New paradigms in post-hepatectomy liver failure

Post-hepatectomy liver failure: A timeline centered review

BACKGROUND

Post-hepatectomy liver failure (PHLF) is a leading cause of postoperative mortality after liver surgery. Due to its significant impact, it is imperative to understand the risk stratification and preventative strategies for PHLF. The main objective of this review is to highlight the role of these strategies in a timeline centered way around curative resection.

DATA SOURCES

This review includes studies on both humans and animals, where they addressed PHLF. A literature search was conducted across the Cochrane Library, Embase, MEDLINE/PubMed, and Web of Knowledge electronic databases for English language studies published between July 1997 and June 2020. Studies presented in other languages were equally considered. The quality of included publications was assessed using Downs and Black's checklist. The results were presented in qualitative summaries owing to the lack of studies qualifying for quantitative analysis.

RESULTS

This systematic review with 245 studies, provides insight into the current prediction, prevention, diagnosis, and management options for PHLF. This review highlighted that liver volume manipulation is the most frequently studied preventive measure against PHLF in clinical practice, with modest improvement in the treatment strategies over the past decade.

CONCLUSIONS

Remnant liver volume manipulation is the most consistent preventive measure against PHLF.

Volumetric Remodeling of the Left Liver After Right Hepatectomy: Analysis of Factors Predicting Degree of Hypertrophy and Post-hepatectomy Liver Failure

BACKGROUND

This study investigated the volumetric remodeling of the left liver after right hepatectomy looking for factors predicting the degree of hypertrophy and severe post-hepatectomy liver failure (PHLF).

METHODS

In a cohort of 121 right hepatectomies, we performed CT volumetrics study of the future left liver remnant (FLR) preoperatively and postoperatively. Factors influencing FLR degree of hypertrophy and severe PHLF were identified by multivariate analysis.

RESULTS

After right hepatectomy, the mean degree of hypertrophy and kinetic growth rate of the left liver remnant were 25% and 3%/day respectively. The mean liver volume recovery rate was 77%. Liver remodeling volume was distributed for 79% on segments 2 and 3 and 21% on the segment 4 (p<0.001). Women showed a greater hypertrophy of segments 2 and 3 compared with men (p=0.002). The degree of hypertrophy of segment 4 was lower in case of middle hepatic vein resection (p=0.004). Left liver remnant kinetic growth rate was associated with the standardized future liver remnant (sFLR) (p<0.001) and a two-stage hepatectomy (p=0.023). Severe PHLF were predicted by intraoperative transfusion (p=0.009), biliary tumors (p=0.013), and male gender (p=0.022).

CONCLUSIONS

Volumetric remodeling of the left liver after right hepatectomy is not uniform and is mainly influenced by gender and sacrifice of middle hepatic vein. Male gender, intraoperative transfusion, and biliary tumors increase the risk of postoperative liver failure after right hepatectomy.

Postoperative Liver Failure: Definitions, Risk factors, Prediction Models and Prevention Strategies

BACKGROUND

Liver resection is the treatment for a variety of benign and malignant conditions. Despite advances in preoperative selection, surgical technique, and perioperative management, post hepatectomy liver failure (PHLF) is still a leading cause of morbidity and mortality following liver resection.

METHODS

A review of the literature was performed utilizing MEDLINE/PubMed and Web of Science databases in May of 2023. The MESH terms "liver failure," "liver insufficiency," and "hepatic failure" in combination with "liver surgery," "liver resection," and "hepatectomy" were searched in the title and/or abstract. The references of relevant articles were reviewed to identify additional eligible publications.

RESULTS

PHLF can have devastating physiological consequences. In general, risk factors can be categorized as patient-related, primary liver function-related, or perioperative factors. Currently, no effective treatment options are available and the management of PHLF is largely supportive. Therefore, identifying risk factors and preventative strategies for PHLF is paramount. Ensuring an adequate future liver remnant is important to mitigate risk of PHLF. Dynamic liver function tests provide more objective assessment of liver function based on the metabolic capacity of the liver and have the advantage of easy administration, low cost, and easy reproducibility.

CONCLUSION

Given the absence of randomized data specifically related to the management of PHLF, current strategies are based on the principles of management of acute liver failure from any cause. In addition, goal-directed therapy for organ dysfunction, as well as identification and treatment of reversible factors in the postoperative period are critical.

E-AHPBA-ESSO-ESSR Innsbruck consensus guidelines for preoperative liver function assessment before hepatectomy

BACKGROUND

Posthepatectomy liver failure (PHLF) contributes significantly to morbidity and mortality after liver surgery. Standardized assessment of preoperative liver function is crucial to identify patients at risk. These European consensus guidelines provide guidance for preoperative patient assessment.

METHODS

A modified Delphi approach was used to achieve consensus. The expert panel consisted of hepatobiliary surgeons, radiologists, nuclear medicine specialists, and hepatologists. The guideline process was supervised by a methodologist and reviewed by a patient representative. A systematic literature search was performed in PubMed/MEDLINE, the Cochrane library, and the WHO International Clinical Trials Registry. Evidence assessment and statement development followed Scottish Intercollegiate Guidelines Network methodology.

RESULTS

Based on 271 publications covering 4 key areas, 21 statements (at least 85 per cent agreement) were produced (median level of evidence 2- to 2+). Only a few systematic reviews (2++) and one RCT (1+) were identified. Preoperative liver function assessment should be considered before complex resections, and in patients with suspected or known underlying liver disease, or chemotherapy-associated or drug-induced liver injury. Clinical assessment and blood-based scores reflecting liver function or portal hypertension (for example albumin/bilirubin, platelet count) aid in identifying risk of PHLF. Volumetry of the future liver remnant represents the foundation for assessment, and can be combined with indocyanine green clearance or LiMAx® according to local expertise and availability. Functional MRI and liver scintigraphy are alternatives, combining FLR volume and function in one examination.

CONCLUSION

These guidelines reflect established methods to assess preoperative liver function and PHLF risk, and have uncovered evidence gaps of interest for future research.

How Much Is Enough? A Surgical Perspective on Imaging Modalities to Estimate Function and Volume of the Future Liver Remnant before Hepatic Resection

Liver resection is the first curative option for most hepatic primary and secondary malignancies. However, post-hepatectomy liver failure (PHLF) still represents a non-negligible postoperative complication, embodying the most frequent cause of hepatic-related mortality. In the absence of a specific treatment, the most effective way to deal with PHLF is its prevention through a careful preoperative assessment of future liver remnant (FLR) volume and function. Apart from the clinical score and classical criteria to define the safe limit of resectability, new imaging modalities have shown their ability to assist surgeons in planning the best operative strategy with a precise estimation of the FLR amount. New technologies leading to liver and tumor 3D reconstruction may guide the surgeon along the best resection planes combining the least liver parenchymal sacrifice with oncological appropriateness. Integration with imaging modalities, such as hepatobiliary scintigraphy, capable of estimating total and regional liver function, may bring about a decrease in postoperative complications. Magnetic resonance imaging with hepatobiliary contrast seems to be predominant since it simultaneously integrates hepatic function and volume information along with a precise characterization of the target malignancy.

Effect of Hepatic Pathology on Liver Regeneration: The Main Metabolic Mechanisms Causing Impaired Hepatic Regeneration

Liver regeneration has been studied for many decades, and the mechanisms underlying regeneration of normal liver following resection are well described. However, no less relevant is the study of mechanisms that disrupt the process of liver regeneration. First of all, a violation of liver regeneration can occur in the presence of concomitant hepatic pathology, which is a key factor reducing the liver's regenerative potential. Understanding these mechanisms could enable the rational targeting of specific therapies to either reduce the factors inhibiting regeneration or to directly stimulate liver regeneration. This review describes the known mechanisms of normal liver regeneration and factors that reduce its regenerative potential, primarily at the level of hepatocyte metabolism, in the presence of concomitant hepatic pathology. We also briefly discuss promising strategies for stimulating liver regeneration and those concerning methods for assessing the regenerative potential of the liver, especially intraoperatively.

