Contribution of mononuclear bone marrow cells to carbon tetrachloride-induced liver fibrosis in rats

Bone marrow mononuclear cells boosts anti-cytogentical aberration effect of N-acetylcysteine and α-lipoic acid in rat's liver and bone marrow: implication of oxidative and inflammatory pathways

This study investigates the hepatoprotective effect of bone marrow mononuclear cells (BM-MNCs) transplantation, N-acetylcysteine (NAC) and α-lipoic acid (ALA). Rats were administrated carbon tetrachloride (CCl₄) (1 mg/kg, i.p.) twice/week for 8 weeks for the induction of hepatotoxicity. 7 groups of rats were used as follows: Normal control, CCl₄, CCl₄ co-administered with BM-MNCs (1 × 10⁶ in 0.1 ml PBS, i.v.), or NAC (300 mg/kg, p.o) or ALA (100 mg/kg, p.o) single or combination. Liver function was tested by measuring serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin as well as interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), total antioxidant capacity (TAC), glutathione peroxidase (Gpx), superoxide dismutase (SOD) and catalase (CAT) activities in liver homogenates. Besides that, estimation of DNA damage was performed. In addition to Micronucleus test and histopathological investigation. CCl₄ treated rats showed elevation in ALT, AST, TNF-α, IL-6 and MDA accompanied by reduction in ALB, IL-10, SOD, CAT, GPx and TAC and increased the number of DNA breaks in liver tissue, showed many micronucleated polychromatic erythrocytes (MnPCEs) in bone marrow. NAC, ALA, BM-MNCs and their combination caused a reduction of ALT, AST, while, increase albumin, CAT, TAC, GPx, SOD as compared to CCl₄ treated groups. Also decrease in MDA, IL-6 and TNF-α concurrently with an increase in IL-10. Moreover, BM-MNCs, NAC, ALA, and their combination decreased DNA tail %, and the count of MnPCEs. BM-MNCs combination with NAC or ALA exerted significant antioxidant, anti-inflammatory and anti-cytogenetical aberrations effect compared to each of them alone.HighlightsCCl₄ elevated ALT, AST, TNF-α, IL-6 and MDACCl₄ reduced ALB, IL-10, SOD, CAT, GPx and TACCCl₄ increased the number of DNA breaks in liverNAC, ALA and BM-MNCs reduced ALT, AST, while, increase albumin, CAT, TAC, GPx, SODNAC, ALA and BM-MNCs decreased in MDA, IL-6 and TNF-α and increased IL-10 [Figure: see text].

Effect of carvedilol versus propranolol on acute and chronic liver toxicity in rats

Non-selective β-blockers have largely been used for prophylaxis of bleeding from gastroesophageal varices, but their hepatic effects and their influence on the development of varices has yet to be clarified. This study examined whether carvedilol would reduce acute and chronic liver injury in rats in comparison to propranolol. Experiment (1) Investigated the effects of carvedilol (1.2 mg/kg) and propranolol (4.0 mg/kg) administered daily for 7 days by gavage on paracetamol (1500 mg/kg i.p.) -induced acute liver injury in rats. Experiment (2) Investigated the effects of carvedilol (1.2 mg/kg) and propranolol (4.0 mg/kg) by gavage daily for 8 weeks on CCl4 -induced chronic liver injury in rats. Biochemical markers and histopathology of the livers were studied. Liver perfusion studies were carried out on CCl4 treated rats. Experiment (1) Carvedilol significantly improved the functional state of the liver in paracetamol-induced acute toxic hepatitis to a greater extent than propranolol. This was evidenced by a greater reduction in elevated serum levels of ALT and AST, hepatic MDA and TNF-α, attenuation of the paracetamol-induced decrease in GSH, together with improvement in the histological architecture of the liver. Experiment (2) Carvedilol was superior to propranolol against CCl4-induced hepatic injury and fibrogenesis. It suppressed hepatic inflammation, attenuated hepatic oxidative stress, and inhibited HSC activation. Carvedilol also decreased portal perfusion pressure. These results suggest that carvedilol might be a therapeutic anti-fibrogenic candidate against hepatic fibrosis, protecting the liver from acute and chronic toxic injury, in addition to lowering portal pressure.

