No evidence of hematopoietic stem cell mobilization in patients submitted to hepatectomy or in patients with acute on chronic liver failure

Liver Macrophage Depletion Ameliorates The Effect of Mesenchymal Stem Cell Transplantation in a Murine Model of Injured Liver

Mesenchymal stem cells (MSCs) therapy show different levels of effectiveness in the context of different types of liver damage, suggesting that the microenvironment of the injured liver is a key determinant for effective stem cell therapy. The objective was to assess the modulatory effect of hepatic stem cell niche components on the transplanted MSCs during liver injury induced by carbon tetrachloride (CCl₄). Superparamagnetic iron oxide (SPIO)-labeled human MSCs were injected intravenously into mice treated with CCl₄ and subjected to hepatic macrophage-depletion. Liver tissues were collected at different intervals post transplantation for subsequent histopathological, morphometric, immunohistochemical, gene expression and ultrastructural studies. The homing of the transplanted MSCs was evidenced by tracing them within the niche by iron staining and immunohistochemical studies. MSCs differentiated into hepatocyte-like cells and intimal smooth muscle cells as evidenced by their expression of human albumin and α-smooth muscle actin with a concomitant increase in the level of mouse hepatocyte growth factor. A post transplantation reduction in the liver fibro-inflammatory reaction was found and was promoted by liver macrophages depletion. Thus, it could be concluded from the present study that prior manipulation of the microenvironment is required to improve the outcome of the transplanted cells.

Therapeutic effect of hepatocyte growth factor-overexpressing bone marrow-derived mesenchymal stem cells on CCl4-induced hepatocirrhosis

Hepatocirrhosis is one of the most severe complications of chronic hepatic disease in terms of medical intervention, and the available therapies are limited and not very successful. In this study, bone marrow-derived mesenchymal stem cells (BM-MSCs) from host rats were transduced with an adenoviral vector labelled with green fluorescent protein (EGFP) to overexpress hepatocyte growth factor (HGF). The therapeutic effect of these modified stem cells (HGF-BM-MSC group) transplanted intravenously into hepatocirrhosis model rats treated with CCl₄ was evaluated using serological, biochemical and histological approaches. We compared the rats in the HGF-BM-MSC group with those in the other groups (rats treated with BM-MSCs, rats treated with HGF and untreated rats (Controls)) in detail. The localisation of EGFP-tagged BM-MSCs in the injured liver was evaluated using a microscope, and the cells co-expressed hepatocyte nuclear factor 4α, albumin and cytokeratin 18. After treatment for 4 weeks, the HGF-BM-MSC, BM-MSC and HGF groups exhibited increased protein and mRNA levels of hepatocyte nuclear factor 4α, albumin and cytokeratin 18, but decreased levels of aspartate aminotransferase, alanine aminotransferase and total bilirubin. These findings indicate that BM-MSC transplantation and HGF application have great potential for the treatment of hepatocirrhosis.

PD-L1 Expression on Circulating CD34＋ Hematopoietic Stem Cells Closely Correlated with T-cell Apoptosis in Chronic Hepatitis C Infected Patients

Background and Objectives

Lack of understanding of the interplay between hematopoietic stem cells (HSCs) and the immune system has severely hampered stem cell research. Programmed death-1 (PD-L1) has been reported on parenchymal cells in patients with chronically inflamed livers and found to play an essential role in T cell homeostasis regulation. However, the bidirectional interaction between HSCs and lymphocytes remains elusive. Here, we aimed to get more insight into circulating CD34+ HSCs PD-L1 expression and T cell apoptosis in chronic HCV infected patients.

Methods

CD34+ HSCs were isolated and purified by immunomagnetic separation. PD-L1 expression was analyzed by quantitative PCR and flow cytometry. Furthermore, co-culture experiments between CD34+ HSCs and T-lymphocytes were established. T-cell lymphocyte apoptosis in peripheral blood and in cultures was detected.

Results

CD34+ HSCs constitutively express low levels of PD-L1. Its expression is up-regulated in chronic HCV infected patients. Moreover, PD-L1 expression on circulating CD34+ HSCs enhanced T cell apoptosis in peripheral blood and co-culture.

Conclusion

Our results suggest novel bidirectional interplay between HSCs and lymphocytes mediated by PD-L1 expression on CD34+ HSCs. PD-L1 expression correlated with T-cell lymphocyte apoptosis. This may contribute to immunomodulatory properties of HSCs which improves its use for allogeneic transplantation.

