Comparative study of portal vein embolization versus portal vein ligation for induction of hypertrophy of the future liver remnant using a mini-pig model

Circulating proliferative factors versus portal inflow redistribution: mechanistic insights of ALPPS-derived rapid liver regeneration

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) can induce accelerated regeneration of future liver remnant (FLR) and effectively reduce the occurrence of liver failure due to insufficient FLR after hepatectomy, thereby increasing the probability of radical resection for previously inoperable patients with liver cancer. However, the exact mechanism by which ALPPS accelerates liver regeneration remains elusive.

METHODS

A review of the literature was performed utilizing MEDLINE/PubMed and Web of Science databases in March of 2024. The key words "liver regeneration/hypertrophy", "portal vein ligation/embolization", "two-stage hepatectomy", "liver partition/split" and "future liver remnant" in combination with "mechanisms", "hemodynamics", "cytokines", "growth factors" or "collaterals" were searched in the title and/or abstract. The references of relevant articles were reviewed to identify additional eligible publications.

RESULTS

Previously, a widely accepted view is that the primary role of liver splitting in ALPPS stage 1 is to accelerate liver regeneration by promoting proliferative factor release, but increasing evidence in recent years reveal that not the circulating factors, but the portal hemodynamic alternations caused by liver parenchyma transection play a pivotal role in ALPPS-associated rapid liver hypertrophy.

CONCLUSION

Parenchyma transection-induced portal hemodynamic alternations are the main triggers or driving forces of accelerated liver regeneration following ALPPS. The release of circulating proliferative factors seems to be a secondary response to liver splitting and plays an auxiliary role in this process.

Preoperative Portal Vein Embolization: Basics Interventional Radiologists Need to Know

One of the major reasons for unresectability of the liver is that the remnant liver volume is insufficient to support postoperative liver function. Post-hepatectomy liver insufficiency is one of the most serious complications in patients undergoing major hepatic resection. Preoperative portal vein embolization is performed with the aim of inducing hypertrophy of the future liver remnant and is thought to reduce the risk of liver insufficiency after hepatectomy. We, interventional radiologists, are required to safely complete the procedure to promote future liver remnant hypertrophy as possible and understand portal vein anatomy variations and hemodynamics, embolization techniques, and how to deal with possible complications. The basic information interventional radiologists need to know about preoperative portal vein embolization is discussed in this review.

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.

Liver Venous Deprivation for Rapid Liver Hypertrophy Before Major Hepatectomy: A Case Report

Liver venous deprivation (LVD) is an emerging, minimally invasive strategy to induce rapid liver hypertrophy of the future liver remnant (FLR) before a major hepatectomy. LVD (aka "double vein embolization") entails same-session percutaneous embolization of the portal and hepatic veins of the planned liver resection. This report discusses LVD's utilization and technical challenges in managing a 49-year-old male with recurrent multifocal colorectal liver metastases (CRLM). The patient initially underwent neoadjuvant FOLFOX chemotherapy followed by a simultaneous laparoscopic sigmoid colectomy and liver surgery (microwave ablation of segment V and wedge resections of segment one and IVb), followed by completion of chemotherapy. The patient had an R0 resection with clear colon and liver surgical margins. Nine months after the initial surgery, the patient had a rise in tumor markers, and surveillance imaging demonstrated recurrence of liver metastases in segments I and V. LVD was performed by interventional radiology, which led to a 28% increase in FLR (segments II, III, and IV); initially measuring 464 cm3 before LVD and measuring 594 cm3 on post-procedure day 21. The patient underwent right hemi-hepatectomy and caudate resection on post-procedure day 29. The patient did not have any complications and was discharged on postoperative day 6. The patient remains disease-free with no evidence of recurrence at 12 months follow-up.

Optimizing Growth of the Future Liver Remnant and Making In-Situ Liver Transsection Safe—A Standardized Approach to ISLT or ALPPS

In-situ splitting of the liver before extended resection has gained broad attention. This two-step procedure requires several measures to make an effective and safe procedure. Although the procedure is performed in many institutions, there is no consensus on a uniform technique. The two steps can be divided into different parts and a standardized technique may render the procedure safer and the results will be easier to evaluate. In this paper, we describe a detailed approach to in-situ splitting that allows making both procedures safe, avoids liver necrosis, and is easily reproducible. In the first procedure the portal branches to segments I and IV to VIII are divided, the arterial branches and bile ducts to these segments are preserved and encircled and the parenchyma between segments II/III and IVa/b is divided. This avoids necrosis and bile leaks of segments I and IV and avoids urgent completion operations. In particular, the handling of vital structures close to the dissection line seems important to us. Complete splitting and securing the right and middle hepatic vein will make the second step of this procedure a minimal-risk procedure at a stage where the patient is still recovering from the more demanding first step.

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

Purpose:

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

Methods:

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

Results:

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

Conclusion:

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

Survey of preoperative management protocol for perihilar cholangiocarcinoma at 10 Japanese high-volume centers with a combined experience of 2,778 cases

BACKGROUND

In Japan, strategies for preoperative management of perihilar cholangiocarcinoma (PHC) have evolved over the last decade; the operative mortality has significantly reduced to <5%.

METHODS

A questionnaire was sent to 10 institutions based on their case volume. Questionnaire was based on: (1) preoperative biliary drainage, (2) bile replacement, (3) role of synbiotics, (4) remnant liver volume enhancement, (5) predicted remnant liver function, (6) imaging, (7) nutrition, and (8) role of Inchinkoto.

RESULTS

The median case volume was 226 (range 105-889) cases, respectively. Eight institutions preferred endoscopic nasobiliary drainage and two preferred endoscopic biliary stenting for biliary drainage. Nine used bile replacement within 2-3 days of biliary drainage. Four used synbiotics preoperatively. The median cutoff value for future remnant liver volume and serum total bilirubin, at which portal vein embolization (PVE) is done, is <40% and <4 mg/dl. The median interval between PVE and surgery was 3-4 weeks. To predict remnant liver function, indocyanine green retention (n = 8) and clearance rate (n = 2) were mainly used. Five used Inchinkoto to improve liver function. Nine used multidetector computed tomography and direct cholangiography for surgical planning.

