Review article: a medicine based on cell transplantation -- is there a future for treating liver diseases?

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.

Granulocyte colony-stimulating factor in severe alcoholic hepatitis: a randomized pilot study

OBJECTIVES

Severe alcoholic hepatitis has high short-term mortality. The aim of this study was to test the hypothesis that treatment of patients with alcoholic hepatitis with granulocyte colony-stimulating factor (G-CSF) might mobilize bone marrow-derived stem cells and promote hepatic regeneration and thus improve survival.

METHODS

Forty-six patients with severe alcoholic hepatitis were prospectively randomized in an open study to standard medical therapy (SMT) plus G-CSF (group A; n=23) at a dose of 5 μg/kg subcutaneously every 12 h for 5 consecutive days or to SMT alone (group B; n=23) at a tertiary care center. We assessed the mobilization of CD34(+) cells on day 6, Child-Turcotte-Pugh (CTP), model for end-stage liver disease (MELD), and modified Maddrey's discriminant function (mDF) scores, and survival until day 90.

RESULTS

There was a statistically significant increase in the number of CD34(+) cells in peripheral blood in group A as compared with group B (P=0.019) after 5 days of G-GSF therapy. There was a significant reduction in median Δ change% in CTP, MELD, and mDF at 1, 2, and 3 months in group A as compared with group B (P<0.05). There was marked improvement in survival in group A as compared with group B (78.3% vs. 30.4%; P=0.001) at 90 days.

CONCLUSIONS

G-CSF is safe and effective in the mobilization of hematopoietic stem cells and improves liver function as well as survival in patients with severe alcoholic hepatitis.

Therapeutic liver repopulation for phenylketonuria

Problems with long-term dietary compliance in phenylketonuria (PKU) necessitate the development of alternative treatment approaches. Therapeutic liver repopulation with phenylalanine hydroxylase (PAH)-expressing cells following hepatocyte or haematopoietic stem cell transplantation has been investigated as a possible novel treatment approach for PKU. Successful therapeutic liver repopulation requires both a stimulus for liver regeneration at the time of cell transplantation and a selective growth advantage for the PAH+ donor cells. Unfortunately, wild-type PAH+ hepatocytes do not enjoy any growth advantage over PAH- cells. Successful correction of hyperphenylalaninemia following therapeutic liver repopulation has been accomplished only in an animal model that yields a selective advantage for the donor cells. Haematopoietic stem cell (HSC)-mediated therapeutic liver repopulation has not been reported in any hyperphenylalaninemic system, and the success of HSC-mediated liver repopulation for PKU may be limited by the slow kinetics of this approach. If therapeutic liver repopulation is to be employed successfully in humans with PKU, an effective method of providing a selective growth advantage for the donor cells must be developed. If this can be achieved, liver repopulation with 10-20% wild-type hepatocytes will likely completely normalize Phe clearance in individuals with PKU.

Therapeutic potential of adult bone marrow stem cells in liver disease and delivery approaches

Hematopoietic stem cells (HSCs) and mesenchymal stem cell (MSCs) are two main subtypes of bone marrow stem cells. Extensive studies have been carried out to investigate the therapeutic potential of BMSCs in liver disease. A number of animal and human studies demonstrated that either HSCs or MSCs could be applied to therapeutic purposes in certain liver diseases. The diseased liver may recruit migratory stem cells, particularly from the bone marrow, to generate hepatocyte-like cells either by transdifferentiation or cell fusion. Transplantation of BMSCs has therapeutic effects of restoration of liver mass and function, alleviation of fibrosis and correction of inherited liver diseases. There are still controversial results over the potential effects of BMSCs on liver diseases, and some of the discrepancies are thought to be lied in the differences of experimental protocols, differences in individual research laboratory, and the uncertainties of the techniques employed. Several potential approaches for BMSCs delivery in liver diseases have been proposed in animal studies and human trials. BMSCs can be delivered via intraportal vein, systemic infusion, intraperitoneal, intrahepatic, intrasplenic. The optimal stem cells delivery should be easy to perform, less invasive and traumatic, minimum side effects, and with high cells survival rate. In this review, we focus on the up-to-date evidence of therapeutic effects of BMSCs on liver disease, the characteristics of various delivery approaches, and the considerations for future studies.

