Mechanism of liver regeneration after liver resection and portal vein embolization (ligation) is different?

Impact of liver volumetric regeneration on survival outcomes in patients with hepatocellular carcinoma after major hepatectomy

PURPOSE

Prognostic value of liver volumetric regeneration (LVR) in patients with hepatocellular carcinoma (HCC) who undergo major hepatectomy remains unknown. The aim of this study was to investigate the impact of LVR on long-term outcomes in these patients.

METHODS

Data of 399 consecutive patients with HCC who underwent major hepatectomy between 2000 to 2018 were retrieved from a prospectively maintained institutional database. The LVR-index was defined as the relative increase in liver volume from 7 days to 3 months (RLV3m/RLV7d, where RLV3m and RLV7d is the remnant liver volume around 3 months and postoperative 7 days after surgery). The optimal cut-off value was determined using the median value of LVR-index.

RESULTS

A total of 131 patients were eligible in this study. The optimal cut off value of LVR-index was 1.194. The 1-, 3-, 5- and 10-year overall survival (OS) rate of patients in the high LVR-index group were significantly better compared to those in the low LVR-index group (95.5%, 84.8%, 75.4% and 49.1% vs. 95.4%, 70.2%, 56.4%, and 19.9%, p = 0.002). Meanwhile, there was no significant difference with regards to time to recurrence between the two groups (p = 0.607). Significance of LVR-index for OS was retained after adjusting for known prognostic factors (p = 0.002).

CONCLUSION

In patients with HCC undergoing major hepatectomy, LVR-index may serve as a prognostic indicator for OS.

Application of associating liver partition and portal vein ligation for staged hepatectomy for initially unresectable hepatocellular carcinoma

OBJECTIVE

To evaluate the safety and efficacy of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) in the treatment of initially unresectable hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) and to preliminarily explore the mechanism of rapid growth of the future liver remnant (FLR).

METHODS

Twenty-four patients with HBV-associated HCC who underwent ALPPS in our hospital from August 2014 to January 2021 were retrospectively studied. Propensity score matching was used to compare oncologic outcomes of patients treated with ALPPS and transarterial chemoembolization (TACE). The expression of YAP and JNK in liver tissue after two stages of ALPPS were detected.

RESULTS

The median standard liver volume (SLV) was 1471.4 ml. Before second stage of ALPPS, the median FLR increased by 74.4%, and the median FLR/SLV increased from 26.1 to 41.6%. Twenty-two patients (91.7%) received staged hepatectomy after a median interval of 15 (9-24) d. The total incidence of postoperative complications in ALPPS group was 54.5%, and of Clavien-Dindo ≥ IIIb postoperative complications (requiring surgical, endoscopic or radiological intervention under general anesthesia) was 9.1%. There was no significant difference in total complications between ALPPS group and TACE group, but there were lower rate of above grade III complications in the TACE group than that in the ALPPS group. The incidence of complications was lower in laparoscopic-ALPPS than that in open surgery. In ALPPS group, the 1-year, 2-year and 5-year overall survival rate were respectively 71.4%, 33.3% and 4.8%. Interval time was an independent risk factor associated with overall survival rate. There was no significant difference in overall survival rate between ALPPS group and TACE group. For advanced HCC (BCLC stage B and C), ALPPS group was not superior to TACE group in overall survival rate. The expression of YAP and p-JNK in the residual liver tissue after second stage procedure was higher than that after first stage procedure, and the co-expression of YAP and p-JNK was observed in the residual liver tissue.

CONCLUSION

ALPPS is a safe and effective treatment for initially unresectable HBV-associated HCC. Laparoscopic technique might improve the effect of ALPPS. YAP and JNK pathway might take a role in rapid FLR increase in ALPPS procedure.

The Influence of Interdisciplinary Work towards Advancing Knowledge on Human Liver Physiology

The knowledge accumulated throughout the years about liver regeneration has allowed a better understanding of normal liver physiology, by reconstructing the sequence of steps that this organ follows when it must rebuild itself after being injured. The scientific community has used several interdisciplinary approaches searching to improve liver regeneration and, therefore, human health. Here, we provide a brief history of the milestones that have advanced liver surgery, and review some of the new insights offered by the interdisciplinary work using animals, in vitro models, tissue engineering, or mathematical models to help advance the knowledge on liver regeneration. We also present several of the main approaches currently available aiming at providing liver support and overcoming organ shortage and we conclude with some of the challenges found in clinical practice and the ethical issues that have concomitantly emerged with the use of those approaches.

Muscularity Defined by the Combination of Muscle Quantity and Quality is Closely Related to Both Liver Hypertrophy and Postoperative Outcomes Following Portal Vein Embolization in Cancer Patients

BACKGROUND

Portal vein embolization (PVE) is a common procedure for preventing hepatic insufficiency after major hepatectomy. While evaluating the body composition of surgical patients is common, the impact of muscularity defined by both muscle quantity and quality on liver hypertrophy after PVE and associated outcomes after major hepatectomy in patients with hepatobiliary cancer remain unclear.

