Selective portal vein embolization and ligation trigger different regenerative responses in the rat liver

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 regeneration after portal vein embolization: comparison between absolute ethanol and N-butyl-cyanoacrylate in an in vivo rat model

PURPOSE

To compare the effects of absolute ethanol (ethanol) and N-butyl-cyanoacrylate (NBCA) on non-embolized liver lobe regeneration in a rat model.

METHODS

Twenty-seven Sprague-Dawley rats underwent portal vein embolization (PVE) using ethanol:lipiodol, 1:1 (ethanol group, n = 11, 40.74%), NBCA:lipiodol, 1:1 (NBCA group, n = 11, 40.74%), or sham treatment (sham group, n = 5, 18.52%). The non-embolized and embolized lobe-to-whole liver weight ratios 14 days after PVE were compared among the groups (n = 5, 18.52%). The expressions of CD68 and Ki-67 and embolized-lobe necrotic area percentages one day after PVE were compared between the ethanol (n = 3, 11.11%) and NBCA (n = 3, 11.11%) groups.

RESULTS

The non-embolized lobe-to-whole liver weight ratio after PVE was significantly higher in the NBCA group (n = 5, 33.33%) than in the ethanol group (n = 5, 33.33%) (84.28% ± 1.53% vs. 76.88% ± 4.12%, P = 0.029). The embolized lobe-to-whole liver weight ratio after PVE was significantly lower in the NBCA group than in the ethanol group (15.72% ± 1.53% vs. 23.12% ± 4.12%, P = 0.029). The proportions of CD68- and Ki-67-positive cells in the non-embolized lobe after PVE were significantly higher in the NBCA group (n = 30, 50%) than in the ethanol group (n = 30, 50%) [60 (48-79) vs. 55 (37-70), P = 0.003; 1 (0-2) vs. 1 (0-2), P = 0.004]. The embolized-lobe necrotic area percentage after PVE was significantly larger in the NBCA group (n = 30, 50%) than in the ethanol group (n = 30, 50%) [29.46 (12.56-83.90%) vs. 16.34 (3.22-32.0%), P < 0.001].

CONCLUSION

PVE with NBCA induced a larger necrotic area in the embolized lobe and promoted greater non-embolized liver lobe regeneration compared with PVE with ethanol.

A prospective study of sequential hepatic vein embolization after portal vein embolization in patients scheduled for right-sided major hepatectomy: Results of feasibility and surgical strategy using functional liver assessment

BACKGROUND

Hepatic vein embolization (HVE) added to portal vein embolization (PVE) can further increase future remnant liver volume (FRLV) compared with PVE alone. This study was aimed to evaluate feasibility of sequential HVE in a prospective trial and to verify surgical strategy using functional FRLV (fFRLV).

METHODS

Hepatic vein embolization was prospectively indicated for post-PVE patients scheduled for right-sided major hepatectomy if the resection limit of fFRLV using EOB-magnetic resonance imaging was not satisfied. The resection limit was fFRLV: 615 mL/m² for predicting post-hepatectomy liver failure. Patients who underwent sequential PVE-HVE (n = 12) were compared with those who underwent PVE alone (n = 31).

RESULTS

All patients underwent HVE with no severe complications. Median fFRLV increased from 396 (range: 251-581) to 634 (range: 422-740) mL/m² by sequential PVE-HVE. From PVE to HVE, both of FRLV (P < .001) and fFRLV (P = .005) significantly increased. The increased width of fFRLV was larger than that of FRLV after performing HVE. Median growth rate was 71.3 (range: 33.3-80.3) %, which was higher than that of PVE alone (27.0%, range: 6.0-78.0). All-cohort resection rate was 88.3%. Strategy of using fFRLV for the resection limit and performing HVE in patients with insufficient functional volume resulted in no liver failure in all patients who underwent hepatectomy.

CONCLUSIONS

Sequential HVE after PVE is feasible and safe, and HVE induced possibility of further liver growth and its functional improvement. Our surgical strategy using fFRLV may be justified.

Simultaneous portal and hepatic vein embolization is better than portal embolization or ALPPS for hypertrophy of future liver remnant before major hepatectomy: A systematic review and network meta-analysis

BACKGROUND

Post-hepatectomy liver failure (PHLF) is the Achilles' heel of hepatic resection for colorectal liver metastases. The most commonly used procedure to generate hypertrophy of the functional liver remnant (FLR) is portal vein embolization (PVE), which does not always lead to successful hypertrophy. Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been proposed to overcome the limitations of PVE. Liver venous deprivation (LVD), a technique that includes simultaneous portal and hepatic vein embolization, has also been proposed as an alternative to ALPPS. The present study aimed to conduct a systematic review as the first network meta-analysis to compare the efficacy, effectiveness, and safety of the three regenerative techniques.

