Biochemical and morphologic effects after extended liver resection in rats: preliminary results

Noninvasive quantification of oxygen saturation in the portal and hepatic veins in healthy mice and those with colorectal liver metastases using QSM MRI

PURPOSE

This preclinical study investigated the use of QSM MRI to noninvasively measure venous oxygen saturation (SvO2) in the hepatic and portal veins.

METHODS

QSM data were acquired from a cohort of healthy mice (n = 10) on a 9.4 Tesla MRI scanner under normoxic and hyperoxic conditions. Susceptibility was measured in the portal and hepatic veins and used to calculate SvO2 in each vessel under each condition. Blood was extracted from the inferior vena cava of 3 of the mice under each condition, and SvO2 was measured with a blood gas analyzer for comparison. QSM data were also acquired from a cohort of mice bearing liver tumors under normoxic conditions. Susceptibility was measured, and SvO2 calculated in the portal and hepatic veins and compared to the healthy mice. Statistical significance was assessed using a Wilcoxon matched-pairs signed rank test (normoxic vs. hyperoxic) or a Mann-Whitney test (healthy vs. tumor bearing).

RESULTS

SvO2 calculated from QSM measurements in healthy mice under hyperoxia showed significant increases of 15% in the portal vein (P < 0.05) and 21% in the hepatic vein (P < 0.01) versus normoxia. These values agreed with inferior vena cava measurements from the blood gas analyzer (26% increase). SvO2 in the hepatic vein was significantly lower in the colorectal liver metastases cohort (30% ± 11%) than the healthy mice (53% ± 17%) (P < 0.05); differences in the portal vein were not significant.

CONCLUSION

QSM is a feasible tool for noninvasively measuring SvO2 in the liver and can detect differences due to increased oxygen consumption in livers bearing colorectal metastases.

Transient steatosis assessed by magnetic resonance imaging predicts outcome after extended hepatectomy in mice

RATIONALE AND OBJECTIVES

Posthepatectomy liver failure (PHLF) remains challenging to diagnose and difficult to treat. The extent of transient regeneration-associated steatosis (TRAS) differs between successful liver regeneration and PHLF. This study aims to quantify TRAS by magnetic resonance imaging (MRI) after hepatectomy in mice.

MATERIALS AND METHODS

Mice (C57BL/6) underwent either extended hepatectomy (EH) or standard hepatectomy (SH). Serial MRI on postoperative days 1-7 was used to compare TRAS and liver remnant growth between groups. Survival was also assessed.

RESULTS

EH was associated with decreased survival and impaired proliferation when compared to SH (p = 0.02 and p = 0.03). MRI showed increased TRAS 48 h after EH compared to SH (11.8 ± 6% vs. 4.3 ± 2%, p < 0.001). Compared to EH survivors, death after EH was associated with increased TRAS 48 h postoperatively (16.4 ± 6% vs. 9.2 ± 5%, p = 0.02).

CONCLUSIONS

EH is associated with increased TRAS and inferior outcomes when compared to SH. MRI may help to predict PHLF after hepatectomy.

Anatomic trisegmentectomy: An alternative treatment for huge or multiple hepatocellular carcinoma of right liver

BACKGROUND

The patients with huge (≥10cm) or multiple hepatocellular carcinoma (HCC) in the right liver and insufficient size of the remnant left liver can not be performed an operation of right hemihepatectomy because of that liver failure will occur post operation. We designed anatomic trisegmentectomy in right liver to increase the ratio of future liver remnant volume (%FLRV), thus increasing resectability of huge or multiple HCC.

METHODS

Thirteen patients were analyzed by preoperative CT scan for liver and tumor volumetries. If the right hemihepatectomy was done, %FLRV would be at the range of 29.6%-37.5%. However, if trisegmentectomy was done, %FLRV would increase by an average of 14.0%. So patients will not undergo postoperative liver failure due to sufficient %FLRV. Therefore, we designed anatomic trisegmentectomy, with retention of segment 5 or segment 8, to increase %FLRV and increase the resectability for huge or multiple HCC.