METHODS

This retrospective review included 126 patients who had undergone hepatobiliary cancer resection after PVE. Muscularity was measured on preoperative computed tomography images by combining the skeletal mass index and intramuscular adipose content. Various factors including the degree of hypertrophy (DH) of the future liver remnant and post-hepatectomy outcomes were compared according to muscularity.

RESULTS

DH did not differ by malignancy type. Patients with high muscularity had better DH after PVE (P = 0.028), and low muscularity was an independent predictor for poor liver hypertrophy after PVE [odds ratio (OR), 3.418; 95% confidence interval (CI), 1.129-10.352; P = 0.030]. In subgroup analyses in which patients were stratified into groups based on primary hepatobiliary tumors and metastases, low muscularity was associated with higher incidence of post-hepatectomy liver failure (PHLF) ≥ grade B (P = 0.018) and was identified as an independent predictor for high-grade PHLF (OR 3.931; 95% CI 1.113-13.885; P = 0.034) among the primary tumor group. In contrast, muscularity did not affect surgical outcomes in patients with metastases.

CONCLUSIONS

Low muscularity leads to poor liver hypertrophy after PVE and is also a predictor of PHLF, particularly in primary hepatobiliary cancer.

Functional transition: Inconsistently parallel to the increase in future liver remnant volume after preoperative portal vein embolization

BACKGROUND

Preoperative portal vein embolization (PVE) is a widely used strategy to enable major hepatectomy in patients with insufficient liver remnant. PVE induces hypertrophy of the future liver remnant (FLR) and a shift of the functional reserve to the FLR. However, whether the increase of the FLR volume (FLRV) corresponds to the functional transition after PVE remains unclear.

AIM

To investigate the sequential relationship between the increase in FLRV and functional transition after preoperative PVE using 3-dimensional (3D) computed tomography (CT) and ^99mTc-galactosyl-human serum albumin (^99mTc-GSA) single-photon emission computed tomography (SPECT) fusion images.

METHODS

Thirty-three patients who underwent major hepatectomy following PVE at the Department of Gastroenterological Surgery I, Hokkaido University Hospital between October 2013 and March 2018 were enrolled. Three-phase dynamic multidetector CT and ^99mTc-GSA SPECT scintigraphy were performed at pre-PVE, and at 1 and 2 wk after PVE; 3D ^99mTc-GSA SPECT CT-fused images were constructed from the Digital Imaging and Communications in Medicine data using 3D image analysis system. Functional FLRV (FFLRV) was defined as the total liver volume × (FLR volume counts/total liver volume counts) on the 3D ^99mTc-GSA SPECT CT-fused images. The calculated FFLRV was compared with FLRV.

RESULTS

FFLRV increased by a significantly larger extent than FLRV at 1 and 2 wk after PVE (P < 0.01). The increase in FFLRV and FLRV was 55.1% ± 41.6% and 26.7% ± 17.8% (P < 0.001), respectively, at 1 wk after PVE, and 64.2% ± 33.3% and 36.8% ± 18.9% (P < 0.001), respectively, at 2 wk after PVE. In 3 of the 33 patients, FFLRV levels decreased below FLRV at 2 wk. One of the three patients showed rapidly progressive fatty changes in FLR. The biopsy at 4 wk after PVE showed macro- and micro-vesicular steatosis of more than 40%, which improved to 10%. Radical resection was performed at 13 wk after PVE. The patient recovered uneventfully without any symptoms of pos-toperative liver failure.

CONCLUSION

The functional transition lagged behind the increase in FLRV after PVE in some cases. Evaluating both volume and function is needed to determine the optimal timing of hepatectomy after PVE.

Cholecystic Venous Anatomy: A Cadaveric Study with Implications for Portal Venous Interruption Procedure

The techniques of portal vein embolization (PVE) or ligation (PVL) have the goals of combining an induced atrophy of metastatic segments with the rapid relative compensatory hypertrophy of the postresection future liver remnant (FLR). Our study examines the anatomy of right-left hepatic lobar venous connections in the adult cadaver using corrosion cast analysis in an effort to define some of the inherent anatomical reasons why both PVL and PVE may be technically unsuccessful. Corrosion cast models of 215 cadaveric liver specimens were evaluated for hepatopetal venous blood flow, with a particular emphasis on cholecystic venous drainage patterns, including 57 cases prepared after lobar portal venous ligation. In 88.8 per cent of corrosion casts, there was a segmental venous communication between the gallbladder and all segments of the liver, except segment II. There was cystic vein drainage directly into a main lobar branch or directly into the portal vein itself in 11.2 per cent of cases. In all 57 cases, after portal lobar venous division, in situ cystic veins allowed persistent venous communication between lobes. Our cadaveric corrosion cast study has suggested that there is extensive intrahepatic cholecystic venous drainage to many segments of the liver. Perfusion from the gallbladder may potentially contribute to a limited response to procedures which interrupt the portal venous flow and could affect their capacity to induce an adequate FLR which would permit a wider hepatectomy.