DATA SOURCES

A systematic search for literature was conducted using the electronic databases Embase, PubMed (MEDLINE), Google Scholar and Cochrane.

RESULTS

The time to operation was significantly shorter in the ALPPS cohort than in the PVE and LVD cohorts by 27 and 22 days, respectively. Intraoperative parameters of blood loss and the Pringle maneuver demonstrated non-significant differences between the PVE and LVD cohorts. There was evidence of a significantly higher FLR hypertrophy rate in the ALPPS cohort when compared to the PVE cohort, but non-significant differences were observed when compared to the LVD cohort. Notably, the LVD cohort demonstrated a significantly better FLR/body weight (BW) ratio compared to both the ALPPS and PVE cohorts. Both the PVE and LVD cohorts demonstrated significantly lower major morbidity rates compared to the ALPPS cohort. The LVD cohort also demonstrated a significantly lower 90-day mortality rate compared to both the PVE and ALPPS cohorts.

CONCLUSIONS

LVD in adequately selected patients may induce adequate and profound FLR hypertrophy before major hepatectomy. Present evidence demonstrated significantly lower major morbidity and mortality rates in the LVD cohort than in the ALPPS and PVE cohorts.

Mechanical homeostasis of liver sinusoid is involved in the initiation and termination of liver regeneration

Organogenesis and regeneration are fundamental for developmental progress and are associated with morphogenesis, size control and functional properties for whole-body homeostasis. The liver plays an essential role in maintaining homeostasis of the entire body through various functions, including metabolic functions, detoxification, and production of bile, via the three-dimensional spatial arrangement of hepatic lobules and has high regenerative capacity. The regeneration occurs as hypertrophy, which strictly controls the size and lobule structure. In this study, we established a three-dimensional sinusoidal network analysis method and determined valuable parameters after partial hepatectomy by comparison to the static phase of the liver. We found that mechanical homeostasis, which is crucial for organ morphogenesis and functions in various phenomena, plays essential roles in liver regeneration for both initiation and termination of liver regeneration, which is regulated by cytokine networks. Mechanical homeostasis plays critical roles in the initiation and termination of organogenesis, tissue repair and organ regeneration in coordination with cytokine networks.

Partial hepatectomy enhances the growth of CC531 rat colorectal cancer cells both in vitro and in vivo

Partial hepatectomy (PHx) is the gold standard for the treatment of colorectal cancer liver metastases. However, after removing a substantial amount of hepatic tissue, growth factors are released to induce liver regeneration, which may promote the proliferation of liver micrometastases or circulating tumour cells still present in the patient. The aim of this study is to assess the effect of PHx on the growth of liver metastases induced by intrasplenic cell inoculation as well as on in vitro proliferation of the same cancer cell line. Liver tumours were induced in 18 WAG/RijHsd male rats, by seeding 250,000 syngeneic colorectal cancer cells (CC531) into the spleen. The left lateral lobe of the liver was mobilized and in half of the animals it was removed to achieve a 40% hepatectomy. Twenty-eight days after tumour induction, the animals were sacrificed and the liver was removed and sliced to assess the relative tumour surface area (RTSA%). CC531 cells were cultured in presence of foetal calf serum, non-hepatectomised (NRS) or hepatectomized rat serum (HRS), and their proliferation rate at 24, 48, and 72 h was measured. RTSA% was significantly higher in animals which had undergone PHx than in the controls (non-hepatectomised) (46.98 ± 8.76% vs. 18.73 ± 5.65%; p < 0.05). Analysing each lobe separately, this difference in favour of hepatectomized animals was relevant and statistically significant in the paramedian and caudate lobes. But in the right lobe the difference was scarce and not significant. In vitro, 2.5% HRS achieved stronger proliferative rates than the control cultures (10% FCS) or their equivalent of NRS. In this experimental model, a parallelism has been shown between the effect of PHx on the growth of colorectal cancer cells in the liver and the effect of the serum on those cells in vitro.