CONCLUSION

With appropriate preoperative management of PHC, surgical morbidity and mortality can be reduced. This survey can provide recommendations to improve PHC perioperative outcomes.

Hepatic hypertrophy and hemodynamics of portal venous flow after percutaneous transhepatic portal embolization

BACKGROUND

Percutaneous transhepatic portal embolization (PTPE) is useful for safe major hepatectomy. This study investigated the correlation between hepatic hypertrophy and hemodynamics of portal venous flow by ultrasound sonography after PTPE.

METHODS

We analyzed 58 patients with PTPE, excluding those who underwent recanalization (n = 10). Using CT volumetry results 2 weeks after PTPE, the patients were stratified into a considerable hypertrophy group (CH; n = 15) with an increase rate of remnant liver volume (IR-RLV) ≥ 40% and a minimal hypertrophy group (MH; n = 33) with an IR-RLV < 40%. We investigated the hemodynamics of portal venous flow after PTPE and the favorable factors for hepatic hypertrophy.

RESULTS

Univariate and multivariate analysis identified the indocyanine green retention rate at 15 min (ICGR15) and increase rate of portal venous flow volume (IR-pFV) at the non-embolized lobe on day 3 after PTPE as independent favorable factors of IR-RLV. Patients with IR-pFV on day 3 after PTPE ≥100% and ICGR15 ≤ 15% (n = 13) exhibited significantly increased IR-RLV compared with others (n = 35).

CONCLUSIONS

Cases with high IR-pFV on day 3 after PTPE exhibited better hepatic hypertrophy. Preserved liver function and increased portal venous flow on day 3 were important.

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

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

Improving Hepatocyte Engraftment Following Hepatocyte Transplantation Using Repeated Reversible Portal Vein Embolization in Rats

Hepatocyte transplantation (HT) has emerged as a promising alternative to orthotopic liver transplantation, yet liver preconditioning is needed to promote hepatocyte engraftment. A method of temporary occlusion of the portal flow called reversible portal vein embolization (RPVE) has been demonstrated to be an efficient method of liver preconditioning. By providing an additional regenerative stimulus, repeated reversible portal vein embolization (RRPVE) could further boost liver engraftment. The aim of this study was to determine the efficiency of liver engraftment of transplanted hepatocytes after RPVE and RRPVE in a rat model. Green fluorescent protein-expressing hepatocytes were isolated from transgenic rats and transplanted into 3 groups of syngeneic recipient rats. HT was associated with RPVE in group 1, with RRPVE in group 2, and with sham embolization in the sham group. Liver engraftment was assessed at day 28 after HT on liver samples after immunostaining. Procedures were well tolerated in all groups. RRPVE resulted in increased engraftment rate in total liver parenchyma compared with RPVE (3.4% ± 0.81% versus 1.4% ± 0.34%; P < 0.001). In conclusion, RRPVE successfully enhanced hepatocyte engraftment after HT and could be helpful in the frame of failure of HT due to low cell engraftment.

Alcohol injection into the portal vein prior to ligation increases liver regeneration rate

BACKGROUND

Failure of portal vein ligation (PVL) to induce hypertrophy is not uncommon. The aim of the study was to evaluate the impact of intraportal alcohol injection prior to ligation on liver regeneration.

METHOD

Forty-two patients with colorectal liver metastases who underwent PVL between 01/2004 and 06/2014 were analyzed. Beginning in 09/2011, alcohol was injected prior to PVL. Patients treated with PVL alone (Alc- group) were compared with those treated with alcohol injection plus PVL (Alc+ group). Liver regeneration was assessed by volumetric increase (VI).

RESULTS

Alc+ (23 patients) and Alc- (19 patients) groups were similar in terms of age, sex and pre-PVL FLRV. Alc- group had a higher risk of recanalization (12 vs. 1, p < 0.001) and cavernous transformation (7 vs. 2, p = 0.055) of the occluded portal vein. Post-PVL FLRV (43.3 ± 14.3% vs. 34.6 ± 6.4%, p = 0.013) and VI (0.44 ± 0.24 vs. 0.28 ± 0.20, p = 0.029) were higher in Alc+ group. On multivariate analysis male sex (B = -0.149) and alcohol injection (B = 0.143) significantly predicted VI.

CONCLUSIONS

Alcohol injection prior to PVL may increase the regeneration of the FLRV by reducing the recanalization of the occluded portal vein.

Update on Liver Failure Following Hepatic Resection: Strategies for Prediction and Avoidance of Post-operative Liver Insufficiency

Liver resection is increasingly used for a variety of benign and malignant conditions. Despite advances in preoperative selection, surgical technique and perioperative management, posthepatectomy liver failure (PHLF) is still a leading cause of morbidity and mortality following liver resection. Given the devastating physiological consequences of PHLF and the lack of effective treatment options, identifying risk factors and preventative strategies for PHLF is paramount. In the past, a major limitation to conducting high quality research on risk factors and prevention strategies for PHLF has been the absence of a standardized definition. In this article, we describe relevant definitions for PHLF, discuss risk factors and prediction models, and review advances in liver assessment tools and PHLF prevention strategies.

PERCUTANEOUS RADIOFREQUENCY ASSISTED LIVER PARTITION WITH PORTAL VEIN EMBOLIZATION FOR STAGED HEPATECTOMY (PRALPPS)

BACKGROUND

When a major hepatic resection is necessary, sometimes the future liver remnant is not enough to maintain sufficient liver function and patients are more likely to develop liver failure after surgery.

AIM

To test the hypothesis that performing a percutaneous radiofrecuency liver partition plus percutaneous portal vein embolization (PRALPPS) for stage hepatectomy in pigs is feasible.

METHODS

Four pigs (Sus scrofa domesticus) both sexes with weights between 25 to 35 kg underwent percutaneous portal vein embolization with coils of the left portal vein. By contrasted CT, the difference between the liver parenchyma corresponding to the embolized zone and the normal one was identified. Immediately, using the fusion of images between ultrasound and CT as a guide, radiofrequency needles were placed percutaneouslyand then ablated until the liver partition was complete. Finally, hepatectomy was completed with a laparoscopic approach.

