Angiogenic cell therapy for hepatic fibrosis

Effect and mechanism of pirfenidone combined with 2-methoxy-estradiol perfusion through portal vein on hepatic artery hypoxia-induced hepatic fibrosis

PURPOSE

The aim of this study was to explore the effect and mechanism of pirfenidone (PFD) combined with 2-methoxyestradiol (2-ME2) perfusion through portal vein on hepatic artery hypoxia-induced hepatic fibrosis.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into 5 groups (n ​= ​3/group): control group, hepatic artery ligation (HAL) group, HAL ​+ ​PFD (portal vein perfusion of PFD) group, HAL+2-ME2 (portal vein perfusion of 2-ME2) group and HAL ​+ ​PFD+2-ME2 group depending on whether they received HAL and/or portal vein perfusion (PFD and/or 2-ME2). Livers were harvested for pathology, western blotting (WB), and quantitative real-time PCR (qRT-PCR).

RESULTS

Sirius red staining showed that portal vein perfusion of drugs resulted in degradation of liver fibrosis. Immunohistochemistry showed decreased hypoxia-inducible factor-1 α (HIF-1α) and α-smooth muscle actin (α-SMA) after portal intravenous drugs infusion compared with HAL group (P ​< ​0.05). WB analysis showed increased Smad7 in HAL ​+ ​PFD group compared with HAL group (P ​< ​0.05). qRT-PCR analysis showed decreased matrix metallo-proteinase 2 (MMP2), transforming growth factor β1 (TGF-β1), monocyte chemoattractant protein-1 (MCP-1), and Collagen I mRNA in HAL ​+ ​PFD group except for tissue inhibitor of metalloproteinase-1 (TIMP-1) compared with HAL group (P ​< ​0.05). Compared with HAL ​+ ​PFD group, the addition of 2-ME2 did not lead to better results in qRT-PCR analysis.

CONCLUSIONS

The portal vein perfusion of PFD significantly reduced the hepatic artery hypoxia-induced fibrosis degree in treated rats by down-regulating the expression of HIF-1α, α-SMA, MMP2, TGF-β1, MCP-1, and Collagen I, as well as up-regulating the TIMP-1 expression and Smad7 protein level. Combined 2-ME2 infusion was not better than PFD alone.

Comparative study on effect of mesenchymal stem cells and endothelial progenitor cells on treatment of experimental CCL4-induced liver fibrosis

BACKGROUND

We speculated impacts of BM-MSCs and UC-EPCs on reversal of hepatic injury induced by carbon tetrachloride (CCl4). Fifty adult rats were divided into five groups: control group, CCl4A group, CCl4B group, CCl4/BM-MSCs group and CCl4/UC-EPCs group. Blood samples were driven to measure concentration of albumin and ALT. Quantitative expression of HGF, TGF-β, MMP-2, and VEGF were assessed by PCR. Histological and immunohistochemistry examination of the liver tissue were performed.

RESULTS

There was elevating albumin (p < .05) and reducing ALT (p < .05) concentrations in groups treated with BM-MSCs and UC-EPCs compared to untreated CCL4A&B groups. UC-EPCs treated group have significantly higher MMP-2 and VEGF (p < .01) genes expression than BM-MSCs treated group. Furthermore, UC-EPCs were more valuable than BMMSCs in increasing gene expression of HGF (p < .05) and immunohistochemistry of α-SMA and Ki-67 (p < .01). BM-MSCs have significantly lower TGF-β (p < .00) compared to UC-EPCs.

CONCLUSION

This study highlighted on liver regeneration role of both UC-EPCs and BM-MSCs in liver fibrosis.

Cell and Tissue Therapy for the Treatment of Chronic Liver Disease

Liver disease is an important clinical problem, impacting 600 million people worldwide. It is the 11th-leading cause of death in the world. Despite constant improvement in treatment and diagnostics, the aging population and accumulated risk factors led to increased morbidity due to nonalcoholic fatty liver disease and steatohepatitis. Liver transplantation, first established in the 1960s, is the second-most-common solid organ transplantation and is the gold standard for the treatment of liver failure. However, less than 10% of the global need for liver transplantation is met at the current rates of transplantation due to the paucity of available organs. Cell- and tissue-based therapies present an alternative to organ transplantation. This review surveys the approaches and tools that have been developed, discusses the distinctive challenges that exist for cell- and tissue-based therapies, and examines the future directions of regenerative therapies for the treatment of liver disease.

New Perspectives in Liver Transplantation: From Regeneration to Bioengineering

Advanced liver diseases have very high morbidity and mortality due to associated complications, and liver transplantation represents the only current therapeutic option. However, due to worldwide donor shortages, new alternative approaches are mandatory for such patients. Regenerative medicine could be the more appropriate answer to this need. Advances in knowledge of physiology of liver regeneration, stem cells, and 3D scaffolds for tissue engineering have accelerated the race towards efficient therapies for liver failure. In this review, we propose an update on liver regeneration, cell-based regenerative medicine and bioengineering alternatives to liver transplantation.

Liver regeneration microenvironment of hepatocellular carcinoma for prevention and therapy

Research on liver cancer prevention and treatment has mainly focused on the liver cancer cells themselves. Currently, liver cancers are no longer viewed as only collections of genetically altered cells but as aberrant organs with a plastic stroma, matrix, and vasculature. Improving the microenvironment of the liver to promote liver regeneration and repair by affecting immune function, inflammation and vasculature can regulate the dynamic imbalance between normal liver regeneration and repair and abnormal liver regeneration, thus improving the microenvironment of liver regeneration for the prevention and treatment of liver cancer. This review addresses the basic theory of the liver regeneration microenvironment, including the latest findings on immunity, inflammation and vasculature. Attention is given to the potential design of molecular targets in the microenvironment of hepatocellular carcinoma (HCC). In an effort to improve the liver regeneration microenvironment of HCC, researchers have extensively utilized the enhancement of immunity, anti-inflammation and the vasculature niche, which are discussed in detail in this review. In addition, the authors summarize the latest pro-fibrotic transition characteristics of the vascular niche and review potential cell therapies for liver disease.

Current Perspectives Regarding Stem Cell-Based Therapy for Liver Cirrhosis

Liver cirrhosis is a major cause of mortality and a common end of various progressive liver diseases. Since the effective treatment is currently limited to liver transplantation, stem cell-based therapy as an alternative has attracted interest due to promising results from preclinical and clinical studies. However, there is still much to be understood regarding the precise mechanisms of action. A number of stem cells from different origins have been employed for hepatic regeneration with different degrees of success. The present review presents a synopsis of stem cell research for the treatment of patients with liver cirrhosis according to the stem cell type. Clinical trials to date are summarized briefly. Finally, issues to be resolved and future perspectives are discussed with regard to clinical applications.

Transplantation of bone marrow-derived endothelial progenitor cells and hepatocyte stem cells from liver fibrosis rats ameliorates liver fibrosis

AIM

To explore the effectiveness for treating liver fibrosis by combined transplantation of bone marrow-derived endothelial progenitor cells (BM-EPCs) and bone marrow-derived hepatocyte stem cells (BDHSCs) from the liver fibrosis environment.

METHODS

The liver fibrosis rat models were induced with carbon tetrachloride injections for 6 wk. BM-EPCs from rats with liver fibrosis were obtained by different rates of adherence and culture induction. BDHSCs from rats with liver fibrosis were isolated by magnetic bead cell sorting. Tracing analysis was conducted by labeling EPCs with PKH26 in vitro to show EPC location in the liver. Finally, BM-EPCs and/or BDHSCs transplantation into rats with liver fibrosis were performed to evaluate the effectiveness of BM-EPCs and/or BDHSCs on liver fibrosis.

