John Plevris

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.

A comparison of computerised tomography, laparoscopic ultrasound and endoscopic ultrasound in the preoperative staging of oesophago-gastric carcinoma

INTRODUCTION AND OBJECTIVE Oesophago-gastric carcinoma is associated with a poor prognosis despite advances in diagnosis and treatment. Accurate preoperative staging of gastro-oesophageal carcinoma is, therefore, essential in order to determine patient selection for potentially curative resection. The aim of this study was to evaluate and compare the role of computerised tomography (CT), laparoscopic ultrasound (LapUS) and endoscopic ultrasound (EUS) in the staging of oesophago-gastric carcinoma. METHODS AND PATIENTS Thirty-six patients with histologically proven carcinoma of the oesophagus or stomach who were considered fit for surgical resection were identified from a prospectively collected database. All patients underwent spiral CT, LapUS and EUS as part of their preoperative staging investigations. RESULTS from the staging modalities were compared retrospectively with final histopathology where available and to intraoperative findings where the tumour was irresectable. RESULTS Locally advanced tumours (T3/T4) were accurately identified by CT in 15/16 (94%) and by EUS in 14/16 (88%). LapUS was unable to detect 11 tumours (of which five were T3/T4) because they were above the diaphragm, but in the locally advanced cases where the tumour could be seen the accuracy was 10/12 (83%). EUS was the best modality for assessing early tumours and locoregional nodal involvement with accuracies of 8/13 (62%) and 21/29 (72%), respectively. EUS accuracies rose to 64, 92 and 83% for T1/T2, T3/T4 and N staging with the exclusion of those patients (n=6) in whom strictures prevented full assessment. LapUS had a specificity of 100%, compared to 90% for CT and was more accurate than CT for assessing distant metastases (accuracy of 26/32 (81%) compared to 23/32 (72%) for CT). CONCLUSIONS Although this study is small it has confirmed that CT, EUS and LapUS act in a complimentary manner to provide the most complete preoperative staging for patients with oesophago-gastric cancer.

Cardiac morbidity and mortality related to orthotopic liver transplantation.

This article briefly discusses the cardiac status of liver transplant recipients and their preoperative cardiac evaluation. It describes in detail perioperative and early and late postoperative complications as well as the cardiac problems associated with immunosuppression. The preoperative cardiovascular status of patients is important in determining how they cope with the stresses imposed by liver transplantation. Minor early cardiac events are common and may influence longer term cardiac morbidity. Immunosuppressive therapy may have short term effects but is likely to adversely affect long term cardiac risk. (Liver Transpl 2004;10:1441–1453.)

Review article: omega-3 fatty acids - a promising novel therapy for non-alcoholic fatty liver disease: REVIEW: OMEGA-3 FATTY ACIDS - A NOVEL THERAPY FOR NAFLD?

Aliment Pharmacol Ther 31, 679–692

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)

The effect of polymorphisms in tumor necrosis factor-alpha, interleukin-10, and transforming growth factor-beta1 genes in acute hepatic allograft rejection.

BACKGROUND The occurrence of acute rejection in orthotopic liver transplantation is unpredictable. The role of cytokines in the process of rejection is not entirely clear. We investigated polymorphisms in the genes encoding tumor necrosis factor (TNF)-alpha, interleukin (IL)-10, and transforming growth factor (TGF)-beta1, which affect the amount of cytokine produced in vitro, in a liver transplant population to determine any association with acute rejection. METHOD DNA was extracted from whole blood of liver transplant patients. After amplification with polymerase chain reactions, the polymorphisms at TNF-alpha -308, IL-10 -1082, and TGF-beta1 +869 and +915 were determined using sequence-specific oligonucleotide probes. Acute cellular rejection was a clinical and histological diagnosis. RESULTS Acute cellular rejection requiring treatment occurred in 68 (48%) of 144 patients. Acute cellular rejection was significantly associated with the TNF-alpha -308 A/A genotype (P<0.02). There was no significant association with either IL-10 or TGF-beta1 polymorphisms in acute rejection. CONCLUSION Patients with a homozygous TNF-alpha -308 genotype A/A are more likely to suffer from acute cellular rejection after liver transplantation.