RESULTS

After trisegmentectomy, the inflow and outflow of remnant liver were maintained well. Severe complications and mortality were not happened post operation. Of the 13 patients, 10 survived up to now. Of the 10 living cases, postoperative lung metastasis was found in 2 and intrahepatic recurrence was found in 1. These 3 patients survive with tumor after comprehensive therapies including oral administration of Sorafenib.

CONCLUSION

Compared to right hemihepatectomy, anatomic trisegmentectomy in right liver guarantees the maximum preservation of %FLRV to increase the resectability of huge or multiple HCC, thus improving the overall resection rate.

Administration of multipotent mesenchymal stromal cells restores liver regeneration and improves liver function in obese mice with hepatic steatosis after partial hepatectomy

Background

The liver has the remarkable capacity to regenerate in order to compensate for lost or damaged hepatic tissue. However, pre-existing pathological abnormalities, such as hepatic steatosis (HS), inhibits the endogenous regenerative process, becoming an obstacle for liver surgery and living donor transplantation.

Recent evidence indicates that multipotent mesenchymal stromal cells (MSCs) administration can improve hepatic function and increase the potential for liver regeneration in patients with liver damage. Since HS is the most common form of chronic hepatic illness, in this study we evaluated the role of MSCs in liver regeneration in an animal model of severe HS with impaired liver regeneration.

Methods

C57BL/6 mice were fed with a regular diet (normal mice) or with a high-fat diet (obese mice) to induce HS. After 30 weeks of diet exposure, 70% hepatectomy (Hpx) was performed and normal and obese mice were divided into two groups that received 5 × 10⁵ MSCs or vehicle via the tail vein immediately after Hpx.

Results

We confirmed a significant inhibition of hepatic regeneration when liver steatosis was present, while the hepatic regenerative response was promoted by infusion of MSCs. Specifically, MSC administration improved the hepatocyte proliferative response, PCNA-labeling index, DNA synthesis, liver function, and also reduced the number of apoptotic hepatocytes.

These effects may be associated to the paracrine secretion of trophic factors by MSCs and the hepatic upregulation of key cytokines and growth factors relevant for cell proliferation, which ultimately improves the survival rate of the mice.

Conclusions

MSCs represent a promising therapeutic strategy to improve liver regeneration in patients with HS as well as for increasing the number of donor organs available for transplantation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0469-y) contains supplementary material, which is available to authorized users.

Anatomic resection of liver segments 6-8 for hepatocellular carcinoma

AIM: To report the devised anatomic liver resection of segments 6, 7 and 8 to improve the resection rate for patients with right liver tumors.

METHODS: We performed anatomic liver resection of segments 6, 7 and 8 to guarantee the maximum preservation of the remaining normal liver tissue. Segment 5 was determined by two steps of Glissonean pedicle occlusion. And a “┏┛” shaped broken resection line was marked upon the diaphragmatic surface of the liver. Selective right hemihepatic inflow occlusion was used to reduce blood loss during parenchymal transection between segments 6 and 5 and between segments 8 and 5. If needed, total hepatic Glissonean pedicle occlusion was used during parenchymal transection between segment 8 and the left liver.

RESULTS: Compared to right hemihepatectomy, the percentage of future liver remnant volume was increased by an average of 13.9% if resection of segments 6, 7 and 8 was performed. Resection of segments 6, 7 and 8 was completed uneventfully. After hepatectomy, the inflow and outflow of segment 5 were maintained. There was no perioperative mortality, postoperative abdominal bleeding or bile leakage in this group. Alpha-fetoprotein (AFP) returned to the normal range within 2 mo after the operation in all the patients. One patient died 383 d postoperatively due to obstructive suppurative cholangitis. One patient suffered from severe liver dysfunction shortly after surgery and had intrahepatic recurrence 4 mo postoperatively. Postoperative lung metastasis was found in one patient. No tumor recurrence was found in the other patients and the parameters including liver function and AFP level were in the normal range.