[Implantation strategy of tissue-engineered liver based on decellularized spleen matrix in rats]

OBJECTIVE

To explore the optimal implantation strategy of tissue-engineered liver (TEL) constructed based on decellularized spleen matrix (DSM) in rats.

METHODS

DSM was prepared by freeze-thawing and perfusion with sodium dodecyl sulfate (SDS) of the spleen of healthy SD rats. Primary rat hepatocytes isolated using modified Seglen 2-step perfusion method were implanted into the DSM to construct the TEL. The advantages and disadvantages were evaluated of 4 transplant strategies of the TEL, namely ectopic vascular anastomosis, liver cross-section suture transplantation, intrahepatic insertion and mesenteric transplantation.

RESULTS

The planting rate of hepatocytes in the DSM was (74.5∓7.7)%. HE staining and scanning electron microscopy showed satisfactory cell status, and immunofluorescence staining confirmed the normal expression of ALB and G6Pc in the cells. For TEL implantation, ectopic vascular anastomosis was difficult and resulted in a mortality rate of 33.3% perioperatively and massive thrombus formation in the matrix within 6 h. Hepatic cross-section suture failed to rapidly establish sufficient blood supply, and no viable graft was observed 3 days after the operation. With intrahepatic insertion method, the hepatocytes in the DSM could survive as long as 14 days. Mesenteric transplantation resulted in a hepatocyte survival rate of (38.3+7.1)% at 14 days after implantation.

CONCLUSION

TEL constructed based on DSM can perform liver-specific functions with a good cytological bioactivity. Mesenteric transplantation of the TEL, which is simple, safe and effective, is currently the optimal transplantation strategy.

Right trisegmentectomy after portal vein embolization in a high-risk toddler with hepatoblastoma

Portal vein embolization (PVE) is a pre-operative treatment modality in adults undergoing hepatectomy with concerns of post-operative liver failure from insufficient future liver remnant (FLR). PVE induces growth in the FLR. The success of this technique is well described in adults, but not in young children with hepatoblastoma.

Portal vein ligation alters coding and noncoding gene expression in rat livers

Portal vein occlusion increases the resectability of initially unresectable liver cancer by inducing hypertrophy in non-occluded liver lobes. However, the mechanisms of how portal vein occlusion induces hepatic hypertrophy remain unclear. A cDNA microarray was used to identify the gene expression signatures of ligated (LLLs) and nonligated liver lobes (NLLLs) at different time points after portal vein ligation (PVL). The results of a bioinformatics analysis revealed that LLLs and NLLLs displayed different gene expression profiles. Moreover, the expression levels of both coding and noncoding RNA were different between LLLs and NLLLs at different time points after PVL. A series test of cluster analysis revealed that the No. 22 and No. 5 expression patterns, which showed altered expression at 24 h and maintained this altered expression over the following 14 days, had the lowest P values and the highest number of differentially expressed genes in both the LLLs and NLLLs. The results of a GO analysis showed the activation of hypoxia pathways in LLLs and the activation of cell proliferation and cell-cycle pathways in NLLLs, suggesting the involvement of these pathways in PVL-induced hepatic hypertrophy and regeneration. These results provide insight into the molecular mechanisms underlying hepatic hypertrophy and regeneration induced by portal vein occlusion, and they identify potential targeting pathways that can promote the clinical application of PVL in liver cancer therapy.

[Portal vein embolization: Present and future]

Portal vein embolization consists of occluding a part of the portal venous system in order to achieve the hypertrophy of the non-embolized liver segments. This technique is used during the preoperative period of major liver resection when the future remnant liver (FRL) volume is insufficient, exposing to postoperative liver failure, main cause of death after major hepatectomy. Portal vein embolization indication depends on the FRL, commonly assessed by its volume. Nowadays, FRL function evaluation seems more relevant and can be measured by 99mTc labelled mebrofenin scintigraphy. Portal vein embolization procedure is mostly performed with percutaneous trans-hepatic access by using ultrasonography guidance and consists of embolic agent injection, such as cyanoacrylate, in the targeted portal vein branches with fluoroscopic guidance. It is a safe and well-tolerated technique, with extremely low morbi-mortality. Portal vein embolization leads to sufficient FRL hypertrophy in about 80% of patients, allowing them to undergo surgery from which they were initially rejected. The two main reasons of non-resection are tumor progression (≈15% of cases) and FRL insufficient hypertrophy (≈5% of cases). When portal vein embolization is not enough to obtain adequate FRL regeneration, hepatic vein embolization may potentiate its effect (liver venous deprivation technique).

Regulatory signatures of liver regeneration distilled by integrative analysis of mRNA, histone methylation, and proteomics

The capacity of the liver to regenerate is likely to be encoded as a plasticity of molecular networks within the liver. By applying a combination of comprehensive analyses of the epigenome, transcriptome, and proteome, we herein depict the molecular landscape of liver regeneration. We demonstrated that histone H3 Lys-4 was trimethylated at the promoter regions of many loci, among which only a fraction, including cell-cycle-related genes, were transcriptionally up-regulated. A cistrome analysis guided by the histone methylation patterns and the transcriptome identified FOXM1 as the key transcription factor promoting liver regeneration, which was confirmed in vitro using a hepatocarcinoma cell line. The promoter regions of cell-cycle-related genes and Foxm1 acquired higher levels of trimethylated histone H3 Lys-4, suggesting that epigenetic regulations of these key regulatory genes define quiescence and regeneration of the liver cells. A quantitative proteome analysis of the regenerating liver revealed that conditional protein degradation also mediated regeneration-specific protein expression. These sets of informational resources should be useful for further investigations of liver regeneration.