In vitro Studies of Transendothelial Migration for Biological and Drug Discovery

Inflammatory diseases and cancer metastases lack concrete pharmaceuticals for their effective treatment despite great strides in advancing our understanding of disease progression. One feature of these disease pathogeneses that remains to be fully explored, both biologically and pharmaceutically, is the passage of cancer and immune cells from the blood to the underlying tissue in the process of extravasation. Regardless of migratory cell type, all steps in extravasation involve molecular interactions that serve as a rich landscape of targets for pharmaceutical inhibition or promotion. Transendothelial migration (TEM), or the migration of the cell through the vascular endothelium, is a particularly promising area of interest as it constitutes the final and most involved step in the extravasation cascade. While in vivo models of cancer metastasis and inflammatory diseases have contributed to our current understanding of TEM, the knowledge surrounding this phenomenon would be significantly lacking without the use of in vitro platforms. In addition to the ease of use, low cost, and high controllability, in vitro platforms permit the use of human cell lines to represent certain features of disease pathology better, as seen in the clinic. These benefits over traditional pre-clinical models for efficacy and toxicity testing are especially important in the modern pursuit of novel drug candidates. Here, we review the cellular and molecular events involved in leukocyte and cancer cell extravasation, with a keen focus on TEM, as discovered by seminal and progressive in vitro platforms. In vitro studies of TEM, specifically, showcase the great experimental progress at the lab bench and highlight the historical success of in vitro platforms for biological discovery. This success shows the potential for applying these platforms for pharmaceutical compound screening. In addition to immune and cancer cell TEM, we discuss the promise of hepatocyte transplantation, a process in which systemically delivered hepatocytes must transmigrate across the liver sinusoidal endothelium to successfully engraft and restore liver function. Lastly, we concisely summarize the evolving field of porous membranes for the study of TEM.

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.

Complete or partial split in associating liver partition and portal vein ligation for staged hepatectomy: A systematic review and meta-analysis

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been adopted by liver surgeons in recent years. However, high morbidity and mortality rates have limited the promotion of this technique. Some recent studies have suggested that ALPPS with a partial split can effectively induce the growth of future liver remnant (FLR) similar to a complete split with better postoperative safety profiles. However, some others have suggested that ALPPS can induce more rapid and adequate FLR growth, but with the same postoperative morbidity and mortality rates as in partial split of the liver parenchyma in ALPPS (p-ALPPS).

AIM

To perform a systematic review and meta-analysis on ALPPS and p-ALPPS.

METHODS

A systematic literature search of PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov was performed for articles published until June 2019. Studies comparing the outcomes of p-ALPPS and ALPPS for a small FLR in consecutive patients were included. Our main endpoints were the morbidity, mortality, and FLR hypertrophy rates. We performed a subgroup analysis to evaluate patients with and without liver cirrhosis. We assessed pooled data using a random-effects model.

RESULTS

Four studies met the inclusion criteria. Four studies reported data on morbidity and mortality, and two studies reported the FLR hypertrophy rate and one study involved patients with cirrhosis. In the non-cirrhotic group, p-ALPPS-treated patients had significantly lower morbidity and mortality rates than ALPPS-treated patients [odds ratio (OR) = 0.2; 95% confidence interval (CI): 0.07–0.57; P = 0.003 and OR = 0.16; 95%CI: 0.03-0.9; P = 0.04]. No significant difference in the FLR hypertrophy rate was observed between the two groups (P > 0.05). The total effects indicated no difference in the FLR hypertrophy rate or perioperative morbidity and mortality rates between the ALPPS and p-ALPPS groups. In contrast, ALPPS seemed to have a better outcome in the cirrhotic group.

CONCLUSION

The findings of our study suggest that p-ALPPS is safer than ALPPS in patients without cirrhosis and exhibits the same rate of FLR hypertrophy.

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.

Associating liver partition and portal vein ligation versus 2-stage hepatectomy: A meta-analysis

BACKGROUND

The aim of this study was to conduct a meta-analysis comparing associating liver partition and portal vein ligation (ALPPS) with conventional 2-stage hepatectomy (TSH) in terms of clinical outcomes and to determine the feasibility and safety of ALPPS.

METHODS

A comprehensive search strategy was adopted to search the PubMed, Embase, Cochrane Library, and China Biology Medicine disc databases for studies comparing ALPPS and TSH. The search was broadened by looking up the reference lists of the retrieved articles. A meta-analysis was performed using the statistical software RevMan (v 5.3; Cochrane Collaboration).

RESULTS

A total of 7 studies involving 561 patients (ALPPS group, 136 patients; TSH group, 425 patients) were included in the present study, all of which were observational studies. Compared with TSH, ALPPS was associated with high completion rates of both stages [odds ratio (OR): 10.68, 95% confidence interval (95% CI): 3.26-34.97, P < .0001]. No significant differences were found in other outcomes such as complications of the first (OR: 4.04, 95% CI: 0.81-20.27, P = .09) and second surgical stage (OR: 1.59, 95% CI: 0.71-3.57, P = .26), liver failure (OR: 0.76, 95% CI: 0.29-1.98, P = .58) and the 90-day mortality rate (OR: 2.20, 95% CI: 1.00-4.84, P = .05).