RESULTS

Normal functional BM-EPCs from liver fibrosis rats were successfully obtained. The co-expression level of CD133 and VEGFR2 was 63.9% ± 2.15%. Transplanted BM-EPCs were located primarily in/near hepatic sinusoids. The combined transplantation of BM-EPCs and BDHSCs promoted hepatic neovascularization, liver regeneration and liver function, and decreased collagen formation and liver fibrosis degree. The VEGF levels were increased in the BM-EPCs (707.10 ± 54.32) and BM-EPCs/BDHSCs group (615.42 ± 42.96), compared with those in the model group and BDHSCs group (P < 0.05). Combination of BM-EPCs/BDHSCs transplantation induced maximal up-regulation of PCNA protein and HGF mRNA levels. The levels of alanine aminotransferase (AST), aspartate aminotransferase, total bilirubin (TBIL), prothrombin time (PT) and activated partial thromboplastin time in the BM-EPCs/BDHSCs group were significantly improved, to be equivalent to normal levels (P > 0.05) compared with those in the BDHSC (AST, TBIL and PT, P < 0.05) and BM-EPCs (TBIL and PT, P < 0.05) groups. Transplantation of BM-EPCs/BDHSCs combination significantly reduced the degree of liver fibrosis (staging score of 1.75 ± 0.25 vs BDHSCs 2.88 ± 0.23 or BM-EPCs 2.75 ± 0.16, P < 0.05).

CONCLUSION

The combined transplantation exhibited maximal therapeutic effect compared to that of transplantation of BM-EPCs or BDHSCs alone. Combined transplantation of autogenous BM-EPCs and BDHSCs may represent a promising strategy for the treatment of liver fibrosis, which would eventually prevent cirrhosis and liver cancer.

Antioxidant, antiapoptotic and amino acid balance regulating activities of 1,7-dihydroxy-3,4,8-trimethoxyxanthone against dimethylnitrosamine-induced liver fibrosis

Liver fibrosis represents the consequences of a sustained wound healing response to chronic liver injury which could be caused by viral, autoimmune, drugs, and so on. Unfortunately, there was no effective therapy available for liver fibrosis in clinic. In this study, we identified the anti-fibrotic effects of 1,7-dihydroxy-3,4,8-trimethoxyxanthone (ZYC-1) on the dimethylnitrosamine (DMN)-induced rat model. ZYC-1 was isolated from Swertia punicea Hemsl and was administrated to DMN-induced rat model. ZYC decreased the hyaluronic acid (HA), type IV collagen (CIV) and hydroxyproline (Hyp) levels and inhibited the expression of α smooth muscle actin (α-SMA) and transforming growth factor beta 1 (TGF-1β). The anti-fibrotic effect of ZYC-1 was also confirmed by Sirius Red staining. Finally, we identified 42 differentially expressed proteins by using proteomics analysis after ZYC-1 treatment, of which 17 were up-regulated and 25 were down-regulated. These Most of the 42 proteins are involved in the oxidative stress pathway, the mitochondrial-mediated apoptotic pathway and the amino acid metabolism pathway. Our study presented the first elucidated mechanisms of xanthone on liver fibrosis in vivo. This study pointed out that ZYC-1 may be used as a lead compound for hepatofibrosis treatment.

Phase 1-2 pilot clinical trial in patients with decompensated liver cirrhosis treated with bone marrow-derived endothelial progenitor cells

The aim of this nonrandomized, open label, phase 1 clinical trial was to evaluate the safety and the feasibility of the treatment with autologous bone marrow-derived endothelial progenitor cells (EPC) in decompensated liver cirrhosis. In addition, the changes in liver function and hepatic venous pressure gradient (HVPG) and their relation with the characteristics of the cellular product were analyzed. Twelve patients with Child-Pugh ≥8 liver cirrhosis underwent bone marrow harvest for ex vivo differentiation of EPC. The final product was administered through the hepatic artery in a single administration. Patients underwent clinical and radiologic follow-up for 12 months. The phenotype and the ability to produce cytokines and growth factors of the final cellular suspension were analyzed. Eleven patients were treated (feasibility 91%). No treatment-related severe adverse events were observed as consequence of any study procedure or treatment. Model for end-stage liver disease score improved significantly (P 0.042) in the first 90 days after cells administration and 5 of the 9 patients alive at 90 days showed a decreased of HVPG. There was a direct correlation between the expression of acetylated-low density lipoprotein and von Willebrand factor in the cellular product and the improvement in liver function and HVPG. The treatment with EPCs in patients with decompensated liver cirrhosis is safe and feasible and might have therapeutic potential. Patients receiving a higher amount of functionally active EPC showed an improvement of liver function and portal hypertension suggesting that the potential usefulness of these cells for the treatment of liver cirrhosis deserves further evaluation.

Hepatic erythropoietin response in cirrhosis

BACKGROUND

Erythropoietin (EPO) is produced in the liver during fetal life, but after birth the production shifts to the kidneys. The liver maintains a production capacity of 10% of the total EPO-production, but can be up-regulated to 100%. Previous studies have demonstrated both elevated and reduced concentrations of EPO in cirrhosis. Increased EPO concentrations could be expected due to anemia, hypoxia, renal hypoperfusion, or EPO-mediated hepatoprotective mechanisms. In contrast, poor hepatic production capacity may cause reduced EPO concentrations in cirrhosis. In the present paper we aimed to study hepatic and renal venous concentrations of EPO in relation to the severity of the disease.

MATERIALS AND METHODS

We included 24 patients with alcoholic cirrhosis and eight age-matched healthy controls. All had a full catheterization performed with the determination of EPO concentrations in the hepatic, renal and femoral veins and artery. All patients were clinically, biochemically, and hemodynamically characterized.

RESULTS

The median arterial EPO concentrations in the cirrhotic patients and controls were 7.1 mIU/mL (range 3.5-179) and 7.2 mIU/mL (range 3.8-15.3), respectively. In the patient group we found no significant correlations to stage of disease of hemodynamic derangement.

CONCLUSION

We found no significant differences in EPO concentrations across the liver, kidney, or peripheral circulation in the patient or control groups; and no significant correlations to clinical, biochemical, or hemodynamic characteristics. This suggests that hepatic EPO synthesis is not enhanced in cirrhosis, but larger scale studies are needed to clarify this question.

Hepatic erythropoietin response in cirrhosis. A contemporary review

The main function of erythropoietin (EPO) is to maintain red blood cell mass, but in recent years, increasing evidence has suggested a wider biological role not solely related to erythropoiesis, e.g. angiogenesis and tissue protection. EPO is produced in the liver during fetal life, but the main production shifts to the kidney after birth. The liver maintains a production capacity of up to 10% of the total EPO synthesis in healthy controls, but can be up-regulated to 90-100%. However, the hepatic EPO synthesis has been shown not to be adequate for correction of anemia in the absence of renal-derived EPO. Elevated circulating EPO has been reported in a number of diseases, but data from cirrhotic patients are sparse and the level of plasma EPO in patients with cirrhosis is controversial. Cirrhosis is characterized by liver fibrosis, hepatic dysfunction and the release of proinflammatory cytokines, which lead to arterial hypotension, hepatic nephropathy and anemia. An increase in EPO due to renal hypoperfusion, hypoxia and anemia or an EPO-mediated hepato-protective and regenerative mechanism is plausible. However, poor hepatic synthesis capacity, a decreasing co-factor level and inflammatory feedback mechanisms may explain a potential insufficient EPO response in end-stage cirrhosis. Finally, the question remains as to whether a potential increase in EPO production in certain stages of cirrhosis originates from the kidney or liver. This paper aims to review contemporary aspects of EPO relating to chronic liver disease.

