Putative human liver progenitor cells in explanted liver.

BACKGROUND/AIMS: Hepatocyte progenitors have frequently been cultured from rodents but reports from human liver are rare. METHODS: Non-parenchymal cell fraction isolated from 19 explant livers (removed at orthotopic liver transplantation for acute or chronic liver disease) and histologically normal human liver was cultured. RESULTS: Proliferating epithelioid colonies were identifiable after 2-3 weeks culture as a very rare event (<1 per million cells plated) expressing mRNAs and protein antigens of mixed hepatocytic/biliary phenotype. Colony survival could be prolonged by transduction of the catalytic sub-unit of telomerase. Hepatocyte growth factor, epidermal growth factor and oncostatin M did not further enhance hepatocytic differentiation. The expression of markers associated with hepatocyte precursor status was investigated by flow cytometry. Cells expressing the stem cell-associated markers CD133 and CD117 were identified at low frequency. The proportion of cells expressing the integrin CD49f was higher in diseased liver than in normal liver, but the proportion expressing the hepatocyte growth factor receptor c-met was lower. Successful enrichment of plated populations for progenitors was not achieved. CONCLUSION: Although there is clear histological evidence of hepatocyte precursors in human explant livers, predictable culture of such cells with differentiation toward mature hepatocyte phenotype remains elusive.

The role of glycine in hepatic ischemia-reperfusion injury.

Glycine is a non-essential amino acid which is cheap, easily available and relatively non-toxic. It is composed of a single carbon attached to an amino and a carboxyl group, with a molecular weight of 75. It is involved in the production of bile, nucleic acids, porphyrins and creatine phosphate. It is part of the normal human diet and is used clinically, as an irrigant solution in urological and gynaecological procedures. Glycine has broad spectrum anti-inflammatory, cytoprotective and immunomodulatory properties whose therapeutic role has largely been un-investigated. Since the demonstration of its cytoprotective effect on hypoxic cultured renal tubule cells, further research has established its mechanism of anti-inflammatory action, which depends on stimulation of glycine sensitive chloride channel receptors on the cell membrane. The mechanism of non-specific cytoprotective effect which is present even in chloride and calcium free media is not clear. However glycine is currently being used experimentally, in human liver transplant recipients and has been shown to be beneficial in animal models of ischemia-reperfusion injury (IRI) in liver and several other organs. This review addresses the properties of glycine, its mechanism of action and its role in modulating IRI with special reference to the liver, with the aim of stimulating translational research into the potential role of glycine as a pharmaceutical agent.

IL-10 gene therapy is therapeutic for dextran sodium sulfate-induced murine colitis.

The transfer of genes encoding immunoregulatory proteins is a promising new strategy in the treatment of intestinal inflammation. Previous work has demonstrated that daily systemic interleukin (IL)-10 therapy is able to prevent disease onset in animal models of colitis but is not sufficient to treat established disease. This study investigates the therapeutic efficacy of an adenovirus encoding IL-10 (AdvmuIL-10) in the treatment of experimental colitis. Colitis was induced in BALB/c mice by the addition of dextran sodium sulfate to the drinking water for 7 days. A single systemic injection of AdvmuIL-10, empty cassette vector (Adv0), or saline vehicle was administered on day 4 after the onset of colitis. The addition of DSS to the drinking water led to an acute, dose-dependent colitis. A single injection of AdvmuIL-10 led to a marked reduction in both stool markers of inflammation (IL-1beta, IL-6, and TNFRII) and serum IL-6. Furthermore, the histological colitis score was significantly reduced in mice receiving AdvmuIL-10 compared to controls (4.9 +/- 1.1 Vs 9.1 +/- 1.2, respectively; P < 0.05). A single systemic injection of AdvmuIL-10 is therapeutic in mice with established DSS colitis. Gene therapy strategies using adenoviral vectors encoding IL-10 may prove to be a potent therapy for chronic inflammation of the colon such as Crohn's disease.

Characteristics of murine histidinaemia and its potential for genetic manipulation.

BACKGROUND: Histidinaemia is an autosomal recessive disorder affecting the hepatic enzyme histidine ammonia lyase (histidase) resulting in elevated plasma and urinary histidine and is prototypic of a series of hepatic cytosolic enzyme defects. AIMS: To characterise the physiology of murine histidinaemia with respect to histidine excretion and catabolism, and explore the potential for manipulating cellular and whole body histidase metabolism by gene transfer. MATERIALS AND METHODS: We studied his/his mice which have a G to A substitution in the gene encoding histidase, using both in vitro transduction of isolated hepatocytes by lipofection with wild-type histidase cDNA, and in vivo transduction of whole liver using a retroviral construct. RESULTS AND CONCLUSION: Histidase cDNA expression restored histidase activity in vivo and in vitro towards normal levels, demonstrated both at the cellular level and by whole body metabolic studies, establishing the potential of this model for the development of new gene therapeutic approaches.

