Beneficial effects of splenectomy on liver regeneration in a rat model of massive hepatectomy

Spleen volume after stage-I associated liver partition and portal vein ligation for staged hepatectomy predicts future liver remnant

BACKGROUND

The spleen has been reported to inhibit liver regeneration following hepatectomy; however, the underlying mechanisms remain poorly understood. In particular, its role in future liver remnant (FLR) regeneration after associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) warrants investigation.

AIM

To evaluate the relationship between splenic volume changes and FLR regeneration following ALPPS-stage I in patients with massive hepatocellular carcinoma (HCC).

METHODS

Clinical data from 65 HCC patients who underwent ALPPS between 2018 and 2021 were retrospectively analyzed. Liver and spleen volumes were measured pre- and post-ALPPS-stage I use the IQQA-Liver system. The kinetic growth rate (KGR) of the FLR was calculated. Pearson correlation and logistic regression were used to identify predictors of FLR hypertrophy. Receiver operating characteristic (ROC) curves were constructed to determine cutoff values for splenic predictors.

RESULTS

Following ALPPS-stage I, FLR volume significantly increased from 35.57%±8.51-54.31%±11.19% of standard liver volume (SLV) (P < 0.001), with a median KGR of 4.65%/day. Splenic volume also increased (218.65 ± 84.77 cm³ vs. 252.69 cm³, P < 0.001). Preoperative splenic volume and spleen volume/SLV ratio negatively correlated with KGR (r = -0.240, P = 0.027; r = -0.218, P = 0.041). Multivariate analysis identified splenic volume (OR = 0.991, P = 0.043), platelet count (OR = 1.014, P = 0.013), Indocyanine Green Retention Rate at 15 min (ICG-R15) (OR = 0.670, P = 0.010), and CNLC stage (P = 0.001) as independent predictors of FLR regeneration. ROC analysis showed that splenic volume > 265.29 cm³ (AUC = 0.645) and spleen volume/SLV ratio > 0.1997 (AUC = 0.646) predicted poor FLR hypertrophy. One- and two-year survival rates were 80.77% and 68.18%, respectively.

CONCLUSION

Preoperative splenic volume is an independent predictor of FLR regeneration after ALPPS. Combined evaluation of splenic volume, platelet count, and liver function may improve patient selection, reduce the risk of postoperative liver failure, and optimize surgical outcomes.

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.

Volume and flow modulation strategies to mitigate post-hepatectomy liver failure

INTRODUCTION

Post hepatectomy liver failure is the most common cause of death following major hepatic resections with a perioperative mortality rate between 40% to 60%. Various strategies have been devised to increase the volume and function of future liver remnant (FLR). This study aims to review the strategies used for volume and flow modulation to reduce the incidence of post hepatectomy liver failure.

METHOD

An electronic search was performed of the MEDLINE, EMBASE and PubMed databases from 2000 to 2022 using the following search strategy "Post hepatectomy liver failure", "flow modulation", "small for size flow syndrome", "portal vein embolization", "dual vein embolization", "ALPPS" and "staged hepatectomy" to identify all articles published relating to this topic.

RESULTS

Volume and flow modulation strategies have evolved over time to maximize the volume and function of FLR to mitigate the risk of PHLF. Portal vein with or without hepatic vein embolization/ligation, ALPPS, and staged hepatectomy have resulted in significant hypertrophy and kinetic growth of FLR. Similarly, techniques including portal flow diversion, splenic artery ligation, splenectomy and pharmacological agents like somatostatin and terlipressin are employed to reduce the risk of small for size flow syndrome SFSF syndrome by decreasing portal venous flow and increasing hepatic artery flow at the same time.

CONCLUSION

The current review outlines the various strategies of volume and flow modulation that can be used in isolation or combination in the management of patients at risk of PHLF.

Transforming one organ into another to overcome challenges in tissue engineering

Tissue engineering (TE) is promising for the regeneration of failed organs. However, immune rejection, shortage of seed cells, and unintegrated blood vessels restrict the development and clinical application of TE. The last factor is the most challenging and intractable. Harnessing the mature blood vessel network in existing dispensable organs could be a powerful approach to effectively overcome the obstacles. After being remodeled to harbor an immunosuppressive and proregenerative niche, these potential target organs can be transformed into other organs with specific physiological functions, compensating the latter's failed native functions. Organ transformation, such as a hepatized spleen, represents an effective and encouraging TE strategy. In this review, we discuss the current development and obstacles of TE and its feasibility and superiority in organ transformation.