Circulating CD34+ hematopoietic stem/progenitor cells paralleled with level of viremia in patients chronically infected with hepatitis B virus

Introduction: Liver regeneration is a heterogeneous process involving proliferation of different cell types in response to injury. Bone marrow derived stem cells may be involved in this process, by making contribution to parenchymal restoration and cellular replacement. We aimed to investigate the correlation between level of circulating mobilized CD34+ hematopoietic stem progenitor cells (HSPCs) and viremia level in patients chronically infected with hepatitis B virus (HBV).

Methods: Blood samples were prospectively collected for assessing percentage and absolute counts of circulating CD34+ HSPCs and viral load level using flow cytometry and RT-PCR respectively. Patients with chronic hepatitis B (CHB) (n = 30), Entecavir (ETV) treated subjects (n = 30) and 20 age and gender matched healthy controls were enrolled in this study. Results were expressed as mean ± SD.

Results and discussion: A significant increase in circulating CD34+ HSPCs level was observed in CHB patients (5 ± 3.1, 324 ± 195 × 10³/ml) as compared to ETV treated subjects (0.57 ± 0.27,1022 ± 325) and healthy controls (0.53 ± 0.37, 694 ± 254, P < 0.001) in regards to percentage and absolute counts respectively. Levels of CD34+ HSPCs strongly and positively correlated with HBV DNA viral load levels in CHB patients (r² = 0.8417, 0.649, P < 0.001).Thus, in chronic liver disorders (CHB), when reduced regenerative capacity of hepatocytes is reached, BMSCs mobilization occurs and their level increases in peripheral blood. The level of circulating CD34+ cells in peripheral blood of CHB patients paralleled with the hepatitis B viral load.

The hematopoietic stem cell number in the peripheral blood of pediatric recipients correlates with the outcome after living donor liver transplantation

It has been proposed that circulating HSCs play a role in graft survival after liver transplantation. The aim was to analyze the relationship between the number of HSCs before and after LDLT and liver function, immune biomarkers, and clinical outcomes in pediatric patients. We studied 15 pairs of adult healthy liver donors and pediatric recipients with ESLD. The CD34/CD45+ cell number was measured in the blood via flow cytometry, and plasma levels of immune biomarkers - via ELISA. CD34/CD45+ cell number in the recipients decreased within the first week after LDLT. The cell number before LDLT was negatively correlated with the plasma levels of CRP and the development of graft dysfunction in the early post-transplant period. After LDLT, the CD34/CD45+ cell number was positively correlated with the pretransplant plasma level of sCD40L, a T-cell activation marker. In adult liver donors, the cell number did not change within the first week after liver resection and was lower than in pediatric recipients. The results suggest that in pediatric recipients, the HSC number may be associated with graft function and could be regarded as a potential predictor of the clinical outcome after LDLT.

Effects of bone marrow-derived mesenchymal stem cells transplanted via the portal vein or tail vein on liver injury in rats with liver cirrhosis

The aim of the present study was to compare the effects of bone marrow-derived mesenchymal stem cells (BMSCs) transplanted via the portal vein or tail vein on liver injury in rats with liver cirrhosis. BMSCs were isolated from rat bone marrow and labeled with green fluorescent protein (GFP). Then, the labeled BMSCs were injected into rats with liver injury via the portal vein or tail vein. Two weeks after transplantation, three rats in each group were sacrificed to test the distribution of GFP in the liver and the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin. Six weeks later, the remaining rats were sacrificed, and serum ALT, AST, albumin, hyaluronic acid (HA), laminin (LN) and procollagen type III (PC-III) levels were measured. The expression of albumin in the liver was analyzed by immunohistochemistry. Two weeks after BMSC transplantation, GFP-positive cells were detected in the livers of rats with BMSCs transplanted via the portal vein and tail vein. Compared with pre-transplantation levels, the ALT levels of the groups with BMSC transplantation via the portal vein and tail vein were significantly decreased after two and six weeks of BMSC transplantation (P<0.05), whereas the AST and albumin levels were not significantly different at two weeks after BMSC transplantation in the two groups (all P>0.05). However, the AST and albumin levels were significantly reduced at six weeks after BMSC transplantation (all P<0.05). At six weeks after BMSC transplantation, the serum HA, LN and PC-III levels in rats transplanted with BMSCs via the portal vein or tail vein had decreased significantly (all P<0.05), as compared with the levels prior to BMSC transplantation. BMSCs transplanted via the portal vein and tail vein achieved similar improvements in liver function in rats with liver cirrhosis, which suggests that peripheral venous administration is a convenient and effective route for BMSC transplantation.