RESULTS

All animals have survived the procedures, with no reported complications. The successful portal embolization process was confirmed both by portography and CT. In the macroscopic analysis of the pieces, the depth of the ablation was analyzed. The hepatic hilum was respected. On the other hand, the correct position of the embolization material on the left portal vein could be also observed.

CONCLUSION

"Percutaneous radiofrequency assisted liver partition with portal vein embolization" (PRALLPS) is a feasible procedure.

Rapid Liver Hypertrophy After Portal Vein Occlusion Correlates with the Degree of Collateralization Between Lobes-a Study in Pigs

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) induces more rapid liver growth than portal vein ligation (PVL). Transection of parenchyma in ALPPS may prevent the formation of collaterals between lobes. The aim of this study was to determine if abrogating the formation of collaterals through parenchymal transection impacted growth rate.

METHODS

Twelve Yorkshire Landrace pigs were randomized to undergo ALPPS, PVL, or "partial ALPPS" by varying degrees of parenchymal transection. Hepatic volume was measured after 7 days. Portal blood flow and pressure were measured. Portal vein collaterals were examined from epoxy casts.

RESULTS

PVL, ALPPS, and partial ALPPS led to volume increases of the RLL by 15.5% (range 3-22), 64% (range 45-76), and 32% (range 18-77), respectively, with significant differences between PVL and ALPPS/partial ALPPS (p < 0.05). In PVL and partial ALPPS, substantial new portal vein collaterals were found. The number of collaterals correlated inversely with the growth rate (p = 0.039). Portal vein pressure was elevated in all models after ligation suggesting hyperflow to the portal vein-supplied lobe (p < 0.05).

CONCLUSIONS

These data suggest that liver hypertrophy following PVL is inversely proportional to the development of collaterals. Hypertrophy after ALPPS is likely more rapid due to reduction of collaterals through transection.

Hammer versus Swiss Army knife: Developing a strategy for the management of bilobar colorectal liver metastases

For patients with bilobar colorectal liver metastases, the recent increase in surgical approaches has resulted in more opportunities to extend the benefits of surgery to patients who were previously deemed unresectable. Surgical options now include anatomic hepatectomy, 1-stage parenchymal sparing hepatectomy, traditional 2-stage hepatectomy with or without portal vein embolization, associated liver partition and portal vein ligation for staged hepatectomy, local ablative techniques, and hepatic arterial infusion therapy. As the diversity of options has increased, controversy has arisen as to the optimal operative management of patients with complex bilateral disease. Moreover, there has been a tendency for various surgeons and groups to champion a single strategy. In contrast to this trend, this article introduces a novel "tailored approach" that takes advantage of all available tools and individually applies them based on an algorithmic assessment of the extent and distribution of metastatic disease.

Identification of cofactors influencing hypertrophy of the future liver remnant after portal vein embolization-the effect of collaterals on embolized liver volume

OBJECTIVE

The purpose of this retrospective study was to monitor hypertrophy of future liver remnant following portal vein embolization (PVE) before planned extended right hepatectomy. However, because individual responses to PVE are highly variable, our focus was to identify cofactors of successful hypertrophy.

METHODS

28 patients with primary or secondary liver tumours, mean age 64.1 ± 12.9 years, underwent PVE. Volumetric analysis of hypertrophy before and after PVE (median 39.0 ± 15.7 days) was performed. The embolized liver segments were investigated for occurrence of reperfusion of their portal branches. Blood parameters before PVE were additionally investigated.

RESULTS

Patients were divided into responders (21/28) and non-responders (7/28) by post-PVE standardized future liver remnant being above or below 25%, respectively. No significant differences between the groups were found regarding biometric and volumetric parameters before PVE. In the entire group after PVE, the mean absolute increase of Segments 2 and 3 was 196.0 ± 84.7 cm³ and the median relative increase was 46.6 ± 98.8%. The formation of left to right hepatic portoportal collaterals exhibited a negative correlation to successful hypertrophy (p = 0.004) as well as low plasma total protein (p = 0.019). Successful embolization of Segment IV showed only a trend to significance (p = 0.098).

CONCLUSION

Cofactors associated with a favourable outcome regarding hypertrophy were the absence of collaterals in the control CT scans and high plasma total protein. Advances in knowledge: Portoportal collaterals negatively influence hypertrophy after PVE. On the other hand, plasma total protein is a positive prognostic indicator on hypertrophy of the liver in our cohort.

Meta-analysis of associating liver partition with portal vein ligation and portal vein occlusion for two-stage hepatectomy

BACKGROUND

Discussion is ongoing regarding whether associating liver partition with portal vein ligation for staged hepatectomy (ALPPS) or portal vein occlusion is better in staged hepatectomy. The aim of this study was to compare available strategies using a two-stage approach in extended hepatectomy.

METHODS

A literature search was performed in MEDLINE, Scopus, the Cochrane Library and Embase, and additional articles were identified by hand searching. Data from the international ALPPS registry were extracted. Clinical studies reporting volumetric changes, mortality, morbidity, feasibility of the second stage and tumour-free resection margins (R0) in two-stage hepatectomy were included.

RESULTS

Ninety studies involving 4352 patients, including 320 from the ALPPS registry, met the inclusion criteria. Among these, nine studies (357 patients) reported on comparisons with other strategies. In the comparison of ALPPS versus portal vein embolization (PVE), ALPPS was associated with a greater increase in the future liver remnant (76 versus 37 per cent; P < 0·001) and more frequent completion of stage 2 (100 versus 77 per cent; P < 0·001). Compared with PVE, ALPPS had a trend towards higher morbidity (73 versus 59 per cent; P = 0·16) and mortality (14 versus 7 per cent; P = 0·19) after stage 2. In the non-comparative studies, complication rates were 39 per cent in the PVE group, 47 per cent in the portal vein ligation (PVL) group and 70 per cent in the ALPPS group. After stage 2, mortality rates were 5, 7 and 12 per cent respectively.

CONCLUSION

ALPPS is associated with greater future liver remnant hypertrophy and a higher rate of completion of stage 2, but this may be at the price of greater morbidity and mortality.