Photo-crosslinked adhesive hydrogel loaded with extracellular vesicles promoting hemostasis and liver regeneration

Hepatectomy is an effective surgical method for the treatment of liver diseases, but intraoperative bleeding and postoperative liver function recovery are still key issues. This study aims to develop a composite hydrogel dressing with excellent hemostatic properties, biocompatibility, and ability to promote liver cell regeneration. The modified gelatin matrix (GelMA, 10%) was mixed with equal volumes of sodium alginate-dopamine (Alg-DA) at concentrations of 0.5%, 1%, and 2%. Then a cross-linking agent (0.1%) was added to prepare different composite hydrogels under UV light, named GelMA/Alg-DA-0.5, GelMA/Alg-DA-1 and GelMA/Alg-DA-2, respectively. All the prepared hydrogel has a porous structure with a porosity greater than 65%, and could be stabilized in a gel state after being cross-linked by ultraviolet light. Physicochemical characterization showed that the elastic modulus, water absorption, adhesion, and compressibility of the composite hydrogels were improved with increasing Alg-DA content. Furthermore, the prepared hydrogel exhibits in vitro degradability, excellent biocompatibility, and good hemostatic function. Among all tested groups, the group of GelMA/Alg-DA-1 hydrogel performed the best. To further enhance its application potential in the field of liver regeneration, adipose-derived mesenchymal stem cell exosomes (AD-MSC-Exo) were loaded into GelMA/Alg-DA-1 hydrogel. Under the same conditions, GelMA/Alg-DA-1/Exo promoted cell proliferation and migration more effectively than hydrogels without extracellular vesicles. In conclusion, the prepared GelMA/Alg-DA-1 composite hydrogel loaded with AD-MSC-Exo has great application potential in liver wound hemostasis and liver regeneration.

Biomechanics in liver regeneration after partial hepatectomy

The liver is a complicated organ within the body that performs wide-ranging and vital functions and also has a unique regenerative capacity after hepatic tissue injury and cell loss. Liver regeneration from acute injury is always beneficial and has been extensively studied. Experimental models including partial hepatectomy (PHx) reveal that extracellular and intracellular signaling pathways can help the liver recover to its equivalent size and weight prior to an injury. In this process, mechanical cues possess immediate and drastic changes in liver regeneration after PHx and also serve as main triggering factors and significant driving forces. This review summarized the biomechanics progress in liver regeneration after PHx, mainly focusing on PHx-based hemodynamics changes in liver regeneration and the decoupling of mechanical forces in hepatic sinusoids including shear stress, mechanical stretch, blood pressure, and tissue stiffness. Also discussed were the potential mechanosensors, mechanotransductive pathways, and mechanocrine responses under varied mechanical loading in vitro. Further elucidating these mechanical concepts in liver regeneration helps establish a comprehensive understanding of the biochemical factors and mechanical cues in this process. Proper adjustment of mechanical loading within the liver might preserve and restore liver functions in clinical settings, serving as an effective therapy for liver injury and diseases.

Sarcopenia Predicts Prognosis of Patients Undergoing Liver Resection for Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

Recently, several studies have investigated the impact of preoperative sarcopenia on the prognosis of patients with hepatocellular carcinoma (HCC) after liver resection, but their conclusions are controversial. Therefore, we performed a meta-analysis to evaluate the prognostic role of sarcopenia in HCC patients undergoing liver resection. PubMed, SinoMed, Embase, Cochrane Library, Medline, and Web of Science databases were systematically searched for all published literature on the prognostic value of preoperative sarcopenia in HCC patients undergoing liver resection. Pooled hazard ratios (HR), odds ratios (OR) and weighted mean differences (WMD) of the 95% confidence intervals (95% CI) were estimated using a fixed-effects or random-effects model. A total of 12 articles with 1,774 patients were included. The results of meta-analysis showed that sarcopenia would increase postoperative complications (OR = 1.30, 95%CI 1.03 ∼ 1.65, P = 0.03), prolong hospital stay (SMD = 0.22, 95%CI 0.05 ∼ 0.39, P = 0.01), and also be associated with shorter overall survival (OS) (HR = 1.69, 95%CI 1.09 ∼ 2.62, P = 0.02) and worse disease free survival (DFS) (HR = 1.54, 95%CI 1.23 ∼ 1.93, P < 0.01). Sarcopenia has an adverse effect on the prognosis of HCC patients undergoing liver resection.

Preoperative evaluation of liver regeneration following hepatectomy in hepatocellular carcinoma using magnetic resonance elastography

BACKGROUND

For patients with hepatocellular carcinoma (HCC) undergoing hepatectomy, insufficient remnant liver regenerative capacity can lead to liver failure. The aim of this study was to evaluate the potential role of magnetic resonance elastography (MRE) for the preoperative prediction of liver regeneration in patients with HCC after partial hepatectomy (PH).

METHODS

A total of 54 patients with HCC undergoing MRE prior to PH were retrospectively included. The total functional liver, volume of preoperative future liver remnant (LVpre), and volume of postoperative liver remnant (LVpost), respectively, were measured, and the regeneration index (RI) and parenchymal hepatic resection rate (PHRR) were manually calculated. Univariate and multivariate logistic regression analyses were conducted to identify factors associated with a high RI, and receiver operating characteristic (ROC) curves were employed to evaluate the diagnostic performance of the liver stiffness (LS) values. Patients were classified into three subgroups based on the value of PHRR: low PHRR (<30%), intermediate PHRR (30-50%), and high PHRR (>50%). Subsequently, Spearman correlation analysis was used to investigate the relationship between LS values and RI in the subgroups.

RESULTS

Multivariable analysis revealed a low LS value was associated with greater odds of a high RI [odds ratio (OR), 0.049; 95% confidence interval (CI): 0.002 to 0.980]. An optimal cutoff value of 3.30 kPa was used to divide all patients into a low RI group and a high RI group with an area under the curve (AUC) value of 0.882 (95% CI: 0.767 to 0.996). A significant negative relationship between RI and LS values (r=-0.799; P<0.001) was observed in the intermediate PHRR subgroup.

CONCLUSIONS

The LS values based on MRE may serve as a potential preoperative predictor of liver regeneration for patients with HCC undergoing PH.

Resectable and transplantable hepatocellular carcinoma: Integration of liver stiffness assessment in the decision-making algorithm

BACKGROUND

Liver resection is a curative treatment for hepatocellular carcinoma (HCC) and an alternative to liver transplantation (LT). However, post-liver resection recurrence rates remain high. This study aimed to determine whether liver stiffness measurement (LSM) correlated with recurrence and to propose a method for predicting HCC recurrence exclusively using pre-liver resection criteria.

METHODS

This retrospective monocentric study included patients who had undergone LR liver resection for HCC between 2015 and 2018 and who had (1) preoperative alpha-fetoprotein scores indicating initial transplant viability and (2) available preoperative LSM data. We developed a predictive score for recurrence over time using Cox univariate regression and multivariate analysis with a combination plot before selecting the optimal thresholds (receiver operating characteristic curves + Youden test).

RESULTS

Sixty-six patients were included. After an average follow-up of 40 months, the recurrence rate was 45% (n = 30). Three-year overall survival was 88%. Four preoperative variables significantly impacted the time to recurrence: age ≥70 years, LSM ≥11 kPa, international normalized ratio (INR) ≥1.2, and maximum HCC diameter ≥3 cm. By assigning 1 point per positive item, patients with a score <2 (n = 22) demonstrated greater mean overall survival (69.7 vs 54.8 months, P = .02) and disease-free survival (52.2 vs 34.7 months, P = .02) than those with a score ≥2. Patients experiencing early recurrence (<1 year) presented a significantly higher preoperative LSM (P = .06).

CONCLUSION

We identified a simple preoperative score predictive of early hepatocellular carcinoma recurrence after liver resection, highlighting the role of liver stiffness. This score could help physicians select patients and make decisions concerning perioperative medical treatment.

Angelica sinensis Polysaccharide and Astragalus membranaceus Polysaccharide Accelerate Liver Regeneration by Enhanced Glycolysis via Activation of JAK2/STAT3/HK2 Pathway

The promotion of liver regeneration is crucial to avoid liver failure after hepatectomy. Angelica sinensis polysaccharide (ASP) and Astragalus membranaceus polysaccharide (AMP) have been identified as being associated with hepatoprotective effects. However, their roles and specific mechanisms in liver regeneration remain to be elucidated. In the present study, it suggested that the respective use of ASP or AMP strikingly promoted hepatocyte proliferation in vitro with a wide range of concentrations (from 12.5 μg/mL to 3200 μg/mL), and a stronger promoting effect was observed in combined interventions. A significantly enhanced liver/body weight ratio (4.20%) on day 7 and reduced serum transaminase (ALT 243.53 IU/L and AST 423.74 IU/L) and total bilirubin (52.61 IU/L) levels on day 3 were achieved by means of ASP-AMP administration after partial hepatectomy in mice. Metabonomics showed that differential metabolites were enriched in glycolysis with high expression of beta-d-fructose 6-phosphate and lactate, followed by significantly strengthened lactate secretion in the supernatant (0.54) and serum (0.43) normalized to control. Upon ASP-AMP treatment, the knockdown of hexokinase 2 (HK2) or inhibited glycolysis caused by 2-deoxy-d-glucose decreased hepatocyte proliferation in vitro and in vivo. Furthermore, pathway analysis predicted the role of JAK2/STAT3 pathway in ASP-AMP-regulated liver regeneration, and phosphorylation of JAK2 and STAT3 was proven to be elevated in this promoting process. Finally, downregulated expression of HK2, an attenuated level of lactate secretion, and reduced hepatocyte proliferation were displayed when STAT3 was knocked out in vitro. Therefore, it can be concluded that ASP-AMP accelerated liver regeneration and exerted a hepatoprotective effect after hepatectomy, in which the JAK2/STAT3/HK2 pathway was actively involved in activating glycolysis.