Skeletal myogenesis by human primordial germ cell-derived progenitors

We have isolated and cultured human primordial germ cells (PGCs) from early embryos. The PGCs expressed embryonic germ (EG) cell-specific surface markers, including Oct4 and Nanos. We derived a cell population from these PGCs that we termed embryoid body-derived (EBD) cells. EBD cells can be extensively expanded in vitro for more than 50 passages and express lineage markers from all three primary germ layers. The myogenic potential of the EBD cells was examined both in vitro and in vivo.In vitro, the EBD cells can be induced to form multinucleated myotubes, which express late skeletal muscle-specific markers, including MHC and dystrophin, when exposed to human galectin-1. In vivo, the EBD cells gave rise to all the myogenic lineages, including the skeletal muscle stem cells known as satellite cells. Strikingly, these cells were able to partially restore degenerated muscles in the SCID/mdx mouse, an animal model of the Duchenne's muscular dystrophy. These results indicate the EBD cells may be a promising source of myogenic stem cells for cell-based therapies for muscle degenerative disorders.

Cellular Transplantation for Liver Diseases

Presently, the orthotropic liver transplantation (OLT) is still the most effective therapeutic for patients with acute or chronic hepatic failure. However, due to the shortage of donor livers, the number of patients benefited from this approach is limited. Therefore, some alternative modalities have been paid attention for restoring the liver function. The cell transplantation is one of the promising modalities to realize this purpose. The types of cells used in the cell transplantation include syngeneic hepatocytes, allogeneic hepatocytes, immortalized hepatocytes, and stem cells derived heptocytes. The stem cells, especially the adult stem cells from bone marrow, are shown as a promising cell source for liver repopulation. The mesenchymal bone marrow stem cells and embryonic stem cells can be induced to differentiate into the hepatic lineage and might be used in the cell transplantation for liver diseases. Compared to OLT, the advantages of cell-based therapy for liver disease are, but not limited to, less invasive, less expensive, easy manipulated, easy expansion of cells in vitro. Cells can be stored in a cell bank for future use. Though most of the current studies are experimental and animal based, the cellular therapy for liver disease is expected to be an effective alternative in clinical settings in near future.

Safety and efficacy profile of G-CSF therapy in patients with acute on chronic liver failure

BACKGROUND/AIM

We aimed to evaluate safety and efficacy of granulocyte-colony stimulating factor treatment in patients with acute on chronic liver failure and the effect of granulocyte-colony stimulating factor on the expression level of CXCR4, vascular endothelial growth factor receptor and very late activation antigen 4.

METHODS

Twenty-four patients with acute on chronic liver failure were randomised to receive standard therapy, standard therapy+granulocyte-colony stimulating factor (5 microg/kg/day for 6 days) and standard therapy+granulocyte-colony stimulating factor (15 microg/kg/day s.c. for 6 days). Data on CD34+cell mobilisation were compared to age-matched peripheral blood haematopoietic stem cell donors treated with granulocyte-colony stimulating factor. On day third of treatment, the expression level of CXCR4, vascular endothelial growth factor receptor and very late activation antigen 4 was analysed in mobilised CD34+ cells.

RESULTS

CD34 cell count increased after the second day of granulocyte-colony stimulating factor injection in both treatment groups compared to the linear increase observed in control. After the fifth day the increase was significantly higher in healthy donors versus patients with acute on chronic liver failure. A decrease in the expression of CXCR4, very late activation antigen 4 and vascular endothelial growth factor receptor compared to premobilisation values was observed. No major side effects were observed.

CONCLUSIONS

Granulocyte-colony stimulating factor treatment is able to induce CD34 mobilisation in patients with acute on chronic liver failure. The expression pattern of CXCR4, very late activation antigen 4 and vascular endothelial growth factor receptor suggests that these molecules are involved in the granulocyte-colony stimulating factor-induced stem cell mobilisation.

