Short-term effects of combined hepatic vein embolization and portal vein embolization for the induction of liver regeneration in a rabbit model

Establishment of a Rat Model of Liver Venous Deprivation: Simultaneous Portal and Hepatic Vein Ligation

BACKGROUND AND AIMS

The aim was to establish a liver venous deprivation (LVD) model in rats, compare hepatic hypertrophy between LVD and associated liver partition and portal vein ligation for staged hepatectomy (ALPPS), and explore the underlying mechanisms.

METHODS

The LVD or extended-LVD (e-LVD) group received portal vein ligation (PVL) combined with hepatic vein ligation (HVL). The ALPPS or e-ALPPS group received PVL plus parenchyma ligation. Liver regeneration was assessed by measuring the liver weight and performing pathological analysis. Liver functions and the sphingosine kinase 1 (SPHK1)/sphingosine-1-phosphate (S1P)/sphingosine-1-phosphate receptor 1 (S1PR1) pathway were also investigated.

RESULTS

All future liver remnants (FLRs) in the ALPPS, e-ALPPS, LVD, and e-LVD groups exhibited significant hypertrophy compared with the control group. The LVD and e-LVD procedures induced similar liver hypertrophy than that in the corresponding ALPPS groups. Furthermore, the LVD and e-LVD methods led to obvious cytolysis in the venous-deprived lobes as well as a noticeable increase in serum transaminase levels, while no necrosis was observed in the ALPPS and e-ALPPS groups. SPHK1/S1P/S1PR1 pathway were distinctly activated after operation, especially in congestive/ischemic livers.

CONCLUSIONS

We describe the first rat model of LVD and e-LVD with simultaneously associated HVL and PVL. Compared with the ALPPS technique, the LVD or e-LVD procedure had a comparable overall effect on the hypertrophy response and a stronger effect on liver function. The SPHK1/S1P/S1PR1 pathway was involved in the LVD- or ALPPS-induced liver remodeling.

Liver Venous Deprivation (LVD) Versus Portal Vein Embolization (PVE) Alone Prior to Extended Hepatectomy: A Matched Pair Analysis

BACKGROUND

To investigate whether liver venous deprivation (LVD) as simultaneous, portal vein (PVE) and right hepatic vein embolization offers advantages in terms of hypertrophy induction before extended hepatectomy in non-cirrhotic liver.

MATERIALS AND METHODS

Between June 2018 and August 2019, 20 patients were recruited for a prospective, non-randomized study to investigate the efficacy of LVD. After screening of 134 patients treated using PVE alone from January 2015 to August 2019, 14 directly matched pairs regarding tumor entity (cholangiocarcinoma, CC and colorectal carcinoma, CRC) and hypertrophy time (defined as time from embolization to follow-up imaging) were identified. In both treatment groups, the same experienced reader (> 5 years experience) performed imaging-based measurement of the volumes of liver segments of the future liver remnant (FLR) prior to embolization and after the standard clinical hypertrophy interval (~ 30 days), before surgery. Percentage growth of segments was calculated and compared.

RESULTS

After matched follow-up periods (mean of 30.5 days), there were no statistically significant differences in relative hypertrophy of FLRs. Mean ± standard deviation relative hypertrophy rates for LVD/PVE were 59 ± 29.6%/54.1 ± 27.6% (p = 0.637) for segments II + III and 48.2 ± 22.2%/44.9 ± 28.9% (p = 0.719) for segments II-IV, respectively.

CONCLUSIONS

LVD had no significant advantages over the standard method (PVE alone) in terms of hypertrophy induction of the FLR before extended hepatectomy in this study population.

Combined biembolization induces higher hypertrophy than portal vein embolization before major liver resection

BACKGROUND

Combined preoperative portal and hepatic vein embolization (biembolization, BE) has been recently described and may further enhance preoperative FLR growth. The objective of this study was to compare the efficacy of combined preoperative biembolization and portal vein embolization (PVE).

METHODS

This study was performed between 2010 and 2017. From 2010 to 2014, patients only underwent preoperative PVE. After 2014, BE was proposed as an alternative to PVE. Liver volumetry was assessed by a CT-scan before BE or PVE and then three weeks later.