Herbal formula, Scutellariae radix and Rhei rhizoma attenuate dimethylnitrosamine-induced liver fibrosis in a rat model

The bioactive components extracted from Scutellariae radix and Rhei rhizoma (SR) have been commonly used to treat liver diseases. The aim of this study was to verify the underlying mechanisms and antifibrotic effects of ethanol extract from the herbal combinatorial formula (SRE) in a dimethylnitrosamine (DMN)-administered rat model, with functional proteome tools. Our results indicated that the hepatic collagen content and alpha-smooth muscle actin expression were obviously alleviated by treatment with SRE. Comprehensive proteomics revealed global protein changes, and the network analysis implied that SRE application would attenuate oxidative stress and cytoskeleton dysregulation caused by DMN exposure. Next, marked downregulation of antioxidant enzymes mediated by DMN treatment was restored in the presence of SRE, while SRE treatment contributed to decreased MDA content. Moreover, protein carbonylation and DNA adduction induced by oxidative stress finally leading to liver injury were also reduced under SRE administration. These findings demonstrate that SRE could effectively prevent hepatic fibrosis mainly through regulating the redox status, and subsequently modulating the modification of intracellular molecules. Our experiments might help in developing novel therapeutic strategies against oxidation-caused liver diseases.

Autologous bone marrow-derived cells in the treatment of liver disease patients

Liver transplantation is universally accepted as a "cure" procedure, and yet is not universally applicable for the treatment of end-stage liver diseases (ESLD) because of the shortage of donors, operative complications, risk of rejection, and high cost. Bioartificial liver device is an option to temporarily improve the liver function and to bridge the patients to liver transplantation. However, bioartificial liver device has many problems in clinical application, such as hepatocyte allograft rejection and maintenance of hepatocyte viability and function. Another therapeutic option is stem cell transplantation. There are two broad types of stem cells: Embryonic stem cells and adult stem cells. The latter are sourced from bone marrow (BM), adipose tissue, and blood. This review will concentrate on BM-derived cells. BM-derived cell transplantation, although not ideal, is theoretically an optimal modality for the treatment of ESLD. Autologous BM-derived cells have no graft rejection, have the capability of regeneration and self-renewal, and are multipotent stem cells that can differentiate into a variety of cell types which include hepatocytes. The pathway from BM-derived cell to hepatocyte is well documented. The present review summarizes the delivery routes of BM-derived cells to the liver, the evidences of engraftment of BM-derived cells in the liver, and the possible mechanisms of BM-derived cells in liver repair and regeneration, and finally, updates the clinical applications.

CD34(+) cell therapy is safe and effective in slowing the decline of hepatic reserve function in patients with decompensated liver cirrhosis

BACKGROUND AND AIM

Preclinical studies in rodent models of chronic liver fibrosis have shown that transplantation of peripheral blood (PB) CD34(+) cells leads to hepatic regeneration and a reduction of liver fibrosis by suppressing hepatic stellate cell activity and increasing matrix metalloproteinase activity. The aim of this study was to examine the safety and clinical efficacy of intrahepatic transplantation of autologous granulocyte colony-stimulating factor (G-CSF)-mobilized PB-CD34(+) cells in patients with decompensated liver cirrhosis.

METHODS

PB-CD34(+) cells were isolated from G-CSF-mobilized apheresis products. Ten patients were treated with G-CSF-mobilized PB-CD34(+) cells (treatment group) and seven patients were treated with standard medical therapy. For mobilization, patients in the treatment group received subcutaneous injections of 10 μg G-CSF/kg/day for 5 days. The cells were then injected at three different doses (5 × 10(5) , 1 × 10(6) and 2 × 10(6) cells/kg) through the hepatic artery. Thereafter, all patients were followed up for 24 months.

RESULTS

G-CSF treatment and leukapheresis were well tolerated, and no serious adverse events were observed. Patients in the treatment group had a significant but transient splenomegaly. After 24 weeks, serum albumin was significantly increased in patients who had received middle or high doses of CD34(+) cells compared with baseline. Doppler ultrasound showed a significant increase in hepatic blood flow velocity and blood flow volume after CD34(+) cell therapy. The hepatic vein pressure gradient decreased in two patients who received high-dose CD34(+) cells at week 16.

CONCLUSIONS

CD34(+) cell therapy is feasible, safe and effective in slowing the decline of hepatic reserve function.

Combination of sorafenib and angiotensin-II receptor blocker attenuates preneoplastic lesion development in a non-diabetic rat model of steatohepatitis

BACKGROUND

Given the well-documented adverse side effects of sorafenib, many sorafenib-treated patients may need the reduced initial dose of the compound, and an alternative sorafenib-based therapy, which exerts similar clinical benefit, is anticipated. An angiostatic therapy with sorafenib is considered one of the promising approaches for chemoprevention of hepatocellular carcinoma. The aim of the current study was to elucidate the combination effect of low dose of sorafenib and angiotensin-II receptor blocker (ARB) on hepatocarcinogenesis, especially in conjunction with angiogenesis.

METHODS

The chemopreventive effect on the development of liver preneoplastic lesions, angiogenesis, and several indices was elucidated in rats. We also performed several sets of in vitro experiments to examine the mechanisms involved.

RESULTS

Using a non-diabetic rat model of steatohepatitis with choline deficient L-amino acid-defined diet, sorafenib demonstrated marked inhibition of preneoplastic lesions in a dose dependent manner. Combined treatment with ARB (losartan) at a clinically comparable dose and half dose of sorafenib resulted in the inhibitory effect equivalent to that of common dose of sorafenib along with suppression of hepatic neovascularization and potent angiogenic factor, vascular endothelial growth factor. Furthermore, similar combined inhibitory outcomes were observed in several sets of in vitro studies.

CONCLUSION

Since the combinatorial treatment using low doses of sorafenib and ARB could sufficiently induce inhibitory effect on the development of preneoplastic lesions at the magnitude similar to the conventional dose of sorafenib, this regimen may provide new strategy for patients intolerant of the usual dose of sorafenib in the future.

Prevention of liver fibrosis by intrasplenic injection of high-density cultured bone marrow cells in a rat chronic liver injury model

Endothelial progenitor cells (EPCs) from bone marrow have proven to be functional for the prevention of liver fibrosis in chronic liver injury. However, expansion of EPCs in culture is complicated and expansive. Previously, we have established a simple method that could enrich and expand EPCs by simple seeding bone marrow cells in high density dots. The purpose of this study is to evaluate whether cells derived from high-density (HD) culture of rat bone marrow cells could prevent the liver fibrosis in a chronic liver injury rat model, induced by carbon tetrachloride (CCl₄). Flow cytometric analysis showed that cells from HD culture were enriched for EPCs, expressing high levels of EPC markers. Intrasplenic injection of HD cultured bone marrow cells in the CCl₄-induced liver injury rat showed an enhanced antifibrogenic effect compared with animals treated with cells from regular-density culture. The antifibrogenic effect was demonstrated by biochemical and histological analysis 4 weeks post-transplantation. Furthermore, cells from HD culture likely worked through increasing neovascularization, stimulating liver cell proliferation, and suppressing pro-fibrogenic factor expression. HD culture, which is a simple and cost-effective procedure, could potentially be used to expand bone marrow cells for the treatment of liver fibrosis.