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.

Ultrasonographic hemodynamics for prediction of poor liver regeneration induced by severe portal vein stenosis in rats

Background

Insufficient portal vein blood flow, such as portal vein stenosis (PVS), plays a significant influence on liver regeneration. Early prediction of poor liver regeneration induced by severe PVS is critical. Ultrasound serves as a first-line imaging technique in diagnosing PVS based on the changes of portal vein hemodynamics. However, there is still no consensus on the criteria for evaluating the degree of PVS. Moreover, which degree of PVS can induce poor liver regeneration still is unclear. Therefore, it is essential to determine the stenosis degree that leads to significantly poor liver regeneration and to evaluate the value of ultrasonographic hemodynamics for predicting poor liver regeneration induced by severe PVS.

Methods

Rats were randomly subjected to sham operation rats group (SOR), PH group (group A), and PVS groups with mild, moderate, or severe stenosis flowing PH (groups B-D). PH group was set up a model of 70% hepatectomy, and PVS groups were produced by different degrees of partial portal vein ligation following PH. In the SOR group and PH group, the portal vein diameter (PVD) and portal vein velocity (PVV) were measured by Ultrasound at preoperative and postoperative 1, 3, 7, and 14 d. In PVS groups, PVD and PVV at the stenotic (PVD_s, PVV_s) and pre-stenotic (PVD_pre, PVV_pre) sites were also detected on 1, 3, 7, and 14 d after surgery, calculating the diameter stenosis ratio (DSR) and accelerating blood flow velocity ratio (AVR). Rats were sacrificed at 1, 3, 7, and 14 d post-surgery, and the expression of proliferating cell nuclear antigen (PCNA) and the liver regeneration rate (LRR) at 14 d were evaluated. The PVV_s, DSR, and AVR in the different groups were analyzed combined with the status of liver regeneration, and receiver operating characteristic (ROC) analysis was also applied to assess the value of PVV_s, DSR, and AVR in diagnosing severe PVS and the resulting poor liver regeneration.

Results

Seventy-two rat models of different degrees of PVS were successfully set up following 70% PH. The stenosis ratios (SRs) of each PVS group were 45.16%±3.44%, 59.21%±3.83%, and 69.56%±2.16%, respectively. Poor liver regeneration appeared to be significant when PVS was greater than 65% (group D), of which the LRR at 14 d was significantly lower compared to PH group (group A) and PVS groups with SR ≤50% (group B) and SR >50-65% (group C), respectively (all P<0.05). Meanwhile, PCNA expression of group D was significantly lower compared to group C at 1 d and groups A-C at 3 d (all P<0.05). Differences were also detected at 3 d between groups A and B and groups A and C (both P<0.05). Among PVS groups, PVV_s accelerated dramatically, with significant differences demonstrated between group D and groups B and C at 1 d, as well as group B and groups C and D at 3 d (all P<0.05). At 1, 3, and 7 d, DSR of groups C and D were significantly higher than that of group A (all P<0.05). At 1 and 3 d, AVR of group D was significantly higher than that of groups B and C (all P<0.05). ROC analysis showed the AUC of PVV_s at 1 d in diagnosing severe PVS was 0.84, while at 3 d, it was unable to differentiate from mild-moderate or severe PVS by PVV_s (P>0.05 vs. AUC =0.50). At 1 and 3 d, the AUC of DSR and AVR in diagnosing severe PVS were all greater than 0.80, comparatively much better in AVR (AUC >0.95). The best cut-off points of AVR at 1 and 3 d were 6.91 and 5.36, with the sensitivity and specificity respectively 100%, 91.67% at 1 d, and 100%, 83.33% at 3 d.