Splenectomy increases the number of circulating hematopoietic stem/progenitor cells in patients with hepatitis C virus-associated liver cirrhosis

AIM

The spleen is not believed to contribute to hematopoiesis in healthy adults. However, several reports have demonstrated that the spleen in adults contains a large number of hematopoietic stem/progenitor cells (HSC). Although splenectomy increases platelet and leukocyte counts, the effects of splenectomy on circulating HSC have not been elucidated. In this study, we evaluated the association between the number of circulating HSC and splenectomy in patients with hepatitis C virus (HCV)-associated liver cirrhosis (LC).

METHODS

In 48 patients with various stages of HCV-associated chronic liver disease and seven patients with LC who underwent splenectomy, and 10 healthy volunteers, we determined the numbers of circulating CD34+ cells and colony-forming unit culture by flow cytometry and methylcellulose culture, respectively. Plasma stromal cell-derived factor-1α (SDF-1α) concentrations were measured using an enzyme-linked immunosorbent assay.

RESULTS

The numbers of circulating CD34+ cells and colony-forming unit culture decreased but the plasma SDF-1α concentration increased with the progression of liver disease. There was an inverse correlation between the number of circulating HSC and the plasma SDF-1α concentration. The numbers of circulating HSC and platelets were determined before and after splenectomy in seven patients with LC. In these patients, the numbers of circulating HSC and platelets increased significantly after splenectomy and the enhancing effect persisted for a long time.

CONCLUSION

Our data suggest that the spleen plays an important role in modulating HSC dynamics in patients with HCV-associated chronic liver disease. Our results also imply that splenectomy may improve liver function in patients with LC.

Concise review: bone marrow autotransplants for liver disease?

There are increasing reports of using bone marrow-derived stem cells to treat advanced liver disease. We consider several critical issues that underlie this approach. For example, are there multipotent stem cell populations in human adult bone marrow? Can they develop into liver cells or supporting cell types? What are stromal stem/progenitor cells, and can they promote tissue repair without replacing hepatocytes? Does reversal of end-stage liver disease require new hepatocytes, a new liver microenvironment, both, neither or something else? Although many of these questions are unanswered, we consider the conceptual and experimental bases underlying these issues and critically analyze results of clinical trials of stem cell therapy of end-stage liver disease.

CD34+ hematopoietic stem cells mobilization, paralleled with multiple cytokines elevated in patients with HBV-related acute-on-chronic liver failure

BACKGROUND

Recent studies indicate that bone marrow (BM)-derived stem cells contribute to liver regeneration. But limited information is available on the dynamic and mechanisms of mobilization of BM-derived hematopoietic stem cells (HSCs) after acute-on-chronic liver failure (ACLF).

AIMS

The purpose of this study was to assess the mobilization of BM-derived CD34+ HSCs in ACLF patients, and elucidate the association of stress-induced cytokines in HSCs mobilization and/or liver repair in ACLF patients.

METHODS

Thirty patients with HBV-related ACLF, 30 patients undergoing chronic hepatitis B, and 20 healthy controls were enrolled. The percentages of peripheral blood CD34+ cells were determined by two-color flow cytometry. The hepatic commitment of mobilized CD34+ cells was investigated by RT-PCR. The serum levels of stress-induced cytokines were determined by enzyme-linked immunosorbent assays.

RESULTS

A significant increase of circulating CD34+ cells was observed in ACLF patients. RT-PCR analyses showed that the mobilized CD34+ cells expressed both CD34 mRNA and liver-specific markers including cytokeratin 19 and α-fetoprotein. In parallel with mobilization of BM-derived CD34+ cells, elevated serum levels of hepatocyte growth factor, interleukin-6, stem cell factor, granulocyte colony-stimulating factor and matrix metalloproteinase 9 were observed in ACLF patients.

CONCLUSION

We demonstrated that ACLF led to mobilization of CD34+ cells, which had a hepatic differentiation potential.