Bone marrow-derived stromal cell therapy in cirrhosis: clinical evidence, cellular mechanisms, and implications for the treatment of hepatocellular carcinoma

Current treatment options for hepatocellular carcinoma (HCC) are often limited by the presence of underlying liver disease. In patients with liver cirrhosis, surgery, chemotherapy, and radiation therapy all carry a high risk of hepatic complications, ranging from ascites to fulminant liver failure. For patients receiving radiation therapy, cirrhosis dramatically reduces the already limited radiation tolerance of the liver and represents the most important clinical risk factor for the development of radiation-induced liver disease. Although improvements in conformal radiation delivery techniques have improved our ability to safely irradiate confined areas of the liver to increasingly higher doses with excellent local disease control, patients with moderate-to-severe liver cirrhosis continue to face a shortage of treatment options for HCC. In recent years, evidence has emerged supporting the use of bone marrow-derived stromal cells (BMSCs) as a promising treatment for liver cirrhosis, with several clinical studies demonstrating sustained improvement in clinical parameters of liver function after autologous BMSC infusion. Three predominant populations of BMSCs, namely hematopoietic stem cells, mesenchymal stem cells, and endothelial progenitor cells, seem to have therapeutic potential in liver injury and cirrhosis. Preclinical studies of BMSC transplantation have identified a range of mechanisms through which these cells mediate their therapeutic effects, including hepatocyte transdifferentiation and fusion, paracrine stimulation of hepatocyte proliferation, inhibition of activated hepatic stellate cells, enhancement of fibrolytic matrix metalloproteinase activity, and neovascularization of regenerating liver. By bolstering liver function in patients with underlying Child's B or C cirrhosis, autologous BMSC infusion holds great promise as a therapy to improve the safety, efficacy, and utility of surgery, chemotherapy, and hepatic radiation therapy in the treatment of HCC.

Scaffold biomaterials for nano-pathophysiology

This review is intended to provide an overview of tissue engineering strategies using scaffold biomaterials to develop a vascularized tissue engineered construct for nano-pathophysiology. Two primary topics are discussed. The first is the biological or synthetic microenvironments that regulate cell behaviors in pathological conditions and tissue regeneration. Second is the use of scaffold biomaterials with angiogenic factors and/or cells to realize vascularized tissue engineered constructs for nano-pathophysiology. These topics are significantly overlapped in terms of three-dimensional (3-D) geometry of cells and blood vessels. Therefore, this review focuses on neovascularization of 3-D scaffold biomaterials induced by angiogenic factors and/or cells. The novel strategy of this approach in nano-pathophysiology is to utilize the vascularized tissue engineered construct as a tissue model to predict the distribution and subsequent therapeutic efficacy of a drug delivery system with different physicochemical and biological properties.

Liposomal oxymatrine in hepatic fibrosis treatment: formulation, in vitro and in vivo assessment

The aim was to develop a liposomal oxymatrine conjugating D-alpha tocopheryl polyethylene glycol 1000 succinate (OMT-LIP) for enhanced therapeutics of hepatic fibrosis. OMT-LIP was prepared using the remote loading method. The influences of formulation compositions on the encapsulation efficiency of OMT-LIP were investigated. Mean particle size, zeta potential, morphology, in vitro release, fibrotic liver targeting, and therapeutics of OMT-LIP were thoroughly assessed. The intraliposomal buffer composition and concentration, extraliposomal phase composition and pH, types of phospholipid, lipid molar ratio composition, and theoretical drug loading are crucial factors to entrap OMT into liposomes. The optimum OMT-LIP presented spherically unilamellar microstructures with entrapment efficiency of 79.7 ± 3.9%, mean particle size of 121.6 ± 52.9 nm, and zeta potential of -5.87 mV. OMT-LIP significantly increased the accumulation of OMT in the fibrotic liver with an 11.5-fold greater AUC than OMT solution in the dimethylnitrosamine (DMN)-induced hepatic fibrosis animals. OMT-LIP could be a potential strategy to improve treatment outcomes for hepatic fibrosis, showing the protective effects to mice given CCl4 and the enhanced therapeutics to mice with either DMN or CCl4-induced hepatic fibrosis.

R2* and R2 mapping for quantifying recruitment of superparamagnetic iron oxide-tagged endothelial progenitor cells to injured liver: tracking in vitro and in vivo

OBJECTIVE

To evaluate clinical 3.0T magnetic resonance for tracking and quantifying superparamagnetic iron oxide (SPIO)-labeled endothelial progenitor cells (EPCs) in vitro and homing to liver with acute injury in vivo.

METHODS

The bone marrow-derived EPCs were isolated and cultured for 4 days and examined in vitro for lineage markers. Then the cultured cells were labeled with a ferumoxides-protamine sulfate complex. Iron uptake was analyzed with an electron microscope and Prussian blue staining. Agarose gel phantoms containing different amounts of EPCs (0-2.5 × 10(6) cells per milliliter of 1.0% agarose gel) were analyzed with 3.0T R2 and R2* relaxometry. For in vivo tracking, liver injury was induced in healthy C57 mice (female, 6 weeks old, weight 19-20 g) by administration of carbon tetrachloride by single intraperitoneal injection. The R2* and R2 mapping of injured and normal livers of C57 mice were conducted by using 3.0T magnetic resonance on Days 0, 1, 4, and 8 after intravenous SPIO-tagged cells transplantation.

RESULTS

Electron microscope and Perls Prussian blue stain revealed the efficiency of SPIO particles uptake was more than 95% and no structural changes of labeled cells were found compared with control group. R2 and R2* values were linearly correlated with the number of iron-loaded cells in the agarose gel phantoms, and R2* values were significantly greater than R2 (P<0.01). R2* values in all groups were obviously greater than R2 (P<0.01). The R2* values of the injured livers were greater than normal on Days 1 and 4 (P<0.01). No significant difference of R2 values could be found among the three groups.

CONCLUSION

Quantitative R2* mapping provides a useful method for quantifying intravascular administered SPIO-tagged EPCs homing to injured livers.

Dual blockade of angiotensin-II and aldosterone suppresses the progression of a non-diabetic rat model of steatohepatitis

AIM

Both angiotensin-II (AT-II) and aldosterone (Ald) play pivotal roles in the pathogenesis of diseases in several organs including the liver. We previously reported that suppression of AT-II and Ald with angiotensin-converting enzyme inhibitor (ACE-I) and selective Ald blocker (SAB), respectively, attenuated the rat liver fibrogenesis and hepatocarcinogenesis. The aim of our current study was to elucidate the combined effects of ACE-I and SAB in the progression of a non-diabetic rat model of steatohepatitis, and the possible mechanisms involved.

METHODS

In the choline-deficient L-amino acid-defined (CDAA) diet-induced model, the effects of ACE-I and SAB on liver fibrosis development and hepatocarcinogenesis were elucidated, especially in conjunction with neovascularization.

RESULTS

Treatment with both ACE-I and SAB suppressed the development of liver fibrosis and glutathione-S-transferase placental form (GST-P) positive pre-neoplastic lesions. The combined treatment with both agents exerted more inhibitory effects as compared with either a single agent along with suppression of the activated hepatic stellate cells (Ac-HSC) and neovascularization, both of which play important roles in these processes. Our in vitro study showed that AT-II type 1 receptor blocker (ARB) and SAB inhibited Ac-HSC proliferation and in vitro angiogenesis along with suppression of the in vivo studies.

CONCLUSION

Dual blockade of AT-II and Ald suppresses the progression of a non-diabetic rat model of steatohepatitis. Because both agents are widely and safely used in clinical practice, this combination therapy could be an effective new strategy against steatohepatitis in the future.

Transplantation of endothelial progenitor cells ameliorates vascular dysfunction and portal hypertension in carbon tetrachloride-induced rat liver cirrhotic model

BACKGROUND AND AIM

In cirrhosis, sinusoidal endothelial cell injury results in increased endothelin-1 (ET-1) and decreased nitric oxide synthase (NOS) activity, leading to portal hypertension. However, the effects of transplanted endothelial progenitor cells (EPCs) on the cirrhotic liver have not yet been clarified. We investigated whether EPC transplantation reduces portal hypertension.