Mechanistic insights of rapid liver regeneration after associating liver partition and portal vein ligation for stage hepatectomy

AIM

To highlight the potential mechanisms of regeneration in the Associating Liver Partition and Portal vein ligation for Stage hepatectomy models (clinical and experimental) that could unlock the myth behind the extraordinary capability of the liver for regeneration, which would help in designing new therapeutic options for the regenerative drive in difficult setup, such as chronic liver diseases. Associating Liver Partition and Portal vein ligation for Stage hepatectomy has been recently advocated to induce rapid future liver remnant hypertrophy that significantly shortens the time for the second stage hepatectomy. The introduction of Associating Liver Partition and Portal vein ligation for Stage hepatectomy in the surgical armamentarium of therapeutic tools for liver surgeons represented a real breakthrough in the history of liver surgery.

METHODS

A comprehensive literature review of Associating Liver Partition and Portal vein ligation for Stage hepatectomy and its utility in liver regeneration is performed.

RESULTS

Liver regeneration after Associating Liver Partition and Portal vein ligation for Stage hepatectomy is a combination of portal flow changes and parenchymal transection that generate a systematic response inducing hepatocyte proliferation and remodeling.

CONCLUSION

Associating Liver Partition and Portal vein ligation for Stage hepatectomy represents a real breakthrough in the history of liver surgery because it offers rapid liver regeneration potential that facilitate resection of liver tumors that were previously though unresectable. The jury is still out though in terms of safety, efficacy and oncological outcomes. As far as Associating Liver Partition and Portal vein ligation for Stage hepatectomy -induced liver regeneration is concerned, further research on the field should focus on the role of non-parenchymal cells in liver regeneration as well as on the effect of Associating Liver Partition and Portal vein ligation for Stage hepatectomy in liver regeneration in the setup of parenchymal liver disease.

Limits of and Complications after Embolization of the Hepatic Artery and Portal Vein to Induce Segmental Hypertrophy of the Liver: A Large Mini-Pig Study

Background: The aim of this study was to compare arterial embolization (AE) with portal vein embolization (PVE) for the induction of segmental hypertrophy regarding procedural efficacy, safety and outcome. Methods: A total of 29 mini pigs were subjected to PVE, AE or assigned to the sham (SO) group. Correspondingly, 75% of the hepatic artery or portal vein branches were embolized. Growth and atrophy of the liver lobes, calculating the liver-to-body weight index (LBWI), laboratory data, arteriography, portography, Doppler ultrasound (US) and histopathology were analyzed. Results: After PVE, 2 animals had to be excluded due to technical problems. After AE, 4 animals had to be excluded because of technical problems and early sacrifice. Postprocedural US demonstrated effective AE and PVE of the respective lobes. Four weeks after PVE, portography showed a slow refilling of the embolized lobe by collateral portal venous vessels. Four weeks after AE, arteriography revealed a slight revascularization of the embolized lobes by arterial neovascularization. Segmental AE led to extensive necrotic and inflammatory alterations in the liver and bile duct parenchyma. Significant hypertrophy of the non-embolized lobe was only noted in the PVE group (LBWI: 0.91 ± 0.28%; p = 0.001). There was no increase in the non-embolized lobe in the AE (LBWI: 0.45 ± 0.087%) and SO group (LBWI: 0.45 ± 0.13%). Conclusion: PVE is safe and effective to induce segmental hypertrophy. Portal reperfusion by collateral vessels may limit hypertrophy. AE did not increase the segmental hepatic volume but carries the risk of extensive necrotic inflammatory damage.

Development of Collateral Pathways in Tumor Obstruction of Confluence of the Hepatic Veins: Neither Fortuitous nor Innocuous

BACKGROUND

Except in Budd-Chiari syndrome, alternative drainage pathways have been described rarely. The aim was to describe the alternative collaterals pathways due to tumor hepatic vein (HV) confluence obstruction and its impact in the setting of liver resection.

STUDY DESIGN

Between 2006 and 2014, preoperative CT scans of 41 patients resected for malignant tumor(s) compressing the HV confluence were assessed for the presence of accessory veins and collateral veins. A 2:1 matched control group was used for comparison of intraoperative outcomes.

RESULTS

Intrahepatic collaterals were observed in 28 (68%) patients, mostly between segments 3/4b and 5/4b, and subcapsular collaterals were observed in 12 (29%) patients. Patients with isolated right HV obstruction and with an accessory right HV present had fewer collateral pathways develop than patients without (6 of 10 patients [60%] vs 18 of 19 [95%]; p = 0.036). Segment 1 hypertrophy was present in only 6 (15%) patients. Compared with the control group, there was a significant increase in blood loss (900 mL [range 100 to 3,500 mL] vs 500 mL [range 100 to 2,600 mL]; p < 0.001), transfusion requirements (71% vs 15%; p < 0.001), and vascular clamping (hepatic pedicle: 85% vs 72%; p < 0.001, inferior vena cava: 41% vs 11%; p < 0.001) in case of HV obstruction.

CONCLUSIONS

Development of collateral pathways is not fortuitous and depends on the number of HVs involved and pre-existing accessory veins. The increased blood loss observed in patients with collaterals leads to consider specific vascular clamping.

[Contralateral hepatic hypertrophy following unilateral yttrium-90 radioembolization : Implications for liver surgery]

BACKGROUND

Preservation of an adequate future liver remnant (FLR) is the principal limitation to liver surgery in patients with primary or secondary liver malignancies. Hence, methods to increase the volume of the FLR in preparation for liver resection are gaining in importance.

OBJECTIVE

In addition to the traditional methods for induction of FLR hypertrophy, such as portal vein embolization (PVE) or portal vein ligation (PVL) with or without parenchymal dissection (ALPPS, in situ split), radioembolization (RE) using yttrium-90 microspheres also leads to a volume increase of non-embolized liver parenchyma. This review outlines its potential role as an alternative procedure for induction of liver hypertrophy.

MATERIAL AND METHODS

Synopsis and critical discussion of the available literature on the mechanisms of induction of liver hypertrophy, the advantages and drawbacks of the traditional methods, and current research on volume changes associated with RE as well as their implications for possible clinical use in preparation for liver surgery.