Conclusions

Poor liver regeneration could be significantly induced when PVS was greater than 65%. Ultrasound can well prove the changes of portal vein hemodynamics in different degrees of PVS in rats. The parameters PVV_s could be regarded as a valid index for diagnosing PVS but were not applicable for evaluating the stenosis degree. Comparatively, the parameters DSR and AVR, especially AVR, proved to be useful for differentiating severe PVS (>65%) in the early postoperative period, predicting the resulting poor liver regeneration.

Splenectomy after partial hepatectomy accelerates liver regeneration in mice by promoting tight junction formation via polarity protein Par 3-aPKC

AIMS

Several experimental studies have demonstrated that removal of the spleen accelerates liver regeneration after partial hepatectomy. While the mechanism of splenectomy promotes liver regeneration by the improvement of the formation of tight junction and the establishment of hepatocyte polarity is still unknown.

MAIN METHODS

We analyzed the cytokines, genes and proteins expression between 70% partial hepatectomy mice (PHx) and simultaneous 70% partial hepatectomy and splenectomy mice (PHs) at predetermined timed points.

KEY FINDINGS

Compared with the PHx group mice, splenectomy accelerated hepatocyte proliferation in PHs group. The expression of Zonula occludens-1 (ZO-1) indicated that splenectomy promotes the formation of tight junction during liver regeneration. TNF-α, IL-6, HGF, TSP-1 and TGF-β1 were essential factors for the formation of tight junction and the establishment of hepatocytes polarity in liver regeneration. After splenectomy, Partitioning defective 3 homolog (Par 3) and atypical protein kinase C (aPKC) regulate hepatocyte localization and junctional structures in regeneration liver.

SIGNIFICANCE

Our data suggest that the time course expression of TNF-α, IL-6, HGF, TSP-1, and TGF-β1 and the change of platelets take part in liver regeneration. Combination with splenectomy accelerates liver regeneration by improvement of the tight junction formation which may help to establish hepatocyte polarity via Par 3-aPKC. This may provide a clue for us that splenectomy could accelerate liver regeneration after partial hepatectomy of hepatocellular carcinoma and living donor liver transplantation.

Comparative study of the effects of terlipressin versus splenectomy on liver regeneration after partial hepatectomy in rats

BACKGROUND

Post-hepatectomy liver failure as a result of insufficient liver remnant is a feared complication in liver surgery. Efforts have been made to find new strategies to support liver regeneration. The aim of this study was to investigate the effects of terlipressin versus splenectomy on postoperative liver function and liver regeneration in rats undergoing 70% partial hepatectomy.

METHODS

Seventy-two male Wistar rats were randomly assigned into three groups (n=24 in each group): 70% partial hepatectomy as control (PHC), 70% partial hepatectomy with splenectomy (PHS) or 70% partial hepatectomy with a micropump for terlipressin administration (PHT). Eight rats in each group were sacrificed on postoperative day (POD) 1, 3 and 7. To assess liver regeneration, immunohistochemical analysis of liver tissue using bromodeoxyuridine (BrdU) and Ki-67 labeling was performed. Portal venous pressure, serum concentrations of creatinine, urea, albumin, bilirubin and prothrombin time as well as liver-, body-weight and their ratio were determined on POD 1, 3 and 7.

RESULTS

The liver-, body-weight and their ratio were not statistically different among the groups. On POD 1, 3 and 7 portal venous pressure in the intervention groups (PHT: 8.13±1.55, 10.38±1.30, 6.25±0.89 cmH₂O and PHS: 7.50±0.93, 8.88±2.42, 5.75±1.04 cmH₂O) was lower compared to the control group (PHC: 8.63±2.06, 10.50±2.45, 6.50±2.67 cmH₂O). Hepatocyte proliferation in the intervention groups was delayed, especially after splenectomy on POD 1 (BrdU: PHS vs PHC, 20.85%±13.05% vs 28.11%±10.10%; Ki-67, 20.14%±14.10% vs 23.96%±11.69%). However, none of the differences were statistically significant.

CONCLUSIONS

Neither the administration of terlipressin nor splenectomy improved liver regeneration after 70% partial hepatectomy in rats. Further studies assessing the regulation of portal venous pressure as well as extended hepatectomy animal models and liver function tests will help to further investigate mechanisms of liver regeneration.