METHODS

Cirrhotic rats were created by the administration of carbon tetrachloride (CCl(4) ) twice weekly for 10 weeks. From week 7, rat bone marrow-derived EPCs were injected via the tail vein in this model once a week for 4 weeks. Endothelial NOS (eNOS), vascular endothelial growth factor (VEGF) and caveolin expressions were examined by Western blots. Hepatic tissue ET-1 was measured by a radioimmunoassay (RIA). Portal venous pressure, mean aortic pressure, and hepatic blood flow were measured.

RESULTS

Endothelial progenitor cell transplantation reduced liver fibrosis, α-smooth muscle actin-positive cells, caveolin expression, ET-1 concentration and portal venous pressure. EPC transplantation increased hepatic blood flow, protein levels of eNOS and VEGF. Immunohistochemical analyses of eNOS and isolectin B4 demonstrated that the livers of EPC-transplanted animals had markedly increased vascular density, suggesting reconstitution of sinusoidal blood vessels with endothelium.

CONCLUSIONS

Transplantation of EPCs ameliorates vascular dysfunction and portal hypertension, suggesting this treatment may provide a new approach in the therapy of portal hypertension with liver cirrhosis.

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 regulation of bone marrow-derived endothelial progenitor cells and endothelial outgrowth cells by the Notch signaling pathway

Endothelial progenitor cells (EPCs) are heterogeneous populations of cells that participate in vasculogenesis and promote tissue regeneration. However the different roles of EPC populations in vasculogenesis and tissue regeneration, as well as their regulation and mechanisms remain elusive. In the present study, we cultured bone marrow (BM)-derived early EPCs (EEPCs) and endothelial outgrowth cells (EOCs), and investigated their roles in liver regeneration and their regulation by the Notch signaling pathway. We found that Notch signaling exhibited different effects on the proliferation and migration of EEPCs and EOCs. Our results also showed that while EEPCs failed to form vessel-like structures in a three dimensional sprouting model in vitro, EOCs could sprout and form endothelial cords, and this was regulated by the Notch signaling. We further showed that, by using a conditional knockout model of RBP-J (the critical transcription factor mediating Notch signaling), Notch signaling differentially regulates EEPCs and EOCs. In a partial hepatectomy (PHx) model, EEPCs Notch-dependently benefitted liver regeneration with respect to liver function and hepatocyte proliferation and apoptosis. In contrast, EOCs appeared not directly involved in the recovery of liver function and the increase of hepatocytes. These data suggested that the RBP-J-mediated Notch signaling differentially regulated the two types of EPCs, which showed different roles in liver regeneration.

Human peripheral blood CD34-positive cells enhance therapeutic regeneration of chronically injured liver in nude rats

We investigated whether transplantation of purified human peripheral blood CD34(+) cells could reduce established liver fibrosis and up-regulate therapeutic regeneration. Human peripheral blood CD34(+) cells were isolated from total mononuclear cells of healthy volunteers by magnetic cell sorting. Recipient nude rats were injected intraperitoneally with carbon tetrachloride (CCl(4)) twice weekly for 3 weeks before single administration of CD34(+) cells. CCl(4) was then re-administered twice weekly for 3 more weeks, and the nude rats were sacrificed. Saline (control group), 1 × 10(5) (low-dose group), 5 × 10(5) (middle-dose group), or 2 × 10(6) (high-dose group) CD34(+) cells/kg body weight were intrasplenically transplanted after CCl(4) treatment for 3 weeks. Reverse transcriptase-polymerase chain reaction analysis of the freshly isolated CD34(+) cells revealed the expression of CD31, keratin19, α-smooth muscle actin (α-SMA), and epithelial growth factor, but not other liver related markers. The transplanted cells differentiated into vascular and sinusoidal endothelial cells, and vascular smooth muscle cells. CD34(+) cell transplantation reduced liver fibrosis in a dose-dependent fashion, with decreased collagen type-I and α-SMA-positive cells after 6 weeks of CCl(4) treatment by Mallory's Azan and immunohistochemical staining. Gelatin zymography showed that the expression levels of active matrix metalloproteinase-2 and -9 in CD34(+) cell transplanted livers were significantly stronger than those in saline-infused livers. In recipients of high-doses of CD34(+) cells, the number of PCNA-positive hepatocyte increased 6 weeks after CCl(4) treatment compared with saline-infused livers. We conclude that human peripheral blood CD34(+) cell transplantation halts established liver fibrosis and promotes hepatic regeneration in CCl(4)-induced chronic liver injury.

Impaired function of bone marrow-derived endothelial progenitor cells in murine liver fibrosis

Liver fibrosis (LF) caused by chronic liver damage has been considered as an irreversible disease. As alternative therapy for liver transplantation, there are high expectations for regenerative medicine of the liver. Bone marrow (BM)- or peripheral blood-derived stem cells, including endothelial progenitor cells (EPCs), have recently been used to treat liver cirrhosis. We investigated the biology of BM-derived EPC in a mouse model of LF. C57BL/6J mice were subcutaneously injected with carbon tetrachloride (CCl(4)) every 3 days for 90 days. Sacrificed 2 days after final injection, whole blood (WB) was collected for isolation of mononuclear cells (MNCs) and biochemical examination. Assessments of EPC in the peripheral blood and BM were performed by flow cytometry and EPC colony-forming assay, respectively, using purified MNCs and BM c-KIT(+), Sca-1(+), and Lin(-) (KSL) cells. Liver tissues underwent histological analysis with hematoxylin/eosin/Azan staining, and spleens were excised and weighed. CCl(4)-treated mice exhibited histologically bridging fibrosis, pseudolobular formation, and splenomegaly, indicating successful induction of LF. The frequency of definitive EPC-colony-forming-units (CFU) as well as total EPC-CFU at the equivalent cell number of 500 BM-KSL cells decreased significantly (p < 0.0001) in LF mice compared with control mice; no significant changes in primitive EPC-CFU occurred in LF mice. The frequency of WB-MNCs of definitive EPC-CFU decreased significantly (p < 0.01) in LF mice compared with control mice. Together, these findings indicated the existence of impaired EPC function and differentiation in BM-derived EPCs in LF mice and might be related to clinical LF.

Induction of LYVE-1/stabilin-2-positive liver sinusoidal endothelial-like cells from embryoid bodies by modulation of adrenomedullin-RAMP2 signaling

Embryonic stem cells (ESCs) are a useful source for various cell lineages. So far, however, progress toward reconstitution of mature liver morphology and function has been limited. We have shown that knockout mice deficient in adrenomedullin (AM), a multifunctional endogenous peptide, or its receptor-activity modifying protein (RAMP2) die in utero due to poor vascular development and hemorrhage within the liver. In this study, using embryoid bodies (EBs)-culture system, we successfully induced liver sinusoidal endothelial-like cells by modulation of AM-RAMP2. In an EB differentiation system, we found that co-administration of AM and SB431542, an inhibitor of transforming growth factor β (TGFβ) receptor type 1, markedly enhanced differentiation of lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1)/stabilin-2-positive endothelial cells. These cells showed robust endocytosis of acetylated low-density lipoprotein (Ac-LDL) and upregulated expression of liver sinusoidal endothelial cells (LSECs)-specific markers, including factor 8 (F8), Fc-γ receptor 2b (Fcgr2b), and mannose receptor C type 1 (Mrc1), and also possessed fenestrae-like structure, a key morphological feature of LSECs. In RAMP2-null liver, by contrast, LYVE-1 was downregulated in LSECs, and the sinusoidal structure was disrupted. Our findings highlight the importance of AM-RAMP2 signaling for development of LSECs.

Effect of exogenous administration of vascular endothelial growth factor on hepatic microvessel density in rats with liver cirrhosis

AIM: To investigate the effect of portal vein administration of vascular endothelial growth factor on the density of hepatic microvessels in rats with liver cirrhosis.

