Influence of Stem Cell Mobilization and Liver Regeneration on Hepatic Parenchymal Chimerism in the Rat

Modulation of hepatic perfusion did not improve recovery from hepatic outflow obstruction

Background

Focal hepatic venous outflow obstruction frequently occurs after extended liver resection and leads to a portal hypertension, arterial hypoperfusion and parenchymal necrosis.

In this study, we investigated the pharmacological modulation of liver perfusion and hepatic damage in a surgical model of hepatic outflow obstruction after extended liver resection by administration of 5 different drugs in comparison to an operative intervention, splenectomy.

Methods

Male inbred Lewis rats (Lew/Crl) were subjected to right median hepatic vein ligation + 70% partial hepatectomy. Treatment consisted of a splenectomy or the application of saline, carvedilol or isosorbide-5-mononitrate (ISMN) (5 mg · kg⁻¹ respectively 7,2 mg · kg⁻¹ per gavage 12 h⁻¹). The splenectomy was performed during operation. The effect of the treatments on hepatic hemodynamics were measured in non-operated animals, immediately after operation (n = 4/group) and 24 h after operation (n = 5/group). Assessment of hepatic damage (liver enzymes, histology) and liver cell proliferation (BrdU-immunohistochemistry) was performed 24 h after operation. Furthermore sildenafil (10 μg · kg⁻¹ i.p. 12h⁻¹), terlipressin (0.05 mg · kg⁻¹ i.v. 12 h⁻¹) and octreotide (10 μg · kg⁻¹ s.c. 12 h⁻¹) were investigated regarding their effect on hepatic hemodynamics and hepatic damage 24 h after operation (n = 4/group).

Results

Carvedilol and ISMN significantly decreased the portal pressure in normal non-operated rats from 11,1 ± 1,1 mmHg (normal rats) to 8,4 ± 0,3 mmHg (carvedilol) respectively 7,4 ± 1,8 mmHg (ISMN). ISMN substantially reduced surgery-induced portal hypertension from 15,4 ± 4,4 mmHg to 9,6 ± 2,3 mmHg. Only splenectomy reduced the portal flow immediately after operation by approximately 25%. No treatment had an immediate effect on the hepatic arterial perfusion. In all treatment groups, portal flow increased by approximately 3-fold within 24 h after operation, whereas hepatic arterial flow decreased substantially. Neither treatment reduced hepatic damage as assessed 24 h after operation. The distribution of proliferating cells appeared very similar in all drug treated groups and the splenectomy group.

Conclusion

Transient relative reduction of portal pressure did not result in a reduction of hepatic damage. This might be explained by the development of portal hyperperfusion which was accompanied by arterial hypoperfusion.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0155-4) contains supplementary material, which is available to authorized users.

Prolonged survival by combined treatment with granulocyte colony-stimulating factor and dipeptidyl peptidase IV inhibitor in a rat small-for-size liver transplantation model

AIM

Despite the great advances and excellent outcomes of liver transplantation (LT), small-for-size (SFS) graft syndrome is a life-threatening complication that remains to be overcome. In the present study, we investigated the therapeutic effect of combined treatment with granulocyte colony-stimulating factor (G-CSF) and a dipeptidyl peptidase IV (DPP-IV) inhibitor on SFS liver graft syndrome.

METHODS

The transplantation of small-sized Lewis donor livers into green fluorescent protein (GFP) transgenic Wistar rats was performed and the recipients were randomly assigned to one of four groups (without treatment, DPP-IV inhibitor treatment, G-CSF treatment and G-CSF/DPP-IV inhibitor combination). Recombinant human G-CSF was injected s.c. at a dose of 2 μg/kg per day starting 5 days prior to transplantation. G-CSF was combined with the p.o. administration of a DPP-IV inhibitor (2 mg/kg per day) after transplantation until the end of the observation period.

RESULTS

The post-transplant survival and liver function of rats treated with G-CSF/DPP-IV inhibitor combination therapy were significantly improved with an increased number of recipient-derived GFP positive cells into the liver grafts. A confocal microscopy study showed cytokeratin (CK)-18 and GFP positive hepatic progenitor cells in the parenchyma of the liver allografts. Untreated rats and rats treated with either G-CSF or DPP-IV inhibitor did not exhibit the prolonged survival and had less GFP and CK-18 positive cells in the liver grafts after SFS LT.