Evaluation of safety of concomitant splenectomy in living donor liver transplantation: a retrospective study

In Asian countries, concomitant splenectomy in living donor liver transplantation (LDLT) is indicated to modulate the portal vein pressure in the small-sized graft to protect against small for size syndrome. While concomitant splenectomy in deceased donor liver transplantation is almost contraindicated based on Western Reports of increased mortality and morbidity rate due to septic complications, there are few studies about that in LDLT. So, we retrospectively investigated the clinical outcome of adult LDLT at Kyoto University Hospital from July 2010 to July 2016. We divided the patients (n = 164) into those with concomitant splenectomy (n = 88) and those without (n = 76). The splenectomy group showed significantly increased operative time and intraoperative blood loss (P = 0.008, P = 0.0007, respectively), and significantly higher rate of postoperative splenic vein thrombosis and cytomegalovirus infection (P = 0.03, P = 0.016, respectively). However, there were no significant differences between the two groups regarding the incidence of postoperative hemorrhage (P = 0.06), post-transplant bacteremia (P = 0.38), infection-related mortality rates (P = 0.8), acute rejection (P = 0.87), and patient and graft survival (P = 0.66, P = 0.67 respectively); finally, model for end-stage liver disease score above 30 was an independent predictor for infection-related mortality post-transplant (HR = 5.99, 95% CI = 2.15-16.67, P = 0.001). In conclusion, concomitant splenectomy in LDLT can be safely performed when indicated.

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.

Hepatectomy combined with microwave ablation of the spleen for treatment of hepatocellular carcinoma complicated with splenomegaly: A retrospective study

The present retrospective study aimed to investigate the mid-term safety and efficacy of hepatectomy combined with microwave ablation of the partial spleen for treatment of liver cancer complicated with hypersplenism. A retrospective analysis was performed on 23 patients who underwent hepatectomy combined with microwave ablation of the partial spleen for liver cancer, complicated with hypersplenism that was secondary to cirrhosis. The splenic and ablated volumes were calculated according to a contrast-enhanced computed tomography scan prior to and 2 weeks after the operation. Complete blood count and liver function tests were examined prior to and following the surgery, and complications and changes in the blood tests were monitored for 6 months. Over this period of investigation, the splenic volume was reduced by a mean value of 34.0%. The levels of serum alanine aminotransferase and aspartate aminotransferase were increased on the first day after the operation (P<0.05), although they recovered to the normal level within 1 week (P<0.05). The total level of bilirubin increased slightly, along with moderately decreased levels of albumin and cholinesterase on the first day, although these changes were not significant compared with the baseline (P>0.05). The white blood cell count was persistently significantly higher compared with the baseline over the course of the 6 months (P>0.05). The platelet count did not increase significantly for the first week after the operation (P>0.05); however, it was revealed to be significantly increased 1 month after the surgery (P<0.05). No significant complications were occurred during the follow-up period. In conclusion, hepatectomy combined with microwave ablation of the spleen was demonstrated to be a safe and effective procedure for patients with liver cancer and hypersplenism in the mid-term.

Liver resection for cancer: New developments in prediction, prevention and management of postresectional liver failure

Hepatic failure is a feared complication that accounts for up to 75% of mortality after extensive liver resection. Despite improved perioperative care, the increasing complexity and extensiveness of surgical interventions, in combination with an expanding number of resections in patients with compromised liver function, still results in an incidence of postresectional liver failure (PLF) of 1-9%. Preventive measures aim to enhance future remnant liver size and function. Numerous non-invasive techniques to assess liver function and predict remnant liver volume are being developed, along with introduction of novel surgical strategies that augment growth of the future remnant liver. Detection of PLF is often too late and treatment is primarily symptomatic. Current therapeutic research focuses on ([bio]artificial) liver function support and regenerative medicine. In this review we discuss the current state and new developments in prediction, prevention and management of PLF, in light of novel insights into the aetiology of this complex syndrome.

LAY SUMMARY

Liver failure is the main cause of death after partial liver resection for cancer, and is presumably caused by an insufficient quantity and function of the liver remnant. Detection of liver failure is often too late, and current treatment focuses on relieve of symptoms. New research initiatives explore artificial support of liver function and stimulation of regrowth of the remnant liver.

