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Background and Aims: Alterations in liver histology influence the liver's capacity to regenerate, but the relevance of each of the different changes in rapid liver growth induction is unknown. This study aimed to analyze the influence of the degree of histological alterations during the first and second stages on the ability of the liver to regenerate., Methods: This cohort study included data obtained from the International ALPPS Registry between November 2011 and October 2020. Only patients with colorectal liver metastases were included in the study. We developed a histological risk score based on histological changes (stages 1 and 2) and a tumor pathology score based on the histological factors associated with poor tumor prognosis., Results: In total, 395 patients were included. The time to reach stage 2 was shorter in patients with a low histological risk stage 1 (13 vs 17 days, P ˂0.01), low histological risk stage 2 (13 vs 15 days, P <0.01), and low pathological tumor risk (13 vs 15 days, P <0.01). Regarding interval stage, there was a higher inverse correlation in high histological risk stage 1 group compared to low histological risk 1 group in relation with future liver remnant body weight ( r =-0.1 and r =-0.08, respectively), and future liver remnant ( r =-0.15 and r =-0.06, respectively)., Conclusions: ALPPS is associated with increased histological alterations in the liver parenchyma. It seems that the more histological alterations present and the higher the number of poor prognostic factors in the tumor histology, the longer the time to reach the second stage., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Hepatectomy is the only potentially curative treatment of hepatic tumors, but remains challenging in case of multiple, bilobar lesions and those located in the vicinity of the hepatic hilum and hepatic veins. Regenerative liver surgery utilizes the unique ability of the liver to re-grow after tissue loss and vascular deprivation. All concepts subsumed under this term aim to increase the resectability of hepatic tumors by stimulating growth of future liver remnant. Many of these techniques have evolved over the last decades. ALPPS (associated liver partition and portal vein ligation for staged hepatectomy) is an advanced technique combining portal vein ligation and parenchymal transection which gave rise to many variants, all with the common goal of extending resectability. This article reviews techniques currently available for regenerative liver surgery focusing on ALPPS, its mechanisms of liver regeneration, indications, advantages, drawbacks, results and future perspectives., (Celsius.)

Objective: To investigate the impact of remote ischemic preconditioning (RIPC) on liver regeneration after major hepatectomy., Summary Background Data: RIPC is a strategy applied at remote sites to mitigate ischemic injury. Unlike other preconditioning approaches, RIPC spares target organs as it acts via systemic VEGF elevations. In the liver, however, VEGF is an important driver of regeneration following resection. Therefore, RIPC may have pro-regenerative effects., Methods: RIPC was applied to C57BL/6 mice through intermittent clamping of the femoral vessels prior to standard 68%-hepatectomy or extended 86%-hepatectomy, with the latter causing liver failure and impaired survival. Liver regeneration was assessed through weight gain, proliferative markers (Ki67, pH3, mitoses), cell cycle-associated molecules, and survival. The role of the VEGF-ID1-WNT2 signaling axis was assessed through WIF1 (a WNT antagonist) and recombinant WNT2 injected prior to hepatectomy., Results: RIPC did not affect regeneration after 68%-hepatectomy, but improved liver weight gain and hepatocyte mitoses after 86%-hepatectomy. Importantly, RIPC raised survival from 40% to 80% after 86%-hepatectomy, indicating the promotion of functional recovery. Mechanistically, the RIPC-induced elevations in VEGF were accompanied by increases in the endothelial transcription factor Id1, its target WNT2, and its hepatocellular effector β-catenin. WIF1 injection prior to 86%-hepatectomy abrogated the RIPC benefits, while recombinant WNT2 had pro-regenerative effects akin to RIPC., Conclusion: RIPC improves the regenerative capacity of marginal liver remnants in a VEGF-dependent way. If confirmed in patients, RIPC may become the preconditioning strategy of choice in the setting of extended liver resections.