CONCLUSION

ALPPS is associated with lower noncompletion rate and had similar perioperative outcomes relative to TSH. However, only retrospective observational studies were included in this meta-analysis, which may have limited the strength of the evidence. High-quality, large-scale studies are required to further evaluate the outcomes of ALPPS.

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.

Delayed liver regeneration in C3H/HeJ mice: possible involvement of haemodynamic and structural changes in the hepatic microcirculation

NEW FINDINGS

What is the central question of this study? The liver regenerative process is complex and involves a sequence of signalling events, but the possible involvement of structural and haemodynamic changes in vivo during this process has never been explored. What is the main finding and its importance? Normal sinusoidal blood flow and velocity are crucial for a normal regenerative response, and delays in these haemodynamic events resulted in impaired liver regeneration in lipopolysaccharide-insensitive, C3H/HeJ mice. Toll-like receptor 4 signalling is required for restoration of normal liver architecture during the liver regenerative process. Liver regeneration is delayed in mice with a defective Toll-like receptor 4 (TLR4; C3H/HeJ mice) but is normal in TLR4 knockouts (TLR4^-/- ). Here, we investigated the possible involvement of structural and haemodynamic changes in vivo in the underlying mechanism. In lipopolysaccharide-sensitive (C3H/HeN and C57BL/6) and lipopolysaccharide-insensitive (C3H/HeJ and TLR4^-/- ) mice, a 70% partial hepatectomy (PH) was performed under inhalational anaesthesia. At days 3 and 7 after PH, the hepatic microcirculation was interrogated using intravital microscopy. Delayed liver regeneration was confirmed in C3H/HeJ, but not in C3H/HeN, C57BL/6 (WT) or TLR4^-/- mice by liver weight-to-body-weight ratio, the percentage of proliferating cell nuclear antigen (PCNA)-positive cells and mitotic index data. At day 3 after PH, sinusoidal red blood cell velocity increased by 100% in C3H/HeN mice, but by only 40% in C3H/HeJ mice. Estimated sinusoidal blood flow was significantly higher at day 7 after PH in C3H/HeN than in C3H/HeJ mice. The hepatic cord width was significantly larger in C3H/HeN than in C3H/HeJ mice at day 3 and it was significantly larger in TLR4^-/- than in C57BL/6 WT mice at day 7 after PH. Hepatocyte nucleus density and functional sinusoidal density was significantly reduced at days 3 and 7 after PH in all mouse strains compared with their zero-time controls. Functional sinusoidal density was significantly lower in C3H/HeJ compared with C3H/HeN mice at day 7 after PH. The present study indicates that altered sinusoidal blood flow and velocity in C3H/HeJ mice may contribute to the observed delay in the regenerative response in these mice. In addition, restoration of normal liver architecture may be delayed in TLR4^-/- mice.

Phase contrast imaging of preclinical portal vein embolization with CO2 microbubbles

Preoperative portal vein embolization (PVE) is employed clinically to avoid postoperative liver insufficiency. Animal models are usually used to study PVE in terms of mechanisms and pathophysiological changes. PVE is formerly monitored by conventional absorption contrast imaging (ACI) with iodine contrast agent. However, the side effects induced by iodine can give rise to animal damage and death. In this study, the feasibility of using phase contrast imaging (PCI) to show PVE using homemade CO₂ microbubbles in living rats has been investigated. CO₂ gas was first formed from the reaction between citric acid and sodium bicarbonate. The CO₂ gas was then encapsulated by egg white to fabricate CO₂ microbubbles. ACI and PCI of CO₂ microbubbles were performed and compared in vitro. An additional increase in contrast was detected in PCI. PCI showed that CO₂ microbubbles gradually dissolved over time, and the remaining CO₂ microbubbles became larger. By PCI, the CO₂ microbubbles were found to have certain stability, suggesting their potential use as embolic agents. CO₂ microbubbles were injected into the main portal trunk to perform PVE in living rats. PCI exploited the differences in the refractive index and facilitated clear visualization of the PVE after the injection of CO₂ microbubbles. Findings from this study suggest that homemade CO₂ microbubbles-based PCI is a novel modality for preclinical PVE research.

Clinical Hepatocyte Transplantation: What Is Next?

Purpose of review

Significant recent scientific developments have occurred in the field of liver repopulation and regeneration. While techniques to facilitate liver repopulation with donor hepatocytes and different cell sources have been studied extensively in the laboratory, in recent years clinical hepatocyte transplantation (HT) and liver repopulation trials have demonstrated new disease indications and also immunological challenges that will require the incorporation of a fresh look and new experimental approaches.

