Implication of stem cell factor in human liver regeneration after transplantation and resection

Controlled Attenuation Parameter Is Associated with a Distinct Systemic Inflammatory Milieu after Clearance of HCV Infection

Hepatitis C virus (HCV) infection is closely associated with lipid metabolism defects along with a high prevalence of hepatic steatosis. After HCV clearance, steatosis persists in many patients. However, the reasons behind this phenomenon are not completely clear. To investigate the association between 92 soluble inflammatory mediators (SIMs) and the steatosis grade, we made use of a cohort of 94 patients with chronic HCV infection who cleared HCV after direct-acting antiviral agent (DAA) treatment. Patients were classified into three groups according to their controlled attenuation parameter (CAP). CAP is associated with ALT, γ-GT and liver stiffness after HCV clearance. While stem cell factor (SCF) and tumor necrosis factor ligand superfamily member 12 (TWEAK) levels were significantly reduced in patients with CAP > 299 dB/m, the levels of fibroblast growth factor (FGF)-21 and interleukin-18 receptor 1 (IL-18R1) were higher in those patients at week 96 after virus clearance. These four markers also showed a linear correlation with CAP values. FGF-21 levels correlated with CAP only after HCV clearance. Taken together, these four biomarkers, namely SCF, TWEAK, FGF-21 and IL-18R1, are associated with CAP status after virus clearance. A potential role of these proteins in the pathogenesis of post-sustained viral response (SVR) nonalcoholic steatohepatitis requires further investigation.

Long-lasting Imprint in the Soluble Inflammatory Milieu despite Early Treatment of Acute Symptomatic Hepatitis C

Background

Treatment with direct-acting antivirals (DAAs) in patients with chronic hepatitis C infection leads to partial restoration of soluble inflammatory mediators (SIMs). In contrast, we hypothesized that early DAA treatment of acute hepatitis C virus (HCV) with DAAs may normalize most SIMs.

Methods

In this study, we made use of a unique cohort of acute symptomatic hepatitis C patients who cleared HCV with a 6-week course of ledipasvir/sofosbuvir. Plasma samples were used for proximity extension assay measuring 92 proteins.

Results

Profound SIM alterations were observed in acute HCV patients, with marked upregulation of interleukin (IL)-6 and CXCL-10, whereas certain mediators were downregulated (eg, monocyte chemoattractant protein-4, IL-7). During treatment and follow-up, the majority of SIMs decreased but not all normalized (eg, CDCP1, IL-18). Of note, SIMs that were downregulated before DAA treatment remained suppressed, whereas others that were initially unchanged declined to lower values during treatment and follow-up (eg, CD244).

Conclusions

Acute hepatitis C was associated with marked changes in the soluble inflammatory milieu compared with both chronic hepatitis patients and healthy controls. Whereas early DAA treatment partly normalized this altered signature, long-lasting imprints of HCV remained.

Serum Levels of Granulocyte-Macrophage-colony-stimulating Factor and Stem-cell Factor During Liver Regeneration after Partial Hepatectomy in Humans

BACKGROUND

Multiple biological functions have been recognized regarding Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) and Stem Cell Factor (SCF).

AIM

To evaluate the serum changes of GM-CSF and SCF in patients undergoing surgical resection for liver tumor, in the regenerative phase after surgery in order to identify the possible relationship with the patient, tumor or surgical variables.

METHODS

Thirty-two consecutive patients (50% male, median age 66), undergoing hepatic resection of liver neoplasm, were evaluated. The liver tumor was Hepatocellular Carcinoma (HCC) in 44% of cases. Other tumors were cholangiocarcinoma and metastasis. Serum levels of GM-CSF and SCF were assessed at baseline and 2 days, 7 days and 4 weeks after surgery. Personal and clinical patient data were also recorded. The statistical analysis was carried out using t-test for unpaired data or ANOVA (repeated measure) for continuous variables and Fisher test for discrete variables.

RESULTS

GM-CSF levels remained constant after surgery and were compared to baseline values. SCF levels, on the other hand, increased during the time, after surgery. The evaluation of SCF levels (fold increase) according to surgical, patient and tumor variables evidenced some differences. At day 7 and week 4, SCF levels were statistically increased: i) in patients undergoing a large resection in comparison with others (p<0.05); ii) in patients non-cirrhotic in comparison with cirrhotic ones (p=0.02) and finally; iii) in patients with non-HCC tumor in comparison with HCC ones (p=0.02).

CONCLUSION

During liver regeneration in humans, SCF serum levels are increased allowing to hypothesize a possible role of this chemokine during tissue growth and remodeling.