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.

Role of the spleen in liver regeneration in relation to transforming growth factor-β1 and hepatocyte growth factor

BACKGROUND

Optimizing the hepatic regenerative capacity is an immediate priority after partial hepatectomy (PH). Recent reports have indicated improvement in liver regeneration after splenectomy, raising interest on the role of the spleen in liver regeneration. However, little is known about the exact mechanism underlying these effects.

MATERIALS AND METHODS

Eight-week-old male Sprague-Dawley rats randomly underwent either 70% PH only (PH, n = 25) or 70% PH combined with splenectomy (PHS, n = 25). The specimens, including liver and/or spleen tissues and sera, were collected and evaluated using immunohistochemistry, Western blotting, enzyme-linked immunosorbent assay, and serum biochemical analyses.

RESULTS

PH induced higher transforming growth factor (TGF)-β1 expression in the liver up to 72 h after PH. The PHS group showed significantly higher numbers of proliferating cell nuclear antigen-positive cells, reflecting higher liver regeneration and lower amounts of liver enzymes compared with the PH group. Splenectomy after PH resulted in increased and decreased serum concentrations of hepatocyte growth factor (HGF) and TGF-β1 in the portal vein, respectively. Moreover, the PHS group demonstrated downregulation of TGF-β1 and its receptor TGF-β-RII and upregulation of HGF and its receptor c-Met in the liver.

CONCLUSIONS

The spleen seemed to exhibit an inhibitory effect on liver regeneration by upregulating TGF-β1 and its receptor TGF-β-RII and downregulating HGF and its receptor c-Met in the liver. Therefore, splenectomy can be considered an option for improving liver regeneration in selected patients with reduced regenerative capacity of the liver.

Prognosis of patients with hepatocellular carcinoma and hypersplenism after surgery: a single-center experience from the People's Republic of China

PURPOSE

As prognosis of patients with hepatocellular carcinoma (HCC) and hypersplenism is rarely reported, this study examined prognostic factors for patients who underwent surgery for this condition.

PATIENTS AND METHODS

This study retrospectively analyzed prognostic factors in 181 consecutive HCC patients using univariate and multivariate analyses, as well as subgroup analyses for disease-free survival (DFS) and overall survival (OS) of two groups: one group who received splenectomies (Sp) and one group who did not (non-Sp).

RESULTS

1, 3, and 5 year OS rates were 88.4%, 67.1%, and 52.8%, respectively; corresponding DFS rates were 67.0%, 43.8%, and 31.6%, respectively. Age ≥55 years old, cigarette smoking, tumor size ≥5 cm, microvascular invasion, and Child-Pugh grade B (versus A) correlated significantly with OS (P<0.05). Interestingly, in patients with tumor lymph node metastasis (TNM) stage I disease, DFS of the Sp-group (median DFS, 24.1 months; n=34) was significantly lower than that of the non-Sp group (median DFS, 62.1 months; n=74), P=0.034; whereas at TNM stage II, OS of the Sp-group (median OS, 79.1 months; n=21) was significantly better than that of the non-Sp group (median OS, 23.3 months; n=30), P=0.018.

CONCLUSION

Hepatectomy without concomitant splenectomy can contribute to improved DFS of TNM stage I HCC patients with hypersplenism, whereas simultaneous hepatectomy and splenectomy can prolong OS for patients at TNM stage II.

Small-for-size syndrome in living-donor liver transplantation using a left lobe graft

In living-donor liver transplantation with a left lobe graft, which can reduce the burden on the donor compared to right lobe graft, the main problem is small-for-size (SFS) syndrome. SFS syndrome is a multifactorial disease that includes aspects related to the graft size, graft quality, recipient factors and even technical issues. The main pathophysiology of SFS syndrome is the sinusoidal microcirculatory disturbance induced by shear stress, which is caused by excessive portal inflow into the smaller graft. The donor age, the presence of steatosis of the graft and a poor recipient status are all risk factors for SFS syndrome. To resolve SFS syndrome, portal inflow modulation, splenectomy, splenic artery modulation and outflow modulation have been developed. It is important to establish strict criteria for managing SFS syndrome. Using pharmacological interventions and/or therapeutic approaches that promote liver regeneration could increase the adequate outcomes in SFS liver transplantation. Left lobe liver transplantation could be adopted in Western countries to help resolve the organ shortage.

