Project description:Organs from nonheart-beating donors are attractive for use in cell therapy. Understanding the nature of molecular perturbations following reperfusion/reoxygenation would be highly significant for nonheart-beating donor cells. Nonheart-beating donor rats hepatocytes were studied for global gene expression with Affymetrix microarraays.
Project description:Organs from non-heart-beating donors are attractive for use in cell therapy. Understanding the nature of molecular perturbations following reperfusion/reoxygenation will be highly significant for non-heart-beating donor cells. We studied non-heart-beating donor rats for global gene expression with Affymetrix microarrays, hepatic tissue integrity, viability of isolated hepatocytes, and engraftment and proliferation of transplanted cells in dipeptidyl peptidase IV-deficient rats. In non-heart-beating donors, liver tissue was morphologically intact for >24 hours with differential expression of 1, 95, or 372 genes, 4, 16, or 34 hours after death, respectively, compared with heart-beating donors. These differentially expressed genes constituted prominent groupings in ontological pathways of oxidative phosphorylation, adherence junctions, glycolysis/gluconeogenesis, and other discrete pathways. We successfully isolated viable hepatocytes from non-heart-beating donors, especially up to 4 hours after death, although the hepatocyte yield and viability were inferior to those of hepatocytes from heart-beating donors (P < 0.05). Similarly, although hepatocytes from non-heart-beating donors engrafted and proliferated after transplantation in recipient animals, this was inferior to hepatocytes from heart-beating donors (P < 0.05). Gene expression profiling in hepatocytes isolated from non-heart-beating donors showed far greater perturbations compared with corresponding liver tissue, including representation of pathways in focal adhesion, actin cytoskeleton, extracellular matrix-receptor interactions, multiple ligand-receptor interactions, and signaling in insulin, calcium, wnt, Jak-Stat, or other cascades.Liver tissue remained intact over prolonged periods after death in non-heart-beating donors, but extensive molecular perturbations following reperfusion/reoxygenation impaired the viability of isolated hepatocytes from these donors. Insights into molecular changes in hepatocytes from non-heart-beating donors offer opportunities for improving donor cell viability, which will advance the utility of non-heart-beating donor organs for cell therapy or other applications.
Project description:Glucocorticoids are widely used therapeutically to suppress inflammatory/immune responses and most of their effects are produced either by altering transcription of specific genes directly, or by altering the expression of transcription factors that subsequently alter the expression of downstream genes. Relevant data from previous studies indicate that the number of genes regulated by glucocorticoid receptor exceeds 4000 in cells and that 358 different genes are regulated in the liver of adrenalectomized males rats treated with a chronic infusion of methylprednisolone for up to 1 week . However, differences in gene expression between males and females in response to glucocorticoid treatment in isolated hepatocytes are not known. Livers were isolated from adult male and female Sprague-Dawley rats and digested with the collagenase perfusion method developed by Berry and Friend (J Cell Biol 43, 506-520;1969). After collagenase treatment, the liver was excised, minced in balanced salt solution, and centrifuged at 50 g for 3 min. Immediately after isolation, hepatocytes were resuspended in Williams E Medium containing penicillin (100 units/ml), streptomycin (100 M-NM-<g/ml), 2 mM glutamine pH 7.4, and 10% fetal bovine serum and plated on collagen-coated 94 x 16 mm cell culture dishes and maintained for 24 hours in a 95% airM-bM-^@M-^S5% CO2, 37M-BM-0C incubator. The medium was then changed to free serum Williams E Medium and maintained in culture for an additional 24 hours. Hepatocytes isolated from male and rats were treated with vehicle (0.01% ethanol) or dexamethasone (100 nm) for 6 hours. Total RNA from cells were extracted by using the RNeasy Midi Kit (Qiagen) according to the manufacturerM-bM-^@M-^Ys instructions. All samples were treated with the RNase-free DNase set (Qiagen) and were kept at -80M-BM-0C until labeling and hybridization.
