated without (Figures 1(a) and 1(c)) and with portosystemic H-shunt (Figures 1(b) and 1(d)). The areal increase of the portal fields is shown in relation to the postoperative time (weeks) and is expressed as mean ± SEM in Figures 1(a) and 1(b) and as correlation coefficient in Figures 1(c) and 1(d). The areal increase of the portal fields was highly significant after the first week (P < .001).

Figure 2

The increase of hepatocytes in the pre-existing portal fields is expressed in Figure 2 in animals operated without (Figures 2(a) and 2(c)) and with portosystemic H-shunt (Figures 2(b) and 2(d)). The increase of hepatocytes is shown in relation to the postoperative time (weeks) and is expressed as mean ± SEM in Figures 2(a) and 2(b) and as correlation coefficient in Figures 2(c) and 2(d). The increase of hepatocytes in the portal fields was highly significant after the first week (P < .001).

Figure 3

The density of hepatocytes per mm² is expressed in Figure 3 in animals operated without (Figures 3(a) and 3(c)) and with portosystemic H-shunt (Figures 3(b) and 3(d)). The density of hepatocytes is shown in relation to the postoperative time (weeks) and is expressed as mean ± SEM in Figures 3(a) and 3(b) and as correlation coefficient in Figures 3(c) and 3(d).