Transplantation of ATP7B-transduced bone marrow mesenchymal stem cells decreases copper overload in rats

BACKGROUND

Recent studies have demonstrated that transplantation of ATP7B-transduced hepatocytes ameliorates disease progression in LEC (Long-Evans Cinnamon) rats, a model of Wilson's disease (WD). However, the inability of transplanted cells to proliferate in a normal liver hampers long-term treatment. In the current study, we investigated whether transplantation of ATP7B-transduced bone marrow mesenchymal stem cells (BM-MSCs) could decrease copper overload in LEC rats.

MATERIALS AND METHODS

The livers of LEC rats were preconditioned with radiation (RT) and/or ischemia-reperfusion (IRP) before portal vein infusion of ATP7B-transduced MSCs (MSCsATP7B). The volumes of MSCsATP7B or saline injected as controls were identical. The expression of ATP7B was analyzed by real-time quantitative polymerase chain reaction (RT-PCR) at 4, 12 and 24 weeks post-transplantation. MSCATP7B repopulation, liver copper concentrations, serum ceruloplasmin levels, and alanine transaminase (ALT) and aspartate transaminase (AST) levels were also analyzed at each time-point post-transplantation.

RESULTS

IRP-plus-RT preconditioning was the most effective strategy for enhancing the engraftment and repopulation of transplanted MSCsATP7B. This strategy resulted in higher ATP7B expression and serum ceruloplasmin, and lower copper concentration in this doubly preconditioned group compared with the saline control group, the IRP group, and the RT group at all three time-points post-transplantation (p<0.05 for all). Moreover, 24 weeks post-transplantation, the levels of ALT and AST in the IRP group, the RT group, and the IRP-plus-RT group were all significantly decreased compared to those of the saline group (p<0.05 compared with the IRP group and RT group, p<0.01 compared with IRP-plus-RT group); ALT and AST levels were significantly lower in the IRP-plus-RT group compared to either the IRP group or the RT group (p<0.01 and p<0.05. respectively).

CONCLUSIONS

These results demonstrate that transplantation of MSCsATP7B into IRP-plus-RT preconditioned LEC rats decreased copper overload and was associated with an increase in MSC engraftment and repopulation.

Differential bone marrow hematopoietic stem cells mobilization in hepatectomized patients

BACKGROUND

The involvement of bone marrow hematopoietic stem cells (BMHSC) mobilization during liver regeneration from hepatectomized patients is under debate. The main aim of this study was to investigate the role of BMHSC mobilization after hepatic resection in 33 patients with liver disease.

METHODS AND RESULTS

Mobilization of CD34(+) BMHSC after 72 h of surgery was found in peripheral blood of some, but not all, of the hepatectomized patients. These CD34(+) cells co-expressed other stem cells markers. The patients without BMHSC mobilization showed high levels of circulating and liver tissue BMHSC (CD34(+) cells) previous to surgery. Therefore, two types of patients: "mobilizers" and "non-mobilizers" were distinguished based on the values of CD34(+) cells before and after surgery. Changes in cytokines involved in the hepatic regeneration (HGF and TGF-β), and in BMHSC mobilization process (SCF, SDF-1, IL-12, or MMP-2), were detected in both groups. In addition, a higher activation previous to surgery of the SDF-1/CXCR4 axis in liver tissue was observed in non mobilizers patients compared to mobilizer patients.

CONCLUSION

BMHSC mobilization seems to be associated with variations in the levels of cytokines and proteolytic enzymes involved in hepatic regeneration and bone marrow matrix degradation. Hepatectomy may be an insufficient stimulus for BMSHC mobilization. The pre-hepatectomy higher levels CD34(+) cells in peripheral blood and liver, associated to the activation of hepatic SDF-1/CXCR4 axis, suggest a BMHSC mobilization process previous to surgery in non mobilizer patients.

Expression of stem cell factor receptor c-kit in human nontumoral and tumoral hepatic cells

INTRODUCTION

The aim of this study was to examine and compare the stem cell factor receptor c-kit expression in hepatocellular carcinoma (HCC) with the corresponding peritumoral tissue. To confirm the immunohistochemical results in the investigated HCC tissues, HCC cell lines were analyzed for c-kit expression.

METHODS

Expression of c-kit (SCF receptor) has been evaluated in 72 HCC and in the corresponding surrounding nontumorous tissue. Additionally, immunohistochemical analysis reverse transcription-polymerase chain reaction was also used to examine the mRNA expression of c-kit protooncogene in tumor homogenates. Furthermore, three HCC cell lines (HUH-7, HepG2, and SK-Hep1) were used for gene-expression analysis of c-kit mRNA.

RESULTS

C-kit expression was detected immunohistochemically in 70% of HCC with different degrees of intensity. Moreover, c-kit expression could also be found in about 90% of the corresponding peritumoral noncirrhotic as well as in cirrhotic liver tissues. C-kit mRNA was detectable in 83% of HCC and in 75% of the corresponding peritumoral noncirrhotic as well as in 100% of corresponding peritumoral cirrhotic samples. In addition, two of the three HCC cell lines (HUH-7 and SK-Hep1) showed a well detectable PCR-product for c-kit.