RESULTS

During the study period, 72 patients underwent radiological procedures that included 41 PVE (PVE group) and 31 BE (BE group). The time elapsing between the procedure and surgery was similar (p = 0.760). The mean percentage of FLR ratio hypertrophy in the PVE group was 31.9% (±34), but reached 51.2% (±42) in the BE group (p = 0.018) and this difference remained significant under multivariate analysis that included age, gender, body mass index, diabetes mellitus, cirrhosis and NASH. The kinetic growth rates were 19% (±17%) and 8% (±13%) in the BE and PVE groups, respectively (p = 0.026).

CONCLUSION

This study shows that BE induces higher hypertrophy than portal vein embolization before major liver resection with no more morbidity.

Dealing with an insufficient future liver remnant: Portal vein embolization and two-stage hepatectomy

Colorectal liver metastases (CLM) are not always resectable at the time of diagnosis. An insufficient future liver remnant is a factor excluding patients from curative intent resection. To deal with this issue, two-stage hepatectomy was introduced approximately 20 years ago. It is a sequential treatment strategy for bilateral CLM, which consists of preoperative chemotherapy, portal vein embolization, and planned first and second liver resections. This study reviews current evidence supporting use of two-stage hepatectomy.

Simultaneous hepatic and portal vein ligation induces rapid liver hypertrophy: A study in pigs

BACKGROUND

Liver hypertrophy induced by partial portal vein occlusion (PVL) is accelerated by adding simultaneous parenchymal transection ("ALPPS procedure"). This preclinical experimental study in pigs tests the hypothesis that simultaneous ligation of portal and hepatic veins of the liver also accelerates regeneration by abrogation of porto-portal collaterals without need for operative transection.

METHODS

A pig model of portal vein occlusion was compared with the novel model of simultaneous portal and hepatic vein occlusion, where major hepatic veins draining the portal vein-deprived lobe were identified with intraoperative ultrasonography and ligated using pledgeted transparenchymal sutures. Kinetic growth was compared, and the portal vein system was then studied after 7 days using epoxy casts of the portal circulation. Portal vein flow and portal pressure were measured, and Ki-67 staining was used to evaluate the proliferative response.

RESULTS

Pigs were randomly assigned to portal vein occlusion (n = 8) or simultaneous portal and hepatic vein occlusion (n = 6). Simultaneous portal and hepatic vein occlusion was well tolerated and led to mild cytolysis, with no necrosis in the outflow vein-deprived liver sectors. The portal vein-supplied sector increased by 90 ± 22% (mean ± standard deviation) after simultaneous portal and hepatic vein occlusion compared with 29 ± 18% after PVL (P < .001). Collaterals to the deportalized liver developed after 7 days in both procedures but were markedly reduced in simultaneous portal and hepatic vein occlusion. Ki-67 staining at 7 days was comparable.

CONCLUSION

This study in pigs found that simultaneous portal and hepatic vein occlusion led to rapid hypertrophy without necrosis of the deportalized liver. The findings suggest that the use of simultaneous portal and hepatic vein occlusion accelerates liver hypertrophy for extended liver resections and should be evaluated further.

Irreversible electroporation of the liver: is there a safe limit to the ablation volume?

Irreversible electroporation is a fast-growing liver ablation technique. Although safety has been well documented in small ablations, our aim is to assess its safety and feasibility when a large portion of liver is ablated. Eighty-seven mice were subjected to high voltage pulses directly delivered across parallel plate electrodes comprising around 40% of mouse liver. One group consisted in 55 athymic-nude, in which a tumor from the KM12C cell line was grown and the other thirty-two C57-Bl6 non-tumoral mice. Both groups were subsequently divided into subsets according to the delivered field strength (1000 V/cm, 2000 V/cm) and whether or not they received anti-hyperkalemia therapy. Early mortality (less than 24 hours post-IRE) in the 2000 V/cm group was observed and revealed considerably higher mean potassium levels. In contrast, the animals subjected to a 2000 V/cm field treated with the anti-hyperkalemia therapy had higher survival rates (OR = 0.1, 95%CI = 0.02–0.32, p < 0.001). Early mortality also depended on the electric field magnitude of the IRE protocol, as mice given 1000 V/cm survived longer than those given 2000 V/cm (OR = 4.7, 95%CI = 1.8–11.8, p = 0.001). Our findings suggest that ionic disturbances, mainly due to potassium alterations, should be warned and envisioned when large volume ablations are performed by IRE.

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.