RESULTS

Both PVE and PVL can achieve a substantial contralateral volume gain of up to 70 %. The development of contralateral hypertrophy can be accelerated by dissecting the liver parenchyma along the intended plane of resection in addition to PVL (in situ split). Compared to these methods, RE achieves less contralateral liver hypertrophy; however, this effect should not be disregarded as RE provides effective treatment of ipsilateral liver tumors along with induction of hypertrophy and may be associated with a reduced risk of tumor progression compared to PVE and PVL.

CONCLUSION

The available data suggest that RE can complement the armamentarium of methods for induction of FLR hypertrophy in specific situations. Further studies are needed to establish its definitive role for this indication and are in preparation.

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

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

Characterization of a porcine model for associating liver partition and portal vein ligation for a staged hepatectomy

BACKGROUND

Publications using the ALPPS (associating liver partition and portal vein ligation for a staged hepatectomy) procedure have demonstrated a future liver remnant growth of 40-160% in only 6-9 days. The present study aimed to develop and describe the first large animal model of ALPPS that can be used for future studies.

METHODS

A total of 13 female domestic pigs underwent ALPPS stage 1 (portal vein division and parenchymal transection) followed by ALPPS stage 2 (completion left-extended hepatectomy) 7 days later. An abdominal computed tomography (CT) scan was performed immediately prior to ALPPS stage 1 surgery and again 7 days later to assess hypertrophy immediately prior to ALPPS stage 2 surgery. Blood samples, as well as tissue analysis for Ki-67, were performed.

RESULTS

On CT volumetric analysis, the mean size of the future liver remnant (FLR) prior to ALPPS stage 1 was 21 ± 2% and 40 ± 6% prior to ALPPS stage 2. The median degree of growth was 75% with a mean kinetic growth rate of 11% per day. Liver weights at autopsy correlated well with CT volumetric analysis (r = 0.87). There was no significant difference in mean lab values [asparate aminotransferase (AST), alanine aminotransferase (ALT), ammonia, International Normalized Ratio (INR) or bilirubin] from baseline until immediately prior to ALPPS stage 2. Post ALPPS stage 2 there was a significant increase in INR from baseline 1.1 to 1.6 (P = 0.012). No post-operative deaths secondary to liver failure were observed.

CONCLUSION

The present study describes the first reproducible large animal model of the ALPPS procedure. The degree of liver growth and the kinetic rate of growth were similar to that which has been demonstrated in human publications. This model will be valuable as future laboratory studies are performed.

Staged resection of bilobar colorectal liver metastases: surgical strategies

BACKGROUND

Radical resection is the treatment of choice for colorectal liver metastases (CLM). Unfortunately, only about 20 % of patients present with initially resectable disease, in most cases due to bilobar disease. In the last two decades, major achievements have been made to extend surgical indications to patients with bilobar CLM, such as two-stage hepatectomy with or without portal vein occlusion and associating liver partition and portal vein ligation for staged hepatectomy (ALPPS).

PURPOSE

The purpose of this review article was to summarize current surgical approaches and their safety and efficacy for patients with initially unresectable bilobar CLM.

CONCLUSION

In selected patients, two-stage hepatectomy and ALPPS are efficient and safe to convert unresectable to resectable CLM. Further studies are required to evaluate long-term outcome of these procedures.

Is the liver kinetic growth rate in ALPPS unprecedented when compared with PVE and living donor liver transplant? A multicentre analysis

BACKGROUND

The clinical perspective on hepatic growth is limited. The goal of the present study was to compare hepatic hypertrophy and the kinetic growth rate(KGR) in patients after the ALPPS (Associating Liver Partition with Portal Vein Ligation for Staged Hepatectomy) procedure, portal vein embolization (PVE) and living donor liver transplantation.

METHODS

Volumetry and KGR of the future liver remnant (FLR) were compared from (15) patients undergoing ALPPS, (53) patients undergoing PVE, (90) recipients of living donor liver grafts and (93) donors of living donor liver grafts.

RESULTS

The degree of hypertrophy was significantly greater after ALPPS (84.3 ± 7.8%) than after PVE (36.0 ± 27.2%) (P < 0.001). The KGR was also significantly greater for ALPPS [32.7 ± 13.6 cubic centimetres (cc)/day] (10.8 ± 4.5%/day) compared with PVE (4.4 ± 3.2 cc/day) (0.98 ± 0.75%/day) (P < 0.001). The FLR of living donor donors had the greatest degree of hypertrophy (107.5 ± 39.2%) and was greater than after ALPPS (P = 0.02), PVE (P < 0.001) and in living donor-recipient grafts (P < 0.001). KGR (cc/day) was greater in FLR of living donor donors compared with both ALPPS (P < 0.001) and PVE (P < 0.001). The KGR in patients undergoing ALPPS and living donor liver transplantation had a linear relationship with the size of FLR.

CONCLUSION

FLR hypertrophy and KGR were greater after ALPPS than PVE. However, the degree of hypertrophy after ALPPS is not unprecedented, as KGR in the FLR from living donor donors is equal to or greater than after ALPPS. The KGR of the FLR in patients after ALPPS and living donor donors correlates directly with the size of the FLR.

Triggered liver regeneration: from experimental model to clinical implications

BACKGROUND

Major liver resection is the only therapeutic option for patients with malignant liver tumors. However, extended hepatectomy often leads to postoperative liver failure, mainly due to insufficient amounts of the remnant liver. Recently, selective portal vein occlusion (PVO) has been introduced to increase the remnant liver volume. This novel surgical technique initiated a progressive development in liver surgery, resulting in a significant increment in potential candidates for curative liver resection.

SUMMARY

The theoretical basis for this great advancement is formed by an understanding of the mechanisms of PVO-induced liver regeneration, mainly obtained from animal studies. The aim of this review is to give a comprehensive overview of the relevant animal models of PVO and to discuss the main characteristics of triggered liver regeneration, including the induced hemodynamic, morphological and functional alterations as well as the underlying molecular mechanisms, which might be of interest in both the laboratory and the clinic. Key Messages: Although basic research revealed the main characteristics of PVO-triggered liver regeneration within the last decades, several important issues regarding the regenerative process remain uncertain. To answer these open questions, additional well-designed animal experiments are needed in the future, which allow further refinement of this surgical technique.