Rescue therapy by portal infusion of autologous stem cells in a case of drug-induced hepatitis

Recent efforts have been directed toward new therapeutic options to approach drug-induced hepatitis. We report a case of acute liver failure associated with Nimesulide in a 67-year-old man, with a medical history of chronic alcohol abuse. The biopsy was compatible with chronic alcoholic liver disease and acute drug-induced injury. The patient was enrolled to receive G-CSF followed by apheresis and selection of peripheral-blood stem cells. After ultrasound-guided injection of CD34+cells in the portal vein, we observed a rapid improvement of synthetic liver function, with particular reference to coagulation parameters. Liver biopsy performed 20 days after, showed wide areas of regeneration. In the next 30 days the laboratory signs of acute decompensation progressively improved. Unfortunately he died of multiple-organ failure related to bacterial infection. Intrahepatic injection of peripheral-blood stem cells seemed safe and produced good periprocedural results with improvement of synthetic profile, suggesting a possible role of stem cells in the regeneration process.

How does human stem cell therapy influence gene expression after liver injury? Microarray evaluation on a rat model

BACKGROUND

Tissue homeostasis is guaranteed by stem proliferating reserve, depending on dynamic changes in gene expression. A high plasticity is shown by the haematopoietic stem cells, potential source for liver regeneration.

AIM

We aimed to evaluate the gene expression modifications induced by human haematopoietic stem cell therapy after liver injury in rats.

SUBJECTS

Rats were sorted as follows: (A) human-haematopoietic stem cell injection after allyl alcohol liver damage; (B) only haematopoietic stem cell injection; (C) only allyl alcohol injection; and (D) sacrifice without any treatment.

METHODS

Livers, spleens and bone marrows were analysed with flow-cytometry. Livers were also studied by reverse-transcription PCR, histology, immunohistochemistry and microarray analysis; selected genes were confirmed by real-time PCR.

RESULTS

In subset A, haematopoietic stem cells were selectively recruited by liver, with respect to the group B, and they improved the liver regeneration process compared to group C. As regards microarrays, haematopoietic stem cell infusion upregulates 265 genes and downregulates 149 genes. Differentially regulated genes belong to a broad range of functional pathways, including proliferation, differentiation, adhesion/migration and transcripts related to oval-cell activation. Real-time PCR validated array results.

CONCLUSIONS

Our study confirmed the capacity of haematopoietic stem cells to contribute to liver regeneration. Moreover, microarray analysis led to the identification of genes whose regulation strongly correlates with a more efficient process of liver repair after haematopoietic stem cell injection.

No Evidence of Hematopoietic Stem Cell Mobilization in Patients Submitted to Hepatectomy or in Patients With Acute on Chronic Liver Failure

BACKGROUND

Liver regeneration is a heterogeneous phenomenon involving the proliferation of different cell lineages in response to injury. Under a strong positive selection pressure bone marrow derived stem cells may be involved in this process, by making a contribution to both parenchymal restoration and endothelial cell replacement. We investigate bone marrow stem cell migration to the liver in patients undergoing hepatectomy or with acute on chronic liver failure.

METHODS

We enrolled 6 patients submitted to hepatectomy, 6 patients to cholecystectomy and 8 patients with acute decompensation of liver cirrhosis. Mobilization of CD34+ cells was evaluated by cytofluorimetry on peripheral blood samples at different time points; baseline, 1, 3, 7, 15 and 30 days after surgery and at admission, 1, 7 and discharge among patients with acute on chronic liver failure. 10 healthy subjects undergoing blood donation were also enrolled to evaluated the basal value of CD34+ cells.

RESULTS

White blood cell counts remained in the normal range (4.1-9.8 x 10(9)/L) in all groups throughout the follow-up. In all patients of Groups 1, 2 and 3, circulating CD34+ failed to show statistically significant differences both as the absolute number and as the percentage at any time point compared to healthy controls.

CONCLUSIONS

Bone marrow derived cell mobilization can not be detected after hepatectomy or during an acute decompensation on a cirrhotic liver. Under these circumstances liver regeneration can probably call upon mature hepatocytes and endogenous progenitor cells. The involvement of extrahepatic progenitors if any, is a rare and limited phenomenon.