Cellular crosstalk during liver regeneration: unity in diversity

The liver is unique in its ability to regenerate from a wide range of injuries and diseases. Liver regeneration centers around hepatocyte proliferation and requires the coordinated actions of nonparenchymal cells, including biliary epithelial cells, liver sinusoidal endothelial cells, hepatic stellate cells and kupffer cells. Interactions among various hepatocyte and nonparenchymal cells populations constitute a sophisticated regulatory network that restores liver mass and function. In addition, there are two different ways of liver regeneration, self-replication of liver epithelial cells and transdifferentiation between liver epithelial cells. The interactions among cell populations and regenerative microenvironment in the two modes are distinct. Herein, we first review recent advances in the interactions between hepatocytes and surrounding cells and among nonparenchymal cells in the context of liver epithelial cell self-replication. Next, we discuss the crosstalk of several cell types in the context of liver epithelial transdifferentiation, which is also crucial for liver regeneration.

SHP2 inhibition enhances Yes-associated protein mediated liver regeneration in murine partial hepatectomy models

Disrupted liver regeneration following hepatectomy represents an “undruggable” clinical challenge associated with poor patient outcomes. Yes-associated protein (YAP), a transcriptional coactivator that is repressed by the Hippo pathway, is instrumental in liver regeneration. We have previously described an alternative, Hippo-independent mechanism of YAP activation mediated by downregulation of protein tyrosine phosphatase nonreceptor type 11 (PTPN11, also known as SHP2) inhibition. Herein, we examined the effects of YAP activation with a selective SHP1/SHP2 inhibitor, NSC-87877, on liver regeneration in murine partial hepatectomy models. In our studies, NSC-87877 led to accelerated hepatocyte proliferation, improved liver regeneration, and decreased markers of injury following partial hepatectomy. The effects of NSC-87877 were lost in mice with hepatocyte-specific Yap/Taz deletion, and this demonstrated dependence on these molecules for the enhanced regenerative response. Furthermore, administration of NSC-87877 to murine models of nonalcoholic steatohepatitis was associated with improved survival and decreased markers of injury after hepatectomy. Evaluation of transcriptomic changes in the context of NSC-87877 administration revealed reduction in fibrotic signaling and augmentation of cell cycle signaling. Cytoprotective changes included downregulation of Nr4a1, an apoptosis inducer. Collectively, the data suggest that SHP2 inhibition induces a pro-proliferative and cytoprotective enhancement of liver regeneration dependent on YAP.

Critical Role of LSEC in Post-Hepatectomy Liver Regeneration and Failure

Liver sinusoids are lined by liver sinusoidal endothelial cells (LSEC), which represent approximately 15 to 20% of the liver cells, but only 3% of the total liver volume. LSEC have unique functions, such as fluid filtration, blood vessel tone modulation, blood clotting, inflammatory cell recruitment, and metabolite and hormone trafficking. Different subtypes of liver endothelial cells are also known to control liver zonation and hepatocyte function. Here, we have reviewed the origin of LSEC, the different subtypes identified in the liver, as well as their renewal during homeostasis. The liver has the exceptional ability to regenerate from small remnants. The past decades have seen increasing awareness in the role of non-parenchymal cells in liver regeneration despite not being the most represented population. While a lot of knowledge has emerged, clarification is needed regarding the role of LSEC in sensing shear stress and on their participation in the inductive phase of regeneration by priming the hepatocytes and delivering mitogenic factors. It is also unclear if bone marrow-derived LSEC participate in the proliferative phase of liver regeneration. Similarly, data are scarce as to LSEC having a role in the termination phase of the regeneration process. Here, we review what is known about the interaction between LSEC and other liver cells during the different phases of liver regeneration. We next explain extended hepatectomy and small liver transplantation, which lead to "small for size syndrome" (SFSS), a lethal liver failure. SFSS is linked to endothelial denudation, necrosis, and lobular disturbance. Using the knowledge learned from partial hepatectomy studies on LSEC, we expose several techniques that are, or could be, used to avoid the "small for size syndrome" after extended hepatectomy or small liver transplantation.

The beneficial impacts of splanchnic vasoactive agents on hepatic functional recovery in massive hepatectomy porcine model

Background

Excessive portal pressure after massive hepatectomy can cause hepatic sinusoidal injury and have deleterious impacts on hepatic functional recovery, contributing to developing post-hepatectomy liver failure. This study aimed to assess the effects of splanchnic vasoactive agents on hepatic functional recovery and regeneration while clarifying the underlying mechanism, using a 70% hepatectomy porcine model.

Methods

Eighteen pigs undergoing 70% hepatectomy were involved in this study and divided into three groups: control (n=6), terlipressin (n=6), and octreotide (n=6). Terlipressin (0.5 mg) and octreotide (0.2 mg) were administered 3 times a day for each group with the first dose starting just before surgery until the 7th postoperative day, at which time the surviving pigs were sacrificed. During the period, portal pressure, liver weight, biochemical analysis, histological injury score, and molecular markers were evaluated and compared between groups.

Results

The 7-day survival rates in the octreotide, terlipressin, and control groups were 100%, 83.3%, and 66.7%, respectively. The portal pressures decreased in both terlipressin and octreotide groups than the control group at 30 minutes, 1 hour and 6 hours after hepatectomy. The amount of regeneration measured by liver weight to body weight ratio at the time of sacrifice in the terlipressin group was smaller than that in the control group (117% vs. 129%, P=0.03). Serum aspartate aminotransferase (AST) and total bilirubin levels at 1 and 6 hours after hepatectomy and prothrombin time/international normalized ratio (PT/INR) at 6 hours after hepatectomy were significantly improved in the terlipressin and octreotide groups compared to the control group. Serum endothelin-1 (ET-1) was significantly lower in the terlipressin group than that in the control group 6 hours after hepatectomy (P<0.01). The histological injury score in the control group was significantly higher than that in the terlipressin group on the 7th postoperative day (P<0.01).

Conclusions

Splanchnic vasoactive agents, such as terlipressin and octreotide, could effectively decrease portal pressure and attenuate liver injury after massive hepatectomy.

Defining the risk of liver failure after minor hepatectomy: a NSQIP analysis of 7029 patients

BACKGROUND

Post-hepatectomy liver failure (PHLF) remains a significant complication after hepatic resection. This study aims to determine the rate of PHLF in patients undergoing resection of 3 or fewer segments and analyze the association of PHLF with perioperative characteristics and postoperative complications.

METHODS

The American College of Surgeons hepatectomy-targeted National Surgical Quality Improvement Program database was queried for patients undergoing left hemi-hepatectomy or partial resection from 2014 to 2018. The primary outcome was PHLF, defined by ISGLS. Multivariable logistic regression models assessed the association between PHLF, preoperative and operative variables and postoperative complications.

RESULTS

Among 7029 patients, 187 (2.7%) experienced PHLF, with clinically significant (grade B/C) PHLF in 1.4%. PHLF was associated with older age, male gender, higher ASA classification, ascites, and elevated SGOT. Preoperative ascites (OR 4.94, 95%CI: 2.45-9.94, p < 0.001) had the strongest association with PHLF. There was no association between PHLF and concurrent colorectal resection, neoadjuvant therapy, or concurrent ablation. Surgical site infection (OR 3.64, 95%CI: 2.40-5.54, p < 0.001), sepsis (OR 3.78, 95%CI: 2.16-6.61, p < 0.001), postoperative invasive procedure (OR 6.92, 95%CI: 4.91-9.76, p < 0.001), and bile leak (OR 4.65, 95%CI: 3.04-7.12, p < 0.001) were associated with PHLF.

CONCLUSION

PHLF after minor hepatectomy is rare and associated with signs of preoperative liver dysfunction. The association with infectious complications suggests a multifactorial etiology and provides targets for quality improvement.