ALPPS: challenging the concept of unresectability--a systematic review

INTRODUCTION

Hepatic resection for malignancy is limited by the amount of liver parenchyma left behind. As a result, two-staged hepatectomy and portal vein occlusion (PVO) have become part of the treatment algorithm. Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been recently described as a method to stimulate rapid and profound hypertrophy.

MATERIALS AND METHODS

A systematic review of the literature pertaining to ALPPS was undertaken. Peer-reviewed articles relating to portal vein ligation (PVL) and in situ split (ISS) of the parenchyma were included.

RESULTS

To date, ALPPS has been employed for a variety of primary and metastatic liver tumors. In early case series, the perioperative morbidity and mortality was unacceptably high. However with careful patient selection and improved technique, many centers have reported a 0% 90-day mortality. The benefits of ALPPS include hypertrophy of 61-93% over a median 9-14 days, 95-100% completion of the second stage, and high likelihood of R0 resection (86-100%).

DISCUSSION

ALPPS is only indicated when a two-stage hepatectomy is necessary and the future liver remnant (FLR) is deemed inadequate (<30%). Use in patients with poor functional status, or advanced age (>70 years) is cautioned. Discretion should be used when considering this in patients with pathology other than colorectal liver metastases (CRLM), especially hilar tumors requiring biliary reconstruction. Biliary ligation during the first stage and routine lymphadenectomy of the hepatoduodenal ligament should be avoided.

CONCLUSIONS

A consensus on the indications and contraindications for ALPPS and a standardized operative protocol are needed.

Rodent models and imaging techniques to study liver regeneration

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

A review of animal models for portal vein embolization

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Current position of ALPPS in the surgical landscape of CRLM treatment proposals

The Authors summarize problems, criticisms but also advantages and indications regarding the recent surgical proposal of associating liver partition and portal vein ligation (PVL) for staged hepatectomy (ALPPS) for the surgical management of colorectal liver metastases. Looking at published data, the technique, when compared with other traditional and well established methods such as PVL/portal vein embolisation (PVE), seems to give real advantages in terms of volumetric gain of future liver remnant. However, major concerns are raised in the literature and some questions remain unanswered, preliminary experiences seem to be promising. The method has been adopted all over the world over the last 2 years, even if oncological long-term results remain unknown, and benefit for patients is questionable. No prospective studies comparing traditional methods (PVE, PVL or classical 2 staged hepatectomy) with ALPPS are available to date. Technical reinterpretations of the original method were also proposed in order to enhance feasability and increase safety of the technique. More data about morbidity and mortality are also expected. The real role of ALPPS is, to date, still to be established. Large clinical studies, even if, for ethical reasons, in well selected cohorts of patients, are expected to better define the indications for this new surgical strategy.

Impact of mesocaval shunt on safe minimal liver remnant: Porcine model

AIM: To investigate the capacity of shunts to relieve portal hypertension and decrease the safe minimal liver remnant in pigs.

METHODS: A subtotal hepatectomy with < 60 mL blood loss and without hepatic pedicle occlusion was performed. The mesenteric venous inflow was diverted through a mesocaval shunt (MCS) constructed using the prepared left renal vein with an end-to-side running suture of 5-0 proline. All 21 animals that underwent subtotal hepatectomy and/or MCS were divided into three groups. In the 15% group, the residual volume was 14%-19% of total liver volume (TLV); in the 15%+ S group, the residual volume was also 14%-19% of TLV with a mesocaval shunt (MCS); and in the 10%+ S group, the residual volume was 8%-13% of TLV with an MCS. In the three groups, the intraoperative portal vein pressure (PVP) and portal vein flow (PVF) were monitored and compared at laparotomy and 1 h post-hepatectomy. The survival rate, sinusoidal endothelial damage, tissue analysis, and serum analysis were investigated among the three groups.

RESULTS: The percentage residual liver volume was 15.9%, 16.1% and 11.8% in the 15%, 15%+ S, 10%+ S groups, respectively. After hepatectomy, PVF and portal-to-arterial flow ratio in the 15%+ S group significantly decreased and hepatic artery flow (HAF) per unit volume significantly increased, compared to those in the 15% group. The PVP in the 15%+ S group and 10%+ S group increased slightly from that measured at laparotomy; however, in the 15% group, the PVP increased immediately and significantly above that observed in the other two groups. The 14-d survival rates were 28.5%, 85.6%, and 14.2% in the 15%, 15%+ S, and 10%+ S groups, respectively. In the 15%+ S group, the shunts effectively attenuated injury to the sinusoidal endothelium, and the changes in the serum and tissue analysis results were significantly reduced compared to those in the 15% and 10%+ S groups.

CONCLUSION: MCS can decompress the portal vein and so attenuate liver injury from hyperperfusion, and make extreme or marginal hepatectomy safer.

Tumour progression and liver regeneration--insights from animal models

Surgery remains the only curative treatment for colorectal liver metastases. For patients with multiple bilobar spread, extended hepatectomy might be required to achieve complete margin-free resection. In such cases, portal vein occlusion has been developed to induce preoperative hypertrophy of the future remnant liver and increase the resectability rate. Evidence now suggests that liver regeneration after hepatectomy and portal vein occlusion has a protumorigenic role, either through an upregulation of growth factors and cytokines or by haemodynamic changes in the blood supply to the liver. Experimental studies have reported a stimulatory effect of liver regeneration on the tumoral volume of liver metastases and on the metastatic potential of cells engrafted in the liver; this effect seems to depend on the timing of hepatectomy and portal vein occlusion. However, the variability of animal tumour models that are used for research in experimental colorectal liver metastases might account for some of the inconsistent and conflicting results. This Review presents clinical and experimental data pertaining to whether liver regeneration causes proliferation of tumour cells. We also analyse the different animal models of colorectal liver metastases in use and discuss current controversies in the field.