Project description:Glucocorticoids are widely used therapeutically to suppress inflammatory/immune responses and most of their effects are produced either by altering transcription of specific genes directly, or by altering the expression of transcription factors that subsequently alter the expression of downstream genes. Relevant data from previous studies indicate that the number of genes regulated by glucocorticoid receptor exceeds 4000 in cells and that 358 different genes are regulated in the liver of adrenalectomized males rats treated with a chronic infusion of methylprednisolone for up to 1 week . However, differences in gene expression between males and females in response to glucocorticoid treatment in isolated hepatocytes are not known.
Project description:We generated chimeric mice with livers that were predominantly repopulated with human hepatocytes. Hepatocytes were isolated from the chimeric mouse livers and their gene expressions were compared with hepatocytes isolated from normal human livers . Cluster and principal components analyses showed that gene expression profiles of hepatocytes from the chimeric mice and those from normal human livers were extremely closed. Additionally, we performed microarray experiments to examine gene expression in human tissues. This data was used for comparison with hepatocytes. A total of 22 tissues (bone marrow, cerebellum, colon, cortex, fetal brain, heart, kidney, liver, lung, pancreas, prostate, salivary gland, skeletal muscle, small intestine, spinal cord, spleen, stomach, testes, thymus, thyroid, trachea and uterus) were examined. The chimeric mice were generated by transplantation of 2 different donor hepatocytes. Hepatocytes were isolated from the mouse livers and normal human livers, and their cDNAs were used for microarray analysis. Total RNA isolated from human tissues and cell cultures were labeled and hybridized to the GeneChip Human Genome U133 Plus 2.0 Array according to the manufacturer's protocol.
Project description:Human hepatocytes differ in gene expression and function across the hexagonal lobules of the tissue microarchitecture, a phenomenon referred to as liver zonation. Hepatocytes also display intra-lobular differences in cell size, but to what extent zonal expression and function correlate with cell size in isolated human hepatocytes is not entirely clear. Here, we first used our accumulated experience of nearly 100 hepatocyte isolations to assess the impact of donor background and process parameters on hepatocyte quality. We observed substantial inter-batch variability in cell size distributions and a tendency for overall cell size to affect the outcome of hepatocyte isolation and cryopreservation. We further separated cells into different size fractions and analyzed them with label-free quantitative proteomics. This showed that protein abundances in different hepatocyte size fractions recapitulated the in vivo expression patterns of well-known zonal markers. We also found that proteins with sequential enrichment across fractions largely represented biological processes with known zonal specificity. This was confirmed by differences in the metabolic activity of zonated CYP enzymes. Altogether, our results show that hepatocyte size corresponds to zonal origin, and that our size fractionation approach can be used to study zone-specific liver functions in vitro.
Project description:Liver transplantation is the only therapeutic option for patients with end-stage liver disease. The shortage of donor organs has led to the search for alternative therapies to restore liver function and bridge patients to transplantation. Our previous work has shown that the proliferation of late gestation E19 fetal hepatocytes is mitogen-independent. This is manifested as differences in the control of ribosome biogenesis, global translation, cell cycle progression and gene expression. In the present study, we investigated whether E19 fetal hepatocytes would engraft and repopulate an injured adult liver. Methods: Fetal hepatocytes were isolated using a monoclonal antibody against a hepatic surface protein, leucine amino peptidase (LAP). LAP+ and LAP- fractions were analyzed by immunofluorescence and microarray. Immunopurified E19 liver cells from DPPIV+ F344 rats were transplanted via splenic injection into partial hepatectomized DPPIV- rats that had been pretreated with mitomycin C. Results: Phenotypic characterization of the LAP+ fetal hepatocytes revealed that more than a third of the isolated cells expressed ductal markers. Transcriptomic analysis revealed that these dual expressing cells represent a distinct subpopulation of less well differentiated hepatocytes. Transplanted immunopurified LAP+ late gestation fetal hepatocytes formed small hepatic, endothelial and occasional ductal colonies within one month. The average size of the colonies derived from the LAP+ cells increased so that by 10 months up to 35% of the liver was repopulated by donor-derived cells. Conclusions: Our studies show that late gestation fetal hepatocytes, despite their being far along in the differentiation process, possess the capacity for extensive liver repopulation. This is likely related to the unexpected presence of a significant proportion of hepatocyte marker-positive cells maintaining a less well differentiated phenotype.