Philip N. Newsome

Highly efficient differentiation of hESCs to functional hepatic endoderm requires ActivinA and Wnt3a signaling

Human embryonic stem cells (hESCs) are a valuable source of pluripotential primary cells. To date, however, their homogeneous cellular differentiation to specific cell types in vitro has proven difficult. Wnt signaling has been shown to play important roles in coordinating development, and we demonstrate that Wnt3a is differentially expressed at critical stages of human liver development in vivo. The essential role of Wnt3a in hepatocyte differentiation from hESCs is paralleled by our in vitro model, demonstrating the importance of a physiologic approach to cellular differentiation. Our studies provide compelling evidence that Wnt3a signaling is important for coordinated hepatocellular function in vitro and in vivo. In addition, we demonstrate that Wnt3a facilitates clonal plating of hESCs exhibiting functional hepatic differentiation. These studies represent an important step toward the use of hESC-derived hepatocytes in high-throughput metabolic analysis of human liver function.

Pathogenesis of non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) represents a spectrum of disease ranging from hepatocellular steatosis through steatohepatitis to fibrosis and irreversible cirrhosis. The prevalence of NAFLD has risen rapidly in parallel with the dramatic rise in obesity and diabetes,1,2 and is rapidly becoming the most common cause of liver disease in Western countries.3 Indeed, NAFLD is now recognized to be the aetiology in many cases previously labelled as cryptogenic cirrhosis.4 In Western populations, estimates of NAFLD prevalence vary between 20 and 30%,5,6 rising up to 90% in morbidly obese individuals.7 The more severe, and clinically significant form of NAFLD, non-alcoholic steatohepatitis (NASH) is less common, affecting an estimated 2–3% of the general population,8 and up to 37% of the morbidly obese.7 Of particular concern, and with significant implications for future disease burden, is the increasing prevalence of NAFLD in children and young adults. Studies have reported a 3% prevalence of NAFLD in the general paediatric population, rising to 53% in obese children.9,10 NAFLD has a strong association with type 2 diabetes, with steatosis present in 70% of type 2 diabetics screened with ultrasound,11 and thus it is now recognized to represent the hepatic manifestation of the metabolic syndrome. NAFLD occurs in all ethnic groups although it appears to have a lower prevalence in African-Americans compared with Hispanic and European Americans. This difference remains even after controlling for obesity and insulin resistance (IR)5,12 and may be related to ethnic differences in lipid homeostasis.5 There are no laboratory, imaging or histological findings which can accurately distinguish between NAFLD and alcohol-induced steatosis or steatohepatitis, and the diagnosis can therefore only be made in the absence of a history of significant alcohol intake. Other specific causes … Address correspondence to J. K. Dowman, Centre for Liver Research, Institute of Biomedical Research, University of Birmingham, Wolfson Drive, B15 2TT, Birmingham, UK. email: j.k.dowman{at}bham.ac.uk

Human cord blood-derived cells can differentiate into hepatocytes in the mouse liver with no evidence of cellular fusion

BACKGROUND & AIMS Studies have indicated that stem cells have unexpected plasticity and can differentiate down a multitude of nonhematopoietic cell lineages in rodents. Our aim was to identify whether human cord blood cells, which are a rich source of stem cells, would be able to differentiate into hepatocytes when infused into nonobese diabetic-severe combined immunodeficient (NOD-SCID) mice. We also wanted to test whether such differentiated cells were the result of cellular fusion or true stem cell transdifferentiation. METHODS Unsorted mononuclear cell preparations of human cord blood were infused into sublethally irradiated NOD-SCID mice. After death, immunohistologic analysis of murine livers was performed using human specific hepatocyte, biliary, and endothelial markers. Fluorescent in situ hybridization (FISH) for mouse and human DNA was also performed. RESULTS We show that human cord blood cells have the ability to engraft into NOD-SCID liver and become mature hepatocytes. We were unable to identify any biliary or endothelial differentiation. Furthermore, we do not detect any evidence of cell fusion in any of the human cells found in the mouse liver, suggesting that human cord blood cells are capable of true transdifferentiation into hepatocytes in vivo. CONCLUSIONS We conclude that hepatocytes can derive from human cord blood cells when infused into NOD-SCID mice in the absence of fusion. The demonstration that human stem cell differentiation can occur in this murine model permits comprehensive study of human stem cell plasticity in vivo.

Addressing liver disease in the UK: a blueprint for attaining excellence in health care and reducing premature mortality from lifestyle issues of excess consumption of alcohol, obesity, and viral hepatitis.