METHODS: Twenty-five male Sprague-Dawley rats with portal hypertension were randomly divided into two groups: treatment group (n = 15) and model group (n = 10). The treatment group was given recombinant rat vascular endothelial growth factor 165 (30 ng/d) via the portal vein for 2 weeks. The model group underwent only sham operation. Ten normal rats were used as normal controls. After treatment, liver histopathology was examined by light microscopy and sinusoidal ultrastructure was observed by transmission electron microscopy. The density of hepatic microvessels was detected by immunostaining of von Willebrand factor (vWF).

RESULTS: Light microscopy examination showed that hepatic fibrosis improved in the treatment group compared with the model group. Electron microscopy analysis showed decreased number of fenestrations in sinusoidal endothelial cells, basement membrane formation, and irregular hepatic sinus endothelial cells. These pathological changes were more severe in the model group than in the treatment group. Microvessel density was higher in fibrotic stroma (2.04 ± 0.61 vs 1.26 ± 0.30, P < 0.01) but lower in liver parenchyma (0.74 ± 0.05 vs 1.32 ± 0.48, P < 0.01) in the treatment group than in the model group. However, microvessel density in both liver stroma and parenchyma was higher in the treatment and model groups than in the normal control group (1.26 ± 0.30, 2.04 ± 0.61 vs 0.70 ± 0.07; 1.32 ± 0.48, 0.74 ± 0.05 vs 0.28 ± 0.08, all P < 0.05).

CONCLUSION: Exogenous administration of vascular endothelial growth factor is capable of increasing the number of microvessels in fibrotic stroma but decreasing that in liver parenchyma.

Advances in the regulation of liver regeneration

Liver regeneration is known to be a process involving highly organized and ordered tissue growth triggered by the loss of liver tissue, and remains a fascinating topic. A large number of genes are involved in this process, and there exists a sequence of stages that results in liver regeneration, while at the same time inhibitors control the size of the regenerated liver. The initiation step is characterized by priming of quiescent hepatocytes by factors such as TNF-α, IL-6 and nitric oxide. The proliferation step is the step during which hepatocytes enter into the cell cycle's G1 phase and are stimulated by complete mitogens including HGF, TGF-α and EGF. Hepatic stimulator substance, glucagon, insulin, TNF-α, IL-1 and IL-6 have also been implicated in regulating the regeneration process. Inhibitors and stop signals of hepatic regeneration are not well known and only limited information is available. Furthermore, the effects of other factors such as VEGF, PDGF, hypothyroidism, proliferating cell nuclear antigen, heat shock proteins, ischemic-reperfusion injury, steatosis and granulocyte colony-stimulating factor on liver regeneration are also systematically reviewed in this article. A tissue engineering approach using isolated hepatocytes for in vitro tissue generation and heterotopic transplantation of liver cells has been established. The use of stem cells might also be very attractive to overcome the limitation of donor liver tissue. Liver-specific differentiation of embryonic, fetal or adult stem cells is currently under investigation.

CD133(+) human umbilical cord blood stem cells enhance angiogenesis in experimental chronic hepatic fibrosis

The in vivo angiogenic potential of transplanted human umbilical cord blood (UCB) CD133(+) stem cells in experimental chronic hepatic fibrosis induced by murine schistosomiasis was studied. Enriched cord blood-derived CD133(+) cells were cultured in primary medium for 3 weeks. Twenty-two weeks post-Schistosomiasis infection in mice, after reaching the chronic hepatic fibrotic stage, transplantation of stem cells was performed and mice were sacrificed 3 weeks later. Histopathology and electron microscopy showed an increase in newly formed blood vessels and a decrease in the fibrosis known for this stage of the disease. By immunohistochemical analysis the newly formed blood vessels showed positive expression of the human-specific angiogenic markers CD31, CD34 and von Willebrand factor. Few hepatocyte-like polygonal cells showed positive expression of human vascular endothelial growth factor and inducible nitric oxide synthase. The transplanted CD133(+) human stem cells primarily enhanced hepatic angiogenesis and neovascularization and contributed to repair in a paracrine manner by creating a permissive environment that enabled proliferation and survival of damaged cells rather than by direct differentiation to hepatocytes. A dual advantage of CD133(+) cell therapy in hepatic disease is suggested based on its capability of hematopoietic and endothelial differentiation.

Bone marrow stem cells and liver regeneration

Development of new approaches to treat patients with hepatic diseases that can eliminate the need for liver transplantation is imperative. Use of cell therapy as a means of repopulating the liver has several advantages over whole-organ transplantation because it would be less invasive, less immunogenic, and would allow the use, in some instances, of autologous-derived cells. Stem/progenitor cells that would be ideal for liver repopulation would need to have characteristics such as availability and ease of isolation, the ability to be expanded in vitro, ensuring adequate numbers of cells, susceptibility to modification by viral vector transduction/genetic recombination, to correct any underlying genetic defects, and the ability of restoring liver function following transplantation. Bone marrow-derived stem cells, such as hematopoietic, mesenchymal and endothelial progenitor cells possess some or most of these characteristics, making them ideal candidates for liver regenerative therapies. Here, we will summarize the ability of each of these stem cell populations to give rise to functional hepatic elements that could mediate repair in patients with liver damage/disease.

Distribution of vascular endothelial growth factor receptor in hepatic arteries and veins of rats with portal hypertension

AIM: To observe the distribution of vascular endothelial growth factor receptor-1 and -2 (VEGFR-1 and -2) in both hepatic arteries and veins of rats with portal hypertension (PHT).

METHODS: Thirty male Sprague-Dawley rats, weighing 180-220 g, were randomly divided into two groups: normal control group (n = 10), and model group (n = 20). The normal control group was given normal drinking water, while the model group was given drinking water containing thioacetamide (TAA). Twelve weeks later, 12 rats who had a portal pressure > 1.57 kPa and obvious pseudolobules were selected for subsequent experiments. The distribution of VEGFR-1 and -2 in both hepatic arteries and veins of these rats was determined by immunohistochemistry.

RESULTS: VEGFR-2 expression in both hepatic arteries and veins of PHT rats significantly increased (t = 24.306, 54.776, both P < 0.05). VEGFR-1 expression in both hepatic arteries and portal veins of PHT models also significantly increased (t = 20.669, 33.210, both P < 0.05). VEGFR-2 expression in hepatic veins was markedly higher than that in hepatic arteries in PHT rats (t = 23.424, P < 0.05). There is no difference in VEGFR-1 expression between hepatic arteries and veins in PHT models (t = 1.434, P > 0.05).

CONCLUSION: VEGFR-2 can decrease the pressure of portal veins possibly by promoting the neovascularization of hepatic veins.

Mediators leading to fibrosis - how to measure and control them in tissue engineering

Fibrosis is the result of an excessive amount of fibrous connective tissue deposited into the extracellular matrix (ECM) space of damaged tissues from injury or disease. Collagens, particularly types I and III are the main constituents of the fibrotic scar tissue as well as a mixture of fibrotic cells. Severely fibrotic tissue will develop chronic healing problems resulting in tissue/organ dysfunction. More attention needs to be given to the fibrotic differentiation and related effects in bioengineered tissues. The current review provides an update on the mechanism behind fibrosis formation as well as technical measurements and preventions.