Characterization of long-term survival of syngeneic hepatocytes in rat peritoneum.

Hepatocyte transplantation is a potential therapy for both acute and chronic hepatic insufficiency and also for treatment of inborn errors of metabolism affecting the liver. The peritoneum is one site for implantation and has several advantages: cells implanted there can be easily identified and observed, and it has a relatively large capacity. Long-term survival using "pure" hepatocytes in the peritoneum have been disappointing. We hypothesized that cotransplantation of hepatocytes with nonparenchymal cells would help maintain differentiated hepatocyte function. Rat liver cells transplanted intraperitoneally into August rats were sacrificed at 7 days, 1, 3, 6, 9, and 12 months and analyzed for presence, basal proliferation, and functionality of hepatocytes. To demonstrate that ectopic hepatocytes remained susceptible to exogenous growth factors affecting cell proliferation, rats 9 and 12 months after transplantation were stimulated with tri-iodothyronine and KGF. Hepatocytes were identified 7 days to >12 months, by H&E and immunohistochemically, as ectopic islands in the omental fat. Functionality was confirmed by glycogen deposition. Basal proliferation in 7-day rats was 28.0 +/- 10/1000 hepatocytes in ectopic islands (cf. 5.70 +/- 2.7/1000 in recipient liver). Proliferation in ectopic islands was greater than host liver. Growth factor-stimulated proliferation in ectopic islands induced a 70-fold increase in DNA synthesis. In conclusion, hepatocytes transplanted with nonparenchymal cells survive, proliferate, and function in the peritoneum of normal rats, and respond to exogenous growth stimuli. Their survival and proliferation in the presence of a normal functioning liver has implications for the potential use of the peritoneal site clinically for supplementation of liver function in metabolic disorders.

Characterization of Long-Term Survival of Syngeneic Hepatocytes in Rat Peritoneum.

Hepatocyte transplantation is a potential therapy for both acute and chronic hepatic insufficiency and also for treatment of inborn errors of metabolism affecting the liver. The peritoneum is one site for implantation and has several advantages: cells implanted there can be easily identified and observed, and it has a relatively large capacity. Long-term survival using "pure" hepatocytes in the peritoneum have been disappointing. We hypothesized that cotransplantation of hepatocytes with nonparenchymal cells would help maintain differentiated hepatocyte function. Rat liver cells transplanted intraperitoneally into August rats were sacrificed at 7 days, 1, 3, 6, 9, and 12 months and analyzed for presence, basal proliferation, and functionality of hepatocytes. To demonstrate that ectopic hepatocytes remained susceptible to exogenous growth factors affecting cell proliferation, rats 9 and 12 months after transplantation were stimulated with tri-iodothyronine and KGF. Hepatocytes were identified 7 days to >12 months, by H&E and immunohistochemically, as ectopic islands in the omental fat. Functionality was confirmed by glycogen deposition. Basal proliferation in 7-day rats was 28.0 ± 10/1000 hepatocytes in ectopic islands (cf. 5.70 ± 2.7/1000 in recipient liver). Proliferation in ectopic islands was greater than host liver. Growth factor-stimulated proliferation in ectopic islands induced a 70-fold increase in DNA synthesis. In conclusion, hepatocytes transplanted with nonparenchymal cells survive, proliferate, and function in the peritoneum of normal rats, and respond to exogenous growth stimuli. Their survival and proliferation in the presence of a normal functioning liver has implications for the potential use of the peritoneal site clinically for supplementation of liver function in metabolic disorders.

Non-surgical treatment of hepatocellular carcinoma.

Primary hepatocellular cancer is a disease with a poor prognosis for which there is little consensus on treatment and a paucity of comparative trials. The coexistence of cancer with cirrhosis complicates treatment, and also confers a high risk for the development of further tumours. Surgery, either by hepatic resection or orthotopic liver transplantation, is only a feasible option in a minority of patients. This article surveys the non-surgical approaches to the treatment of hepatocellular cancers-local ablation techniques, arterial embolization with and without chemotherapy, conventional chemotherapy and hormonal modulation, and targeted and external irradiation.