A pilot study of indocyanine green clearance as an early predictor of graft function

Primary graft dysfunction occurs in up to 10% of liver transplant recipients and is the major reason for early mortality and retransplantation. The conventionally used markers of early graft functio—i.e., correction of acidosis, glucose requirement, consumption of potassium, serum alanine transaminase (ALT),* prothrombin time (PT), bile flow, resolution of encephalopathy and haemodynamic instability can be very misleading as they are dependent on numerous other factors. The aim of this study was to assess the use of indocyanine green clearance (ICG) as a measure of graft function. Peripheral ICG clearance was measured 18–24 hr after liver transplantation in twenty-three consecutive patients (24 transplants). Doppler ultrasonography confirmed normal hepatic arterial blood flow. Correlations between ICG clearance and other markers of graft function and outcome were sought. The mean ICG clearance was 406 mls/min (SD 137.5). A threshold value of 200 ml/min reliably predicted outcome. Significant correlations were found between ICG clearance and times to normalization of PT (P<0.02) and to the correction of acidosis (P<0.05). No correlation was found with ALT, PT, bile flow, glucose requirement, or consumption of potassium. ICG clearance measured on the day after liver transplantation accurately reflects graft function and may be used to predict graft survival and final outcome.

Potential of Hematopoietic Stem Cell Therapy in Hepatology: A Critical Review

Adult stem cell plasticity raised expectations regarding novel cellular therapies of regenerative medicine after findings of unexpected plasticity were reported. In this review, reports of hematopoietic stem cells (HSCs) contributing to hepatocytic lineages are critically discussed with reference to rodent and human models. In particular, the role of liver injury and the potential contribution HSCs make to hepatic regeneration in both injury and physiological maintenance is reviewed. The relative contributions of genomic plasticity and cell fusion are studied across different model systems, highlighting possible factors that may explain differences between often conflicting reports. Insights from experimental studies will be described that shed light on the mechanisms underlying the migration, engraftment, and transdifferentiation of HSCs in liver injury. Although it appears that under differing circumstances, macrophage fusion, HSC fusion, and HSC transdifferentiation can all contribute to hepatic epithelial lineages, a much greater understanding of the factors that regulate the long‐term efficacy of such cells is needed before this phenomenon can be used clinically.

Bone marrow‐derived stem cells in liver repair: 10 years down the line

Hematopoietic stem cells have potential in the field of regenerative medicine because of their capacity to form cells of different lineages. Bone marrow stem cells have been shown to contribute to parenchymal liver cell populations, and although this may not be functionally significant, it has sparked interest in the field of autologous stem cell infusion as a possible treatment for cirrhosis. In this review, we will examine the evidence for the contribution of bone marrow‐derived cells to populations of liver cells and for the functional contribution of bone marrow‐derived cells to both liver fibrosis and repair. The mechanisms by which cells are trafficked from the bone marrow to the liver are complex; the stromal derived factor‐1/CXC receptor 4 axis is central to this process. There are limited data in liver injury, but we will examine findings from the bone marrow transplantation literature and discuss their relevance to liver disease. Stromal derived factor‐1 also has a role in endogenous liver stem cell accumulation. Some groups have already started infusing autologous bone marrow cells into patients with cirrhosis. We will review these trials in the context of the basic science that we have discussed, and we will consider targets for investigation in the future. Liver Transpl 16:118–129, 2010.

Age, anemia, and obesity-associated oxygen desaturation during upper gastrointestinal endoscopy

Although upper gastrointestinal endoscopy is generally a safe procedure, it is known to be associated with arterial oxygen desaturation. We studied 82 patients undergoing diagnostic upper gastrointestinal endoscopy following a standard premedication consisting of xylocaine throat spray and intravenous midazolam. The mean duration of endoscopy was 8.5 +/- 0.42 min and the mean dose of midazolam was 6.3 +/- 0.15 mg. The baseline SaO2 was 94.91 +/- 0.27% and it decreased after pre-medication to 92.84 +/- 0.40% (p < 0.001) and after intubation to 91.21 +/- 0.40% (p < 0.001). A fall greater than 4% saturation occurred for 15.68% of the total endoscopy time. SaO2 < 90% was seen for 16.7% and SaO2 < 85% occurred for 2.33% total endoscopy time. In patients > 65 years old, hemoglobin < 10 g/dl, or body mass index > 28, the baseline saturation was significantly lower and a reduced SaO2 was seen throughout the procedure. We identify old age, anemia, and obesity as independent risk factors for arterial oxygen desaturation. We recommend continuous monitoring before sedation, and giving supplemental oxygen to patients with these risk factors from the outset of upper gastrointestinal endoscopy.