Change of liver function in hypertrophying lobe of rabbit liver after portal branch ligation

Triggered liver regeneration: from experimental model to clinical implications

BACKGROUND

Major liver resection is the only therapeutic option for patients with malignant liver tumors. However, extended hepatectomy often leads to postoperative liver failure, mainly due to insufficient amounts of the remnant liver. Recently, selective portal vein occlusion (PVO) has been introduced to increase the remnant liver volume. This novel surgical technique initiated a progressive development in liver surgery, resulting in a significant increment in potential candidates for curative liver resection.

SUMMARY

The theoretical basis for this great advancement is formed by an understanding of the mechanisms of PVO-induced liver regeneration, mainly obtained from animal studies. The aim of this review is to give a comprehensive overview of the relevant animal models of PVO and to discuss the main characteristics of triggered liver regeneration, including the induced hemodynamic, morphological and functional alterations as well as the underlying molecular mechanisms, which might be of interest in both the laboratory and the clinic. Key Messages: Although basic research revealed the main characteristics of PVO-triggered liver regeneration within the last decades, several important issues regarding the regenerative process remain uncertain. To answer these open questions, additional well-designed animal experiments are needed in the future, which allow further refinement of this surgical technique.

Computed tomography perfusion study of hemodynamic changes and portal hyperperfusion in a rabbit model of small-for-size liver

BACKGROUND

Portal hyperperfusion in the small-for-size (SFS) liver can threaten survival of rabbits. Therefore, it is important to understand the hemodynamic changes in the SFS liver.

METHODS

Twenty rabbits were divided into two groups: a control group and a modulation group. The control group underwent an extended hepatectomy. The modulation group underwent the same procedure plus splenectomy to reduce portal blood flow. CT perfusion examinations were performed on all rabbits before and after operation. Perfusion parameter values, especially portal vein perfusion (PVP), were analyzed.

RESULTS

PVP in the modulation group was lower than in the control group after operation (P=0.002). In the control group, postoperative PVP increased by 193.7+/-55.1% compared with preoperative PVP. A weak correlation was found between the increased percentage of PVP and resected liver-to-body weight ratio (RLBWR) (r=0.465, P=0.033). In the modulation group, postoperative PVP increased by 101.4+/-32.5%. No correlation was found between the increased percentage of PVP and RLBWR (r=0.167, P=0.644). Correlations were found between PVP and serum alanine aminotransferase, aspartate aminotransferase, and total bilirubin after surgery (P<0.05).

CONCLUSION

We successfully evaluated the characteristics of hemodynamic changes as well as the effects of splenectomy in the SFS liver in rabbits by the CT technique.

Relationship between CT volumetry and functional liver volume using technetium-99m galactosyl serum albumin scintigraphy in patients undergoing preoperative portal vein embolization before major hepatectomy: a preliminary study

To clarify the relationship between morphological measurements of hepatic volume by computed tomography (CT-vol) and functional volume (RI-vol) by technetium-99m galactosyl human serum albumin (99mTc-GSA) scintigraphy, and its clinical significance, we examined 16 patients with a background liver status of either normal liver function (n=4), chronic hepatitis or cirrhosis (n=7), or obstructive jaundice (n=5). In five patients who underwent preoperative portal vein embolization (PVE), volumetric measurement was performed 2 weeks after PVE. The mean values of CT-vol and RI-vol of the right lobe were 692+/-147 cm3 (66.1+/-10.7%) and 668+/-159 cm3 (67.8+/-13.2%), respectively, and those of the left lobe were 329+/-138 cm3 (33.9+/-10.6%) and 328+/- 170 cm3 (32.2+/-13.2%), respectively. There were no significant differences in the volume measurements between the two volumetric techniques. Correlations between CT-vol and RI-vol in the right and left lobes were positive and significant (r=0.912 and 0.903, respectively; both P's<0.001). The mean values of post-PVE CT-vol and RI-vol of the right lobe in five patients were significantly different (628+/-149 and 456+/-211 cm3, respectively; P=0.033). However, the mean values of post-PVE CT-vol and RI-vol of the left lobe were not different (496+/-124 and 483+/-129 cm3, respectively). We propose that volumetric measurement by 99mTc-GSA scintigraphy is useful for detecting changes in functional volume of individual lobes of the liver and is a more dynamic method compared with detection of morphological changes by CT scan.