Ceramides and sphingosine-1-phosphate mediate the distinct effects of M1/M2-macrophage infusion on liver recovery after hepatectomy

Post-hepatectomy liver dysfunction is a life-threatening morbidity that lacks efficient therapy. Bioactive lipids involved in macrophage polarization crucially regulate tissue injury and regeneration. Herein, we investigate the key bioactive lipids that mediate the cytotherapeutic potential of polarized-macrophage for post-hepatectomy liver dysfunction. Untargeted lipidomics identified elevation of ceramide (CER) metabolites as signature lipid species relevant to M1/M2 polarization in mouse bone-marrow-derived-macrophages (BMDMs). M1 BMDMs expressed a CER-generation-metabolic pattern, leading to elevation of CER; M2 BMDMs expressed a CER-breakdown-metabolic pattern, resulting in upregulation of sphingosine-1-phosphate (S1P). After infusing M1- or M2-polarized BMDMs into the mouse liver after hepatectomy, we found that M1-BMDM infusion increased M1 polarization and CER accumulation, resulting in exaggeration of hepatocyte apoptosis and liver dysfunction. Conversely, M2-BMDM infusion enhanced M2 polarization and S1P generation, leading to alleviation of liver dysfunction with improved hepatocyte proliferation. Treatment of exogenous CER and S1P or inhibition CER and S1P synthesis by siRNA targeting relevant enzymes further revealed that CER induced apoptosis while S1P promoted proliferation in post-hepatectomy primary hepatocytes. In conclusion, CER and S1P are uncovered as critical lipid mediators for M1- and M2-polarized BMDMs to promote injury and regeneration in the liver after hepatectomy, respectively. Notably, the upregulation of hepatic S1P induced by M2-BMDM infusion may have therapeutic potential for post-hepatectomy liver dysfunction.

Predicting the risk of post-hepatectomy portal hypertension using a digital twin: A clinical proof of concept

BACKGROUND & AIMS

Despite improvements in medical and surgical techniques, post-hepatectomy liver failure (PHLF) remains the leading cause of postoperative death. High postoperative portal vein pressure (P_PV) and portocaval gradient (PCG), which cannot be predicted by current tools, are the most important determinants of PHLF. Therefore, we aimed to evaluate a digital twin to predict the risk of postoperative portal hypertension (PHT).

METHODS

We prospectively included 47 patients undergoing major hepatectomy. A mathematical (0D) model of the entire blood circulation was assessed and automatically calibrated from patient characteristics. Hepatic flows were obtained from preoperative flow MRI (n = 9), intraoperative flowmetry (n = 16), or estimated from cardiac output (n = 47). Resection was then simulated in these 3 groups and the computed P_PV and PCG were compared to intraoperative data.

RESULTS

Simulated post-hepatectomy pressures did not differ between the 3 groups, comparing well with collected data (no significant differences). In the entire cohort, the correlation between measured and simulated P_PV values was good (r = 0.66, no adjustment to intraoperative events) or excellent (r = 0.75) after adjustment, as well as for PCG (respectively r = 0.59 and r = 0.80). The difference between simulated and measured post-hepatectomy PCG was ≤3 mmHg in 96% of cases. Four patients suffered from lethal PHLF for whom the model satisfactorily predicted their postoperative pressures.

CONCLUSIONS

We demonstrated that a 0D model could correctly anticipate postoperative PHT, even using estimated hepatic flow rates as input data. If this major conceptual step is confirmed, this algorithm could change our practice toward more tailor-made procedures, while ensuring satisfactory outcomes.

LAY SUMMARY

Post-hepatectomy portal hypertension is a major cause of liver failure and death, but no tool is available to accurately anticipate this potentially lethal complication for a given patient. Herein, we propose using a mathematical model to predict the portocaval gradient at the end of liver resection. We tested this model on a cohort of 47 patients undergoing major hepatectomy and demonstrated that it could modify current surgical decision-making algorithms.

The vascular endothelial growth factor signaling pathway regulates liver sinusoidal endothelial cells during liver regeneration after partial hepatectomy

INTRODUCTION

Liver regeneration after partial hepatectomy is a very complex and well-regulated procedure. It utilizes all liver cell types, which are associated with signaling pathways involving growth factors, cytokines, and stimulatory and inhibitory feedback of several growth-related signals. Liver sinusoidal endothelial cells (LSECs) contribute to liver regeneration after partial hepatectomy. Vascular endothelial growth factor (VEGF) has various functions in LSECs. In this review, we summarize the relationship between VEGF and LSECs involving VEGF regulatory activity in the vascular endothelium.

AREAS COVERED

Maintenance of the fenestrated LSEC phenotype requires two VEGF pathways: VEGF stimulated-NO acting through the cGMP pathway and VEGF independent of nitric oxide (NO). The results suggest that VEGF is a key regenerating mediator of LSECs in the partial hepatectomy model. NO-independent pathway was also essential to the maintenance of the LSEC in liver regeneration.

EXPERT OPINION

Liver regeneration remains a fascinating and significative research field in recent years. The liver involved of molecular pathways except for LSEC-VEGF pathways that make the field of liver further depth studies should be put into effect to elaborate the undetermined confusions, which will be better to understand liver regeneration.

Liver Regeneration after Hepatectomy and Partial Liver Transplantation

The liver is a unique organ with an abundant regenerative capacity. Therefore, partial hepatectomy (PHx) or partial liver transplantation (PLTx) can be safely performed. Liver regeneration involves a complex network of numerous hepatotropic factors, cytokines, pathways, and transcriptional factors. Compared with liver regeneration after a viral- or drug-induced liver injury, that of post-PHx or -PLTx has several distinct features, such as hemodynamic changes in portal venous flow or pressure, tissue ischemia/hypoxia, and hemostasis/platelet activation. Although some of these changes also occur during liver regeneration after a viral- or drug-induced liver injury, they are more abrupt and drastic following PHx or PLTx, and can thus be the main trigger and driving force of liver regeneration. In this review, we first provide an overview of the molecular biology of liver regeneration post-PHx and -PLTx. Subsequently, we summarize some clinical conditions that negatively, or sometimes positively, interfere with liver regeneration after PHx or PLTx, such as marginal livers including aged or fatty liver and the influence of immunosuppression.

Post hepatectomy liver failure (PHLF) - Recent advances in prevention and clinical management

BACKGROUND

Posthepatectomy liver failure (PHLF) is a relatively rare but feared complication following liver surgery, and associated with high morbidity, mortality and cost implications. Significant advances have been made in detailed preoperative assessment, particularly of the liver function in an attempt to predict and mitigate this complication.

METHODS

A detailed search of PubMed and Medline was performed using keywords "liver failure", "liver insufficiency", "liver resection", "postoperative", and "post-hepatectomy". Only full texts published in English were considered. Particular emphasis was placed on literature published after 2015. A formal systematic review was not found feasible hence a pragmatic review was performed.

RESULTS

The reported incidence of PHLF varies widely in reported literature due to a historical absence of a universal definition. Incorporation of the now accepted definition and grading of PHLF would suggest the incidence to be between 8 and 12%. Major risk factors include background liver disease, extent of resection and intraoperative course. The vast majority of mortality associated with PHLF is related to sepsis, organ failure and cerebral events. Despite multiple attempts, there has been little progress in the definitive and specific management of liver failure. This review article discusses recent advances made in detailed preoperative evaluation of liver function and evidence-based targeted approach to managing PHLF.

CONCLUSION

PHLF remains a major cause of mortality following liver resection. In absence of a specific remedy, the best approach is mitigating the risk of it happening by detailed assessment of liver function, patient selection and general care of a critically ill patient.

Associated liver partition and portal vein ligation for staged hepatectomy: a review

Outcomes of liver resection have improved with advances in surgical techniques, improvements in critical care and expansion of resectability criteria. However, morbidity and mortality following liver resection continue to plague surgeons. Post-hepatectomy liver failure (PHLF) due to inadequate future liver remnant (FLR) is an important cause of morbidity and mortality following liver resection. Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a novel two-staged procedure described in 2012, which aims to induce rapid hypertrophy of the FLR unlike conventional two-stage hepatectomy, which require a longer time for FLR hypertrophy. Careful patient selection and modifications in surgical technique has improved morbidity and mortality rates in ALPPS. Colorectal liver metastases (CRLM) confers the best outcomes post-ALPPS. Patients <60 years old and low-grade fibrosis with underlying hepatocellular carcinoma (HCC) are also eligible for ALPPS. Evidence for other types of cancers is less promising. Current studies, though limited, demonstrate that ALPPS has comparable oncological outcomes with conventional two-stage hepatectomy. Modifications such as partial-ALPPS and mini-ALPPS have shown improved morbidity and mortality compared to classic ALPPS. ALPPS may be superior to conventional two-stage hepatectomy in carefully selected groups of patients and has a promising outlook in liver surgery.

Systematic review of MARS treatment in post-hepatectomy liver failure

BACKGROUND

Post-hepatectomy liver failure (PHLF) remains a serious complication after major liver resection with severe 90-day mortality. Molecular adsorbent recirculating system (MARS) is a potential treatment option in PHLF. This systematic review sought to analyze the experiences and results of MARS in PHLF.

