Improved hepatocyte function of future liver remnant of cirrhotic rats after portal vein ligation: a bonus other than volume shifting

Assessment of remnant liver function and volume after selective ligation of portal vein and hepatic artery in a rat model

Purpose:

To evaluate liver regeneration after selective ligation of portal vein and hepatic artery by 3D Computed Tomography in an experimental model.

Methods:

Sixteen Wistar rats were randomized into four equal groups: Group I- control (sham), Group II- isolated selective ligation of the hepatic artery, Group III- isolated selective ligation of the portal vein and Group IV- combined ligation of portal vein and hepatic artery. Before procedure and five days after a 3D CT Scan was performed to analyze the hypertrophy, weight and function of the remnant liver.

Results:

The largest regeneration rate and increase of weight in the hypertrophied lobe was detected in group IV, the first with an average of 3.99 (p=0.006) and the last varying from 6.10g to 9.64g (p=0.01). However, total liver weight and the R1 ratio (Hypertrophied Lobe Weight/Total Liver Weight) was higher in group III (P<0.001) when compared with groups I, II and IV and showed no difference between them. The immunohistochemical examination with PCNA also found higher percentages with statistical significance differences in rats of groups III and IV. It was possible to confirm a strong correlation between hypertrophied lobe weight and its imaging volumetric study. Liver function tests only showed a significant difference in serum gamma-glutamyltransferase and phosphorous.

Conclusion:

There is a largest liver regeneration after combined ligation of portal vein and hepatic artery and this evidence may improve the knowledge of surgical treatment of liver injuries, with a translational impact in anima nobile.

Progress of liver resection for hepatocellular carcinoma in Taiwan

Taiwan is a well-known endemic area of hepatitis B. Hepatocellular carcinoma (HCC) has consistently been the first or second highest cause of cancer death over the past 20 years. This review article describes the progress of liver resection for HCC in Taiwan in the past half century. The mortality rate for HCC resection was 15-30% in Taiwan in the 1970s. The rate decreased to 8-12% in the early 1990s, and it declined to <1-3% recently. The development of new operative instruments, and surgical techniques, increased knowledge of liver anatomy and pathophysiology after hepatectomy, and more precise patient selection have contributed to this improvement. The use of intermittent hepatic inflow blood occlusion, a restrictive blood transfusion policy and intraoperative ultrasonography, have also led to substantial improvements in resectability and safety for HCC resection in Taiwan. Advances in non-operative modalities for HCC treatment have also helped to improve long-term outcomes of HCC resection. Technical innovations have allowed the application of complex procedures such as mesohepatectomy, unroofing hepatectomy, major portal vein thrombectomy, hepatic vein reconstruction in resection of the cranial part with preservation of the caudal part of the liver, and inferior vena cava and right atrium tumor thrombectomy under cardiopulmonary bypass. In selected patients, including patients with end-stage renal failure, renal graft recipients, patients with portal hypertension, hypersplenic thrombocytopenia and/or associated gastroesophageal varices, octogenarian, ruptured HCC, recurrent HCC and metastatic HCC can also be resected with satisfactory survival benefits. We conclude that the results of liver resection for HCC in Taiwan are improving. The indications for HCC resection continue extending with lower the surgical risks and increasing the long-term survival rate.

Portal branch ligation does not counteract the inhibiting effect of temsirolimus on extrahepatic colorectal metastatic growth

The mTor-inhibitor temsirolimus (TEM) has potent anti-tumor activities on extrahepatic colorectal metastases. Treatment of patients with advanced disease may require portal branch ligation (PBL). While PBL can induce intrahepatic tumor growth, the effect of PBL on extrahepatic metastases under TEM treatment is unknown. Therefore, we analyzed the effects of TEM treatment on extrahepatic metastases during PBL-associated liver regeneration. GFP-transfected CT26.WT colorectal cancer cells were implanted into the dorsal skinfold chamber of BALB/c-mice. Mice were randomized to four groups (n = 8). One was treated daily with TEM (1.5 mg/kg), PBS-treated animals served as controls. Another group underwent PBL of the left liver lobe and received daily TEM treatment. Animals with PBL and PBS treatment served as controls. Tumor vascularization and growth as well as tumor cell migration, proliferation and apoptosis were studied over 14 days. In non-PBL animals TEM treatment inhibited tumor cell proliferation as well as vascularization and growth of the extrahepatic metastases. PBL did not influence tumor cell engraftment, vascularization and metastatic growth. Of interest, TEM treatment significantly reduced tumor cell engraftment, neovascularization and metastatic groth also after PBL. PBL does not counteract the inhibiting effect of TEM on extrahepatic colorectal metastatic growth.