Hematopoietic stem cell mobilization into the peripheral circulation in patients with chronic liver diseases

OBJECTIVE

The present study was aimed to investigate and compare the kinetics of bone marrow-derived hematopoietic stem cells (BMHSC) migration in the peripheral blood and liver in response to liver injury in patients with chronic liver disease (CLD).

METHODS

In all, 45 CLD patients staged with Child-Pugh A, B and C and 15 healthy participants were evaluated for the concentration of circulating BMHSC by a flow cytometric analysis of CD133(+) /CD34(+) cells. In addition, homing BMHSC and hepatic progenitors were assessed by the immunohistochemical detection of CD133(+) and OV6(+) cells in liver biopsy specimens from Child-Pugh A and B patients.

RESULTS

No significant difference in the percentage of circulating CD133(+) /CD34(+) cells was observed among all groups of patients. In liver tissues, OV6(+) cells increased significantly in Child-Pugh B cases (P < 0.05), while CD133(+) cells were distributed sparsely in the periportal region in Child-Pugh A and B patients. OV6(+) cells were significantly correlated with CD34(+) cells but not with CD133(+) cells in Child-Pugh A and B patients (P < 0.01 and P < 0.05, respectively).

CONCLUSIONS

Various degrees of severity in CLD neither evoked the mobilization of BMHSC into the circulation nor triggered their homing into liver tissue, thus excluding extrahepatic stem cell-mediated repair. The recovery process seems to be dependent on proliferating endogenous liver progenitors (OV6(+) cells).

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.

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.

Bone marrow stem cells contribute to alcohol liver fibrosis in humans

Bone marrow-derived stem cell (BMSC) contribution to liver repair varies considerably and recent evidence suggests these cells may contribute to liver fibrosis. We investigated the mobilization and hepatic recruitment of bone marrow (BM) stem cells in patients with alcohol liver injury and their contribution to parenchymal/non-parenchymal liver cell lineages. Liver biopsies from alcoholic hepatitis (AH) patients and male patients, who received a female liver transplant and developed AH, were analyzed for BM stem cell content by fluorescence in situ hybridization and immunostaining. Y chromosome analysis was performed, along with co-staining for hepatocyte, biliary, myofibroblast, and Ki-67 markers. Blood CD34(+) levels were quantified in AH patients by flow cytometry. AH patients had increased CD34(+) cell counts in liver tissue (1.834% +/- 0.605%; P < 0.05) and in blood (0.195% +/- 0.063%; P < 0.05) as compared with matched controls (0.299% + 0.208% and 0.067% +/- 0.01%). A proportion of hepatic myofibroblasts were BM-derived (7.9%-26.8%) as deemed by the co-localization of Y chromosome/alpha-smooth muscle actin (alpha-SMA) staining. In the cross-sex liver grafts with AH, 5.025% of the myofibroblasts were co-staining for CD34, suggesting that a population of CD34(+) cells were contributing to the hepatic myofibroblast population. There was no evidence of BM contribution to hepatocyte or biliary cell differentiation, nor evidence of increased hepatocyte regeneration. Alcohol liver injury mobilizes CD34(+) stem cells into the circulation and recruits them into the liver. These BMSCs contribute to the hepatic myofibroblast population but not to parenchymal lineages and do not promote hepatocyte repair.

Stem cells in acute liver failure

Patients with acute liver failure are a particularly challenging group, with unique difficulties faced in treatment decisions. Life-saving therapy is available, but organ shortage, delays in transplantation, and complications in management result in a high mortality in this group of patients even after transplant. Any pharmacologic intervention that improved outcomes in this population of critically ill patients would be of great benefit. Based on available evidence, different scenarios of participation of HSCs in liver recovery are conceivable. Encouraging HSCs to differentiate into hepatocytes or supply paracrine and cellular level support to accelerate ongoing local repair mechanisms and assist a failing liver with inadequate mass and functional capacity might be directed to occur effectively in humans. Evidence within small animal models of liver injury and observations within the human population suggest that this might also be encouraged. The use of pharmacologic agents to mobilize hematopoietic stem cells is well established and effectively used in a different population of patients. As such, extending the use of these drugs, such as plerixafor, to the human population has a sound basis. However, there is a need for clarification of the mechanisms by which these cells exert their effect as well as which specific population of cells is involved in the regenerative process. To be clinically relevant in scenarios of acute liver failure, stem cell mobilizing strategies would have to impact survival when administered well after injury. Applications in other settings may also prove useful. Limits to liver resection exist where the size of the future liver remnant governs the extent of resection possible. Preexisting functional impairment may be restrictive, and strategies involving stem cells may assist the future liver remnant in both normal and functionally impaired livers. Benefit has already been reported from treatment with G-CSF in other injured tissues, including the injured myocardium and acutely injured kidney. However, as yet no clinical trial exists to assess the effects of stem cell mobilization in humans with acute liver failure. The familiarity in the use of and success demonstrated in the clinical and experimental use of plerixafor and G-CSF make exploration of hematopoietic stem cells as therapy in patients with acute liver failure appealing.