METHODS

Following the PRISMA guidelines, a systematic literature review using PubMed and Embase was performed. Non-randomized trials were assessed by the MINORS criteria.

RESULTS

2884 records were screened and 22 studies were extracted (no RCT). They contained 809 patients including 82 patients with PHLF. Five studies (n = 34) specifically investigated the role of MARS in patients with PHLF. In these patients, overall 90-day survival was 47%. Patients with primary PHLF had significantly better 90-day survival compared to patients with secondary PHLF (60% vs 14%, p = 0.03) and treatment was started earlier (median POD 6 (range 2-21) vs median POD 30 (range 15-39); p < 0.001). Number of treatments differed non-significantly in these groups. Safety and feasibility of early MARS treatment following hepatectomy was demonstrated in one prospective study. No major adverse events have been reported.

CONCLUSION

Early MARS treatment is safe and feasible in patients with PHLF. Currently, MARS cannot be recommended as standard of care in these patients. Further prospective studies are warranted.

The Endothelium as a Driver of Liver Fibrosis and Regeneration

Liver fibrosis is a common feature of sustained liver injury and represents a major public health problem worldwide. Fibrosis is an active research field and discoveries in the last years have contributed to the development of new antifibrotic drugs, although none of them have been approved yet. Liver sinusoidal endothelial cells (LSEC) are highly specialized endothelial cells localized at the interface between the blood and other liver cell types. They lack a basement membrane and display open channels (fenestrae), making them exceptionally permeable. LSEC are the first cells affected by any kind of liver injury orchestrating the liver response to damage. LSEC govern the regenerative process initiation, but aberrant LSEC activation in chronic liver injury induces fibrosis. LSEC are also main players in fibrosis resolution. They maintain liver homeostasis and keep hepatic stellate cell and Kupffer cell quiescence. After sustained hepatic injury, they lose their phenotype and protective properties, promoting angiogenesis and vasoconstriction and contributing to inflammation and fibrosis. Therefore, improving LSEC phenotype is a promising strategy to prevent liver injury progression and complications. This review focuses on changes occurring in LSEC after liver injury and their consequences on fibrosis progression, liver regeneration, and resolution. Finally, a synopsis of the available strategies for LSEC-specific targeting is provided.

Peer review of mortality after hepatectomy in Australia

BACKGROUND

The data within the Australian and New Zealand Audit of Surgical Mortality (ANZASM) provides a unique opportunity to consider the contributing factors to perioperative deaths as determined by peer review. Consideration of the factors contributing to mortality after hepatectomy can provide greater insight into how deaths can be prevented. The objective of this study was to determine the reasons for patient deaths post-hepatectomy in Australia.

METHODS

ANZASM data from 1 January 2010 to 30 Jun 2017 was reviewed and all deaths following hepatectomy were selected for analysis. Assessors determinations of whether management could have been improved were reviewed, and then classified into groups of significant clinical events using thematic analysis with a data driven approach.

RESULTS

The study included 88 deaths reported to ANZASM after hepatectomy. The assessors questioned the decision to operate in 23/88 (25%) patients with a further nine (10%) patients insufficiently investigated prior to resection. ANZASM assessors determined that there was a delay in recognising a significant complication in 16/88 (18%) patients.

CONCLUSION

Multi-disciplinary decision making is strongly recommended when deciding which patients to treat with hepatic resection. Optimal care post-hepatectomy includes early recognition of complications and enactment of an adequate rescue plan.

Spleen volumetry and liver transient elastography: Predictors of persistent posthepatectomy decompensation in patients with hepatocellular carcinoma

BACKGROUND

Posthepatectomy decompensation remains a frequent and poor outcome after hepatectomy, but its prediction is still inaccurate. Liver stiffness measurement can predict posthepatectomy decompensation, but there is a so-called "gray zone" that requires another predictor. Because splenomegaly is an objective sign of portal hypertension, we hypothesized that spleen volumetry could improve the identification of patients at risk.

METHODS

Patients with hepatocellular carcinoma who underwent hepatectomy in our tertiary center between August 2014 and December 2017 were reviewed. The primary endpoint was to determine if the spleen volumetry and liver stiffness measurement were independent predictors of posthepatectomy decompensation, and secondarily, to determine if they were synergistic through a theoretic predictive model.

RESULTS

One hundred and seven patients were included. The median follow-up time was 3 months (3-5). Postoperative 90-day mortality was 4.7%. By multivariate analysis, liver stiffness measurement and spleen volumetry predicted posthepatectomy decompensation. The liver stiffness measurement had a cutoff point of 11.6 kPa (area under receiver operating curve = 0.71 confidence interval 95% 0.71-0.88, sensitivity: 89%, specificity: 47%). The spleen volumetry cutoff point was 381.1 cm³ (area under receiver operating curve = 0.78, 95% confidence interval 0.77-0.93, sensitivity: 55%, specificity: 91%). The spleen volumetry improved prediction of posthepatectomy decompensation, because use of the spleen volumetry increased sensitivity (from 62% to 97%) and the negative predictive value (from 96% to 100%) along with a negligible decrease in specificity (from 96.7 to 93.4) and positive predictive value (from 64% to 59%) (P = .003).

CONCLUSION

Spleen volumetry (>380 cm³) and liver stiffness measurement (>12 kPa) are non-invasive, independent, and synergistic tools that appear to be able to predict posthepatectomy decompensation. The importance of this finding is that these measurements may help to anticipate posthepatectomy decompensation and may possibly be used to direct alternative treatments to resection.

The Predictive Role of Tenascin-C and Cellular Communication Network Factor 3 (CCN3) in Post Hepatectomy Liver Failure in a Rat Model and 50 Patients Following Partial Hepatectomy

Background

Matricellular proteins of the extracellular matrix (ECM) include tenascin-C (TNC) and cellular communication network factor 3 (CCN3). This study aimed to investigate the role of TNC and CCN3 as prognostic factors for post hepatectomy liver failure (PHLF) in a rat model of partial hepatectomy and 50 patients following partial hepatectomy.

Material/Methods

Sprague-Dawley rats underwent 85% (n=53) or 90% hepatectomy (n=53) in the partial hepatectomy (PHx) model. TNC and CCN3 mRNA expression in residual liver tissue was evaluated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and enzyme-linked immunoassay (ELISA) determined the serum levels of TNC and CCN3. In 50 patients who underwent partial hepatectomy, TNC and CCN3 serum levels were measured on postoperative day 1 and day 3.

Results

In the rat partial hepatectomy model, mRNA and serum levels of TNC and CCN3 were significantly increased within the first 24 h, and were higher in the 90% PHx group compared with the 85% PHx group. Fifty patients who underwent partial hepatectomy, included patients with PHLF (n=12) and patients without PHLF (n=38). Multivariate analysis confirmed that serum levels on postoperative day 3 TNC^high+CCN3^high was a significant predictor of PHLF, which was associated with more than twice the risk of severe morbidity when compared with the low-risk patients (80% vs. 30%) and a significantly longer hospital stay (17 days vs. 8 days).

Conclusions

Further studies are needed to evaluate the potential role of the matricellular proteins, TNC and CCN3 as early clinical predictors for PHLF.

Modulating Portal Hemodynamics With Vascular Ring Allows Efficient Regeneration After Partial Hepatectomy in a Porcine Model

OBJECTIVE

To investigate safety and efficacy of temporary portal hemodynamics modulation with a novel percutaneously adjustable vascular ring (MID-AVR) onto a porcine model of 75% hepatectomy.

BACKGROUND

Postoperative liver failure is a leading cause of mortality after major hepatectomy. Portal flow modulation is an increasingly accepted concept to prevent postoperative liver failure. Nonetheless, the current strategies have shortcomings.

METHODS

Resection was performed under hemodynamic monitoring in 17 large, white pigs allocated into 2 groups. Eight pigs had ring around the portal vein for 3 days with the aim of reducing changes in hemodynamics due to hepatectomy. Analysis of hemodynamics, laboratory, and histopathological parameters was performed.

RESULTS

Percutaneous inflation, deflation, and removal of the MID-AVR were safe. Two (25%) pigs in the MID-AVR group and 4 (45%) controls died before day 3 (P = NS). A moderate increase of portal flow rate per liver mass after resection was associated with better survival (P = 0.017). The portocaval pressure gradient was lower after hepatectomy in the MID-AVR group (P = 0.001). Postoperative serum bilirubin levels were lower in the MID-AVR group (P = 0.007 at day 5). In the MID-AVR group, the Ki67 index was significantly higher on day 3 (P = 0.043) and the architectural derangement was lower (P < 0.05). Morphometric quantification of the bile canaliculi revealed a significantly lower number of intersection branches (P < 0.05) and intersection nodes (P < 0.001) on day 7 compared with the preoperative specimen, in the control group. These differences were not found in the ring group.

