Primary 3-dimensional culture of mouse hepatocytes

Complex 3-dimensional structures with good functions have been obtained under the primary mixcoculture of mouse hepatocytes with mouse liver fibroblasts without serum. Albumin secretion is kept above 10 μg/10⁶ cells and urea synthesis reaches 25 μg/10⁶ on the 7th day of culture. Avoiding serum affection, liver fibroblasts’ effects on hepatocytes’ viability, functions and 3-dimensional structure forming in primary serum-free culture have been studied. Important effects of the mesenchyma, especially the direct adherence of fibroblasts to hepatocytes, are shown.     

Advances in studies on hepatic stem cells

The question whether hepatic stem cells exist or not has been debated for several decades. Current researches confirm that there are hepatic stem cells in the liver. Oval cells, putative bipotential hepatic stem cells, are probably located within canals of Hering, portal tracts or branches of biliary trees. Bone marrow is a potential source of oval cells, indicating that there exists a close relationship between liver and hematopoiesis in adulthood. Hepatic stem cells are able to proliferate in vitro and can be induced to differentiate into hepatocytes. This will provide a promising approach of cell transplantation, tissue engineering and gene therapy for liver diseases. In this review, the evidence of their presence, origin, identification, proliferation in vitro, differentiation by induction, application prospects of hepatic stem cells and future directions for the field are discussed.     

Platinum-group element （PGE） geochemistry of the Emeishan basalts in the Pan-Xi area, SW China

Mantle plume represents massive mantle-derived magma activity and mainly causes the generation of the magma-associated deposits. The economically impor- tant magmatic deposits include Cu-Ni-PGE, V-Ti-Fe, and chromite deposits, e.g., the Bushveld giant PGE…     

Phenotypic analysis of the medullary-type CD4−CD8+ thymocytes in mice

Phenotypic analysis of the medullary-type CD4 CD8⁺ (CD8SP) thymocytes has revealed phenotypic heterogeneity within this cell population. The phenotype of mature peripheral CDS⁺T cells is TCRαβ⁺CD3⁺Qa-2⁺HSA 3G11⁻6C10, whereas in the medullary-type CD8SP thymocytes, 20% are Qa-2⁺; 33%, HAS; 30%, 3G11; and 70% are 6C10. The disparate expression patterns of these four cell surface markers suggest that medullary-type CD8SP thymocytes may undergo phenotypic maturation process. According to the distribution of these four cell surface markers, six subgroups of CD8SP thymocytes have been identified. The precursor-progeny relationship along with developmental pathway is postulated as follows: 6C10⁺HSA⁺3G11 Qa-2→ 6C10⁺HSA⁺ 3G11⁺Qa-2 → 6C10 HSA⁺3G11⁺Qa-2 → 6C10⁻HSA⁻3G11⁺Qa-2 → 6C10⁻HSA⁻3G11 Qa-2 → 6C10⁻HA S 3G11 Qa-2⁺, the cells in the last subgroup exit the thymus and home into periphery.     

Adhesion of subsets of human blood mononuclear cells to porcine endothelial cells

Cellular immune response is a major barrier to xenotransplantation, and cell adhesion is the first step in intercellular recognition. Flow-cytometric adhesion assay has been used to investigate the differential adhesions of monocyte (Mo), natural killer cell (NK) and T lymphocyte (T) present within human peripheral blood mononuclear cells (PBMC) to porcine aortic endothelial cells (PAEC), and to demonstrate the effect of human interferon-γ (hIFN-γ) or/and tumor necrosis factor-α (hTNF-α) pretreatment of PAEC on their adhesiveness for different PBMC subsets. The preferential sequence for PBMC subset binding to resting PAEC is Mo, NK and T cells, among which T cells show the slightest adherence; hTNF-α can act across the species, and augment Mo, NK and T cell adhesion ratios by 40%, 110% and 3 times, respectively. These results confirm at the cell level that host Mo and NK cells are major participants in the cellular xenograft rejection, thereby, providing a prerequisite for further studying the human Mo/NK-PAEC interactive mechanisms.     

Immunoinhibitory effect of soluble HLA-G1 on the cytotoxicity of NK92 cells

HLA-G (human leukocyte antigen-G) is a non-classical HLA class I molecule, playing an important immuno-modulatory role in maintaining maternal immune tolerance of the semiallogenic fetus and organ transplantation. In this study, the cDNA sequence of extracellular domain of HLA-G1 was subcloned into the pET28a vector and a soluble 35 kD fusion protein (His-sHLA-G1) with six histine residues was obtained. In the 4 h 51Cr-release assay the fusion protein obviously inhibited the cytotoxicity of NK92 cells in a dose-dependent manner. These results indicated that sHLA-G1, as an activated immunoinhibitor, may provide an effective approach to overcoming the immune rejection of transplantation.     

Human endothelial senescence can be induced by TNF-α

TNF-α is one of the most important proinflammatory cytokines in mediating multiple physio-pathological functions during immunological responses. Vascular endothelial cells, when stimulated by TNF-α, can increase the expression of multiple cytokines and cellular adhesion molecules and, in turn, actively promote the inflammatory responses by recruiting and activating of leukocytes to the inflammatory site. In addition to endothelial death induced by TNF-α, we found for the first time that TNF-α can also induce the human endothelial cells senescence. The induced senescent endothelial cells will display SA-β-Gal staining and they were arrested in G0-G1 phase. We found that †Ψ_m would always be up-regulated in response to TNF-α stimulation at early time but when the cells become senescent, †ψ_m shows a tendency to decrease. It may reflect the sthenic function of mitochondria at early time in response to TNF-α stimulation and decay when the endothelial cells were induced senescent. ROS fluctuates at early time and also decreases when the endothelial cells become senescent. Our results show that the change of mitochondrial function may be related to the senescent process.     

Human endothelial senescence induced by IL-1α in vitro

Interleukin 1(IL-1) is an important proinflammatory cytokine that causes pleiotropic effects. Vascular endothelial cells stimulated by IL-1α can lead to the inflammatory response. Reactive oxygen species (ROS) are also generated at the site of inflammation and serve as an important factor against foreign invader. Here we report that long-term stimulation of human vein endothelial cells with IL-1α can accelerate their senescence associated with β-galactosidase activity. The flow cytometric analyses showed that most of the induced cells entered G0-G1 phase. DNA damage was more severe in senescent cells by comet assay. The induced cells by IL-1α had higher levels of ROS and malonyldialdehyde (MDA), lower activity of antioxidant enzymes and lower capacity of total antioxidant systems than control, which led to cell damage and cell degeneration, that is to say, which contributed to cellular senescence. Our results gave a direct proof to a new hypothesis-"the inflammation hypothesis of aging" on cellular level, and also provided a basis for the study on anti-aging and aging-related diseases.