Hedgehog pathway mediates early acceleration of liver regeneration induced by a novel two-staged hepatectomy in mice

BACKGROUND & AIMS

ALPPS, a novel two-staged approach for the surgical removal of large/multiple liver tumors, combines portal vein ligation (PVL) with parenchymal transection. This causes acceleration of compensatory liver growth, enabling faster and more extensive tumor removal. We sought to identify the plasma factors thought to mediate the regenerative acceleration following ALPPS.

METHODS

We compared a mouse model of ALPPS against PVL and additional control surgeries (n=6 per group). RNA deep sequencing was performed to identify candidate molecules unique to ALPPS liver (n=3 per group). Recombinant protein and a neutralizing antibody combined with appropriate surgeries were used to explore candidate functions in ALPPS (n=6 per group). Indian hedgehog (IHH/Ihh) levels were assessed in human ALPPS patient plasma (n=6).

RESULTS

ALPPS in mouse confirmed significant acceleration of liver regeneration relative to PVL (p<0.001). Ihh mRNA, coding for a secreted ligand inducing hedgehog signaling, was uniquely upregulated in ALPPS liver (p<0.001). Ihh plasma levels rose 4h after surgery (p<0.01), along with hedgehog pathway activation and subsequent cyclin D1 induction in the liver. When combined with PVL, Ihh alone was sufficient to induce ALPPS-like acceleration of liver growth. Conversely, blocking Ihh markedly inhibited the accelerating effects of ALPPS. In the small cohort of ALPPS patients, IHH tended to be elevated early after surgery.

CONCLUSIONS

Ihh and hedgehog pathway activation provide the first mechanistic insight into the acceleration of liver regeneration triggered by ALPPS surgery. The accelerating potency of recombinant Ihh, and its potential effect in human ALPPS may lead to a clinical role for this protein.

LAY SUMMARY

ALPPS, a novel two-staged hepatectomy, accelerates liver regeneration, thereby helping to treat patients with otherwise unresectable liver tumors. The molecular mechanisms behind this accelerated regeneration are unknown. Here, we elucidate that Indian hedgehog, a secreted ligand important for fetal development, is a crucial mediator of the regenerative acceleration triggered by ALPPS surgery.

Associated Liver Partition and Portal Vein Ligation (ALPPS) vs Selective Portal Vein Ligation (PVL) for Staged Hepatectomy in a Rat Model. Similar Regenerative Response?

Associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage hepatectomy technique which can be associated with a hypertrophic stimulus on the future liver remnant (FLR) stronger than other techniques–such as portal vein ligation (PVL). However, the reason of such hypertrophy is still unclear, but it is suggested that liver transection combined with portal vein ligation (ALPPS) during the first stage of this technique may play a key role. The aim of this study is to compare the hypertrophic stimulus on the FLR and the clinical changes associated with both ALPPS and PVL in a rat surgical model. For this purpose, three groups of SD rats were used, namely ALPPS (n = 30), PVL (n = 30) and sham-treated (n = 30). The second stage of ALPPS (hepatectomy of the atrophic lobes), was performed at day 8. Blood and FLR samples were collected at 1, 24, 48 hours, 8 days and 12 weeks after the surgeries. ALPPS provoked a greater degree of hypertrophy of the FLR than the PVL at 48 hours and 8 days (p<0.05). The molecular pattern was also different, with the highest expression of IL-1β at 24h, IL-6 at 8 days, and HGF and TNF-α at 48 hours and 8 days (p<0.05). ALPPS also brought about a mild proliferative stimulus at 12 weeks, with a higher expression of HGF and TGF-β (p<0.05) than PVL. Clinically, ALPPS caused a significant liver damage during the first 48 hours, with a recovery of liver function at day 8. In conclusion, ALPPS seems to induce higher functional hypertrophy on the FLR than PVL at day 8. Such regenerative response seems to be leaded by a complex interaction between pro-mitogenic (IL-6, HGF, TNF-α) and antiproliferative (IL1-β and TGF-β) cytokines.