The ALPPS technique for bilateral colorectal metastases: three "variations on a theme"

The aim of this study was to assess feasibility of technical variations of the associating liver partition and portal vein ligation for staged hepatectomy technique (ALPPS) with regard to three different ways of liver splitting. The ALPPS technique was applied in the classic form consisting in ligation of the right portal vein, limited resections on the left lobe and splitting along the umbilical fissure; the right lobe was removed 1 week later. The first variation was "left ALPPS": ligation of the left portal vein, multiple resections on the right hemiliver and splitting along the main portal fissure. The second variation was "rescue ALPPS", consisting in simple splitting of the liver along the main portal fissure several months after a radiological portal vein embolization that did not allow satisfactory liver hypertrophy. The third variation was "right ALPPS", consisting in ligation of the posterolateral branch of right portal vein, left lateral sectionectomy, multiple resections on the right anterior and left medial section and splitting along the right portal fissure. In all cases auxiliary deportalized liver was removed 1 week later. 4 patients with colorectal metastases were included. Morbidity was defined according to the Clavien-Dindo classification: grade I (2 events), grade IIIb (1 event). Postoperative mortality was nil. Median follow-up was 4 months and to date all patients are still alive. ALPPS technique, in its "classical" and modified forms, is a good option for selected patients with bilateral colorectal metastases and represents a feasible alternative to classical two-stage hepatectomy.

Autologous bone marrow-derived mesenchymal stem cell transplantation promotes liver regeneration after portal vein embolization in cirrhotic rats

BACKGROUND

Preexisting cirrhosis usually leads to an inadequate and delayed regeneration of the future liver remnant (FLR) after portal vein embolization (PVE). Bone marrow-derived mesenchymal stem cells (BMSC) are promising candidates for therapeutic applications in liver diseases. In this study, the efficacy of autologous BMSCs transplantation to promote FLR regeneration was investigated in a rat cirrhotic model.

METHODS

Autologous BMSCs were expanded and labeled with PKH26, and then were injected immediately into nonembolized lobes after PVE through portal vein in cirrhotic rat. At 7, 14, and 28 d after this, liver weight and Ki-67 labeling index were measured, and blood analysis was performed. Cirrhotic degree of FLR was assessed by hydroxyproline content assay and histopathology. Gene expressions of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), interleukin-10 (IL-10), and matrix metalloproteinase-9 (MMP-9) were detected with real-time reverse transcriptase-polymerase chain reaction. Distribution and hepatocyte differentiation of BMSCs in FLR were determined by confocal microscopy.

RESULTS

Autologous BMSCs significantly increased the FLR weight ratio to the total liver and the Ki-67 labeling index, and serum albumin levels were significantly higher and total bilirubin levels were significantly lower in the BMSCs group compared with the controls without BMSCs transplantation 14 and 28 d post-PVE. BMSCs significantly decreased the hydroxyproline content and collagen accumulation, up-regulated the expressions of HGF, IL-10, VEGF, and MMP-9 28 d post-PVE, and expressed hepatocyte-specific markers, such as α-fetoprotein, cytokeratin 18, and albumin in a time-dependent manner in FLR.

CONCLUSIONS

Autologous BMSCs can differentiate into hepatocyte and promote FLR regeneration after PVE in cirrhotic liver, which may be through improving local microenvironment by decreasing cirrhosis, up-regulating the gene expressions of VEGF, HGF, IL-10, and MMP-9.

Intrahepatic left to right portoportal venous collateral vascular formation in patients undergoing right portal vein ligation

PURPOSE

We investigated intrahepatic vascular changes in patients undergoing right portal vein ligation (PVL) or portal vein embolization (PVE) in conjunction with the ensuing hypertrophic response and function of the left liver lobe.

METHODS

Between December 2008 and October 2011, 7 patients underwent right PVL and 14 patients PVE. Computed tomographic (CT) volumetry to assess future remnant liver (FRL) and functional hepatobiliary scintigraphy were performed in all patients before and 3 weeks after portal vein occlusion. In 18 patients an intraoperative portography was performed to assess perfusion through the occluded portal branches.

RESULTS

In all patients after initially successful PVL, reperfused portal veins were observed on CT scan 3 weeks after portal occlusion. This was confirmed in all cases during intraoperative portography. Intrahepatic portoportal collaterals were identified in all patients in the PVL group and in one patient in the PVE group. In all other PVE patients, complete occlusion of the embolized portal branches was observed on CT scan and on intraoperative portography. The median increase of FRL volume after PVE was 41.6 % (range 10-305 %), and after PVL was only 8.1 % (range 0-102 %) (p = 0.179). There were no differences in FRL function between both groups.

CONCLUSION

Preoperative PVE and PVL are both methods to induce hypertrophy of the FRL in anticipation of major liver resection. Compared to PVE, PVL seems less efficient in inducing hypertrophy of the nonoccluded left lobe. This could be caused by the formation of intrahepatic portoportal neocollateral vessels, through which the ligated portal branches are reperfused within 3 weeks.

Surgical options for initially unresectable colorectal liver metastases

Although the frontiers of liver resection for colorectal liver metastases have broadened in recent decades, approximately 75% of these patients present with unresectable metastases at the time of their diagnosis. In the past, these patients underwent only palliative treatment, without the chance of a cure. In the previous two decades, several therapeutic strategies have been developed that render resectable those metastases that were initially unresectable, thus offering the chance of long-term survival and even a cure to these patients. The oncosurgical modalities that are available include liver resection following portal vein ligation/embolization, “two-stage” liver resection, one-stage ultrasonically guided liver resection, hepatectomy following conversion chemotherapy, and liver resection combined with thermal ablation. Moreover, in recent years, certain authors have recommended the revisiting of the concept of liver transplantation in highly selected patients with unresectable colorectal liver metastases and favorable prognostic factors. By employing such therapies, the number of patients with colorectal liver metastases who undergo a potentially curative treatment could increase to 40%. The safety profile of these approaches is acceptable (morbidity rates as high as 45%, mortality rates of less than 5%). Furthermore, the 5-year survival rates (approximately 30%) are significantly increased over those that were achieved with palliative treatment.