Recent findings

Growth advantage and regenerative stimulus are necessary to allow donor hepatocytes to proliferate. Current research efforts focus on mechanisms of donor hepatocyte expansion in response to liver injury/preconditioning. Moreover, latest clinical evidence shows that important obstacles to HT include optimizing engraftment and limited duration of effectiveness, with hepatocytes being lost to immunological rejection. We will discuss alternatives for cellular rejection monitoring, as well as new modalities to follow cellular graft function and near-to-clinical cell sources.

Summary

HT partially corrects genetic disorders for a limited period of time and has been associated with reversal of ALF. The main identified obstacles that remain to make HT a curative approach include improving engraftment rates, and methods for monitoring cellular graft function and rejection. This review aims to discuss current state-of-the-art in clinical HT and provide insights into innovative approaches taken to overcome these obstacles.

Hepatic resection for primary and secondary liver malignancies

Liver surgery has become the standard treatment of primary liver cancer and liver metastases from colorectal cancer. Also, patients with non-colorectal liver metastases are increasingly offered surgery due to the low morbidity and excellent long-term results. The evolution of two-stage procedures helps to increase resectability. Also, laparoscopic and robotic liver surgery are constantly developed.

Intrahepatic Size Regulation in a Surgical Model: Liver Resection-Induced Liver Regeneration Counteracts the Local Atrophy following Simultaneous Portal Vein Ligation

BACKGROUND/AIM

Liver size regulation is based on the balance between hepatic regeneration and atrophy. To achieve a better understanding of intrahepatic size regulation, we explored the size regulation of a portally deprived liver lobe on a liver subjected to concurrent portal vein ligation (PVL) and partial hepatectomy (PHx).

MATERIALS AND METHODS

Using a surgical rat model consisting of right PVL (rPVL) plus 70% PHx, we evaluated the size regulation of liver lobes 1, 2, 3, and 7 days after the operation in terms of liver weight and hepatocyte proliferation. Portal hyperperfusion was confirmed by measuring portal flow. The portal vascular tree was visualized by injection of a contrast agent followed by CT imaging of explanted livers. Control groups consisted of 70% PHx, rPVL, and sham operation.

RESULTS

The size of the ligated right lobe increased to 1.4-fold on postoperative day 7 when subjected to rPVL + 70% PHx. The right lobe increased to 3-fold when subjected to 70% PHx alone and decreased to 0.3-fold when subjected to rPVL only. The small but significant increase in liver weight after the combined procedure was accompanied by a low proliferative response. In contrast, hepatocyte proliferation was undetectable in the right lobe undergoing atrophy after PVL only. The caudate lobe in the rPVL + 70% PHx group increased to 4.6-fold, which is significantly more than in the other groups. This increase in liver weight was paralleled by persisting portal hyperperfusion and a prolonged proliferative phase of 3 days.

CONCLUSIONS

A discontinued portal blood supply does not always result in atrophy of the ligated lobe. The concurrent regenerative stimulus induced by 70% PHx seemed to counteract the local atrophy after a simultaneously performed rPVL, leading to a low but prolonged regenerative response of the portally deprived liver lobe. This observation supports the conclusion that portal flow is not necessary for liver regeneration. The persisting portal hyperperfusion may be crucial for the specific kinetics of prolonged liver regeneration after rPVL + 70% PHx in the portally supplied caudate lobe. Both observations deserve more attention regarding the underlying mechanism in further studies.

Liver regeneration following repeated reversible portal vein embolization in an experimental model

BACKGROUND

Portal vein embolization (PVE) is used routinely to prevent postoperative liver failure as a result of anticipated insufficient future liver remnant volume following resection. The authors have recently developed a technique for temporary PVE. The aim of this study was to assess the effect of repeated reversible PVE on hepatocyte proliferation and subsequent liver hypertrophy in rodents.

METHODS

Four treatments were compared (n = 21 rats per group): single reversible PVE, two PVEs separated by 14 days, partial portal vein ligation or sham procedure. The feasibility and tolerance of the procedure were assessed. Volumetric imaging by CT was used to estimate the evolution of liver volumes. After death, the weight of liver lobes was measured and hepatocyte proliferation evaluated by immunostaining.

RESULTS

Embolization of portal branches corresponding to 70 per cent of total portal flow was performed successfully in all animals. Repeated PVE induced additional hepatocyte proliferation. Repeated embolization resulted in superior hepatocyte proliferation in the non-occluded segments compared with portal vein ligation (31·1 versus 22·2 per cent; P = 0·003). The non-occluded to total liver volume ratio was higher in the repeated PVE group than in the single PVE and sham groups (P = 0·050 and P = 0·001 respectively).