Vasculogenesis and angiogenesis in the endometrium during menstrual cycle and implantation

Blood vessels develop via two subsequent processes, vasculogenesis and angiogenesis, both being of crucial importance during menstrual cycle and implantation. These processes are also involved in the development of the fetal and placental vasculatures. During vasculogenesis, formation of the earliest primitive capillaries is achieved by in situ differentiation of hemangiogenic stem cells that are derived from pluripotent mesenchymal cells. The subsequent process, angiogenesis, is characterized by development of new vessels from already existing vessels, and is a well coordinated process initiated by stimulation of various growth factors. Vasculogenesis and angiogenesis are important and complex processes involving extensive interplay between cells and growth factors. The development, maturation and maintenance of the vascular network are necessary for successful hemochorial placentation as well as normal embryonic development and growth. In this review, we outline the basic mechanisms of vasculogenesis and angiogenesis in the endometrium during the menstrual cycle and different stages of implantation, and consider how this data can be applied to human pregnancy. Recent studies have shown that during the initiation steps of implantation, angiogenic factors trigger vasculogenesis and angiogenesis. Different inducers and stimulators affect angiogenesis and vasculogenesis by directly or indirectly stimulating proliferation, differentiation and migration of endothelial or respective precursor cells. As a conclusion, understanding the mechanisms of angiogenesis and the roles of angiogenic factors during the menstrual cycle and implantation may provide new insights and possible approaches for embryo implantation and healthy pregnancy.

Bone marrow mesenchymal stem cells modulate the expression of RhoA and P27 in hepatic stellate cells

AIM: To investigate the effects of bone marrow mesenchymal stem cells (MSCs) on the mRNA and protein expression of RhoA (Ras homolog gene family member A) and P27 in hepatic stellate cells (HSCs) and explore the mechanisms how MSCs regulate cell cycle progression of HSCs.

METHODS: MSCs were isolated from rat bone marrow and propagated in culture flasks. Meanwhile, HSCs and fibroblasts were thawed and passaged. An indirect co-culture system between MSCs/fibroblasts and HSCs was established using a Transwell membrane system (diameter: 24 mm; pore size: 0.4 μm). HSCs were randomly divided into three groups: blank control group (HSCs alone), negative control group (HSCs plus fibroblasts), and experimental group (HSCs plus MSCs). Cell proliferation was tested by WST-8 assay. Cell-cycle phases were determined by flow cytometry. The mRNA and protein expression of RhoA and P27 in HSCs was determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively.

RESULTS: After 24 h of co-culture, the reduced rate of cell proliferation in the experimental group was significantly higher than those in the blank control group and negative control group co-culture(both P < 0.01). Flow cytometry analysis showed that, after 12 hours of co-culture, the percentage of HSCs in the G₀/G₁ phase in the experimental group was significantly higher than those in the two control groups (both P < 0.01), while the percentage of HSCs in the S phase in the experimental group was significantly lower than those in the two control groups (both P < 0.01). After 12 h of co-culture, the expression level of RhoA mRNA in the experimental group was significantly lower than those in the two control groups (both P < 0.01), whereas the expression level of P27 mRNA showed no significant differences between the experimental group and the two control groups (both P > 0.05). The expression level of RhoA protein in the experimental group was significantly lower than those in the two control groups (both P < 0.01), whereas the expression level of P27 in the experimental group was significantly higher than those in the two control groups (both P < 0.01). No correlation was noted between the expression of RhoA and P27 mRNAs (r = 0.105). However, a negative correlation was noted between the expression of RhoA and P27 proteins (r = -0.943, P < 0.01).

CONCLUSION: MSCs inhibit the proliferation of HSCs possibly by modulating the RhoA-P27 pathway to alter cell cycle progression of HSCs. The upregulation of P27 protein may be due to the downregulation of RhoA activity.

Pharmacological inhibition of integrin alphavbeta3 aggravates experimental liver fibrosis and suppresses hepatic angiogenesis

The vitronectin receptor integrin alphavbeta3 promotes angiogenesis by mediating migration and proliferation of endothelial cells, but also drives fibrogenic activation of hepatic stellate cells (HSCs) in vitro. Expecting antifibrotic synergism, we studied the effect of alphavbeta3 inhibition in two in vivo models of liver fibrogenesis. Liver fibrosis was induced in rats by way of bile duct ligation (BDL) for 6 weeks or thioacetamide (TAA) injections for 12 weeks. A specific alphavbeta3 (alphavbeta5) inhibitor (Cilengitide) was given intraperitoneally twice daily at 15 mg/kg during BDL or after TAA administration. Liver collagen was determined as hydroxyproline, and gene expression was quantified by way of quantitative polymerase chain reaction. Liver angiogenesis, macrophage infiltration, and hypoxia were assessed by way of CD31, CD68 and hypoxia-inducible factor-1alpha immunostaining. Cilengitide decreased overall vessel formation. This was significant in portal areas of BDL and septal areas of TAA fibrotic rats and was associated with a significant increase of liver collagen by 31% (BDL) and 27% (TAA), and up-regulation of profibrogenic genes and matrix metalloproteinase-13. Treatment increased gamma glutamyl transpeptidase in both models, while other serum markers remained unchanged. alphavbeta3 inhibition resulted in mild liver hypoxia, as evidenced by up-regulation of hypoxia-inducible genes. Liver infiltration by macrophages/Kupffer cells was not affected, although increases in tumor necrosis factor alpha, interleukin-18, and cyclooxygenase-2 messenger RNA indicated modest macrophage activation.

CONCLUSION

Specific inhibition of integrin alphavbeta3 (alphavbeta5) in vivo decreased angiogenesis but worsened biliary (BDL) and septal (TAA) fibrosis, despite its antifibrogenic effect on HSCs in vitro. Angiogenesis inhibitors should be used with caution in patients with hepatic fibrosis.

Notch-RBP-J signaling regulates the mobilization and function of endothelial progenitor cells by dynamic modulation of CXCR4 expression in mice

Bone marrow (BM)-derived endothelial progenitor cells (EPC) have therapeutic potentials in promoting tissue regeneration, but how these cells are modulated in vivo has been elusive. Here, we report that RBP-J, the critical transcription factor mediating Notch signaling, modulates EPC through CXCR4. In a mouse partial hepatectomy (PHx) model, RBP-J deficient EPC showed attenuated capacities of homing and facilitating liver regeneration. In resting mice, the conditional deletion of RBP-J led to a decrease of BM EPC, with a concomitant increase of EPC in the peripheral blood. This was accompanied by a down-regulation of CXCR4 on EPC in BM, although CXCR4 expression on EPC in the circulation was up-regulated in the absence of RBP-J. PHx in RBP-J deficient mice induced stronger EPC mobilization. In vitro, RBP-J deficient EPC showed lowered capacities of adhering, migrating, and forming vessel-like structures in three-dimensional cultures. Over-expression of CXCR4 could at least rescue the defects in vessel formation by the RBP-J deficient EPC. These data suggested that the RBP-J-mediated Notch signaling regulated EPC mobilization and function, at least partially through dynamic modulation of CXCR4 expression. Our findings not only provide new insights into the regulation of EPC, but also have implications for clinical therapies using EPC in diseases.

Effect of human umbilical cord blood-derived mesenchymal stem cells in a cirrhotic rat model

BACKGROUND/AIM

Cirrhosis is a long-term consequence of chronic hepatic injury and no effective therapy is currently available for this disease. Recent reports have shown that the mesenchymal stem cells (MSCs) have the capacity to differentiate into hepatocytes, and umbilical cord blood is a rich source of MSCs. Hence, we investigated the effect of infusing of human umbilical cord blood-derived MSCs (HMSCs) in carbon tetrachloride (CCl4)-induced cirrhosis in a rat model.

METHODS

The effect of HMSCs on cirrhosis was evaluated using haematoxylin and eosin and Masson's trichrome staining. To evaluate cirrhosis-related factors, we measured protein and mRNA expression of transforming growth factor beta1 (TGF-beta1), collagen type I and alpha-smooth muscle actin (alpha-SMA).