Granulocyte colony-stimulating factor enhances bone marrow mononuclear cell homing to the liver in a mouse model of acute hepatic injury

BACKGROUND

Experiments have reported that granulocyte colony stimulating factor (G-CSF) can mobilize stem cells. However, few studies have examined the effect of G-CSF on bone marrow mononuclear cell (BMMC) mobilization, in particular regarding their capability to home to acutely injured liver.

AIMS

The aim of this study was to evaluate the effort of G-CSF on BMMC homing to the liver following chemically-induced hepatic failure.

METHODS

BMMC were isolated from mice, pre-labeled with PKH26 and infused into the mice in which hepatic injury had been induced followed by administration of G-CSF or vehicle. Livers were studied by fluorescent microscopy after transplantation of pre-labeled BMMC.

RESULTS

PKH26 labeled cells were found in liver tissue at 102 ± 10 cells/high power field in the BMMC+G-CSF group and 30 ± 5 cells/high power field in the BMMC group, but none in the G-CSF group and the control group (P < 0.05). In the former two groups the majority of PKH26 labeled cells colocalized with proliferative cell nuclear antigen (PCNA). The number of PCNA positive cells in the BMMC+G-CSF group was 20 ± 4 cells/high power field, while in the BMMC group it was 14 ± 2 cells/high power field, in the G-CSF group 12 ± 2 cells/high power field, and 8 ± 1 cells/high power field in the control group. Moreover, albumin expression was increased in the BMMC+G-CSF treated group (149 ± 7/high power field) relative to the BMMC group (48 ± 6/high power field), the G-CSF group (44 ± 5/high power field) and the vehicle group (30 ± 6/high power field), with the former three groups showing elevated levels as compared to vehicle control (30 ± 6) (P < 0.05).

CONCLUSION

Transplanted BMMC may home to injured liver, which appears to be enhanced by G-CSF administration.

Stem cell mobilization is life saving in an animal model of acute liver failure

OBJECTIVE

No therapy except liver transplantation currently exists for patients with acute liver failure (ALF). The aim of this study was to determine whether pharmacologic mobilization of endogenous hematopoietic stem cells (HSCs) can aid in liver repair and improve survival in an animal model of ALF.

METHODS

Rodents were treated with a single near-lethal intraperitoneal injection of carbon tetrachloride (CCl4). After 12 hours, animals were randomized to receive plerixafor and granulocyte colony-stimulating factor (G-CSF), agents known to mobilize marrow-derived stem cells, or saline vehicle injection. Mice were observed for survival, and serial assessment of liver injury by serum transaminase measurements, and histologic analysis was performed.

RESULTS

In our ALF model, 7-day survival after injection of CCl4 was 25%. Administration of plerixafor and G-CSF following CCl4 resulted in 87% survival (n = 8, P < 0.05). On serial histopathologic analysis, animals treated with plerixafor and G-CSF demonstrated less hepatic injury compared with control animals. Evaluation of peripheral blood demonstrated an increase in circulating HSCs in response to plerixafor and G-CSF, and immunostaining suggested the infiltration of HSCs into the hepatic parenchyma after stem cell mobilization.

CONCLUSIONS

Our results suggest a possible new treatment strategy for patients with ALF, a group for whom either liver transplantation or death is frequently the outcome. Pharmacologic agents that mobilize HSCs may lead to an infiltration of the injured liver with cells that may participate in or expedite liver regeneration. This therapy has the potential to avert liver transplantation in some patients with ALF and may be of benefit in a wide variety of medical and surgical patients with liver injury.