Tumour growth of colorectal rat liver metastases is inhibited by hepatic arterial infusion of the mTOR-inhibitor temsirolimus after portal branch ligation

Portal branch ligation (PBL) can be performed before major hepatic resection of colorectal liver metastases (mCRC) to increase the remnant liver mass. However, PBL may also stimulate mCRC growth through hepatic arterial hyperperfusion and growth factor release. Herein, we studied whether hepatic arterial infusion (HAI) of the mTOR-inhibitor temsirolimus (Tem) is capable of inhibiting the growth of colorectal liver metastases after PBL. WAG/Rij rats were randomized to four groups (n=6 each) and underwent subcapsular implantation of 5×10(5) CC531 cells into the left liver lobe. The animals of two groups underwent simultaneous PBL of the tumour bearing liver lobe. Ten days later animals underwent a HAI either of temsirolimus (Tem and PBL Tem) or saline solution (Sham and PBL Sham). Tumour size was analyzed at days 10 and 13 using three-dimensional ultrasound. In Sham controls tumour volume increased by 43%. After PBL Sham tumour volume increased by 52%. In contrast, in animals undergoing HAI of temsirolimus the tumour growth was not only completely inhibited, but tumour volume was found decreased, irrespective of PBL. After HAI of temsirolimus immunohistochemistry revealed an increased cleaved caspase-3 activity, indicating stimulation of apoptotic cell death. In parallel temsirolimus treatment was associated with a significant reduction of PECAM-1 positive cells within the tumour tissue, implying a reduced tumour vascularisation. HAI of temsirolimus is capable of inhibiting the growth of CC531 colorectal rat liver metastases also after PBL.

A review of animal models for portal vein embolization

BACKGROUND

Portal vein embolization (PVE) is a preoperative intervention to increase the future remnant liver (FRL) through regeneration of the non-embolized liver lobes. This review assesses all the relevant animal models of PVE available, to guide researchers who intend to study PVE.

MATERIALS AND METHODS

We performed a systematic literature search in Medline and Pubmed, from 1993-June 2013, using search headings "PVE" and "portal vein ligation". Articles were included when meeting the selection criteria: experimental animal study on PVE or portal vein ligation and experiments described in 5 animals or more.

RESULTS

Sixty-one articles were selected, describing six different animal models. Most articles reported experiments with rats, rabbits, and pigs. In rats, the increase in wet-weight ratio of the non-occluded liver or total liver weight is greatest in the first 7 d with values ranging from 75%-80.5% on day 7. The volume increase of FRL in the rabbit model is greatest in the first 7 d with values ranging from 33.6%-80% on day 7. In pigs, the largest gain in volume of the FRL was seen in the first 2 wk.

CONCLUSIONS

The choice of the model depends on the specific aim of the study. Evaluating the increase in liver volume and liver function after PVE, larger animals as the pig, rabbit, or the dog is useful because of the possibility to apply computed tomography volumetry. To evaluate mechanisms of regeneration after PVE, the rat model is useful, because of the variety of antibodies commercially available.

Multiple low doses of erythropoietin delay the proliferation of hepatocytes but promote liver function in a rat model of subtotal hepatectomy

PURPOSE

The impact of various doses of erythropoietin (EPO) on liver regeneration after partial hepatectomy (PH) in different animal models is still under debate. We investigated the impact of low doses of EPO on liver regeneration in a rat model of subtotal hepatectomy.

METHODS

We established a 90 % PH rat model with perioperative injections of low-dose EPO (1,000 IU/kg). We analyzed survival and hepatocyte proliferation in animals treated with or without EPO and assessed liver function by blood ammonia measurement and the indocyanine green 15-min retention test.

RESULTS

Low doses of EPO treatment improved the survival of rats after 90 % PH. Unexpectedly, during the first 24 h after the operation, liver regeneration in the EPO-treated rats was inhibited. DNA synthesis, cell proliferation, and the expression of cyclins and p-STAT3 peaked 48 h after PH, which was delayed by about 24 h vs. the control rats. Furthermore, EPO treatment increased the serum level of IL-6 and protected the hepatocytes from apoptosis.

CONCLUSION

Low doses of EPO do not stimulate early hepatocyte proliferation in the regenerating liver, but contribute to liver protection by inducing IL-6 and inhibiting apoptosis.

Comparison of percutaneous transhepatic portal vein embolization and unilateral portal vein ligation

AIM: To compare the effect of percutaneous transhepatic portal vein embolization (PTPE) and unilateral portal vein ligation (PVL) on hepatic hemodynamics and right hepatic lobe (RHL) atrophy.