RESULTS

Histological findings showed that liver fibrosis in rats was alleviated by HMSCs infusion. Interestingly, CM-DiI-labelled HMSCs expressed the hepatocyte-specific markers, human albumin and alpha-fetoprotein. Infusion of HMSCs significantly inhibited TGF-beta1, collagen type I and alpha-SMA expressions in CCl4-induced cirrhotic rats.

CONCLUSION

Our results showed that HMSCs infusion could improve liver fibrosis in rats with CCl4-induced cirrhosis, raising the possibility for clinical use of HMSCs in the treatment of cirrhosis.

Nerve growth factor-mediated paracrine regulation of hepatic stellate cells by multipotent mesenchymal stromal cells

AIMS

Multipotent mesenchymal stromal cells (MSC) have been reported to prevent the development of liver fibrosis and have emerged as a promising strategy for cell-based therapy. However, the underlying therapeutic mechanism remains unclear. Hepatic stellate cells (SC) activation is a pivotal event in the development of liver fibrosis.

MAIN METHODS

We hypothesized that MSC play an important role in regulating SC proliferation and apoptosis through paracrine mechanisms. To investigate the paracrine interactions between MSC and SC, a co-culture experimental model was developed using human MSC (hMSC) and human SC (hSC).

KEY FINDINGS

We demonstrate that hMSC and hSC both express nerve growth factor (NGF) receptor p75. Results acquired from transwell co-culture experiments using hSC and hMSC showed that hMSC secrete NGF, which enhances hSC apoptosis. Transcription factor nuclear factor kappa B (NF-KappaB) and B cell leukemia-xl (Bcl-xl) take part in the process.

SIGNIFICANCE

These findings demonstrated that hMSC indirectly modulate activated hSC in vitro via NGF-mediated signaling cascades and provide a potential mechanism of how transplanted MSC are effective in treating liver fibrosis.

Administration of human peripheral blood-derived CD133+ cells accelerates functional recovery in a rat spinal cord injury model

STUDY DESIGN

Magnetically isolated, peripheral blood-derived CD133+ cells were used as the therapeutic agent of spinal cord injury (SCI). A rat model was used to investigate the hypothesis that the cell therapy using this clinically accessible cell fraction could be an attractive option for injured spinal cord.

OBJECTIVE

Given the capacity for the peripheral blood-derived CD133+ cells in vivo to produce neurogenesis via vasculogenesis as the feasible candidate for SCI in the clinical setting, the focus of the experiment was to investigate whether the cells could contribute to histologic and functional recovery of SCI after transplantation.

SUMMARY OF BACKGROUND DATA

No evidence for peripheral blood-derived CD133+ cells application to SCI and no experimental studies showed functional recovery from SCI using this cell fraction have been published.

METHODS

Contusion SCI was induced by placing a 25-g rod onto the spinal cord for 90 seconds in athymic nude rats. CD133+ cells or phosphate-buffered saline was administered intravenously immediately after SCI. The animals were analyzed at specific times after transplantation by several methods to examine histologic vasculogenesis and neurogenesis and to confirm functional recovery from SCI.

RESULTS

After cell transplantation, intrinsic angiogenesis and axonal regeneration were enhanced, and cavity formation was reduced in injured spinal cord, histologically, with significant functional recovery. Gene expression of vascular endothelial growth factor increased in the cell-administrated group.

CONCLUSION

The administration of CD133+ cells has a therapeutic potential to a rat spinal cord injury model and could be an optional treatment for spinal cord injury in the clinical settings.

Endothelial progenitor cells and their potential therapeutic applications

Endothelial progenitor cells (EPCs) are derived from the bone marrow (BM) and peripheral blood (PB), contributing to tissue repair in various pathological conditions via the formation of new blood vessels, that is, neovascularization. EPCs can be mobilized into the circulation in response to growth factors and cytokines released following stimuli such as vascular trauma, wounding and cancer. EPCs are involved in vasculogenesis during embryogenesis, but are now recognized to have a significant bearing upon disease outcome through their contribution to neovascularization in a variety of pathological states in adulthood. EPCs exist in very small numbers, especially in circulating blood in adults where they only account for 0.01% of all cells. We discuss the contribution and potential therapeutic applications of EPCs in disease, also noting the prognostic value of PB EPC numbers, especially in heart disease and cancer.

[Clinical application of stem cells in liver diseases]

Most liver diseases lead to hepatic dysfunction with organ failure. Liver transplantation is the best curative therapy, but it has some limitations such as donor shortage, possibility of rejection, and maintenance of immunosuppressant. New therapies have been actively searched for over several decades, primarily in the form of artificial liver support devices and hepatocyte transplantation, but both of these modalities remain experimental. Stem cells have recently shown promise in cell therapy because they have the capacity for self-renewal and multilineage differentiation, and are applicable to human diseases. Very recent reports of unexpected plasticity in adult bone marrow have raised hopes of stem cell therapy offering exciting therapeutic possibilities for patients with chronic liver disease. Both rodent and human embryonic stem cells, bone marrow hematopoietic stem cells, mesenchymal stem cells, umbilical cord blood cells, fetal liver progenitor cells, adult liver progenitor cells, and mature hepatocytes have been reported to be capable of self-renewal, giving rise to daughter hepatocytes both in vivo and in vitro. These cells can repopulate livers in animal models of liver injury and appear to be able to improve liver function. However, significant challenges still exist before these cells can be used in humans, such as the lack of consensus about the immunophenotype of liver progenitor cells, uncertainty of the physiological role of reported candidate stem/progenitor cells, practicality of obtaining sufficient quantity of cells for clinical use, and concerns over ethics, long-term efficacy, and safety. There have been reports of phase 1 trials using stem cell transplantation in humans for liver diseases, but more effective trials are needed. We review the use of stem cells (focusing on adult ones) and the reported human clinical trials, and highlight the challenges facing clinicians in their quest to use liver stem cells to save lives.

Critical review of clinical trials of bone marrow stem cells in liver disease

Morbidity and mortality from cirrhosis is increasing rapidly in the Western world. Currently the only effective treatment is liver transplantation, an increasingly limited and expensive resource. Consequently, there has been great hope that stem cells may offer new therapeutic approaches in the management of liver disease. In this review we critically appraise the 11 published clinical studies of bone marrow stem cells in liver disease, and focus on the unresolved issues regarding their role. We outline the different mechanisms by which stem cells may impact on liver disease, as well as highlight the importance of the type of stem cell chosen. There are multiple different stem cell populations that have, in rodent studies, been shown to have differing effects on liver regeneration and fibrogenesis/degradation. Thus, choice of cell should reflect the desired or expected mechanism of action. The importance, and methods, of studying the fate of stem cells infused in clinical studies is emphasized as we seek to translate observations in rodents into the clinical setting. Finally, we discuss which cohorts of patients with liver disease would benefit from stem cell therapy, as well as establish minimum criteria for future clinical trials of stem cells.

Hedgehog-mediated paracrine interaction between hepatic stellate cells and marrow-derived mesenchymal stem cells

During liver injury, bone marrow-derived mesenchymal stem cells (MSCs) can migrate and differentiate into hepatocytes. Hepatic stellate cell (SC) activation is a pivotal event in the development of liver fibrosis. Therefore, we hypothesized that SCs may play an important role in regulating MSC proliferation and differentiation through the paracrine signaling pathway. We demonstrate that MSCs and SCs both express hedgehog (Hh) pathway components, including its ligands, receptors, and target genes. Transwell co-cultures of SCs and MSCs showed that the SCs produced sonic hedgehog (Shh), which enhanced the proliferation and differentiation of MSCs. These findings demonstrate that SCs indirectly modulate the activity of MSCs in vitro via the Hh pathway, and provide a plausible explanation for the mechanisms of transplanted MSCs in the treatment of liver fibrosis.