Interaction between sinusoidal endothelial cells and hepatocytes is a prerequisite for liver function. Upon tissue loss, both liver cell populations need to be regenerated. Repopulation occurs in a coordinated pattern, first through the regeneration of parenchyme (hepatocytes), which then produces vascular endothelial growth factor (VEGF) to enable the subsequent angiogenic phase. The signals that instruct hepatocytes to induce timely VEGF remain unidentified. Given that liver is highly vascularized, we reasoned that fluctuations in oxygenation after tissue loss may contribute to the coordination between hepatocyte and sinusoidal endothelial cell proliferation. To prevent drops in oxygen after hepatectomy, mice were pretreated with inositol trispyrophosphate (ITPP), an allosteric effector of hemoglobin causing increased O 2 release from heme under hypoxic conditions. ITPP treatment delayed liver weight gain after hepatectomy. Comparison with controls revealed the presence of a hypoxic period around the peak of hepatocyte mitosis. Inhibition of hypoxia led to deficient hepatocyte mitosis, suppressed the regenerative Vegf wave, and abrogated the subsequent reconstruction of the sinusoidal network. These ITPP effects were ongoing with the reduction in hepatocellular hypoxia inducible factor 2a (Hif2a). In contrast, Hif1a was unaffected by ITPP. Hif2a knockdown phenocopied all effects of ITPP, including the mitotic deficiencies, Vegf suppression, and angiogenic failure., Conclusions: Oxygen is a key regulator of liver regeneration. Hypoxia-inherent to the expansion of parenchyme-activates Hif2a to couple hepatocyte mitosis with the angiogenic phase. Hif2a acts as a safeguard to initiate sinusoidal reconstruction only upon successful hepatocyte mitosis, thereby enforcing a timely order onto cell type-specific regeneration patterns. These findings portray the hypoxia-driven Hif2a-Vegf axis as a prime node in coordinating sinusoidal endothelial cell-hepatocyte crosstalk during liver regeneration. (Hepatology 2016;64:2198-2209)., (© 2016 by the American Association for the Study of Liver Diseases.)

Background: Posthepatectomy liver failure (PHLF) may occur after ALPPS (Associating liver partition and portal vein ligation for staged hepatectomy) despite a sufficient standardized future liver remnant (sFLR) volume. The aim of this study was to test kinetic growth rate (KGR) after ALPPS stage 1, describing the percentage increase of sFLR per day, as a predictor of PHLF after completion of ALPPS., Methods: The ability of KGR to predict PHLF after ALPPS stage 2 was investigated in 38 patients. PHLF was defined according to the "50-50" and ISGLS criteria., Results: Completion of ALPPS was achieved in 95% (36/38) of patients. The incidence of PHLF was 22% (8/36) and 36% (13/36) according to "50-50" and ISGLS criteria, respectively. Whereas a sFLR cut off at 30% alone failed to predict PHLF, KGR ≥6%/day after stage 1 was associated with a significant reduced risk of PHLF ("50-50", p = 0.03/ISGLS, p = 0.03) after stage 2. Adherence to both concomitant KGR ≥6%/day and sFLR ≥30% reduced the incidence of PHLF to 0%., Conclusions: Assessment of KGR is a novel tool to estimate the risk of PHLF after ALPPS. Respecting KGR and sFLR after ALPPS stage 1 may increase safety in patients undergoing ALPPS., (Copyright © 2016 International Hepato-Pancreato-Biliary Association Inc. Published by Elsevier Ltd. All rights reserved.)