CONCLUSION

Our results suggest that combined treatment with G-CSF and DPP-IV inhibitor may synergistically induce migration and differentiation of recipient-derived stem cells into the hepatic progenitor cells, resulting in the amelioration of SFS liver graft syndrome.

Reduced hepatic arterial perfusion impairs the recovery from focal hepatic venous outflow obstruction in liver-resected rats

BACKGROUND

Extended partial hepatectomy (PH) in patients is leading to portal hyperperfusion but reduced hepatic arterial perfusion (HAP), and is invariably causing focal hepatic venous outflow obstruction (FHVOO). We observed in a rat model that PH in combination with right median hepatic vein ligation (RMHV-L) caused confluent parenchymal necrosis interspersed with viable portal tracts in the obstructed territory and large sinusoidal vascular canals in the border zone. Lack of HAP impaired the spontaneous course of recovery in terms of enlarged parenchymal necrosis, delayed regeneration, and the absence of draining vascular canals. We aimed to investigate whether pharmacological intervention modulates the imbalance between portal venous and hepatic arterial inflow, aggravates the liver damage, and delays the recovery process after FHVOO in liver-resected rats.

METHODS

Male Lewis rats were subjected to 70% PH and RMHV-L. Molsidomine or NG-nitro-L-arginine methyl ester (L-NAME) or saline were applied daily. Hepatic damage, microcirculation, regeneration, and vascular remodeling were evaluated at postoperative days 1, 2, and 7. Animals subjected to RMHV-L only were used as "no HAP" control.

RESULTS

Significant increase of portal venous inflow with a concomitant decrease in HAP was observed in all groups after PH. Molsidomine treatment did neither affect hepatic hemodynamics nor the spontaneous recovery. In contrast, L-NAME treatment further decreased HAP which impaired hepatic microcirculation, aggravated parenchymal damage, decelerated recovery, and impaired the formation of sinusoidal canals.

CONCLUSIONS

Reduction of HAP through inhibition of nitric oxide production worsened the recovery from FHVOO. Drugs increasing HAP need to be evaluated to reverse the hyperperfusion-induced impairment of the spontaneous course after FHVOO.

CD133+ stem cell mobilization after partial hepatectomy depends on resection extent and underlying disease

BACKGROUND

Bone marrow stem cells (BMSC) can participate to liver regeneration. However, conflicting results have been reported on this topic in patients undergoing liver resection.

AIMS

To assess the impact of liver resection extent and presence of underlying liver disease in modulating BMSC mobilization.

METHODS

We enrolled 29 patients undergoing liver resection of different extents, 5 surgical controls and 10 blood donors. Circulating CD133+ BMSC were measured by flow cytometry at different time-points after surgery. The hepatic commitment of mobilized BMSC was investigated by polymerase chain reaction. Liver specimens were collected during surgery for histopathological analysis. Hepatocyte growth factor and granulocyte-colony stimulating factor serum levels were measured by enzyme-linked immunosorbent assay.

RESULTS

BMSC mobilization was found in patients undergoing major liver resection, especially in the presence of underlying disease. Ductular reactions were noted in patients with chronic hepatopathy and the hepatic progenitor-like cells expressed CD133, NCAM, cytokeratin-19, and alpha-fetoprotein. Hepatocyte growth factor and granulocyte-colony stimulating factor levels increased following liver resection and the contemporaneous presence of liver disease was associated with their highest raise.

CONCLUSIONS

Liver repair is mainly an endogenous process. BMSC become important in case of extensive resection, especially in the presence of underlying hepatopathy and hepatic progenitor-like cells activation. Hepatocyte growth factor and granulocyte-colony stimulating factor seem to be involved in the dynamics underlying hepatic regeneration and BMSC recruitment.

Does granulocyte-colony stimulating factor administration induce damage or repair response in schistosomiasis?

AIM

To introduce Granulocyte-colony stimulating factor (G-CSF) as a new therapeutic modality for schistosomiasis through stem cell mobilization, immunomodulation or fibrosis remodeling.