A human umbilical cord stem cell rescue therapy in a murine model of toxic liver injury

BACKGROUND

Several studies have demonstrated that bone marrow contains a subpopulation of stem cells capable of participating in the hepatic regenerative process, even if some reports indicate quite a low level of liver repopulation by human stem cells in the normal and transiently injured liver.

AIMS

In order to overcome the low engraftment levels seen in previous models, we tried the direct intraperitoneal administration of human cord blood stem cells, using a model of hepatic damage induced by allyl alcohol in NOD/SCID mice.

METHODS

We designed a protocol based on stem cell infusion following liver damage in the absence of irradiation. Flow cytometry, histology, immunohistochemistry and RT-PCR for human hepatic markers were performed to monitor human cell engraftment.

RESULTS

Human stem cells were able to transdifferentiate into hepatocytes, to improve liver regeneration after damage and to reduce the mortality rate both in both protocols, even if with qualitative and quantitative differences in the transdifferentiation process.

CONCLUSIONS

We demonstrated for the first time that the intraperitoneal administration of stem cells can guarantee a rapid liver engraftment. Moreover, the new protocol based on stem cell infusion following liver damage in the absence of irradiation may represent a step forward for the clinical application of stem cell transplantation.

Effect on function of rat hepatocytes cultured with bone marrow cells

AIM: To study of the effect on the function of rat hepatocytes cultured with bone marrow cells.

METHODS: Rat hepatocytes were isolated by the modified two-step method described by Seglen. The primary cultured hepatocytes and bone marrow cells were served as cocultured group, and single cultured hepatocytes as control group. The yield and viability were assessed by trypan blue exclusion. The morphologic changes of cultured hepatocytes were observed. The concentrations of albumin and urea in the supernatant in different cultural period were examined.

RESULTS: The albumin synthesis (13.75 > 2.179, P < 0.05) and urea level (7.27 > 2.179, P < 0.05) had fluctuating changes in one week, and cocultured group had higher albumin synthesis and urea level.

CONCLUSION: Cocultured hepatocytes with bone marrow cells can improve the function of hepatocytes.

Hepatocytes transplantation in rats with acute hepatic failure

AIM: To study the effect of allogeneic hepatocytes transplantation (HcT) intraperitoneally, intrasplenically or through vena portae in rats with acute hepatic failure (AHF) induced by D-galactosamine (D-gal).

METHODS: AHF rats were induced by D-gal. HcT was carried out 60h after intoxication, and all rats were divided into six groups: GroupⅠ received 2×10¹⁰/L hepatocytes 1 mL intraperitoneally with cyclosporin A (CsA) at 10 mg/kg simultaneously; Group Ⅱ received 1 mL normal saline (NS) intraperitoneally with CsA10 mg/kg; Group Ⅲ received 2×10¹⁰/L hepatocytes 1 mL through vena portae; Group Ⅳreceived 1mL NS through vena portae; Group Ⅴreceived 2×10¹⁰/L hepatocytes 1 mL intrasplenically; Group Ⅵ received 1 mL NS intrasplenically. After 1 wk the survival rates, liver function and liver histology of all rats were observed.

RESULTS: The survival rate of Group Ⅰ was higher than that of GroupⅡ (60 % vs 20%, P < 0.01), and their liver function and liver histology were obviously improved as compared with GroupⅡ. Similarly, the survival rate of Group Ⅴ was higher than that of Group Ⅵ (47% vs 20%, P < 0.05), and the liver function and liver histology were also improved in GroupⅤas compared with Group Ⅵ. On the other hand, the survival rate of Group Ⅲ was similar to that of GroupⅥ (20% vs 13.3%, P > 0.05), and their liver function and liver histology were also not improved significantly as compared with Group Ⅱ.

CONCLUSION: After HcT intraperitoneally or intrasplenically, the survival rates of AHF rats intoxicated with D-gal are increased, and the liver function and histology are also improved. On the contrary, the survival rate, liver function and liver histology of AHF rats through vena portae HcT are not improved.