CONCLUSIONS

MID-AVR is safe for portal hemodynamics modulation. It might improve liver regeneration by protecting liver microarchitecture.

Scintigraphic liver function and transient elastography in the assessment of patients with resectable hepatocellular carcinoma

BACKGROUND

Hepatobiliary scintigraphy (HBS) is used to quantify total and regional liver function. Transient elastography (TE) provides a non-invasive alternative to percutaneous biopsy to assess liver fibrosis and cirrhosis. This study aims to determine the correlation between HBS and histopathology of liver parenchyma, and to compare these with TE in patients with resectable hepatocellular carcinoma (HCC).

METHODS

Patients who underwent surgery for HCC between 2000 and 2016 after preoperative HBS were included. Non-tumorous liver tissue was evaluated for inflammation, steatosis, ballooning, siderosis and fibrosis. Correlation analysis was performed between HBS results and histopathological scoring. These were also compared with TE and surgical outcomes.

RESULTS

71 patients underwent preoperative HBS of whom 24 also had TE. HBS correlated with portal and lobular inflammation as well as fibrosis. TE correlated with portal and lobular inflammation, ballooning and fibrosis. A significant correlation was found between HBS and TE. No association was found with overall postoperative morbidity and mortality.

CONCLUSION

HBS and TE show a moderate to strong correlation. HBS and TE share discriminatory features of histopathological scoring and show a weak to moderate correlation with hepatic inflammation and fibrosis.

Stress test of liver function using technetium-99m-mebrofenin hepatobiliary scintigraphy

Technetium-99m (Tc) mebrofenin hepatobiliary scintigraphy (HBS) enables a quantitative assessment of liver function. This is normally performed in a fasting state and might therefore reflect the resting liver function. We evaluated the change in liver function using HBS after stimulation with an oral metabolic challenge. Healthy volunteers aged 50-60 (n=12) or older than or equal to 75 (n=12) years underwent two sequential HBS. The first scan was performed after an overnight fast and the second scan was performed after the administration of chocolate milk. Hepatic Tc-mebrofenin uptake rate (cMUR) was calculated and the difference was expressed as percentage. cMUR after fasting was 10.9±2.5%/min/m (mean±SD) and increased by 20% to 13.0±3.1%/min/m after stimulation with chocolate milk (P<0.001). cMUR increased markedly after the administration of an oral metabolic challenge in comparison with fasting. This may be a consequence of hepatocyte stimulation, reflecting the hepatic functional reserve capacity.

Practical guidelines for the use of technetium-99m mebrofenin hepatobiliary scintigraphy in the quantitative assessment of liver function

Surgical resection remains the most important curative treatment for liver tumors; however, it harbors the risk of developing posthepatectomy liver failure. The principal risk is associated with the quality and quantity of the future remnant liver. Therefore, preoperative assessment of the future remnant liver is essential in patients scheduled for major liver resection. Technetium-99m mebrofenin hepatobiliary scintigraphy (HBS) in combination with single-photon emission computed tomography/computed tomography is increasingly applied for the quantitative assessment of liver function before major liver surgery. This dynamic quantitative liver function test allows assessment of both total and regional liver function, represented by the hepatic mebrofenin uptake rate, thereby assisting in adequate patient selection. Since routine implementation, it has shown to reduce the risk of posthepatectomy liver failure and has proven to be more valuable than volumetric assessment. To ensure optimal and reproducible results that can be compared across different centers, it is crucial to standardize the methodology and ensure practical applicability of this technique, thereby facilitating external validation and multicenter trials. This article provides an overview of the HBS methodology used at some of the largest HBS centers and covers practical details in the application of HBS for the quantitative scintigraphic assessment of liver function.

Should We Have Blind Faith in Liver Volumetry?

Introduction: Liver volumetry is a routine procedure performed before major hepatectomy or living donor liver transplantation (LDLT) to anticipate the remnant liver volume and prevent liver failure. However, many parameters may impact its accuracy and no large-scale studies have evaluated inter-rater variabilities. We aimed to determine the reliability of volumetric assessments for whole organs in deceased-donor liver transplantations (DDLT) and partial organs in LDLT settings. Patients & Methods: Eight operators (four surgeons + four radiologists) analysed 30 preoperative CT scans (15 whole cirrhotic livers in the DDLT group + 15 partial healthy grafts in the LDLT group), using five software systems. The computed volumes were compared with liver weight; liver density being considered as1. Results: Inter-rater and inter-software concordances were excellent with coefficients of correlation >0.9. However, calculations overestimated the real volumes in 25 cases by a mean of 249 ± 206 [14-771] cc in the DDLT group and 138 ± 92cc [39-375] in the LDLT group. The mean calculations were significantly higher than liver weights in the LDLT group only (p=0.04). The radiologists overestimated the surgeons’ assessment in 24 cases, the differences exceeding 6% in some cases. The type of software used significantly impacted results in the DDLTgroup. Conclusions: Despite its unanimously recognised utility, we highlight significant discrepancies between estimated and real liver volumes. The global overestimation may lead to leave of too small remnant liver, with potentially dramatic consequences. In case of border-line estimations, we recommend a repetition of the evaluation by another operator (surgeon + radiologist working in concert).

Predictors of post-hepatectomy liver failure in patients undergoing extensive liver resections for hepatocellular carcinoma

Backgrounds/Aims

To determine the prevalence of post-hepatectomy liver failure/insufficiency (PHLF/I) in patients undergoing extensive hepatic resections for hepatocellular carcinoma (HCC) and to assess the predictive value of preoperative factors for post-hepatectomy liver failure or insufficiency (PHLF/I).

Methods

A retrospective review of patients who underwent liver resections for HCC between 2001 and 2013 was conducted. Preoperative parameters were assessed and analyzed for their predictive value of PHLF/I. Definitions used included the 50–50, International Study Group of Liver Surgery (ISGLS) and Memorial Sloan Kettering Cancer Centre (MSKCC) criteria.

Results

Among the 848 patients who underwent liver resections for HCC between 2001 and 2013, 157 underwent right hepatectomy (RH) and extended right hepatectomy (ERH). The prevalence of PHLF/I was 7%, 41% and 28% based on the 50–50, ISGLS and MSKCC criteria, respectively. There were no significant differences in PHLF/I between RH and ERH. Model for End-Stage Liver Disease (MELD) score and bilirubin were the strongest independent predictors of PHLF/I based on the 50–50 and ISGLS/MSKCC criteria, respectively. Predictive models were developed for each of the criteria with multiple logistic regression.

Conclusions

MELD score, bilirubin, alpha-fetoprotein and platelet count showed significant predictive value for PHLF/I (all p<0.05). A composite score based on these factors serves as guideline for physicians to better select patients undergoing extensive resections to minimize PHLF.

Liver hypertrophy: Underlying mechanisms and promoting procedures before major hepatectomy

Various procedures can promote hypertrophy of the future liver remnant (FLR) before major hepatectomy to prevent postoperative liver failure. The pathophysiological situation following portal vein embolization (PVE), hepatic artery ligation/embolization or hepatectomy remains unclear. On one hand, the main mechanisms of hepatic regeneration appear to be driven by hepatic hypoxia (involving the hepatic arterial buffer response), an increased portal blood flow inducing shear stress and the involvement of several mediators (inflammatory cytokines, vasoregulators, growth factors, eicosanoids and several hormones). On the other hand, several factors are associated with impaired liver regeneration, such as biliary obstruction, malnutrition, diabetes mellitus, male gender, age, ethanol and viral infection. All these mechanisms may explain the varying degrees of hypertrophy observed following a surgical or radiological procedure promoting hypertrophy the FLR. Radiological procedures include left and right portal vein embolization (extended or not to segment 4), sequential PVE and hepatic vein embolization (HVE), and more recently combined PVE and HVE. Surgical procedures include associated liver partition and portal vein ligation for staged hepatectomy, and more recently the combined portal embolization and arterial ligation procedure. This review aimed to clarify the pathophysiology of liver regeneration; it also describes radiological or surgical procedures employed to improve liver regeneration in terms of volumetric changes, the feasibility of the second step and the benefits and drawbacks of each procedure.