METHODS

In this study, a 5 d course of human recombinant G-CSF (100 μg/kg sc) was applied to Schistosoma mansoni-infected mice at different stages of disease (5 d before infection as well as 3, 5 and 7 wk post-infection). The animals were sacrificed at 10 d as well as 4, 6 and 8 wk post infection. Mice were examined for: (1) Total leukocyte count which is an accepted surrogate marker for the stem cell mobilization into the circulation; (2) Egg count in intestine and liver tissue to assess the parasitic load; and (3) Histopathological changes in Hx/E and Masson trichrome stained sections as well as collagen content in Sirius red-stained liver sections to determine the severity of liver fibrosis.

RESULTS

Mice developed leukocytosis. The egg load and the number of granulomas were not affected by the G-CSF treatment but there was an obvious change in the composition of granulomas towards an increased cellularity. Moreover, fibrosis was significantly decreased in treated groups compared to untreated animals (collagen content either preinfection or at 3 and 5 wk post infection: 5.8 ± 0.5, 4.7 ± 0.5, 4.0 ± 0.7 vs 8.2 ± 0.9; P ≤ 0.01).

CONCLUSION

Although G-CSF did not cause direct elimination of the parasite, it enhanced granulomatous reaction and reduced the fibrosis. Further investigation of the underlying mechanisms of these two actions is warranted.

Effects of granulocyte colony stimulating-factor in a rat model of acute liver injury

BACKGROUND/AIM

Controversial experimental observations suggest that granulocyte colony stimulating-factor may promote hepatic regeneration after hepatectomy and chemical injury either by directly stimulating adult liver cells or facilitating the mobilization of bone marrow cells and their homing to the liver. We investigated whether different schedules of granulocyte colony stimulating-factor administration protect against experimental acute liver injury.

METHODS

Acute liver injury was induced in Sprague-Dawley fed rats by injecting a single intraperitoneal dose of carbon tetrachloride. Recombinant human granulocyte colony stimulating-factor or vehicle was given daily after intoxication (4 days) or before (7 days) and after carbon tetrachloride administration. Liver injury and regeneration were assessed 2 and 4 days after damage. Bone marrow cells mobilization was evaluated by the white blood cell count and the assessment of circulating clonogenic haematopoietic progenitors (colony forming unit-cells).

RESULTS

In this experimental model, although granulocyte colony stimulating-factor induced the significant mobilization of colony forming unit-cells, the study cytokine had no effect on liver injury (serum alanine amino transaminase level and necrotic index) and liver regeneration (mitotic index and bromodeoxyuridine incorporation), regardless of the administration schedule.

CONCLUSIONS

This study does not support the conclusion that: (1) granulocyte colony stimulating-factor exerts a protective effect against toxic-induced, non-lethal acute liver injury and (2) promotes hepatocyte regeneration.

Mobilization of bone marrow-derived hematopoietic and endothelial stem cells after orthotopic liver transplantation and liver resection

In animals, the bone marrow (BM) is a source of liver-repopulating cells with therapeutic potential in case of tissue damage. However, the early response of human BM-derived stem cells (SC) to liver injury is still unknown. Here, we studied 24 patients undergoing orthotopic liver transplantation (OLT) for end-stage liver disease or hepatocellularcarcinoma, and 13 patients submitted to liver resection. The concentration of circulating BM-derived SC was determined by phenotypic analysis and clonogenic assays. Moreover, we assessed the serum level of inflammatory and tissue-specific cytokines. Reverse transcriptase-polymerase chain reaction and fluorescence-in situ hybridization were also used to characterize mobilized SC. At baseline, patients showed a significant lower concentration of circulating CD133(+), CD34(+) SC and clonogenic progenitors (colony-forming unit cells) than healthy controls. However, the time-course evaluation of peripheral blood cells after OLT demonstrated the significant early mobilization of multiple subsets of hematopoietic and endothelial stem/progenitor cells. Cytogenetic and molecular analyses of CD34(+) cells showed the host origin of mobilized SC and the expression of transcripts for GATA-4, cytokeratin 19, and alpha-fetoprotein hepatocyte markers. In contrast with OLT, only total circulating CD34(+) cells significantly increased after liver resection. Mobilization of BM cells after OLT or liver surgery was associated with increased serum levels of granulocyte-colony stimulating factor, interleukin-6, stem cell factor, hepatocyte growth factor, and vascular endothelial growth factor. In summary, we demonstrate that tissue damage after OLT and liver resection induces increased serum levels of multiple cytokines but only ischemia/reperfusion injury associated with OLT results in the remarkable mobilization of BM stem/progenitor cells.