Sustained function in atrophying liver tissue after portal branch ligation in the rat

BACKGROUND

Preoperative segmental portal vein occlusion has become a common method to prevent liver failure after extended hepatic resection. To date, it is not elucidated whether atrophy by portal deprivation with concomitant contralateral regeneration leads to impaired liver function. We addressed this question by examining the expression of liver function proteins related to glucose homeostasis and acute-phase response in a corresponding animal model.

MATERIALS AND METHODS

Male Wistar rats were subjected to either portal branch ligation (PBL), partial hepatectomy (PH), or sham operation (SO). The mRNA expression and chronological distribution of glucose-6-phosphatase (G6P), glucagon receptor (GR), glceraldehyd-3-phosphate-dehydrogenase (GAPDH), albumin, fibronectin, and C1-esterase-inhibitor (C1-Inh) genes were examined by Northern-blot hybridizations. Determinations of serum-glucose and glycogen staining by periodic acid and Schiff were performed to analyze changes in glucose mobilization and storage.

RESULTS

In regenerating liver tissue after PH and PBL, we detected a selective reduction of transcripts encoding G6P during the prereplicative period 6 and 12 h after surgery and a contemporary drop in serum glucose levels. This impairment proved to be more distinct after PH than after PBL. Compared with the residual liver after PH, the level of glycogen disappearance was lower after PBL in the regenerating lobe. In the portal-deprived liver tissue, the expression of genes coding for G6P, GR, GAPDH, albumin, fibronectin, and C1-Inh was not altered compared with the SO group.

CONCLUSIONS

Overall, portal-deprived liver tissue undergoing atrophy retains its liver-specific differentiation and function and helps to maintain homeostasis during the fast regeneration of the non-occluded liver lobe.

Evaluation of preoperative portal embolization for safe hepatectomy, with special reference to assessment of nonembolized lobe function with 99mTc-GSA SPECT scintigraphy

BACKGROUND

Preoperative portal embolization (PE) is used to stimulate liver hypertrophy in the nonembolized lobe. We studied liver volume and function with computed tomography and technetium-99m-galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy before PE and at 1 or 2 weeks after PE.

METHODS

Right PE was performed in 30 patients. Morphologic and functional hypertrophy in the left lobe after PE was determined and related to the presence or absence of cholestasis, biliary drainage of the embolized lobe, and postoperative liver failure.

RESULTS

The volume of the left lobe and (99m)Tc-GSA uptake increased rapidly for the first week after PE, but no significant increase was seen during the second week. Morphologic hypertrophy was less pronounced in patients with jaundice (P =.03). When PE was performed at a total bilirubin level above 2 mg/dL, the interval between PE and surgery was prolonged because of cholangitis and liver abscess formation. The net morphologic hypertrophy ratio was significantly higher in livers that had undergone left lobe drainage only (9.1% +/- 0.9%) compared with those in which there was drainage of the embolized lobes (5.7% +/- 0.9%; P =.03). The volume and (99m)Tc-GSA uptake of the left lobe in the second week after PE was significantly smaller in patients with postoperative liver failure (33.7% +/- 2.4% and 18.0% +/- 2.1%, respectively) than in patients without liver failure (46.2% +/- 1.4% and 38.4% +/- 2.3%; P =.003 and P =.01, respectively).

CONCLUSION

In the nonembolized lobe, the functional increase in (99m)Tc-GSA uptake is more pronounced than suggested by the degree of morphologic hypertrophy. Whenever possible, biliary drainage should not be performed in the lobe undergoing hepatectomy. (99m)Tc-GSA SPECT scintigraphy is useful for the evaluation of postoperative liver failure.