A versatile microfluidic tool for the 3D culture of HepaRG cells seeded at various stages of differentiation.

The development of livers-on-a-chip aims to provide pharmaceutical companies with reliable systems to perform drug screening and toxicological studies. To that end, microfluidic systems are engineered to mimic the functions and architecture of this organ. In this context we have designed a device that reproduces series of liver microarchitectures, each permitting the 3D culture of hepatocytes by confining them to a chamber that is separated from the medium conveying channel by very thin slits. We modified the structure to ensure its compatibility with the culture of hepatocytes from different sources. Our device was adapted to the migratory and adhesion properties of the human HepaRG cell line at various stages of differentiation. Using this device, it was possible to keep the cells alive for more than 14 days, during which they achieved a 3D organisation and acquired or maintained their differentiation into hepatocytes. Albumin secretion as well as functional bile canaliculi were confirmed on the liver-on-a-chip. Finally, an acetaminophen toxicological assay was performed. With its multiple micro-chambers for hepatocyte culture, this microfluidic device architecture offers a promising opportunity to provide new tools for drug screening applications.

Effects of pentoxifylline on intestinal bacterial overgrowth, bacterial translocation and spontaneous bacterial peritonitis in cirrhotic rats with ascites.

BACKGROUND: Prophylaxis of spontaneous bacterial peritonitis with norfloxacin has been associated to development of antibiotic resistance. We investigated whether pentoxifylline compared to norfloxacin reduces bacterial translocation and spontaneous bacterial peritonitis in rats with CCl(4)-induced cirrhosis and ascites. METHOD: After development of cirrhosis and ascites, animals were randomly allocated to receive pentoxifylline (16 mg/kg/d every 8h, oral route, n=13) or placebo (n=12) for 15 days. An additional group of 8 cirrhotic rats was given norfloxacin (5mg/kg/d for 15 days). Six healthy rats served as controls. Cecal flora and the prevalence of bacterial translocation and spontaneous bacterial peritonitis were analysed. Serum and ascitic fluid levels of TNF-alpha and cecal levels of malondialdehyde were also measured. RESULTS: Pentoxifylline in comparison to placebo reduced intestinal bacterial overgrowth (21% vs. 67%, p=0.04), bacterial translocation to cecal lymph nodes (23% vs. 75%, p=0.03) and prevented spontaneous bacterial peritonitis (0% vs. 33%, p=0.04) by Enterobacteriaceae. Norfloxacin administration induced similar results. Pentoxifylline (0.18 ± 0.10 nmol/mg), but not norfloxacin (0.25 ± 0.13; p=0.02), significantly reduced cecal mucosal levels of malondialdehyde compared to placebo (0.33 ± 0.16; p=0.03). CONCLUSION: In cirrhotic rats with ascites: (a) pentoxifylline as well as norfloxacin reduced intestinal bacterial overgrowth and bacterial translocation and prevented spontaneous bacterial peritonitis; (b) pentoxifylline, but not norfloxacin, reduced oxidative stress in cecal mucosal.

New preservation strategies for preventing liver grafts against cold ischemia reperfusion injury.

BACKGROUND: In spite of improvements in University of Wisconsin (UW) preservation solution, the injury from grafts during cold storage is an unresolved problem in liver transplantation. The aim of the present study was to evaluate the beneficial effect on ischemia-reperfusion injury associated with liver transplantation of the inversion of K(+) and Na(+) concentrations and the replacement of hydroxyethyl starch (HES) by polyethylene glycol (PEG) in UW preservation solution. METHODS: Using an orthotopic liver transplantation model, the effects on rat liver preservation of a modified preservation solution (UW-PEG) were evaluated, based on the inversion of K(+) and Na(+) concentration and the replacement of HES by PEG 35 kDa (0.03 mmol/L) in UW preservation solution. RESULTS: The use of UW-PEG preservation solution ameliorated the biochemical and histological parameters of hepatic damage. Thus, at 24 h after transplantation, transaminase levels were reduced significantly when livers were preserved during 8 h in UW-PEG preservation solution compared with the original UW solution. In addition, histological findings revealed fewer and smaller areas of hepatocyte necrosis. The benefits of UW-PEG solution cannot be explained by modifications in oxidative stress or neutrophil accumulation associated with liver transplantation. However, the results of hepatic and portal blood flow indicated that the benefits of this modified preservation solution, UW-PEG were associated with improvements in the microcirculatory disorders after reperfusion. CONCLUSIONS: The UW-PEG solution, while retaining all the advantages of UW solution, improved hepatic ischemia-reperfusion injury associated with liver transplantation.

Past and future approaches to ischemia-reperfusion lesion associated with liver transplantation.

Ischemia-reperfusion (I/R) injury associated with liver transplantation remains a serious complication in clinical practice, in spite of several attempts to solve the problem. The present review focuses on the complexity of I/R injury, summarizing conflicting results obtained from the literature about the mechanisms responsible for it. We also review the therapeutic strategies designed in past years to reduce I/R injury, attempting to explain why most of them have not been applied clinically. These strategies include improvements in pharmacological treatments, modifications of University of Wisconsin (UW) preservation solution based on a variety of additives, and gene therapy. Finally, we will consider new potential protective strategies using trimetazidine, 5-amino-4-imidazole carboxamide riboside (AICAR), melatonin, modulators of the renin-angiotensin system (RAS) and the phosphatidylinositol-3-OH kinase (PI3K)-Akt and the p42/p44 extracellular signal-regulated kinases (Erk 1/2) pathway. These strategies have shown promising results for I/R injury but have not been tested in experimental liver transplantation to date. Moreover, we will review ischemic preconditioning, taking into account the recent clinical studies that suggest that this surgical strategy could be appropriate for liver transplantation.