CONCLUSION: Anatomic liver resection of segments 6, 7 and 8 can be a conventional operation to improve the overall resection rate for hepatocellular carcinoma.

Secreted factors of human liver-derived mesenchymal stem cells promote liver regeneration early after partial hepatectomy

Rapid liver regeneration is required after living-donor liver transplantation and oncologic liver resections to warrant sufficient liver function and prevent small-for-size syndrome. Recent evidence highlights the therapeutic potential of mesenchymal stem cells (MSC) for treatment of toxic liver injury, but whether MSC and their secreted factors stimulate liver regeneration after surgical injury remains unknown. Therefore, the aim of this study is to investigate the effect of human liver-derived MSC-secreted factors in an experimental liver resection model. C57BL/6 mice were subjected to a 70% partial hepatectomy and treated with either concentrated MSC-conditioned culture medium (MSC-CM) or vehicle control. Animals were analyzed for liver and body weight, hepatocyte proliferation, and hepatic gene expression. Effects of MSC-CM on gene expression in a human hepatocyte-like cell line (Huh7 cells) were analyzed using genome-wide gene expression arrays. Liver regeneration was significantly stimulated by MSC-CM as shown by an increase in liver to body weight ratio and hepatocyte proliferation. MSC-CM upregulated hepatic gene expression of cytokines and growth factors relevant for cell proliferation, angiogenesis, and anti-inflammatory responses. In vitro, treatment of Huh7 cells with MSC-CM significantly altered expression levels of ~3,000 genes. Functional analysis revealed strong effects on networks associated with protein synthesis, cell survival, and cell proliferation. This study shows that treatment with MSC-derived factors can promote hepatocyte proliferation and regenerative responses in the early phase after surgical resection. MSC-CM may represent a feasible new strategy to promote liver regeneration in patients undergoing extensive liver resection or after transplantation of small liver grafts.

Early effects of portal flow modulation after extended liver resection in rat

INTRODUCTION

The incidence of small-for-size-liver-syndrome after liver transplantation and extended liver resection may be reduced by portal flow modulation. However, many aspects of the small-for-size-liver-syndrome pathogenesis are still unclear. In this experimental study we evaluated the early effects of portal flow modulation after 80% hepatic resection in rats.

MATERIALS AND METHODS

Rats were randomised in: sham operation (G1), conventional hepatic resection (G2), splenectomy and hepatic resection (G3), splenic transposition followed by hepatic resection after three weeks (G4). Six hours after operation, oxygen saturation of hepatic vein blood, glutathione, and standard liver markers were measured from hepatic venous blood. Glutathione measurement and histopatological examination were performed in the remnant liver.

RESULTS

Total bilirubin and liver glutathione did not show differences between groups. Aspartate aminotransferase and alanine aminotransferase significantly increased in G2-G4 groups. Blood glutathione and oxygen saturation of hepatic vein blood were lower in G2 than in other groups. A gradient of micro-vesicular degeneration was more severe in G2 compared with G3 and G4. Apoptosis, hemorrhagic necrosis, mitochondrial damage and leucocyte adhesion were evident in G2.

CONCLUSION

The portal flow modulation induced by splenectomy or splenic transposition was effective in limiting early damage after extended liver resection.

Role of reactive oxygen species in the early stages of liver regeneration in streptozotocin-induced diabetic rats

Diabetes mellitus is a risk factor for prognosis after liver resection. In previous work, we found a pro-apoptotic state in the diabetic rat liver. In this work, this was also observed 1 hour post-partial hepatectomy (PH) and resulted in a deficient regenerative response 24 hours post-PH. Treatment with insulin and/or Desferoxamine (DES) (iron chelator) or Tempol (TEM) (free radicals scavenger) was effective in preventing the liver reactive oxygen species (ROS) production induced by diabetic state. High levels of ROS play a role in hepatic lipid peroxidation in diabetes before and after PH, and lead to increased pro-apoptotic events, which contribute to a reduced regenerative response. This becomes of relevance for the potential use of antioxidants/free radical scavengers plus insulin for improvement of post-surgical recovery of diabetic patients subjected to a PH.