1,721,011 research outputs found
Anionic binding sites on rat hepatocyte surface during embryonic development: preliminary report.
No full text
Pregnancy-related changes of galactose recognition system on sinusoidal rat liver cells.
No full textHuman hepatocytes in three-dimensional culture on Innovative biopolymeric scaffolds as a useful system for in vitro toxicology tests
No full textP 1.6
HUMAN HEPATOCY
TES IN THREE-
DIMENSIONAL CULTURE ON INNOVATIVE
BIOPOLYMERIC SCAFFOLDS
AS AN USEFUL SYSTEM
FOR
IN VITRO
TOXICOLOGY TESTS
Stampella A. (a), Massimi M. (b), Barbetta A.
(c), Rizzitelli G. (c), Dentini M. (c), Conti
Devirgiliis L. (a)
(a) Department of Biology and Biotechnology Charles Darwin, Sapienza University of
Rome, Rome, Italy
(b) Department of Basic and Applied Biology, University of L’Aquila, L’Aquila, Italy
(c) Department of Chemistry, Sapienza University of Rome, Rome, Italy
Many innovative biomaterials have recently be developed as scaffolds to replace
physiological matrix components and their im
provement has led to significant advances in
culture techniques in terms of cell survival, quantitative expansion, maintenance of
differentiated phenotype and specific cell functions. A key point in achieving these goals
has been to maintain a three-dimensional culture and the typical cyto-architecture of the
tissue by improving the extracellular matrix geometry and by promoting cell-cell contacts
and reciprocal adhesions. These bio-artificial
systems represent a real hope as functional
substitutes for damaged organs and tissues and have provoked a great interest in the field of
regenerative medicine. Concerning hepatocyte cultures, since the liver is the main organ
involved in detoxification processes and in the defence of organisms against harmful
molecules, in addition to their biomedical applications, these systems can be utilized as
invaluable tool for toxicology tests for analyzing the effects on metabolism of new drugs,
or for screening potentially toxic substances. The aim of our research was to identify the
most suitable biomaterial for the technological applications with hepatocytes. Since the
possibility to improve the performance of thes
e systems depends strongly on the methods
used to create the scaffolds, here we analyzed
porous matrices made of gelatin or blends of
gelatin and glycosaminoglycans, obtained with different methods for the culture of the C3A
cell line, considered a
good model of human hepatocytes. Scaffolds were obtained using
either a concentrated emulsi
on-templating technique known as High Internal Phase
Emulsion (HIPE) or a gas foaming technique; the latter method uses an inert gas instead of
the internal liquid phase toluene, avoiding the use of organic solvent and allowing the
creation of scaffolds with la
rger pores and interconnections. Cell viability was analysed
using MTS and LDH assays; ultrastructural morphology and three-dimensional cell
organization into the scaffold were assessed by SEM; albumin and urea secretion, as the
main metabolic markers of hepatocyte functions, were monitored using, respectively, an
ELISA kit and a colorimetric assay. Finally
Cytochrome P450-3A4 activity was quantified
by a luminescent method. Values of activity of this important enzyme of the detoxification
system, obtained in the absence or in the pr
esence of specific inducing molecules, were
compared between the different culture conditions
The lobular expression of the rat asialoglycoprotein receptor is regulated at post-transcriptional level
No full textThe purpose of this study was to define the distribution of the asialoglycoprotein receptor (ASGP-R) main peptide, rat hepatic lectin (RHL)-1, within the rat liver lobule and to investigate its possible modulation in physiological states characterised by marked changes of receptorial expression. In particular, we chose livers from rats partially hepatectomised or at the end of pregnancy, as models, respectively, of decreased or increased expression of the ASGP-R, and used the in situ hybridisation and immunocytochemistry techniques to analyse in parallel the lobular distributions of RHL-1 mRNA and protein. In normal rat liver, although the RHL-1 mRNA was homogeneously distributed, the RHL-1 peptide was predominantly localised on the surface of pericentral hepatocytes with a gradient of expression towards the periportal zone. This gradient of expression of RHL-1 peptide was reduced in regenerating livers, in which the positive stain was restricted to a few layers of cells around the central vein. In contrast, livers at the end of pregnancy showed an overall increase of the peptide with a concomitant flattening of the gradient across the liver plate. In all the conditions, we never observed important changes in the pattern of expression of the specific mRNA. These findings indicate that the distribution of ASGP-R is heterogeneous across the liver lobule, with a pattern of expression prevalently modulated at the posttranscriptional level
Retinoic acid modulates gap junctional intercellular communication in hepatocytes and hepatoma cells
No full textThe galactose-specific receptor system in rat liver cells during development
No full textThe number and distribution of galactose-specific binding sites were investigated in rat liver cells during perinatal development. Ligand binding to hepatocytes, macrophages and endothelial cells was followed with in vitro and in situ experiments by electron microscopy, using lactosylated bovine serum albumin adsorbed onto 5 nm colloidal gold particles as ligand. Binding capacity, starting at a late stage of fetal development, is very low both on the hepatocyte and on the macrophage surface, which show single particles statistically distributed. By contrast, bound particles are absent from fetal endothelial cells, which also lack the typical coated regions. In vivo, experiments at 37 degrees C show that endocytosis occurs to some extent in prenatal life. These results indicate that the expression of galactose-specific receptors' activity on the different liver cell types follows different developmental patterns, which are independently modulated
Multiple parameters are involved in the effects of cadmium on prenatal hepatocytes
No full textCadmium, a toxic heavy metal, expresses its toxicity by affecting several cellular functions, such as enzyme activities, DNA repair systems, redox state of the cell and signal transduction. Although the liver is a known target organ, the mechanisms involved in cadmium toxicity are not yet clarified, especially during prenatal development. Here we consider the effects of cadmium on viability, proliferation, adhesion and defence mechanisms in primary adult and fetal rat hepatocytes. Fetal hepatocytes are less sensitive to cadmium toxicity, they appear to be unaffected or even stimulated by treatments that strongly inhibit DNA synthesis in adult cells. The behaviour of proteins involved in cell cycle regulation also differs from adult cells, according to the proliferative state. In addition, following Cd exposure, E-cadherin/beta-catenin complex disassembles in both cell types, with fetal cells being influenced at higher doses. The beta-catenin is not found in the nucleus, ruling out a direct role on DNA synthesis stimulation. Finally, metallothionein is more easily inducible in fetal hepatocytes, while Cd intracellular concentrations and HSP protein levels are not differentially affected. In conclusion, multiple cellular targets are affected by Cd in primary hepatocytes and the adverse effects of the metal are always better counteracted by fetal cells
Effect of zinc deficiency on neutrophil transmigration and junction proteins distribution in Caco-2
No full text- …