Bone marrow-derived stem cells in liver repair: 10 years down the line

Hematopoietic stem cells have potential in the field of regenerative medicine because of their capacity to form cells of different lineages. Bone marrow stem cells have been shown to contribute to parenchymal liver cell populations, and although this may not be functionally significant, it has sparked interest in the field of autologous stem cell infusion as a possible treatment for cirrhosis. In this review, we will examine the evidence for the contribution of bone marrow-derived cells to populations of liver cells and for the functional contribution of bone marrow-derived cells to both liver fibrosis and repair. The mechanisms by which cells are trafficked from the bone marrow to the liver are complex; the stromal derived factor-1/CXC receptor 4 axis is central to this process. There are limited data in liver injury, but we will examine findings from the bone marrow transplantation literature and discuss their relevance to liver disease. Stromal derived factor-1 also has a role in endogenous liver stem cell accumulation. Some groups have already started infusing autologous bone marrow cells into patients with cirrhosis. We will review these trials in the context of the basic science that we have discussed, and we will consider targets for investigation in the future.

Regeneration of graft livers and limited contribution of extrahepatic cells after partial liver transplantation in humans

BACKGROUND

Liver regeneration is still not fully understood. Partial liver transplantation (LT) can provide the opportunity to investigate the mechanisms of liver regeneration, including the contribution of extrahepatic cells to liver regeneration.

METHODS

Of 61 patients transplanted with partial liver graft between August 1997 and October 2006, 56 patients were studied, including 49 adults and 7 children. Sequential computed tomography volumetric analysis was performed for volume measurement, while proliferating cell nuclear antigen (PCNA) labeling index was investigated for liver cell proliferation in nonprotocol liver biopsy specimens. In addition, 15 male recipients who had female liver grafts were investigated in order to detect Y chromosomes as extrahepatic cells in nonprotocol liver biopsy specimens.

RESULTS

Graft volume per standard liver volume was markedly increased after adult-to-adult living-donor (LD) LT. In pediatric transplants, there was no volume increase over time. PCNA labeling index was vigorous in adult-to-adult LDLT in the early period after LDLT. No Y chromosome was evident in hepatocytes from female-donor male-recipient grafts during or after liver regeneration. However, in the cases of failing grafts of this type, many Y-chromosome-positive cells were observed in the graft liver. The character of those cells was CD34(-), CK9(-), hepatocyte-specific antigen(-), and CD68(+/-).

CONCLUSION

In adult-to-adult LDLT, vigorous liver regeneration occurs in the graft liver, demonstrated by not only volumetric but cell kinetic analysis. Involvement of extrahepatic cells in normal liver regeneration seems limited.

Adhesion of human haematopoietic (CD34+) stem cells to human liver compartments is integrin and CD44 dependent and modulated by CXCR3 and CXCR4

BACKGROUND/AIMS

Haematopoietic stem cells (HSC) have previously been shown in some studies to migrate to damaged and diseased liver where a small proportion will engraft. Such cells can promote liver repair in rodent models of liver injury and lead to improved liver function in uncontrolled clinical studies. In order to maximize the engraftment of cells for clinical applications it is necessary to understand the molecular mechanisms that regulate stem cell recruitment and retention. Our aim therefore was to determine which factors where involved in adhesion of circulating HSC to liver endothelium and sequestration around epithelial cells within the liver.

METHODS

We examined the ability of CD34+ populations from peripheral and mobilized blood and the CD34-expressing cell line KG1a to bind to human hepatic sinusoidal endothelial (HSEC) and biliary epithelial cells (BEC) in vitro.

RESULTS

We report that all CD34(+) populations express alpha4beta1, beta2 integrins and CD44. Liver tissue sections and primary liver cells expressed the corresponding ligands VCAM-1/fibronectin, ICAM-1 and CD44. Pertussis toxin was shown to decrease binding of CD34(+) cells and the cells migrated to CXCR3 and CXCR4 ligands.

CONCLUSIONS

CD34(+) populations use alpha4beta1, beta2 integrins and CD44 receptors to bind to the ligands VCAM-1/fibronectin, ICAM-1, and hyaluronic acid expressed on sinusoidal vessels in tissue sections and to primary human HSEC. Binding to BEC was mediated by the interaction of beta1 and beta2 integrins with VCAM-1 and ICAM-1 respectively. A role for chemokines is supported by our finding that pertussis toxin inhibits CD34(+) cell adhesion to BEC and HSEC and by the ability of CD34(+) cells to migrate to CXCR3 and CXCR4 ligands.