Identification and expression analysis of a heat-shock protein 70 gene in Polycelis sp

Heat-shock protein 70 (HSP70) is ubiquitously found in a variety of organisms and plays an important role in cytoprotection, environmental monitoring, and disease resistance. In this study, the full-length complementary DNA (cDNA) of hsp70 from planarian Polycelis sp. was first cloned using rapid amplification of cDNA ends (RACE). The expression levels of Pyhsp70 were analyzed in the presence of various stressors by real-time PCR, and its temporal-spatial expression patterns were also examined in both intact and regenerative animals by whole-mount in situ hybridization. The results show that (1) the deduced amino acid sequence of Pyhsp70 includes three typical HSP70 family signature motifs and is highly conserved during evolution; (2) Pyhsp70 expression is induced by prolonged starvation, tissue damage, and ionic liquid but inhibited by high or low temperatures; and (3) Pyhsp70 mRNA is mainly expressed in the head peripheral region and in the regenerating blastema during regeneration. These results suggest that the highly expressed Pyhsp70 gene may contribute to enhance cytoprotection and tolerance against stress-induced molecular damage, and the migration of neoblasts to the wound, which might also be involved in the proliferation and differentiation of neoblasts. Our work provides basic data for the study of stress responses and regenerative mechanism in freshwater planarians.

Associating liver partition with portal vein ligation and staged hepatectomy (ALPPS) for the treatment of liver tumors in children

Resection is the only curative treatment option for primary and secondary malignant tumors of the liver. Although curative resection is associated with long-term survival rates, it can only be performed in 10% of patients with primary tumors and 25% of patients with liver metastases. Liver insufficiency is one of the most serious postoperative complications of patients undergoing extensive liver resections. When total liver resection is necessary liver transplant is mandatory, with the burden of long-term immunosuppression and its complications. Among several different strategies to increase the resectability of liver tumors, portal vein occlusion (embolization or ligature), bilateral tumor resection in two stages, and resection combined with loco regional therapy are the most popular. A new strategy for patients with marginally resectable liver tumors previously considered to be unresectable was formally reported by Baumgart et al. in 2011, originally developed by Hans Schlitt in 2007. This technique consists of a two-staged hepatectomy with initial portal vein ligation and in situ splitting of the liver parenchyma, and it is known as ALPPS (associating liver partition with portal vein ligation for staged hepatectomy). The aim of this study is to present the first series of pediatric patients with marginally resectable liver tumors previously considered to be unresectable treated with two-stage hepatectomy with initial portal vein ligation and in situ splitting of the liver parenchyma. Two patients were diagnosed with hepatoblastoma, and one each with rhabdomyosarcoma, hepatocellular carcinoma, and nodular focal hyperplasia. ALPPS technique was considered whenever the future liver remnant (FLR) was 40% or less of the total liver volume (TLV) determined by CT or MRI scans. The ratio of FLR to TLV before the first procedure ranged from 0.15 to 0.38, with a mean±sd of 0.253±0.07. In all patients, a rapid growth of the FLR was observed. Estimates of the FRL volume prior to surgical treatment ranged from 110cc to 750cc, with a mean±sd of 361.6±213.75cc. Just before the second procedure, the volume of the remnant liver ranged from 225cc to 910cc, with a mean±sd of 563.6cc±221.7cc. The FRL volume increase had a mean±sd of 72.56%±29.05%, with a median of 83.8%. The second procedure was performed after 7 to 12days with a median of 11days. The only postoperative complication observed in one patient was an asymptomatic right pleural effusion that was aspirated during the second procedure with no further complications. ALPPS was shown to be effective and a safe procedure to treat large tumors in children.

Activins and Follistatin in Chronic Hepatitis C and Its Treatment with Pegylated-Interferon-α Based Therapy

Pegylated-interferon-α based therapy for the treatment of chronic hepatitis C (CHC) is considered suboptimal as not all patients respond to the treatment and it is associated with several side effects that could lead to dose reduction and/or termination of therapy. The currently used markers to monitor the response to treatment are based on viral kinetics and their performance in the prediction of treatment outcome is moderate and does not combine accuracy and their values have several limitations. Hence, the development of new sensitive and specific predictor markers could provide a useful tool for the clinicians and healthcare providers, especially in the new era of interferon-free therapy, for the classification of patients according to their response to the standard therapy and only subscribing the novel directly acting antiviral drugs to those who are anticipated not to respond to the conventional therapy and/or have absolute contraindications for its use. The importance of activins and follistatin in the regulation of immune system, liver biology, and pathology has recently emerged. This review appraises the up-to-date knowledge regarding the role of activins and follistatin in liver biology and immune system and their role in the pathophysiology of CHC.

Rodent models and imaging techniques to study liver regeneration

The liver has the unique capability of regeneration from various injuries. Different animal models and in vitro methods are used for studying the processes and mechanisms of liver regeneration. Animal models were established either by administration of hepatotoxic chemicals or by surgical approach. The administration of hepatotoxic chemicals results in the death of liver cells and in subsequent hepatic regeneration and tissue repair. Surgery includes partial hepatectomy and portal vein occlusion or diversion: hepatectomy leads to compensatory regeneration of the remnant liver lobe, whereas portal vein occlusion leads to atrophy of the ipsilateral lobe and to compensatory regeneration of the contralateral lobe. Adaptation of modern radiological imaging technologies to the small size of rodents made the visualization of rodent intrahepatic vascular anatomy possible. Advanced knowledge of the detailed intrahepatic 3D anatomy enabled the establishment of refined surgical techniques. The same technology allows the visualization of hepatic vascular regeneration. The development of modern histological image analysis tools improved the quantitative assessment of hepatic regeneration. Novel image analysis tools enable us to quantify reliably and reproducibly the proliferative rate of hepatocytes using whole-slide scans, thus reducing the sampling error. In this review, the refined rodent models and the newly developed imaging technology to study liver regeneration are summarized. This summary helps to integrate the current knowledge of liver regeneration and promises an enormous increase in hepatological knowledge in the near future.