Objectives: To evaluate the use of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI)-derived fat- and liver function-measurements for prediction of future liver remnant (FLR) growth after portal vein occlusion (PVO) in patients scheduled for major liver resection., Methods: Forty-five patients (age, 59 ± 13.9 y) who underwent Gd-EOB-DTPA-enhanced liver MRI within 24 ± 18 days prior to PVO were included in this study. Fat-Signal-Fraction (FSF), relative liver enhancement (RLE) and corrected liver-to-spleen ratio (corrLSR) of the FLR were calculated from in- and out-of-phase (n=42) as well as from unenhanced T1-weighted, and hepatocyte-phase images (n=35), respectively. Kinetic growth rate (KGR, volume increase/week) of the FLR after PVO was the primary endpoint. Receiver operating characteristics analysis was used to determine cutoff values for prediction of impaired FLR-growth., Results: FSF (%) showed significant inverse correlation with KGR (r=-0.41, p=0.008), whereas no significant correlation was found with RLE and corrLSR. FSF was significantly higher in patients with impaired FLR-growth than in those with normal growth (%FSF, 8.1 ± 9.3 vs. 3.0 ± 5.9, p=0.02). ROC-analysis revealed a cutoff-FSF of 4.9% for identification of patients with impaired FLR-growth with a specificity of 82% and sensitivity of 47% (AUC 0.71 [95%CI:0.54-0.87]). Patients with impaired FLR-growth according to the FSF-cutoff showed a tendency towards higher postoperative complication rates (posthepatectomy liver failure in 50% vs. 19%)., Conclusions: Liver fat-content, but not liver function derived from Gd-EOB-DTPA-enhanced MRI is a predictor of FLR-growth after PVO. Thus, liver MRI could help in identifying patients at risk for insufficient FLR-growth, who may need re-evaluation of the therapeutic strategy., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Objective: The aim of this study was to assess the impact of postoperative hypophosphatemia on liver regeneration after major liver surgery in the scenario of Associating Liver Partition with Portal vein ligation for Staged hepatectomy (ALPPS) and living liver donation (LLD). Background: Hypophosphatemia has been described to reflect the metabolic demands of regenerating hepatocytes. BothALPPS and LLDare characterized by an exceptionally strong liver regeneration and may be of particular interest in the context of posthepatectomy hypophosphatemia. Methods: Serumphosphate changes within the first 7 postoperative days after ALPPS (n=61) and LLD (n=54) were prospectively assessed and correlated with standardized volumetry after 1 week. In a translational approach, postoperative phosphate changes were investigated in mice and in vitro. Results: After ALPPS stage 1 and LLD, serum phosphate levels significantly dropped from a preoperative median of 1.08 mmol/L [interquartile range (IQR) 0.92--1.23] and 1.07 mmol/L (IQR 0.91--1.21) to a postoperative median nadir of 0.68 and 0.52 mmol/L, respectively. A pronounced phosphate drop correlated well with increased liver hypertrophy (P< 0.001). Patients with a low drop of phosphate showed a higher incidence of posthepatectomy liver failure after ALPPS (7% vs 31%, P=0.041). Like in humans, phosphate drop correlated significantly with degree of hypertrophy in murine ALPPS and hepatectomy models (P<0.001). Blocking phosphate transporter (Slc20a1) inhibited cellular phosphate uptake and hepatocyte proliferation in vitro. Conclusion: Phosphate drop after hepatectomy is a direct surrogate marker for liver hypertrophy. Perioperative implementation of serum phosphate analysis has the potential to detect patients with insufficient regenerative capacity at an early stage. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to assess the effect of Ω3 fatty acids (Ω3FA) on fatty and lean liver in hepatic surgery. Background: The global spread of energy-dense diets has led to an endemic rise in fatty liver disease and obesity. Besides metabolic pathologies, steatosis enhances hepatic sensitivity to ischemia reperfusion (I/R) and impedes liver regeneration (LR). Steatosis limits the application of liver surgery, still the main curative option for liver cancer. Ω3FA are known to reverse steatosis, but how these lipids affect key factors defining surgical outcomes--that is, I/R, LR, and liver malignancy--is less clear. Methods: We established a standardized mouse model of high fat diet (HFD)-induced steatosis followed by V3FA treatment and the subsequent assessment of Ω3FA effects on I/R, LR, and liver malignancy (n = 5/group), the latter through a syngeneic metastasis approach. Fatty liver outcomes were com- pared with lean liver to assess steatosis-independent effects. Nonparametric statistics were applied. Results: Ω3FA reversed HFD-induced steatosis and markedly protected against I/R, improved LR, and prolonged survival of tumor-laden mice. Remarkably, these beneficial effects were also observed in lean liver, albeit at a smaller scale. Notably, mice with metastases in fatty versus lean livers were associated with improved survival. Conclusions: Ω3FA revealed multiple beneficial effects in fatty and lean livers in mice. The improvements in I/R injury, regenerative capacity, and oncological outcomes await confirmatory studies in humans. [ABSTRACT FROM AUTHOR]