Assessment of liver phagocytic activity using EPR spectrometry and imaging

Best Practices and Progress in Precision-Cut Liver Slice Cultures

Thirty-five years ago, precision-cut liver slices (PCLS) were described as a promising tool and were expected to become the standard in vitro model to study liver disease as they tick off all characteristics of a good in vitro model. In contrast to most in vitro models, PCLS retain the complex 3D liver structures found in vivo, including cell–cell and cell–matrix interactions, and therefore should constitute the most reliable tool to model and to investigate pathways underlying chronic liver disease in vitro. Nevertheless, the biggest disadvantage of the model is the initiation of a procedure-induced fibrotic response. In this review, we describe the parameters and potential of PCLS cultures and discuss whether the initially described limitations and pitfalls have been overcome. We summarize the latest advances in PCLS research and critically evaluate PCLS use and progress since its invention in 1985.

Evaluation of the uptake function of liver in rats with obstructive jaundice before and after relief from obstruction by superparamagnetic iron oxide-enhanced magnetic resonance imaging

The aim of this study was to investigate the changes in the uptake function of the liver in rats with obstructive jaundice prior to and following relief from obstructive jaundice, and to investigate whether superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) could be used to assess liver uptake function. In total, 40 male Sprague Dawley rats were randomly assigned into four groups: Obstructive jaundice, internal drainage, external drainage and sham surgery. The common bile ducts in the obstructive jaundice group were ligated. Internal drainage (ID) and external drainage (ED) groups were ligated, followed by internal drainage or external drainage, respectively. The T2 and T2* values of the liver parenchyma were measured. Liver sections were stained with Perls' Prussian blue, and hematoxylin and eosin. The number of SPIO-nanoparticle clusters was counted manually using a microscope. Total bilirubin of the blood was measured. Results showed that the T2 and T2* values and total bilirubin of the obstructive jaundice group were significantly higher compared to the other three groups. The number of SPIO-nanoparticle clusters in the obstructive jaundice group was significantly lower compared to the other three groups. In conclusion, obstructive jaundice suppresses liver uptake function in rats, which may be reversed by internal and external biliary drainage. However, no significant difference was found between the therapeutic effect of ID and ED on liver uptake function. Thus, SPIO-enhanced MRI may be used to evaluate the uptake function of the liver.

Increased serum enzyme levels associated with kupffer cell reduction with no signs of hepatic or skeletal muscle injury

Macrophage colony-stimulating factor (M-CSF) is a hematopoietic growth factor that is responsible for the survival and proliferation of monocytes and the differentiation of monocytes into macrophages, including Kupffer cells (KCs) in the liver. KCs play an important role in the clearance of several serum enzymes, including aspartate aminotransferase and creatine kinase, that are typically elevated as a result of liver or skeletal muscle injury. We used three distinct animal models to investigate the hypothesis that increases in the levels of serum enzymes can be the result of decreases in KCs in the apparent absence of hepatic or skeletal muscle injury. Specifically, neutralizing M-CSF activity via a novel human monoclonal antibody reduced the CD14(+)CD16(+) monocyte population, depleted KCs, and increased aspartate aminotransferase and creatine kinase serum enzyme levels in cynomolgus macaques. In addition, the treatment of rats with clodronate liposomes depleted KCs and led to increased serum enzyme levels, again without evidence of tissue injury. Finally, in the osteopetrotic (Csf1(op)/Csf1(op)) mice lacking functional M-CSF and having reduced levels of KCs, the levels of serum enzymes are higher than in wild-type littermates. Together, these findings support a mechanism for increases in serum enzyme levels through M-CSF regulation of tissue macrophage homeostasis without concomitant histopathological changes in either the hepatic or skeletal system.

In vivo MRI and ex vivo quantification of iron and Kupffer cells demonstrate residual phagocytic activity in mouse liver after a gadolinium chloride injection

Kupffer cells (KCs), the resident macrophages of the liver, display a phagocytic activity that is not well quantified in animal models. Its experimental invalidation in rodents has been carried out by various means, among which the gadolinium chloride (GdCl₃) injection has been widely used, and has been generally monitored by ex vivo techniques. The aim of our study was to determine the KC phagocytic activity induced in mouse liver following a single GdCl₃ injection, through Magnetic Resonance Imaging (MRI) measurement of liver uptake of Ferumoxide in vivo, and through ex vivo quantification of Perls positive and F4/80 labeled macrophages. In this study, we showed that 24 h after an IV injection at a dose of 50 mg/kg body weight, GdCl₃ did not induce any hepato-cellular damage, nor did it strongly suppress liver phagocytic activity, as demonstrated by the persistent hepatic uptake of the iron-based MRI contrast agent Ferumoxide. In the GdCl₃-treated mice, the injection of Ferumoxide produced an increase in the liver proton transverse relaxation rate R2 which averaged 71 ± 24% of that of the control animals. The ex vivo iron and immune phenotypic quantification, performed after the Ferumoxide injection and MRI, confirmed the presence of activated phagocytes in the liver of the GdCl₃-treated animals, with a global iron score and F4/80 positive cell count respectively averaging 85 ± 26% and 46 ± 13% of their values in the untreated mice. In vivo MRI evaluation of the liver phagocytic activity using Ferumoxide may further prove useful in the follow up of both experimental and human pathologies.