Involvement of heat shock proteins in gluten-sensitive enteropathy

Gluten-sensitive enteropathy, also known as coeliac disease (CD), is an autoimmune disorder occurring in genetically susceptible individuals that damages the small intestine and interferes with the absorption of other nutrients. As it is triggered by dietary gluten and related prolamins present in wheat, rye and barley, the accepted treatment for CD is a strict gluten-free diet. However, a complete exclusion of gluten-containing cereals from the diet is often difficult, and new therapeutic strategies are urgently needed. A class of proteins that have already emerged as drug targets for other autoimmune diseases are the heat shock proteins (HSPs), which are highly conserved stress-induced chaperones that protect cells against harmful extracellular factors. HSPs are expressed in several tissues, including the gastrointestinal tract, and their levels are significantly increased under stress circumstances. HSPs exert immunomodulatory effects, and also play a crucial role in the maintenance of epithelial cell structure and function, as they are responsible for adequate protein folding, influence the degradation of proteins and cell repair processes after damage, and modulate cell signalling, cell proliferation and apoptosis. The present review discusses the involvement of HSPs in the pathophysiology of CD. Furthermore, HSPs may represent a useful therapeutic target for the treatment of CD due to the cytoprotective, immunomodulatory, and anti-apoptotic effects in the intestinal mucosal barrier.

Liver remnant hypertrophy induction--how often do we really use it in the time of computer assisted surgery?

PURPOSE

To evaluate the significance of the hypertrophy concept in patients requiring extended liver resections for colorectal metastasis in the time of computer assisted surgery.

METHODS

Retrospective analysis of patient collective undergoing major liver surgery. 2D CT, 3D CAS with Fraunhofer MeVis Sofware. Portal vein embolisation (PVE) with the Amplazer Plug, portal vein ligation (PVL) as 1. Stage operative procedure.

RESULTS

2D CT data identified 29 patients out of 319 (2002-2009) to be at risk for liver failure after resection. After 3D CAS analysis and virtual operation planning, only 7/29 were at true risk and were submitted to portal vein occlusion (PVO). Another 5 patients were submitted to the hypertrophy concept for intraoperative finding of insufficient parenchyma quality. In total, 12 patients underwent PVO (6 PVE/6 PVL). 9/12 patients went to stage 2 and were successfully operated. There was no difference in future remnant liver volume (FRLV) gain or waiting time to step 2 between the groups, though survival was better in the PVE group.

CONCLUSION

PVO is an effective approach if the patient's future remnant liver (FRL) is too small on 2D CT volumetry. 3D CAS has great impact on the analysis of FRL capacity and in augmenting resectability - in our experience only patients with insufficient FRLV on the virtual resection plan have to take the risk of PVO to maintain the chance of liver resection.

Ischemia/reperfusion in clamped lobes facilitates liver regeneration of non-clamped lobes after selective portal vein ligation

BACKGROUND

Hypertrophy of non-clamped liver lobes and the atrophy of clamped lobes have been shown to be interactive. Here, a rat model of selective lobe occlusion was established to study the effect of contralateral ischemia/reperfusion (I/R) on regeneration of non-clamped lobes.

METHODS

Left lateral and middle liver lobes were pretreated with I/R. In the experimental (IR + PVL) group, portal veins of the left and middle lobes were ligated. A group given similar portal vein ligation but no I/R (PVL) was the positive control.

RESULTS

Compared with the PVL group, the IR + PVL had higher, but not remarkable, levels of serum transaminases; weights of non-clamped lobes in the IR + PVL group comparatively increased much more notably. At 24-h post-surgery, the IR + PVL group's PCNA mRNA was up-regulated compared with the PVL group. At 72-h post-surgery, PCNA protein was up-regulated significantly, while TGF-β1 was down-regulated in the IR + PVL group notably, compared with the PVL group.

CONCLUSION

The I/R pretreatment given to the clamped lobes facilitates liver regeneration of non-clamped lobes after selective portal vein ligation, which may result from down-regulated TGF-β1 expression in non-clamped lobes.

Role of portal vein embolization in hepatocellular carcinoma management and its effect on recurrence: a case-control study

BACKGROUND

Liver regeneration that occurs after portal vein embolization (PVE) may have adverse effects on the microscopic tumor foci in the residual liver mass in patients with hepatocellular carcinoma (HCC).

METHODS

Fifty-four HCC patients with inadequate functional residual liver volume were offered PVE during a seven-year period. Among them, 34 (63%) patients underwent curative resection. They were compared with a matched control group (n = 102) who underwent surgery without PVE. Postoperative complications, pattern of recurrence, and survival were compared between groups.