Cryopreserved hepatic progenitor cells derived from human embryonic stem cells can arrest progression of liver fibrosis in rats

Hepatocytes generated from human embryonic stem cells (hESCs) are considered to be an excellent candidate for restoring the liver function deficiencies. We have earlier standardized a three-step differentiation protocol to generate functional hepatocyte-like cells (HLCs) from hESCs, which expressed the major hepatic markers. We have also found that the HLCs remain stable and functional even after extended period of in vitro culture and cryopreservation. In the present study, we have aimed to investigate the therapeutic potential of cryopreserved-thawed hESC-derived hepatic progenitor cells following transplantation in carbon tetrachloride-induced fibrotic rat livers. Significant therapeutic effects, including improved hepatic histology and normal serum biochemistry of hepatic enzymes along with increased survival rate, were observed in the cell transplanted rats. This result is an encouraging indication to develop methods for clinical application of hESC-derived hepatic lineage cells.

Bone marrow cell transplantation is associated with fibrogenic cells apoptosis during hepatic regeneration in cholestatic rats

Liver fibrosis is accompanied by hepatocyte death and proliferation of α-SMA+ fibrogenic cells (activated hepatic stellate cells and myofibroblasts), which synthesize extracellular matrix components that contribute to disorganization of the hepatic parenchyma and loss of liver function. Therefore, apoptosis of these fibrogenic cells is important to hepatic regeneration. This study aimed to analyze the effect of cell therapy using bone marrow mononuclear cell (BMMNC) transplantation on α-SMA expression and on apoptosis of hepatic cells during liver fibrosis induced by bile duct ligation (BDL). Livers were collected from normal rats, fibrotic rats after 14 and 21 days of BDL, and rats that received BMMNC at 14 days of BDL and were analyzed after 7 days. Apoptosis in fibrogenic cells was analyzed by immunoperoxidase, confocal microscopy, and Western blotting, and liver regeneration was assessed by proliferating cell nuclear antigen staining. Results showed that caspase-3 and proliferating cell nuclear antigen expression were significantly increased in the BMMNC-treated group. Additionally, confocal microscopy analysis showed cells coexpressing α-SMA and caspase-3 in these animals, suggesting fibrogenic cell death. These results suggest a novel role for BMMNC in liver regeneration during fibrotic disease by stimulating fibrogenic cells apoptosis and hepatocyte proliferation, probably through secretion of specific cytokines that modulate the hepatic microenvironment toward an antifibrogenic balance.

Bone marrow progenitor cells do not contribute to liver fibrogenic cells

AIM

To investigate the contribution of bone marrow (BM) cells to hepatic fibrosis.

METHODS

To establish a model of chimerism, C57Bl/6 female mice were subjected to full-body irradiation (7 Gy) resulting in BM myeloablation. BM mononuclear cells obtained from male transgenic mice expressing enhanced green fluorescent protein (GFP) were used for reconstitution. Engraftment was confirmed by flow cytometry. To induce liver injury, chimeric animals received carbon tetrachloride (CCl(4)) 0.5 mL/kg intraperitoneally twice a week for 30 d (CCl(4) 30 d) and age-matched controls received saline (Saline 30 d). At the end of this period, animals were sacrificed for post mortem analysis. Liver samples were stained with hematoxylin and eosin to observe liver architectural changes and with Sirius red for collagen quantification by morphometric analysis. α-smooth muscle actin (α-SMA) was analyzed by confocal microscopy to identify GFP+ cells with myofibroblast (MF) characteristics. Liver tissue, BM and peripheral blood were collected and prepared for flow cytometric analysis using specific markers for detection of hepatic stellate cells (HSCs) and precursors from the BM.

RESULTS

Injury to the liver induced changes in the hepatic parenchymal architecture, as reflected by the presence of inflammatory infiltrate and an increase in collagen deposition (Saline 30 d = 11.10% ± 1.12% vs CCl(4) 30 d = 12.60% ± 0.73%, P = 0.0329). Confocal microscopy revealed increased reactivity against α-SMA in CCl(4) 30 d compared to Saline 30 d, but there was no co-localization with GFP+ cells, suggesting that cells from BM do not differentiate to MFs. Liver flow cytometric analysis showed a significant increase of CD45+/GFP+ cells in liver tissue (Saline 30 d = 3.2% ± 2.2% vs CCl(4) 30 d = 5.8% ± 1.3%, P = 0.0458), suggesting that this increase was due to inflammatory cell infiltration (neutrophils and monocytes). There was also a significant increase of common myeloid progenitor cells (CD117+/CD45+) in the livers of CCl(4)-treated animals (Saline 30 d = 2.16% ± 1.80% vs CCl(4) 30 d = 5.60% ± 1.30%, P = 0.0142). In addition the GFP-/CD38+/CD45- subpopulation was significantly increased in the CCl(4) 30 d group compared to the Saline 30 d group (17.5% ± 3.9% vs 9.3% ± 2.4%, P = 0.004), indicating that the increase in the activated HSC subpopulation was not of BM origin.

CONCLUSION

BM progenitor cells do not contribute to fibrosis, but there is a high recruitment of inflammatory cells that stimulates HSCs and MFs of liver origin.