Autologous bone marrow cell infusion therapy for liver cirrhosis

The plasticity of bone marrow cells (BMC) has been confirmed by autopsy results of female recipients of BMC from male donors. To establish new clinical therapies for patients with liver cirrhosis using autologous BMC, we developed a new in vivo murine model using green fluorescent protein (GFP) and repeated carbon tetrachloride (CCl(4)) injection. We found that BMC infused through the tail vein, efficiently repopulated cirrhotic liver tissue and, under the influence of persistent liver damage induced by carbon tetrachloride, differentiated into albumin-producing hepatocytes. Moreover, such BMC infusions into mice with cirrhosis improved liver function and reduced mortality. The latter observation correlated with the strong expression of matrix metalloproteinases (MMP), particularly MMP-9, and reduced hepatic fibrosis. The results from the 'GFP/CCl(4) model' showed that cell therapy using autologous BMC has the potential to become an effective treatment for patients with liver failure due to advanced liver cirrhosis. This review summarizes previous findings plus these recent experimental results, as well as recent clinical trials of BMC transfusion into patients with end-stage chronic liver disease.

Bone marrow cell transplant does not prevent or reverse murine liver cirrhosis

We tested the effect of bone marrow cell (BMC) transplantation in either preventing or reversing cirrhosis on an experimental model of chronic liver disease. Female Wistar rats were fed a liquid alcohol diet and received intraperitoneal injections of carbon tetrachloride (CCl4) over 15 weeks. Ten animals (cell-treated group) received five injections of BMCs during the cirrhosis induction protocol (on the 4th, 6th, 8th, 10th, and 12th weeks) and four animals received the cells after liver injury was established through tail vein. Nine animals (nontreated group) were submitted to the previously described protocols; however, they received vehicle injections. Analyses were performed to verify whether the infusion of cells was effective in preventing the development of cirrhosis in our model of induction, and if the cells could reverse cirrhosis once it was established. Hepatic architecture and fibrotic septa were analyzed in liver slices stained with hematoxilin & eosin and Sirius red, respectively. Fibrosis quantification was measured by Sirius red histomorphometry. Indirect immunofluorescence was performed to detect the amount of tissue transglutaminase 2. Blood analyses were performed to assess liver injury and function by the assessment of alanine aminotransferase and albumin. Ultrasound was performed to analyze the portal vein caliber and presence of ascitis. Cirrhosis features (regenerative nodules and fibrous septa) were observed in histopathology after 15 weeks of continuous hepatic injury in nontreated and cell-treated groups. Collagen content, immunofluorescence analysis, and biochemical and ultrasound parameters were similar in nontreated and cell-treated groups; however, both groups showed significant differences compared to a normal control group. Cell infusions with bone marrow-derived cells seem to be ineffective in improving morphofunctional parameters of the liver when applied to chronic cases either during or after establishment of the hepatic lesion.

Feasibility and safety of G-CSF administration to induce bone marrow-derived cells mobilization in patients with end stage liver disease

BACKGROUND/AIMS

To evaluate feasibility, safety and pattern of bone marrow-derived cells (BMC) mobilization in patients with end stage liver cirrhosis following granulocyte-colony stimulating factor (G-CSF) administration.

METHODS

Eight patients with severe liver cirrhosis (Child-Pugh score B-C, spleen diameter less than 170 mm) were included. They were treated with G-CSF (5 microg/kg b.i.d for three consecutive days) to mobilize BMC, evaluated as circulating CD34+ve cells (flow cytometry) and myeloid CFU-GM progenitors (in vitro colony growth assay). Co-expression in CD34+ve cells markers of differentiation (Thy1, CD133, CXCR4, c1qRp) were investigated on CD34+ve cells by double direct immunofluorescence. Data from 40 healthy haematopoietic stem cell donors were used as controls.

RESULTS

Mobilization of CD34+ve cells occurred in all patients. It was paralleled by expansion of circulating CFU-GM progenitors. Circulating CD34+ve cells co-expressed epithelial and stem cell markers in both cirrhotics and volunteer stem cell donors. G-CSF was well tolerated, no adverse event occurred, a significant reversible increase of splenic longitudinal diameter was observed.

CONCLUSIONS

(i) G-CSF mobilization of BMC co-expressing epithelial and stem markers occurred in all cirrhotic patients; (ii) splenomegaly up to 170 mm does not prevent safe BMC mobilization following G-CSF in patients with end stage liver disease; (iii) mobilized BMC may represent an easy immature cell source potentially useful for novel approaches for liver regeneration.