CONCLUSION

Repeated reversible PVE successfully induced additional hepatocyte proliferation and subsequent liver hypertrophy. Surgical relevance Portal vein embolization (PVE) is used routinely to prevent postoperative liver failure as a result of anticipated insufficient future liver remnant volume following resection. In the present study, a technique of repeated temporary PVE was developed in a rat model; this induced additional hepatocyte proliferation and an increase in liver volume compared with single embolization. This novel approach might help induce major hypertrophy of the future remnant liver, which could increase the rate of patients amenable to major liver resections.

An updated systematic review of the evolution of ALPPS and evaluation of its advantages and disadvantages in accordance with current evidence

The main obstacle to achieving an R0 resection after a major hepatectomy is inability to preserve an adequate future liver remnant (FLR) to avoid postoperative liver failure (PLF). Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a novel technique for resecting tumors that were previously considered unresectable, and this technique results in a vast increase in the volume of the FLR in a short period of time. However, this technique continues to provoke heated debate because of its high mortality and morbidity.The evolution of ALPPS and its advantages and disadvantages have been systematically reviewed and evaluated in accordance with current evidence. Electronic databases (PubMed and Medline) were searched for potentially relevant articles from January 2007 to January 2016.ALPPS has evolved into various modified forms. Some of these modified techniques have reduced the difficulty of the procedure and enhanced its safety. Current evidence indicates that the advantages of ALPPS are rapid hypertrophy of the FLR, the feasibility of the procedure, and a higher rate of R0 resection in comparison to other techniques. However, ALPPS is associated with worse major complications, more deaths, and early tumor recurrence.Hepatobiliary surgeons should carefully consider whether to perform ALPPS. Some modified forms of ALPPS have reduced the mortality and morbidity of the procedure, but they cannot be recommended over the original procedure currently. Portal vein embolization (PVE) is still the procedure of choice for patients with a tumor-free FLR, and ALPPS could be used as a salvage procedure when PVE fails. More persuasive evidence needs to be assembled to determine whether ALPPS or two-stage hepatectomy (TSH) is better for patients with a tumor involving the FLR. Evidence with regard to long-term oncological outcomes is still limited. More meticulous comparative studies and studies of the 5-year survival rate of ALPPS could ultimately help to determine the usefulness of ALPPS. Indications and patient selection for the procedure need to be determined.

[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.

Establishment of a rat model: Associating liver partition with portal vein ligation for staged hepatectomy

BACKGROUND

We adapted the anatomically oriented parenchyma-preserving resection technique for associating liver partition with portal vein ligation (PVL) for staged hepatectomy (ALPPS) in rats and examined the role of revascularization in intrahepatic size regulation.

METHODS

We performed the procedures based on anatomic study. The ALPPS procedure consisted of a 70% PVL (occluding the left median, left lateral, and right lobes), parenchymal transection (median lobe) and partial (10%) hepatectomy (PHx; caudate lobe). The transection effect was evaluated by measuring the extent of hepatic atrophy or regeneration of individual liver lobes in the ALPPS and control groups (70% PVL and 10% PHx without transection). The survival rates after stage II resection and collateral formation within the portal vein system was examined.

RESULTS

Anatomic study revealed a close spatial relationship between the demarcation line and the middle median hepatic vein. This enabled placing the transection plane without injuring the hepatic vein. Transection was achieved via stepwise clamping, followed by 2-3 parenchyma-preserving piercing sutures on both sides of the clamp. Ligated liver lobes atrophy was significantly enhanced after ALPPS compared with the control group. In contrast, both a significantly greater relative weight of the regenerated lobe and proliferation index on the first postoperative day were observed. All animals tolerated stage II-resection without complications. Portoportal collaterals were only observed in the control group.

CONCLUSION

We developed an anatomically precise technique for parenchymal transection. The lack of a dense vascular network between the portalized and deportalized lobes may play an important role in accelerating regeneration and atrophy augmentation.

Liver regeneration after partial hepatectomy

Liver regeneration after partial hepatectomy is an extremely complicated pathophysiologic process, which involves the up-regulation of many proliferation associated proteins and genes. The molecular mechanisms responsible for initiating, maintaining, and terminating this process are still under active investigation and remain one of the research focuses in the field of regenerative medicine. Studies of the mechanism of liver regeneration can provide a theoretical foundation for regeneration promotion and hepatic failure prevention, which is extremely important in clinical practice. This review aims to elucidate the molecular mechanism responsible for the initiation, proliferation and termination of liver regeneration.

[Vascular management in anatomical liver resection]

The vascular management in anatomical liver resection plays a pivotal role in maintaining an adequately functional residual liver volume. In this respect it is essential to guarantee an adequate portal and arterial inflow as well venous outflow for the whole residual liver (lobe or segments). To achieve this, the liver surgeon should have excellent perioperative imaging, surgical expertise based on knowledge of vascular anatomy, physiology and hemodynamics of the liver and a well-designed and cautious operative strategy. The use of intraoperative ultrasonography (with or without contrast enhancement) and modern parenchymal dissectors (e.g. ultrasound or water jet dissectors) are strongly recommended.