Is there new hope for patients with marginally resectable liver malignancies

Advances in surgical technique and better perioperative management have significantly improved patient outcomes after liver surgery. Even major hepatectomy can be performed safely with low morbidity and mortality. Post-resection liver failure is among the most feared complications after extended hepatectomy. In order to increase the future liver remnant (FLR) and to expand the pool of candidates for surgical resection, Schnitzbauer et al recently presented a new 2-stage surgical approach which combines right portal vein ligation (rPVL) with in situ splitting (ISS) of the liver parenchyma. In comparison to other current strategies, such as interventional portal vein embolization, hypertrophy of the FLR was more pronounced (median volume increase = 74%; range: 21%-192%) and more rapid (after a median of 9 d; range: 5-28 d) after rPVL and ISS. In this commentary, we discuss the technical aspects and clinical impact of rPVL combined with ISS. Based on the reported data, this new 2-stage therapeutic approach represents a promising new strategy for patients with locally advanced liver disease, previously regarded as marginally resectable or even unresectable, potentially enabling curative resection. However, morbidity is significant and mortality not negligible.

Preoperative percutaneous transhepatic portal vein embolization with ethanol injection

OBJECTIVE

The purpose of this article is to evaluate the feasibility and efficacy of preoperative percutaneous transhepatic portal vein embolization with ethanol injection.

MATERIALS AND METHODS

We retrospectively evaluated 143 patients who underwent percutaneous transhepatic portal vein embolization. Hypertrophy of the future liver remnant was assessed by comparing the volumetric data obtained from CT image data before and after percutaneous transhepatic portal vein embolization. The evaluation of effectiveness was based on changes in the absolute volume of the future liver remnant and the ratio of the future liver remnant to the total estimated liver volume.

RESULTS

Ten of 143 patients (7.0%) underwent additional embolization because of recanalization and insufficient hypertrophy of the future liver remnant. The mean increase in the ratio of the future liver remnant was 33.6% (p < 0.0001), and the mean ratio of future liver remnant to total estimated liver volume increased from 34.9% to 45.7% (p < 0.0001). Although most of the patients complained of pain after ethanol injection, they were gradually relieved of pain in a few minutes by conservative treatment. Fever (38-39°C) was reported after 47 of 151 (31.1%) percutaneous transhepatic portal vein embolization sessions and was resolved within a few days. Transient elevation of the liver transaminases was observed after the procedures and resolved within about a week. Major complications occurred in nine of 151 (6%) percutaneous transhepatic portal vein embolization sessions, but no patients developed hepatic insufficiency or severe complications precluding successful resection. One hundred twenty patients underwent hepatic resection, and two patients developed hepatic failure after surgery.

CONCLUSION

Preoperative percutaneous transhepatic portal vein embolization with ethanol is a feasible and effective procedure to obtain hypertrophy of the future liver remnant for preventing hepatic failure after hepatectomy.

Improved Hepatocyte Engraftment After Portal Vein Occlusion in LDL Receptor-Deficient WHHL Rabbits and Lentiviral-Mediated Phenotypic Correction In Vitro

Innovative cell-based therapies are considered as alternatives to liver transplantation. Recent progress in lentivirus-mediated hepatocyte transduction has renewed interest in cell therapy for the treatment of inherited liver diseases. However, hepatocyte transplantation is still hampered by inefficient hepatocyte engraftment. We previously showed that partial portal vein embolization (PVE) improved hepatocyte engraftment in a nonhuman primate model. We developed here an ex vivo approach based on PVE and lentiviral-mediated transduction of hepatocytes from normal (New Zealand White, NZW) and Watanabe heritable hyperlipidemic (WHHL) rabbits: the large animal model of familial hypercholesterolemia type IIa (FH). FH is a life-threatening human inherited autosomal disease caused by a mutation in the low-density lipoprotein receptor (LDLR) gene, which leads to severe hypercholesterolemia and premature coronary heart disease. Rabbit hepatocytes were isolated from the resected left liver lobe, and the portal branches of the median lobes were embolized with Histoacryl® glue under radiologic guidance. NZW and WHHL hepatocytes were each labeled with Hoechst dye or transduced with lentivirus expressing GFP under the control of a liver-specific promoter (mTTR, a modified murine transthyretin promoter) and were then immediately transplanted back into donor animals. In our conditions, 65-70% of the NZW and WHHL hepatocytes were transduced. Liver repopulation after transplantation with the Hoechst-labeled hepatocytes was 3.5 ± 2%. It was 1.4 ± 0.6% after transplantation with either the transduced NZW hepatocytes or the transduced WHHL hepatocytes, which was close to that obtained with Hoechst-labeled cells, given the mean transduction efficacy. Transgene expression persisted for at least 8 weeks posttransplantation. Transduction of WHHL hepatocytes with an LDLR-encoding vector resulted in phenotypic correction in vitro as assessed by internalization of fluorescent LDL ligands. In conclusion, our results have applications for the treatment of inherited metabolic liver diseases, such as FH, by transplantation of lentivirally transduced hepatocytes.

Liver hypertrophy and accelerated growth of implanted tumors in nonembolized liver of rabbit after left portal vein embolization

BACKGROUND

Portal vein embolization (PVE) has become a standard preoperative procedure to promote hypertrophy of the future remnant liver to reduce postoperative liver failure. Whether PVE accelerates tumor growth is still controversial. We developed a left PVE procedure and investigated its effect on liver hypertrophy and tumor growth in a rabbit liver tumor model.

MATERIALS AND METHODS

VX2 tumors were implanted in both the external left and right middle lobe (the bilateral group) or in the external left lobe only (the unilateral group) of rabbit liver. Both groups were further divided into a PVE or a sham/control group. Tumor volume and tumor growth rate as volume relative increase were determined by ultrasound. Liver volume-to-body weight index, an index for liver volume, was compared. Serum HGF was measured by ELISA.

RESULTS

In the bilateral PVE group, tumor volume and relative increase value in the nonembolized lobe were significantly (71% and 65%, respectively) greater than those in the control group at 5 d post-PVE. In the unilateral PVE group, liver volume-to-body weight index of the nonembolized lobes was significantly increased by 17%. Increase of serum HGF level after PVE was correlated well with both tumor growth and liver hypertrophy.

CONCLUSIONS

Left PVE promoted both the growth of implanted tumors and liver hypertrophy in the nonembolized liver, in which serum HGF might play an important role.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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