Pharmacological Mobilization of Endogenous Bone Marrow Stem Cells Promotes Liver Regeneration after Extensive Liver Resection in Rats

Rapid regeneration of the remnant liver is critical for preventing liver failure and promoting recovery after extensive liver resection. Numerous studies have demonstrated the involvement of bone marrow-derived stem cells in liver regeneration and the potential benefits of bone marrow stem cell therapy. To avoid the preparation of stem cells, we proposed in this study to mobilize endogenous bone marrow stem cells pharmacologically with a combination of AMD3100 (A), an antagonist of CXCR4 and low-dose FK506 (F). Here we show that AF combination therapy significantly increased lineage negative (Lin-) CD34+ and Lin-CD133+ stem cells in peripheral blood and enhanced recruitment of CD133+ cells into the remnant liver in a rat model of 85% partial hepatectomy. Recruiting CD133+ stem cells in the remnant liver was associated with increased proliferation of hepatic oval cells and paralleled the increased SDF-1, CXCR4 and HGF expression. Importantly, AF combination therapy increased the number of Ki67 positive hepatocytes and BrdU incorporation in the remnant liver and improved serum levels of albumin. Our results demonstrate that pharmacological mobilization of endogenous bone marrow stem cells with AF combination therapy can enhance endogenous stem cell mobilization to promote liver regeneration and improve liver function after extensive hepatectomy.

Resection for Klatskin tumors: technical complexities and results

Klatskin's tumors, actually-redefined as perihilar cholangiocarcinoma (phCCA) do represent 50-70% of all CCAs and develop in a context of chronic inflammation and cholestasis of bile ducts. Surgical resection provides the only chance of cure for this disease but is technically challenging because of the complex, intimate and variable relationship between biliary and vascular structures at this location. Five years survival rates range between 25-45% (median 27-58 months) in case of R0 resection and 0-23% (median 12-21 months) in case of R1 resection respectively. It should be noted that the major costs of high radicality are represented by relative high morbidity and mortality rates (i.e., 20-66% and 0-9% respectively). Considering the fact that radical resection may represent the only curative treatment of phCCA, we focused our review on surgical planning and techniques that may improve resectability rates and outcomes for locally advanced phCCA. The surgical treatment of phCCA can be successful when following aspects have been fulfilled: (I) accurate preoperative diagnostic aimed to identify the tumor in all its details (localization and extension) and to study all the risk factors influencing a posthepatectomy liver failure (PHLF): i.e., liver volume, liver function, liver quality, haemodynamics and patient characteristics; (II) High end surgical skills taking in consideration the local extension of the tumor and the vascular invasion which usually require an extended hepatic resection and often a vascular resection; (III) adequate postoperative management aimed to avoid major complications (i.e., PHLF and biliary complications). These are technically challenging operations and must be performed in a high volume centres by hepato-biliary-pancreas (HBP)-surgeons with experience in microsurgical vascular techniques.

Predicting adverse events in patients undergoing hepatectomy-validation of preoperative nomogram and risk score

BACKGROUND/PURPOSE

Much research exists on preoperative measures of postoperative mortality in the surgical treatment of liver malignancies, but little on morbidity, a more common outcome. This study aims (i) to validate the published calculations as acceptable measures of postoperative mortality and (ii) to assess the value of these published measures in predicting postoperative morbidity.

METHODS

Data were collected from a prospectively managed dataset of 1059 hepatectomies performed in Louisville, Kentucky from December 1990 to April 2014. Preoperative data were used to assign scores for each of two published measures and the scores were sorted into clinically relevant groups with corresponding ordinal scores, according to the previously published literature (Dhir nomogram and Simons risk score).

RESULTS

After selection, 851 hepatectomies were analyzed. Both the Dhir nomogram (p = 0.0004) and Simons risk score (p = 0.0017) were acceptable predictors of postoperative mortality. In the analysis of morbidity, Dhir scores were a poor predictor of morbidity. The Simons ordinal risk score was predictive of complications (p = 0.0029), the number of complications (p = 0.0028), complication grade (p = 0.0033), and hepatic-specific complications (p = 0.0003).

CONCLUSION

The Simons ordinal risk score can be useful in assessing postoperative morbidity among hepatectomy patients.

Update on the Mechanisms of Liver Regeneration

Liver possesses many critical functions such as synthesis, detoxification, and metabolism. It continually receives nutrient-rich blood from gut, which incidentally is also toxin-rich. That may be why liver is uniquely bestowed with a capacity to regenerate. A commonly studied procedure to understand the cellular and molecular basis of liver regeneration is that of surgical resection. Removal of two-thirds of the liver in rodents or patients instigates alterations in hepatic homeostasis, which are sensed by the deficient organ to drive the restoration process. Although the exact mechanisms that initiate regeneration are unknown, alterations in hemodynamics and metabolism have been suspected as important effectors. Key signaling pathways are activated that drive cell proliferation in various hepatic cell types through autocrine and paracrine mechanisms. Once the prehepatectomy mass is regained, the process of regeneration is adequately terminated. This review highlights recent discoveries in the cellular and molecular basis of liver regeneration.

剪切力对肝脏切除术后肝窦内皮细胞的作用

肝切除术是肝脏疾病尤其是肝脏肿瘤的重要治疗手段, 并且在肝切除术后会出现肝脏血流动力学的改变. 肝窦内皮细胞是肝窦毛细血管内一类特殊的内皮细胞, 对血流变化十分敏感. 本文就肝脏切除术后血流产生的剪切力作用于肝窦内皮细胞, 从而调节肝细胞再生和肝组织恢复的作用及机制作一综述.

Postoperative Decrease in Platelet Counts Is Associated with Delayed Liver Function Recovery and Complications after Partial Hepatectomy

Peripheral platelet counts decrease after partial hepatectomy; however, the implications of this phenomenon are unclear. We assessed if the observed decrease in platelet counts was associated with postoperative liver function and morbidity (complications grade ≤ II according to the Clavien-Dindo classification). We enrolled 216 consecutive patients who underwent partial hepatectomy for primary liver cancers, metastatic liver cancers, benign tumors, and donor hepatectomy. We classified patients as either low or high platelet percentage (postoperative platelet count/preoperative platelet count) using the optimal cutoff value calculated by a receiver operating characteristic (ROC) curve analysis, and analyzed risk factors for delayed liver functional recovery and morbidity after hepatectomy. Delayed liver function recovery and morbidity were significantly correlated with the lowest value of platelet percentage based on ROC analysis. Using a cutoff value of 60% acquired by ROC analysis, univariate and multivariate analysis determined that postoperative lowest platelet percentage ≤ 60% was identified as an independent risk factor of delayed liver function recovery (odds ratio (OR) 6.85; P < 0.01) and morbidity (OR, 4.90; P < 0.01). Furthermore, patients with the lowest platelet percentage ≤ 60% had decreased postoperative prothrombin time ratio and serum albumin level and increased serum bilirubin level when compared with patients with platelet percentage ≥ 61%. A greater than 40% decrease in platelet count after partial hepatectomy was an independent risk factor for delayed liver function recovery and postoperative morbidity. In conclusion, the decrease in platelet counts is an early marker to predict the liver function recovery and complications after hepatectomy.

Effects of Intravenous Pharmacopuncture with Harmonizing and Releasing Formulas on Hepatic Recovery after Partial Hepatectomy in Rats

The objective of this study was to find out the effect of intravenous pharmacopuncture on hepatic recovery after partial hepatectomy in rats. Male Sprague-Dawley rats were randomly divided into five groups: normal group, control group, saline group, and two experimental groups. Except for those in the normal group, the rats underwent partial hepatectomy. Those in the control group did not receive any treatment. Those in the saline group received an intravenous injection with saline. Those in the two experimental groups received intravenous pharmacopuncture with SihoJigak-tang or DanchiSoyo-san extracts (10 mg/kg). Serum total bilirubin and liver regeneration rate were measured on Day 7 after partial hepatectomy. Intravenous pharmacopuncture with SihoJigak-tang significantly increased the liver regeneration rate, and intravenous pharmacopuncture with DanchiSoyo-san significantly decreased serum total billirubin after partial hepatectomy.

Establishing a Porcine Model of Small for Size Syndrome following Liver Resection

BACKGROUND

Small for size syndrome (SFSS) is responsible for a high proportion of mortalities and morbidities following extended liver resection.

AIM

The aim of this study was to establish a porcine model of SFSS.

METHODS

Twenty-four Landrace pigs underwent liver resection with a remnant liver volume of 50% (group A, n = 8), 25% (group B, n = 8), and 15% (group C, n = 8). After resection, the animals were followed up for 8 days and clinical, laboratory, and histopathological outcomes were evaluated.

RESULTS

The survival rate was significantly lower in group C compared with the other groups (p < 0.001). The international normalized ratio, bilirubin, aspartate transaminase, alanine transaminase, and alkaline phosphatase levels increased shortly after surgery in groups B and C, but no change was observed in group A (p < 0.05 for all analyses). The histopathological findings in group A were mainly mild mitoses, in group B severe mitoses and hepatocyte ballooning, moderate congestion, and hemorrhage, along with mild necrosis, and in group C extended tissue damage with severe necrosis, hemorrhage, and congestion.

