A new approach to isolation and culture of human Kupffer cells.

Macrophages are a diverse population of cells that are able to adapt to specific tissue environments. Kupffer cells are liver resident macrophages and form the largest population of fixed tissue macrophages. Their isolation offers an exciting opportunity to study this subpopulation of uniquely adapted cells. However existing Kupffer cell isolation techniques are tedious and are still largely based on enzymatic digestion to liberate tissue macrophages from the closely associated surrounding tissue. Isolation techniques have continually evolved over the last 3 decades but are neither easily applicable nor user friendly. This is highlighted by a review of current literature which will show that there is a scarcity of published studies employing human Kupffer cells. The other difficulty with Kupffer cells and some other populations of macrophages in culture is the strong tenacity with which they adhere to solid substrate and their resistance to conventional sub-culture dissociation agents. The difficulty with cell dissociation has previously required cells to be grown in suspension culture. This has been achieved by culturing macrophages in Teflon bags but unfortunately this deprives cells of the maturation signals generated by adherence. In this article we have upped the ante by describing a 'user friendly' method for Kupffer cell isolation and new culture techniques that allow Kupffer cells to be grown in adherency whilst at the same time circumventing the difficulties posed by the adherence of these unique cells.

Expression of DC-SIGN and DC-SIGNR on human sinusoidal endothelium: a role for capturing hepatitis C virus particles.

Hepatic sinusoidal endothelial cells are unique among endothelial cells in their ability to internalize and process a diverse range of antigens. DC-SIGNR, a type 2 C-type lectin expressed on liver sinusoids, has been shown to bind with high affinity to hepatitis C virus (HCV) E2 glycoprotein. DC-SIGN is a closely related homologue reported to be expressed only on dendritic cells and a subset of macrophages and has similar binding affinity to HCV E2 glycoprotein. These receptors function as adhesion and antigen presentation molecules. We report distinct patterns of DC-SIGNR and DC-SIGN expression in human liver tissue and show for the first time that both C-type lectins are expressed on sinusoidal endothelial cells. We confirmed that these receptors are functional by demonstrating their ability to bind HCV E2 glycoproteins. Although these lectins on primary sinusoidal cells support HCV E2 binding, they are unable to support HCV entry. These data support a model where DC-SIGN and DC-SIGNR on sinusoidal endothelium provide a mechanism for high affinity binding of circulating HCV within the liver sinusoids allowing subsequent transfer of the virus to underlying hepatocytes, in a manner analogous to DC-SIGN presentation of human immunodeficiency virus on dendritic cells.

Evaluation of the neural response telemetry (NRT) capabilities of the nucleus research platform 8: initial results from the NRT trial.

The purpose of this study was to evaluate the performance of the new features of the Nucleus Research Platform 8 (RP8), a system developed specifically for research purposes The RP8 consists of a research implant, a speech processor and a new NRT software (NRT v4), and includes comparisons of the different artefact-cancellation methods, NRT threshold, and recovery function measurements. The system has new artefact-suppression techniques and new diagnostic capabilities; their performance has been verified in animal experiments. In this study, NRT data were collected from 15 postlingually deafened adult cochlear implant patients intraoperatively and up to 6 months postoperatively after switch-on. The initial investigation in two clinics in Europe focused primarily on the enhanced NRT capabilities Results from the trial in two European clinics indicate that NRT measurements can be obtained with lower noise levels. A comparison of the different artefact-cancellation techniques showed that the forward-masking paradigm implemented in the Nucleus 3 system is still the method of choice. The focus of this report is on recovery function characteristics, which may give insight into auditory nerve fiber properties with regard to higher stimulation rates.