CONCLUSION

Hepatocytes express the c-kit receptor at different grade of intensity under normal and altered pathological conditions. The presence of c-kit on HCC cell lines supports the assumption that SCF might play a role in the regulation of proliferative activity of tumorous and nontumorous hepatic cells.

Serum levels of stem cell factor and their clinical significances in patients with severe hepatitis

AIM: To investigate the serum levels of stem cell factor (SCF) and their clinical significances in patients with severe hepatitis.

METHODS: A total of 45 hepatitis patients (including 15 cases of acute hepatitis, 16 cases of chronic hepatitis and 14 cases of severe hepatitis) and 15 healthy subjects (as controls) were collected from our hospital . The severe hepatitis patients were divided into survival subgroup (n = 4) and death subgroup (n = 10). Serum levels of SCF were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS: The levels of serum SCF were significantly higher in severe hepatitis than those in acute hepatitis, chronic hepatitis and the controls (2403.1 ± 42.8 ng/L vs 2354.9 ± 19.0 ng/L, 2376.7 ± 16.4 ng/L, 2358.4 ± 16.0 ng/L; all P < 0.05), and also higher in the death subgroup than those in the survival subgroup (2418.1 ± 50.7 ng/L vs 2376.3 ± 11.7 ng/L, P < 0.05). The levels of serum SCF showed significantly positive correlation (r = 0.38, P < 0.01) with those of hepatocyte growth factor (HGF) and significantly negative correlation with those of albumin and prothrombin time activity (PTA).

CONCLUSION: Serum levels of SCF may reflect the degree of hepatic injury and the prognosis of severe hepatitis patients, indicating that stem cells may be required for liver regeneration in severe hepatitis patients.

Elevation of serum stem-cell factor in postoperative biliary atresia

BACKGROUND

Biliary atresia (BA) is one of the most common causes of neonatal cholestasis. Stem-cell factor (SCF) has been implicated in the development of fibrosis in various diseases. The objective of the present study was to examine the significant role of SCF in BA.

METHODS

Fifty-seven pediatric patients with BA after Kasai operation and 30 healthy children were recruited. The mean ages of BA patients and controls were 6.1 +/- 0.6 years and 6.1 +/- 0.7 years, respectively. The patients were categorized into two groups according to their serum levels of total bilirubin (TBil < 2 mg/dL, no jaundice vs TBil > or = 2 mg/dL, persistent jaundice) and alanine aminotransferase (ALT < 100 vs ALT > or = 100 U/L). The serum SCF levels were determined on commercially available enzyme-linked immunosorbent assay.

RESULTS

The mean serum SCF level of the BA children was higher than that of normal controls (748.3 +/- 17.9 pg/mL vs 582.2 +/- 17.3 pg/mL; P < 0.001). Subsequent analysis demonstrated that the BA patients with serum ALT > or = 100 U/L had significantly greater levels of serum SCF compared to those with serum ALT < 100 U/L (796.5 +/- 22.6 pg/mL vs 694.7 +/- 25.0 pg/mL, respectively; P = 0.002). In addition, serum SCF levels were significantly elevated in the patients with portal hypertension (PH) compared with those without PH (810.0 +/- 18.8 pg/mL vs 634.1 +/- 20.1 pg/mL, P < 0.001).

CONCLUSION

The current study showed that BA patients had higher serum SCF levels compared with controls. The significant elevation in SCF levels is associated with the presence of PH and the degree of hepatic injury. These findings suggest that SCF may play a part in the pathogenesis of hepatic fibrosis in BA patients after Kasai procedure.

Mesenchymal stem cells over-expressing hepatocyte growth factor improve small-for-size liver grafts regeneration

Ischemia-reperfusion (I/R) associated with small-for-size liver transplantation (SFSLT) impairs liver graft regeneration. Mesenchymal stem cells (MSCs) have the capability, under specific conditions, of differentiating into hepatocytes. Hepatocyte growth factor (HGF) has potent anti-apoptotic and mitogenic effects on hepatocytes during liver injury, and has been utilized in many experimental and clinical applications. In this study, we implanted HGF-expressing MSCs into liver grafts via the portal vein, using a 30% small-for-size rat liver transplantation model. HGF, c-met expression, hepatic injury and liver regeneration were assessed after liver transplantation. Our study demonstrated that MSCs over-expressing HGF prevented liver failure and reduced mortality in rats after SFSLT. These animals also exhibited improved liver function and liver weight recovery during the early post-transplantation period. Using green fluorescent protein (GFP) gene as a marker, we demonstrated that the engrafted cells and their progeny incorporated into remnant livers and produced albumin. These findings suggest that MSCs genetically modified to over-express HGF and implanted in the liver graft, may offer a novel approach to promoting liver regeneration after small-for-size transplantations.

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.