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.

Monosegment ALPPS: A new variant of the techniques for rapid hepatic regeneration. Critical review of the initial results of our series

Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS) is a novel surgical technique that provides fast and effective growth of liver remnant volume, allowing surgical resection of hepatic lesions initially considered unresectable. Short and long-term results and the convenience of carrying out this technique are issues that still remain under debate while waiting for the final outcomes of the multicenter registries with larger number of cases. The aim of this paper is to describe, from a critical point of view, the outcomes of the cases performed at our center (n=8). On the other hand, it is possible to leave only one hepatic segment as a liver remnant and we illustrate this new surgical procedure (ALPPS monosegment) performed in one patient.

ALPPS: from human to mice highlighting accelerated and novel mechanisms of liver regeneration

OBJECTIVES

To develop a reproducible animal model mimicking a novel 2-staged hepatectomy (ALPPS: Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy) and explore the underlying mechanisms.

BACKGROUND

ALPPS combines portal vein ligation (PVL) with liver transection (step I), followed by resection of the deportalized liver (step II) within 2 weeks after the first surgery. This approach induces accelerated hypertrophy of the liver remnant to enable resection of massive tumor load. To explore the underlying mechanisms, we designed the first animal model of ALPPS in mice.

METHODS

The ALPPS group received 90% PVL combined with parenchyma transection. Controls underwent either transection or PVL alone. Regeneration was assessed by liver weight and proliferation-associated molecules. PVL-treated mice were subjected to splenic, renal, or pulmonary ablation instead of hepatic transection. Plasma from ALPPS-treated mice was injected into mice after PVL. Gene expression of auxiliary mitogens in mouse liver was compared to patients after ALPPS or PVL.

RESULTS

The hypertrophy of the remnant liver after ALPPS doubled relative to PVL, whereas mice with transection alone disclosed minimal signs of regeneration. Markers of hepatocyte proliferation were 10-fold higher after ALPPS, when compared with controls. Injury to other organs or ALPPS-plasma injection combined with PVL induced liver hypertrophy similar to ALPPS. Early initiators of regeneration were significantly upregulated in human and mice.

CONCLUSIONS

ALPPS in mice induces an unprecedented degree of liver regeneration, comparable with humans. Circulating factors in combination with PVL seem to mediate enhanced liver regeneration, associated with ALPPS.

Clinical Hepatocyte Transplantation: Practical Limits and Possible Solutions

Since the first human hepatocyte transplants (HTx) in 1992, clinical studies have clearly established proof of principle for this therapy as a treatment for patients with acquired or inherited liver disease. Although major accomplishments have been made, there are still some specific limitations to this technology, which, if overcome, could greatly enhance the efficacy and implementation of this therapy. Here, we describe what in our view are the most significant obstacles to the clinical application of HTx and review the solutions currently proposed. The obstacles of significance include the limited number and quality of liver tissues as a cell source, the lack of clinical grade reagents, quality control evaluation of hepatocytes prior to transplantation, hypothermic storage of cells prior to transplantation, preconditioning treatments to enhance engraftment and proliferation of donor cells, tracking or monitoring cells after transplantation, and the optimal immunosuppression protocols for transplant recipients.

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.

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.

In-line phase contrast imaging of hepatic portal vein embolization with radiolucent embolic agents in mice: a preliminary study

It is crucial to understand the distribution of embolic agents inside target liver during and after the hepatic portal vein embolization (PVE) procedure. For a long time, the problem has not been well solved due to the radiolucency of embolic agents and the resolution limitation of conventional radiography. In this study, we first reported use of fluorescent carboxyl microspheres (FCM) as radiolucent embolic agents for embolizing hepatic portal veins. The fluorescent characteristic of FCM could help to determine their approximate location easily. Additionally, the microspheres were found to be fairly good embolizing agents for PVE. After the livers were excised and fixed, they were imaged by in-line phase contrast imaging (PCI), which greatly improved the detection of the radiolucent embolic agents as compared to absorption contrast imaging (ACI). The preliminary study has for the first time shown that PCI has great potential in the pre-clinical investigation of PVE with radiolucent embolic agents.

Small animal magnetic resonance imaging: an efficient tool to assess liver volume and intrahepatic vascular anatomy

BACKGROUND

To develop a noninvasive technique to assess liver volumetry and intrahepatic portal vein anatomy in a mouse model of liver regeneration.