CONCLUSIONS

Combination of clinical, laboratory, and histopathological evaluations is needed to confirm the diagnosis of SFSS. 75% liver resection in porcine model results in SFSS. 85% liver resection causes irreversible liver failure.

Liver sinusoidal endothelial cells: Physiology and role in liver diseases

Liver sinusoidal endothelial cells (LSECs) are highly specialized endothelial cells representing the interface between blood cells on the one side and hepatocytes and hepatic stellate cells on the other side. LSECs represent a permeable barrier. Indeed, the association of 'fenestrae', absence of diaphragm and lack of basement membrane make them the most permeable endothelial cells of the mammalian body. They also have the highest endocytosis capacity of human cells. In physiological conditions, LSECs regulate hepatic vascular tone contributing to the maintenance of a low portal pressure despite the major changes in hepatic blood flow occurring during digestion. LSECs maintain hepatic stellate cell quiescence, thus inhibiting intrahepatic vasoconstriction and fibrosis development. In pathological conditions, LSECs play a key role in the initiation and progression of chronic liver diseases. Indeed, they become capillarized and lose their protective properties, and they promote angiogenesis and vasoconstriction. LSECs are implicated in liver regeneration following acute liver injury or partial hepatectomy since they renew from LSECs and/or LSEC progenitors, they sense changes in shear stress resulting from surgery, and they interact with platelets and inflammatory cells. LSECs also play a role in hepatocellular carcinoma development and progression, in ageing, and in liver lesions related to inflammation and infection. This review also presents a detailed analysis of the technical aspects relevant for LSEC analysis including the markers these cells express, the available cell lines and the transgenic mouse models. Finally, this review provides an overview of the strategies available for a specific targeting of LSECs.

Phase I clinical trial of olprinone in liver surgery

PURPOSE

Post-hepatectomy liver failure is one of the most serious complications liver surgeons must overcome. We previously examined olprinone, a selective phosphodiesterase III inhibitor, and demonstrated its hepatoprotective effects in rats and pigs. We herein report the results of a phase I clinical trial of olprinone in liver surgery (UMIN000004975).

METHODS

Twenty-three patients who underwent hepatectomy between 2011 and 2015 were prospectively registered. In the first 6 cases, olprinone (0.1 μg/kg/min) was administered for 24 h from the start of surgery. In the remaining 17 cases, olprinone (0.05 μg/kg/min) was administered from the start of surgery until just before the transection of the liver parenchyma. The primary endpoint was safety, and the secondary endpoint was efficacy. For the evaluation of efficacy, the incidence of post-hepatectomy liver failure in 20 hepatocellular carcinoma patients was externally compared with 20 propensity score-matched patients.

RESULTS

No intraoperative side effects were observed, and the morbidity rates in the analyzed cohorts were acceptable. The rate of post-hepatectomy liver failure frequency tended to be lower in the olprinone group.

CONCLUSIONS

The safety of olprinone in liver surgery was confirmed. The efficacy of olprinone will be re-evaluated in clinical trials.

The beneficial role of simultaneous splenectomy after extended hepatectomy: experimental study in pigs

BACKGROUND

The role of hepatic hemodynamic modulation in the development of "small-for-size" syndrome (SFSS) after extended hepatectomy (EH) or living-donor liver transplantation is still controversial. We have designed an experimental study to investigate the effect of hemodynamic parameters of the liver circulation on the development of SFSS after EH in a porcine model.

METHODS

Eighteen pigs were randomly divided into two groups: group A has received EH (75%-80%) without splenectomy, and group B with EH and simultaneous splenectomy was carried out. Portal hemodynamics, liver function tests, histologic findings, injury and survival rates were compared between groups A and B.

RESULTS

The 7-d survival rate in the splenectomy group was significantly improved compared with group A (88.9% versus 44.4%, P < 0.05). Portal vein pressure, portal vein flow, and liver function tests in the splenectomy group were significantly lower than in group A immediately after splenectomy and postoperatively until the day of sacrifice. Histologic findings in group A clearly illustrate severe inflammation, bridging necrosis, ischemic cholangitis, and severe congestion, while in group B there were less serious histologic changes.

CONCLUSIONS

Our experimental study indicates that perioperative portal modulation can successfully prevent the manifestation of SFSS after EH. Therefore, by focusing on "flow" rather than on "size," researchers may understand better the pathophysiology of this syndrome.

The anterior hanging-approach improves postoperative course after right hepatectomy in patients with colorectal liver metastases. Results of a prospective study with propensity-score matching comparison

PURPOSE

To establish the role of the anterior approach with liver hanging maneuver for right hepatectomy in patients with colorectal liver metastases (CRLM).

SUMMARY BACKGROUND DATA

The indications for hepatectomy in patients with CRLM are expanding. The liver remnant must be protected to avoid morbidity.

METHODS

We prospectively enrolled all patients with the diagnosis of CRLM requiring right hepatectomy from 2009 to 2012. In all cases right hepatectomy with an anterior-hanging maneuver approach was attempted. We compared the group of patients who underwent this procedure with a group of patients who had previously undergone a conventional right hepatectomy. To minimize selection bias, propensity score matching was performed, based on baseline patient characteristics.

RESULTS

A right hepatectomy was planned in 57 cases. The anterior-hanging approach was feasible in 85% of cases. Overall morbidity was similar. In-hospital mortality due to hepatic insufficiency was 2.3% in anterior-hanging group compared to 9% in the conventional group (p = 0.30). The incidence of ascites was significantly greater in the conventional group (AH: 18% vs Conv: 54%; p = 0.002), and hospital stay was longer (AH: 10.9 ± 5.7 vs Conv: 14.4 ± 8.1 days; p = 0.05). Bilirubin levels were significantly lower in anterior-hanging group in day 1 and 3. There were no differences on recurrence nor survival.

CONCLUSIONS

The anterior-hanging approach for right hepatectomy in patients with CRLM can be used safely with a high feasibility rate. Its use contributes to improve postoperative course.

Central hepatectomy versus extended hepatectomy for liver malignancy: a matched cohort comparison

OBJECTIVE

To compare surgical outcomes between matched central hepatectomy (CH) and extended hepatectomy (EH) groups.

BACKGROUND

Surgical choices for centrally located liver tumours are limited. The traditional EH harbours substantial risks, whereas CH is an alternative parenchymal-sparing resection that may improve peri-operative morbidity.

METHODS

A review of 4661 liver resections at a single institution was performed. The cases (CH) were matched in a 1:1 ratio with EH controls.

RESULTS

The CH group was matched for demographic, tumour and laboratory factors with either right EH or combined (right/left) EH groups (n = 63 per group). Colorectal liver metastases were the most common diagnosis occurring in 70% of the patients. Higher intra-operative blood loss was observed in the right EH(P = 0.01) and combined EH groups (P < 0.01) compared with the CH group. There was a trend towards lower 90-day morbidity in the CH group (43%) compared with the right EH(59%, P = 0.1) and combined EH groups (56%, P = 0.2). The length of hospital stay was significantly longer in the control groups (P < 0.01 for both). The control groups had significantly higher post-operative bilirubin and International Normalized Ratio (INR) levels compared with the CH group. A post-operative bilirubin higher than 4 mg/dl was observed in 2% of the CH group compared with 39% of the right EH group (P < 0.01) and 52% of the combined EH group (P < 0.01). No differences in the rates of bile leak/biloma, post-hepatectomy liver failure or 90-day mortality were found.

CONCLUSIONS

CH, as compared with EH, was safe and associated with a shorter hospital stay and less post-operative liver dysfunction. CH should be considered in patients with centrally located tumours amenable to such a resection.

Defining Post Hepatectomy Liver Insufficiency: Where do We stand?

BACKGROUND

Post-hepatectomy liver failure (PHLF) is a major source of morbidity and mortality in patients undergoing liver resection. The aim of this review is to summarize the recent literature available on PHLF including its definition, predictive factors, preoperative risk assessment, severity grading, preventative measures, and management strategies.

METHODS

A systematic literature search was carried out with the search engines PubMed, Medline, and Cochrane Database using the keywords related to "liver failure", "posthepatectomy", and "hepatic resection".

RESULTS

Liver resection is a curative treatment of liver tumors. However, it leads to concurrent death and regeneration of the remaining hepatocytes. Factors related to the patient, liver parenchyma and the extent of surgery can inhibit regeneration leading to PHLF.

CONCLUSION

Given its resistance to treatment and the high postoperative mortality associated with PHLF, great effort has been put in to both accurately identify patients at high risk and to develop strategies that can help prevent its occurrence.