Differentiation of bone marrow-derived mesenchymal stem cells into hepatocyte-like cells on nanofibers and their transplantation into a carbon tetrachloride-induced liver fibrosis model

There are limited data available on the effect of a physicochemical microenvironment on mesenchymal stem cell (MSC) differentiation and repopulation of the liver. Therefore, in this study nanofibers have been used to better differentiate and maintain the function and engraftment of differentiating MSCs both in vitro and in vivo. Mouse MSCs were differentiated into early (day 18) and late (day 36) hepatocyte-like cells (HLCs) in the presence or absence of ultraweb nanofibers (nano(+) and nano(-)) and their transplantation for recovery in mice with CCl(4) induced hepatic fibrosis was investigated. In the nano(+) group, hepatocyte markers-ALB and HNF4α- were elevated in a time-dependent manner; however, those were similar levels or slightly decreased in the nano(-) group from day 18 to 36. Ultrastructural studies of the differentiated cells revealed some similarities to hepatocytes. Urea production, secretion of albumin and α-fetoprotein, and metabolic activity of the CYP450 enzymes were significantly increased within in vitro differentiated HLCs on nanofibers at day 36. MSCs, early and late HLCs in both nano(-) and nano(+) culture conditions that were transplanted by an intravenous route caused a decrease in liver fibrosis when engrafted in the recipient liver and were able to differentiate into functional hepatocytes (ALB(+)), except for late HLCs in the nano(-) group. Late HLCs transplanted in the nano(+) group were more effective in rescuing liver failure, enhancing serum ALB, homing transplanted cells and undergoing functional engraftment than the other groups. These results showed that topographic properties of nanofibers enhance differentiation of HLCs from MSCs and maintain their function in long-term culture, which has implications for cell therapies.

Decreased collagen types I and IV, laminin, CK-19 and α-SMA expression after bone marrow cell transplantation in rats with liver fibrosis

Bone marrow cells have frequently been tested in animal models of liver fibrosis to assess their role in hepatic regeneration. The mononuclear fraction of bone marrow cells is of particular interest, as many studies show that these cells may be beneficial to treat hepatic fibrosis. In this study, we used the bile duct ligation model to induce hepatic fibrosis in an irreversible manner, and rats were treated with bone marrow mononuclear (BMMN) cells after fibrosis was established. Analysis of collagen types I and IV, laminin and α-SMA showed a decreased expression of these proteins in fibrotic livers after 7 days of BMMN cell injection. Moreover, cytokeratin-19 analysis showed a reduction in bile ducts in the BMMN cell-treated group. These results were accompanied by ameliorated levels of hepatic enzymes GPT (Glutamic-pyruvic transaminase), GOT (glutamic-oxaloacetic transaminase) and alkaline phosphatase (AP). Therefore, we showed that BMMN cells decrease hepatic fibrosis by significantly reducing myofibroblast numbers and through reduction of the collagen and laminin-rich extracellular matrix of fibrotic septa and hepatic sinusoids.

Current status of stem cell therapy for liver diseases

Liver failure is one of the main causes of death worldwide and is a growing health problem. Since the discovery of stem cell populations capable of differentiating into specialized cell types, including hepatocytes, the possibility of their utilization in the regeneration of the damaged liver has been a focus of intense investigation. A variety of cell types were tested both in vitro and in vivo, but the definition of a more suitable cell preparation for therapeutic use in each type of liver lesions is yet to be determined. Here we review the protocols described for differentiation of stem cells into hepatocytes, the results of cell therapy in animal models of liver diseases, as well as the available data of the clinical trials in patients with advanced chronic liver disease.

Mesenchymal stem cells showed the highest potential for the regeneration of injured liver tissue compared with other subpopulations of the bone marrow

We have previously reported that bone marrow cells (BMCs) participate in the regeneration after liver injury. However, it is not established that this is the result of differentiation of hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs) or the combination of both. We investigated the contribution of each cell fraction to the regenerative process. First, we confirmed that transplanted stem cells migrate directly to injured liver tissue without dispersing to other organs. Next, we divided green fluorescent protein (GFP)-expressing BMCs into three populations as mononuclear cells, MSCs and HSCs. We then compared the engraftment capacity after transplantation of each fraction of cells into liver-injured mice. Of these, the MSCs transplanted group showed the highest GFP fluorescence intensities in liver tissue by flow cytometry analysis and confocal microscopic observation. Furthermore, MSCs showed differentiation potential into hepatocytes when co-cultured with injured liver cells, which suggests that MSCs showed highest potential for the regeneration of injured liver tissue compared with those of the other two cell refractions.