Review of the surgical approach to prevent small-for-size syndrome in recipients after left lobe adult LDLT

Left lobe liver grafts increase the donor safety in adult-to-adult living-donor liver transplantation (ALDLT). However, the left lobe graft provides about 30-50 % of the required liver volume to adult recipients, which is insufficient to sustain their metabolic demands, which can lead to small-for-size syndrome (SFSS). Transient portal hypertension and microcirculatory hemodynamic derangement, apart from outflow obstruction, during the first week after reperfusion are the critical events associated with small-for-size graft transplantation. The incidence of SFSS in left lobe ALDLT can be decreased by increasing the left lobe graft volume by effective utilization of the caudate lobe with preserved vascular supply, by modulating the portal pressure with splenectomy or a porto-systemic shunt or by hepatic venous outflow reconstruction to prevent the development of venous congestion. In this review, we discuss the pathophysiology of SFSS and the various surgical strategies that can be performed to prevent SFSS in an effort to enhance the donor safety during living-donor liver transplantation.

Interleukin-17A plays a pivotal role after partial hepatectomy in mice

BACKGROUND

Liver regeneration after partial hepatectomy (PH) is regulated by tumor necrosis factor (TNF)-α derived from the Kupffer cell. Furthermore, it was reported from our laboratory that interleukin (IL)-17A enhances the production of TNF-α by the Kupffer cell, suggesting that IL-17A may play a role in liver regeneration.

OBJECTIVE

The purpose was to determine the role of IL-17A and the spleen in liver regeneration after PH.

METHODS

Two mouse models including the wild-type (WT) mice or the IL-17A knockout (KO) mice underwent PH. Animals were killed at the designated time points; liver tissues were harvested for further investigation. Proliferation of hepatocytes was evaluated. Furthermore, the messenger RNA and protein expression of TNF-α and IL-6 were measured in the liver. In another set of experiments, the two animal models underwent splenectomy before PH. In an in vitro study, CD4-positive lymphocytes in the spleen were isolated from mice, and the number of IL-17A-positive cells was investigated.

RESULTS

Liver regeneration was significantly impaired in the KO mice compared with the WT mice. This was associated with suppression of cell proliferation assessed by cell proliferation markers in the KO mice. In the WT mice that underwent splenectomy, liver regeneration was significantly delayed compared with animals without splenectomy. In contrast, splenectomy did not affect liver regeneration in the KO mice. IL-17A-positive lymphocytes increased significantly in the spleen in the WT mice after PH.

CONCLUSIONS

These results indicate that IL-17A derived from CD4-positive lymphocytes in the spleen is a key regulator in liver regeneration after PH.

New paradigms in post-hepatectomy liver failure

INTRODUCTION

Liver failure after hepatectomy remains the most feared postoperative complication. Many risk factors are already known, related to patient's comorbidities, underlying liver disease, received treatments and type of resection. Preoperative assessment of functional liver reserve must be a priority for the surgeon.

METHODS

Physiopathology of post-hepatectomy liver failure is not comparable to fulminant liver failure. Liver regeneration is an early phenomenon whose cellular mechanisms are beginning to be elucidated and allowing most of the time to quickly recover a functional organ. In some cases, microscopic and macroscopic disorganization appears. The hepatocyte hyperproliferation and the asynchronism between hepatocytes and non-hepatocyte cells mitosis probably play a major role in this pathogenesis.

RESULTS

Many peri- or intra-operative techniques try to prevent the occurrence of this potentially lethal complication, but a better understanding of involved mechanisms might help to completely avoid it, or even to extend the possibilities of resection.

CONCLUSION

Future prevention and management may include pharmacological slowing of proliferation, drug or physical modulation of portal flow to reduce shear-stress, stem cells or immortalized hepatocytes injection, and liver bioreactors. Everything must be done to avoid the need for transplantation, which remains today the most efficient treatment of liver failure.