RESULTS

In the PVE group, a pre-embolization functional residual liver volume of 23% (12-33.5%) improved to 34% (20-54%) (p = 0.005) at the time of surgery. When the two groups were compared, minor (PVE, 24%; control, 29%; p = 0.651) and major (PVE, 18%; control, 15%; p = 0.784) complications were similar. After a follow-up period of 35 months (standard deviation 25 months), extrahepatic recurrences were detected in 10 PVE patients (29%) and 41 control patients (40%) (p = 0.310). Intrahepatic recurrences were seen in 10 (29%) and 47 (46%) cases (p = 0.109) in the PVE and control groups, respectively. In the PVE group, 41% (n = 14) of the recurrences were detected before one year, compared with 42% (n = 43) in the control group (p = 1). Disease-free survival rates at 1, 3, and 5 years were 57, 29, and 26% in the control group and 60, 42, and 42% in the PVE group (log-rank, p = 0.335). On multivariate analysis, PVE was not a factor affecting survival (p = 0.821).

CONCLUSIONS

Portal vein embolization increases the resectability of initially unresectable HCC due to inadequate functional residual liver volume, and it has no deleterious oncological effect after major resection of HCC.

31P MR spectroscopic imaging detects regenerative changes in human liver stimulated by portal vein embolization

PURPOSE

First, to evaluate hepatocyte phospholipid metabolism and energetics during liver regeneration stimulated by portal vein embolization (PVE) using proton-decoupled (31)P MR spectroscopic imaging ((31)P-MRSI). Second, to compare the biophysiologic differences between hepatic regeneration stimulated by PVE and by partial hepatectomy (PH).

MATERIALS AND METHODS

Subjects included six patients with hepatic metastases from colorectal cancer who were scheduled to undergo right PVE before definitive resection of right-sided tumor. (31)P-MRSI was performed on the left liver lobe before PVE and 48 h following PVE. Normalized quantities of phosphorus-containing hepatic metabolites were analyzed from both visits. In addition, MRSI data at 48 h following partial hepatectomy were compared with the data from the PVE patients.

RESULTS

At 48 h after PVE, the ratio of phosphomonoesters to phosphodiesters in the nonembolized lobe was significantly elevated. No significant changes were found in nucleoside triphosphates (NTP) and Pi values. The phosphomonoester (PME) to phosphodiester (PDE) ratio in regenerating liver 48 h after partial hepatectomy was significantly greater than PME/PDE 48 h after PVE.

CONCLUSION

(31)P-MRSI is a valid technique to noninvasively evaluate cell membrane metabolism following PVE. The different degree of biochemical change between partial hepatectomy and PVE indicates that hepatic growth following these two procedures does not follow the same course.

Tissue damage with different surgical techniques in a porcine model of liver resection: implications for living-donor liver transplantation?

Background/purpose

For living-donor liver transplantation (LDLT) it is of paramount importance to preserve as much viable liver tissue as possible to avoid postoperative complications in the donor and recipient. The depth of tissue damage caused by common surgical techniques for liver resection has not been studied so far.

Methods

Here we compared the depth of tissue damage and the immunohistochemical expression of heat shock protein (HSP) 70, a marker for tissue damage, in a porcine model of liver resection, to assess the effect of different surgical techniques, i.e., blunt dissection (BD), and dissection with an ultrasound aspirator (UA), an ultrasound scalpel (US), or a water-jet (WJ).

Results

Analysis with linear mixed effects models (LME) showed significantly less tissue damage with BD and UA than with US and WJ (joint p value <0.001). Damage also increased within 6 h after surgery (p value = 0.004). Semiquantitative evaluation of HSP 70 showed increased expression after resection with US compared to all other resection methods (p value <0.001), indicating increased tissue damage with this method.

Conclusion

We suggest that in cases of liver resection for LDLT surgeons should reevaluate using US and WJ because of possible excessive tissue damage compared to BD and UA. Overall we advocate the use of BD as it requires no special equipment and, hence, has considerably higher cost-effectiveness without compromising tissue preservation and clinical outcome and is readily available even in low-tech environments.

Liver functional volumetry for portal vein embolization using a newly developed 99mTc-galactosyl human serum albumin scintigraphy SPECT-computed tomography fusion system

BACKGROUND

We developed a new combined (99m)Tc-galactosyl human serum albumin (GSA) scintigraphy single-photon emission computed tomography (SPECT)/CT system to evaluate the changes in functional liver volume with portal vein embolization (PVE).

METHODS

We performed a prospective analysis of 25 patients treated with right PVE, and evaluated their functional liver volume perioperatively with a (99m)Tc-GSA scintigraphy SPECT-CT fusion system. The percentage of the non-tumorous remnant liver volume (%LV) and the percentage of functional remnant liver volume (%FLV) were estimated by using the following calculations: (future remnant volume - tumor volume)/(total liver volume - tumor volume) and functional future remnant liver volume/functional total liver volume, respectively.