Liver disease in the UK stands out as the one glaring exception to the vast improvements made during the past 30 years in health and life expectancy for chronic disorders such as stroke, heart disease, and many cancers. Mortality rates have increased 400% since 1970, and in people younger than 65 years have risen by almost five-times. Liver disease constitutes the third commonest cause of premature death in the UK and the rate of increase of liver disease is substantially higher in the UK than other countries in western Europe. More than 1 million admissions to hospital per year are the result of alcohol-related disorders, and both the number of admissions and the increase in mortality closely parallel the rise in alcohol consumption in the UK during the past three decades. The aim of this Commission is to provide the strongest evidence base through involvement of experts from a wide cross-section of disciplines, making firm recommendations to reduce the unacceptable premature mortality and disease burden from avoidable causes and to improve the standard of care for patients with liver disease in hospital. From the substantial number of recommendations given in our Commission, we selected those that will have the greatest effect and that need urgent implementation. Although the recommendations are based mostly on data from England, they have wider application to the UK as a whole, and are in accord with the present strategy for health-care policy by the Scottish Health Boards, the Health Department of Wales, and the Department of Health and Social Services in Northern Ireland.

Systematic review: the diagnosis and staging of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis.

Aliment Pharmacol Ther 2011; 33: 525–540

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.

Presence and severity of non-alcoholic fatty liver disease in a large prospective primary care cohort.

BACKGROUND & AIMS Non-alcoholic fatty liver disease (NAFLD) is a common cause of abnormal LFTs in primary care, but there are no data defining its contribution nor reporting the range of NAFLD severity in this setting. This study seeks to calculate the range of disease severity of NAFLD in a primary care setting. METHODS Adult patients with incidental abnormal LFTs, in the absence of a previous history, or current symptoms/signs of liver disease were prospectively recruited from eight primary care practices in Birmingham. NAFLD was diagnosed as fatty liver on ultrasound, negative serological liver aetiology screen, and alcohol consumption ≤30 and ≤20 g/day in males and females, respectively. The NAFLD Fibrosis Score (NFS) was calculated to determine the presence or absence of advanced liver fibrosis in subjects identified with NAFLD. RESULTS Data from 1118 adult patients were analysed. The cause of abnormal LFTs was identified in 55% (614/1118) of subjects, with NAFLD (26.4%; 295/1118) and alcohol excess (25.3%; 282/1118) accounting for the majority. A high NFS (>0.676) suggesting the presence of advanced liver fibrosis was found in 7.6% of NAFLD subjects, whereas 57.2% of NAFLD patients had a low NFS (<-1.455) allowing advanced fibrosis to be confidently excluded. CONCLUSIONS NAFLD is the commonest cause of incidental LFT abnormalities in primary care (26.4%), of whom 7.6% have advanced fibrosis as calculated by the NFS. This study is the first of its kind to highlight the burden of NAFLD in primary care and provide data on disease severity in this setting.

A concise review of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome and the incidence of which is rising rapidly due to the increasing epidemic of obesity in both adults and children. The initial accumulation of fat followed by subsequent inflammation is central to the development of liver damage, and is critically influenced by host factors including age, gender, presence of diabetes, genetic polymorphisms and more recently by the gut microbiome. An increasing body of data suggest that NAFLD is also an independent risk factor of cardiovascular disease, which remains the commonest cause of mortality in such patients. This review focusses on the pathogenesis of NAFLD, and the evolution of new approaches to the management and treatment of NAFLD.

Hematopoietic stem cell trafficking in liver injury

Bone marrow (BM) hematopoietic stem cells (HSCs) have been shown to facilitate regeneration in multiple nonhematopoietic tissues by either generating epithelial cells or altering the inflammatory response. Depending on injury type, the predominant mechanism of epithelial lineage regeneration occurs by spontaneous cell fusion or transdifferentiation. Irrespective of the mechanism, mobilization from the BM is a prerequisite. Mechanisms by which HSCs mobilize into damaged organs are currently under scrutiny. Murine and human studies have shown that the chemokine SDF‐1 and its receptor CXCR4 participate in the mobilization of HSCs from BM and in the migration of HSCs to injured liver. SDF‐1 is a potent HSC chemoattractant and is produced by the liver. Production is increased during liver injury leading to increased HSC migration to the liver, a finding diminished by neutralizing anti‐CXCR4 antibodies. Additional factors have been implicated in the control of hepatic migration of HSCs such as IL‐8, hepatocyte growth factor, and MMP‐9. Matriceal remodeling is an essential component in HSC engraftment, and MMP‐9 expression is increased in liver injury. This review focuses on the complex interaction of chemokines, adhesion molecules, and extracellular matrix factors required for successful migration and engraftment of HSCs into the liver. Dalakas, E., Newsome, P. N., Harrison, D. J., Plevris, J. N. Hematopoietic stem cell trafficking in liver injury. FASEB J. 19, 1225–1231 (2005)

Safety and efficacy of liraglutide in patients with type 2 diabetes and elevated liver enzymes: Individual patient data meta-analysis of the LEAD program

Non‐alcoholic fatty liver disease has reached epidemic proportions in type 2 diabetes (T2D). Glucagon‐like peptide‐1 analogues are licensed in T2D, yet little data exist on efficacy and safety in liver injury.