MATERIALS AND METHODS

Fifty-two C57BL/6 male mice underwent magnetic resonance imaging (MRI) of the liver using a 4.7 T small animal MRI system after no treatment, 70% partial hepatectomy (PH), or selective portal vein embolization. The protocol consisted of the following sequences: three-dimensional-encoded spoiled gradient-echo sequence (repetition time per echo time 15 per 2.7 ms, flip angle 20°) for volumetry, and two-dimensional-encoded time-of-flight angiography sequence (repetition time per echo time 18 per 6.4 ms, flip angle 80°) for vessel visualization. Liver volume and portal vein segmentation was performed using a dedicated postprocessing software. In animals with portal vein embolization, portography served as reference standard. True liver volume was measured after sacrificing the animals. Measurements were carried out by two independent observers with subsequent analysis by the Cohen κ-test for interobserver agreement.

RESULTS

MRI liver volumetry highly correlated with the true liver volume measurement using a conventional method in both the untreated liver and the liver remnant after 70% PH with a high interobserver correlation coefficient of 0.94 (95% confidence interval, 0.80-0.98 for untreated liver [P < 0.001] and 0.90-0.97 after 70% PH [P < 0.001]). The diagnostic accuracy of magnetic resonance angiography for the occlusion of one branch of the portal vein was 0.95 (95% confidence interval, 0.84-1). The level of agreement between the two observers for the description of intrahepatic vascular anatomy was excellent (Cohen κ value = 0.925).

CONCLUSIONS

This protocol may be used for noninvasive liver volumetry and visualization of portal vein anatomy in mice. It will serve the dynamic study of new strategies to enhance liver regeneration in vivo.

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.

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.

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS): tips and tricks

BACKGROUND

Posthepatectomy liver failure is the most severe complication after major hepatectomies and it is associated with an insufficient future liver remnant (FLR). Associating liver partition and portal vein ligation (PVL) has recently been described as a revolutionary strategy to induce a rapid and large FLR volume increase. We aim to describe our surgical technique, patient management, and preliminary results with this new two-stage approach.

TECHNIQUE

During the first stage, liver partition and PVL of the diseased hemiliver are performed. The completion surgery is carried out after volumetric studies have demonstrated a sufficient FLR and provided the patient is in good condition. This is usually achieved after 7 days. In the second step, the patient undergoes a completion surgery with right hepatectomy, right trisectionectomy, or left trisectionectomy.

RESULTS

Fifteen patients with advanced liver tumors were treated. Nine patients were males and the mean age was 54 years old. The mean difference between the preoperative and postoperative FLR volume was 303 ml (p < 0.001), which represented a mean volume increase of 78.4 %. All resections were R0. Morbidity and mortality rates were 53 and 0 %, respectively. The average hospital stay was 19 days.

CONCLUSIONS

The presented technique was feasible and safe in the hands of experienced hepatobiliary surgeons, with satisfactory short-term results. It induces rapid liver hypertrophy and at the same time it offers the possibility of cure to patients previously declared unresectable.

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.

Prognostic importance of some clinical and therapeutic factors for the effect of portal vein embolization in patients with primarily inoperable colorectal liver metastases

INTRODUCTION

Portal vein embolization (PVE) may increase the resectability of liver metastases. However, the problem of PVE is insufficient growth of the liver or tumor progression in some patients. The aim of this study was to evaluate the significance of commonly available clinical factors for the result of PVE.

MATERIAL AND METHODS

Portal vein embolization was performed in 38 patients with colorectal liver metastases. Effects of age, gender, time between PVE and liver resection, oncological therapy after PVE, indocyanine green retention rate test, synchronous, metachronous and extrahepatic metastases, liver volume before and after PVE, increase of liver volume after PVE and the quality of liver parenchyma before PVE on the result of PVE were evaluated.

RESULTS

Liver resection was performed in 23 (62.2%) patients within 1.3 ±0.4 months after PVE. Tumor progression occurred in 9 (23.7%) patients and 6 (15.8%) patients had insufficient liver hypertrophy. Significant clinical factors of PVE failure were number of liver metastases (cut-off - 4; odds ratio - 4.7; p < 0.03), liver volume after PVE (cut-off 1000 cm(3); odds ratio - 5.1; p < 0.02), growth of liver volume after PVE (cut-off 150 cm(3); odds ratio - 18.7; p < 0.002), oncological therapy administered concomitantly with PVE (p < 0.003).

CONCLUSIONS

Negative clinical factors of resectability of colorectal cancer liver metastases after PVE included more than four liver metastases, liver volume after PVE < 1000 cm(3), growth of the contralateral lobe by less than 150 cm(3) and concurrent oncological therapy.

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.