METHODS: Between March 2005 and March 2009, 13 cases were selected for PTPE (n = 9) and PVL (n = 4) in the RHL. The PTPE group included hilar bile duct carcinoma (n = 2), intrahepatic cholangiocarcinoma (n = 2), hepatocellular carcinoma (n = 2) and liver metastasis (n = 3). The PVL group included hepatocellular carcinoma (n = 2) and liver metastasis (n = 2). In addition, observation of postoperative hepatic hemodynamics obtained from computed tomography and Doppler ultrasonography was compared between the two groups.

RESULTS: Mean ages in the two groups were 58.9 ± 2.9 years (PVL group) vs 69.7 ± 3.2 years (PTPE group), which was a significant difference (P = 0.0002). Among the indicators of liver function, including serum albumin, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, platelets and indocyanine green retention rate at 15 min, no significant differences were observed between the two groups. Preoperative RHL volumes in the PTPE and PVL groups were estimated to be 804.9 ± 181.1 mL and 813.3 ± 129.7 mL, respectively, with volume rates of 68.9% ± 2.8% and 69.2% ± 4.2%, respectively. There were no significant differences in RHL volumes (P = 0.83) and RHL volume rates (P = 0.94), respectively. At 1 mo after PTPE or PVL, postoperative RHL volumes in the PTPE and PVL groups were estimated to be 638.4 ± 153.6 mL and 749.8 ± 121.9 mL, respectively, with no significant difference (P = 0.14). Postoperative RHL volume rates in the PTPE and PVL groups were estimated to be 54.6% ± 4.2% and 63.7% ± 3.9%, respectively, which was a significant difference (P = 0.0056). At 1 mo after the operation, the liver volume atrophy rate was 14.3% ± 2.3% in the PTPE group and 5.4% ± 1.6% in the PVL group, which was a significant difference (P = 0.0061).

CONCLUSION: PTPE is a more effective procedure than PVL because PTPE is able to occlude completely the portal branch throughout the right peripheral vein.

Effects of chitosan-nanoparticle-mediated tight junction opening on the oral absorption of endotoxins

Recently, we reported a pH-responsive nanoparticle (NP) system shelled with chitosan (CS), which could effectively increase the oral absorption of insulin and produce a hypoglycemic effect, presumably due to the CS-mediated tight junction (TJ) opening. It has been often questioned whether CS can also enhance the absorption of endotoxins present in the small intestine. To address this concern, we studied the effect of CS NPs on the absorption of lipopolysaccharide (LPS), the most commonly found toxin in the gastrointestinal tract. To follow their biodistribution by the single-photon emission computed tomography/computed tomography, LPS and insulin were labeled with (99m)Tc-pertechnetate ((99m)Tc-LPS) and (123)iodine ((123)I-insulin), respectively. The (99m)Tc-LPS was ingested 1 h prior to the administration of the (123)I-insulin-loaded NPs to mimic the physiological conditions. The confocal and TEM micrographs show that the orally administered CS NPs were able to adhere and infiltrate through the mucus layer, approach the epithelial cells and mediate to open their TJs. The radioactivity associated with LPS was mainly restricted to the gastrointestinal tract, whereas (123)I-insulin started to appear in the urinary bladder at 3 h post administration. This observation indicates that the insulin-loaded in CS NPs can traverse across the intestinal epithelium and enter the systemic circulation, whereas LPS was unable to do so, probably because of the charge repulsion between the anionic LPS in the form of micelles and the negatively charged mucus layer. Our in vivo toxicity study further confirms that the enhancement of paracellular permeation by CS NPs did not promote the absorption of LPS. These results suggest that CS NPs can be used as a safe carrier for oral delivery of protein drugs.

Activation of inactive hepatocytes through histone acetylation: a mechanism for functional compensation after massive loss of hepatocytes

The mechanisms by which hepatic function is maintained after extensive parenchymal loss are unclear. In this study, we propose a novel concept of "functional heterogeneity" of hepatocytes based on their different expression of acetylated histones, the markers of active gene transcription, to explain the powerful compensatory capability of the liver. In the healthy human liver, only a fraction of the hepatocytes were marked by acetylated histones (ac-H2AK5, ac-H2BK5, ac-H3K9, ac-H3K14, ac-H3K27, and ac-H3K9/14). With the progression of cirrhosis, the ratio of the positive cells was gradually elevated, accompanied by the gradual exhaustion of the negative cells. By examining the global transcriptome of the mouse hepatocytes, we observed that the primed genes in the positive cells were much more numerous than those in negative cells. In a 70% hepatectomized mouse, the remnant hepatocytes were extensively activated, and the liver function was well maintained even when regeneration was severely inhibited. The functional compensation was absolutely dependent on the elevated expression of acetyl-histones. Additionally, when liver regeneration was blocked, the metabolism-related genes seemed to be preferentially transcribed. In conclusion, we demonstrate that normally, part of the active hepatocytes are competent for routine physiological requirements. The inactive hepatocytes, delicately regulated by acetyl-histones, act as a functional reservoir for future activation to restore the liver function after massive parenchymal loss.