RESULTS

Before PVE, the correlation was strongly significant between %LV and %FLV of the non-embolized liver, and the data were nearly equal (the regression coefficient was 1.005, P < 0.0001). In contrast, after PVE, there was a significant correlation between %LV and %FLV (P < 0.0001), but the regression coefficient was 1.192. The % LV increased significantly, from 38.1 to 52.0%, and the increment was 13.9% (P < 0.0005). The %FLV was also increased significantly, from 36.6 to 58.0%, and the increment was 21.4% (P < 0.0001). The increment was 7.5% greater for the %FLV compared to that of the %LV (P < 0.001).

CONCLUSIONS

The (99m)Tc-GSA scintigraphy SPECT-CT fusion system can estimate the correct functional liver volume and is useful in comparison with conventional CT volumetry.

The efficacy of portal vein embolization prior to right extended hemihepatectomy for hilar cholangiocellular carcinoma: a retrospective cohort study

BACKGROUND/PURPOSE

Preoperative portal vein embolization was introduced to minimize complications after extended hepatectomy. This retrospective cohort study was conducted to compare outcomes with and without portal vein embolization before hepatectomy for hilar cholangiocellular carcinoma.

METHODS

This study was conducted with 35 patients who underwent right extended hemihepatectomy for hilar cholangiocellular carcinoma from 2001 to 2008. Preoperative portal vein embolization was performed in 14 patients (embolization group) and not performed in 21 patients (non-embolization group).

RESULTS

The groups did not differ in terms of sex, age, operative time, transfusion, postoperative serum bilirubin level, prothrombin time, and length of intensive care unit (ICU) stay. Although blood loss was higher in the embolization group than in the non-embolization group (P = .009), no major complications were observed between embolization and resection. At presentation, future liver remnant was smaller in the embolization group (19.8%, range 16-35%) than in non-embolization group (28.3%, 15-47%; P = .001). After embolization, the volume of the future liver remnant increased significantly to 27.2% (range, 23-42%; P = .001). Future liver remnants just before operation were similar in both groups (P > .99). There was no significant difference in terms of the rate of morbidity and in-hospital mortality. No statistically significant differences were observed in disease-free survival (P = .52) and overall survival (P = .30).

CONCLUSIONS

Portal vein embolizations do not increase the rate of morbidity, in-hospital mortality, local recurrence and system metastasis. Therefore it can be considered safe and effective for patients with small future liver remnants. Embolization can lessen postoperative liver failure and widen the indication of the surgical resection, especially in patients with marginal future liver remnants.

Analysis of time-course gene expression profiles of sinusoidal endothelial cells during liver regeneration in rats

Liver regeneration (LR) after partial hepatectomy (PH) requires the coordinate contribution of different cell types. Liver sinusoidal endothelial cells (LSECs), representing the largest population of nonparenchymal cells, are proven to be crucial in LR. However, the details about their implications in regeneration are not still clear. In this study, percoll density centrifugation and immunomagentic bead methods were used to isolate LSECs with high purity and yield; global transcriptional profiles of LSECs during the regeneration were investigated by microarray. 1,629 genes were identified to be LR-related. Among them, there were 833 known genes whose expression patterns were clustered into eight classes. Gene function enrichment analysis showed that genes involved in the major LSEC functions, i.e., coagulation, phagocytosis, and transport, were highly enriched in cluster characterized by rapid induction and gradual return, suggesting the quick reestablishment of LSEC function after PH. Genes in immunity/inflammation and defense response were enriched in clusters exhibiting transient downregulation and quick recovery, possibly being associated with suppression of immunity/inflammation pathway in LSECs at early phase. Genes in glycogen synthesis and glycolysis were enriched in the clusters marked by "significant increase and gradual return" and "slight increase and then downregulation", implying an enhanced carbohydrate metabolism at early phase; detoxification-related genes were markedly distributed in the cluster with feature of rapid increase and then reduction, which was helpful in eliminating waste substance. Taken together, the measurement of gene expression profiling of LSECs and expression pattern analysis of functionally categorized genes gave insight into the mechanism of action of this cell on LR.

Portal vein ligation accelerates tumor growth in ligated, but not contralateral lobes

AIM: To investigate the mechanisms of liver growth and atrophy after portal vein ligation (PVL) and its effects on tumor growth.

METHODS: Mice were subjected to PVL, partial hepatectomy, or sham surgery. The morphological alterations, activation of transcription factors, and expression of cytokines and growth factors involved in liver regeneration were evaluated. In a separate set of experiments, murine colorectal carcinoma cells were injected via the portal vein and the effect of each operation on liver tumor growth was studied.

RESULTS: Liver regeneration after PVL and partial hepatectomy were very similar. In ligated lobes, various cytokines, transcription factors and regulatory factors were significantly upregulated compared to non-ligated lobes after PVL. Atrophy in ligated lobes was a result of early necrosis followed by later apoptosis. Tumor growth was significantly accelerated in ligated compared to non-ligated lobes.

CONCLUSION: Tumor growth was accelerated in ligated liver lobes and appeared to be a result of increased growth factor expression.