Relationship of hepatic functional parameters with changes of functional liver volume using technetium-99m galactosyl serum albumin scintigraphy in patients undergoing preoperative portal vein embolization: a follow-up report

BACKGROUND

To identify predictors of changes in functional hepatic volumes after portal vein embolization (PVE) before hepatectomy, we examined the relationship between hepatic functional parameters and changes in functional volume of the embolized and non-embolized liver based on a previous volumetric analysis.

MATERIAL AND METHODS

Subjects were 24 patients who underwent PVE, which was performed through the trans-ileocolic vein (n = 4) or by percutaneous transhepatic puncture (n = 20). The RI liver volume parameter was measured by liver scintigraphy with technetium-(99m) galactosyl human serum albumin ((99m)Tc-GSA). Computed tomography (CT) volume parameter was also measured.

RESULTS

Significant atrophy of the embolized liver and hypertrophy of the non-embolized liver (change of 72 ± 108 cm(3) and 111 ± 91 cm(3), respectively) (change of 7.8%) was observed after PVE. The change in these RI volume parameters (change of 173 ± 175 cm(3) and 145 ± 137 cm(3) , respectively) (16.5%) was significantly greater than CT volume parameters (P < 0.01). CT vol and RI vol in the embolized and non-embolized liver were well correlated (r = 0.75 and 0.69, respectively). However, the correlation between CT and RI volume parameters in the embolized and non-embolized liver after PVE was very weak (r = 0.17 and 0.03, respectively). Only alkaline phosphatase level correlated negatively with atrophic CT volume parameter of the embolized liver (r = -0.455, P < 0.05). When compared with CT volume parameter, more parameters were significantly correlated with changes of RI volume parameter in the embolized liver: pre-PVE pressure; ICGR15; and serum levels of hyaluronate, total bilirubin, albumin, and alkaline phosphatase. Only platelet count was significantly correlated with hypertrophy of the non-embolized liver.

CONCLUSION

RI volume parameter might more accurately reflect functional changes in the embolized liver and non-embolized liver than CT volume parameter. Correlated parameters might allow us to predict the functional effect of PVE.

Impaired liver regeneration of steatotic rats after portal vein ligation: a particular emphasis on (99m)Tc-DISIDA scintigraphy and adiponectin signaling

BACKGROUND & AIMS

Portal vein ligation (PVL) is increasingly employed prior to major hepatectomy in order to enhance the volume of the future liver remnant (FLR) and to avoid post-hepatectomy liver failure. The efficacy of PVL on subjects with non-alcohol fatty liver disease (NAFLD) is largely unknown.

METHODS

Sprague-Dawley rats fed with normal diet (control) and methionine-choline deficient diet (MCD) were used. The animals underwent PVL and were sacrificed at indicated time points.

RESULTS

Livers from MCD rats exhibited a decreased BrdU and Ki-67 labelling index, and an increased apoptotic index after PVL compared to normal rats; as a net effect, MCD rats exhibited a decrease in their restituted liver mass and redistributed volume ratio, compared to normal rats. Normal rats displayed similar serum levels of ICG15-R before and after PVL; whereas MCD rats displayed reduced ICG15-R after PVL. Using (99m)Tc-DISIDA scintigraphy examination, livers from MCD rats exhibited decreased HEF and prolonged TE(1/2) of FLR after PVL, indicating deteriorating hepatocyte function despite the shift in volume. The basal level of plasma TNFalpha, IL-1alpha, IL-1beta, and IL-10 of MCD rats was significantly increased before PVL compared to normal rats; however their plasma level did not increase in response to PVL as in normal rats. Hepatic adiponectin mRNA surged in MCD rats after PVL, whereas its receptors, AdipoR1 and AdipoR2, were paradoxically down-regulated. PPARalpha, a down-stream molecule of AdipoR2 axis, was also decreased in MCD rats.

CONCLUSIONS

Reduced regenerated liver mass and deteriorated hepatocyte function of the FLR from steatotic rats after PVL may be associated with deranged Kupffer cell-mediated cytokine expression and disrupted adiponectin signalling.