Transforming growth factor β inhibits the proliferation of human umbilical vein endothelial cells (HUVEC) depending on the isoform of TGF/β and culture conditions. When the cells are plated on substratum without pretreatment with extracellular matrices (ECM), the effect of TGFβ1 is biphasic while TGFβ2 inhibits the growth of HUVEC dose-dependently. The growth inhibition of HUVEC by TGFβ is not linked to a direct effect on the entry to S-phase DNA synthesis. In HUVEC cultured on the substratum coated with gelatin or collagen, growth inhibition by TGFβ is not observed. In addition, the susceptibility to TGFβ is reduced significantly in HUVEC at later cell passages. Cross-linking studies with radiolabeled TGFβ1 revealed is oform-specific 180 and 80 kDa TGFβ binding proteins on HUVEC. Phosphatidylinositol-specific phospholipase C induces the release of the 180 kDa protein from the cells, suggesting that the 180 kDa protein is attached to the cell membrane through a phosphatidylinositol anchor. Pretreatment of the substratum with ECM and changes in the number of cell passages did not alter the expression of TGFβ1-binding proteins in HUVEC. The data suggest that the susceptibility of HUVEC to TGFβ is not regulated at the level of receptor/binding proteins, and that growth inhibition of HUVEC by TGFβ is linked to the regulation of ECM required for the interaction between the cells and the substratum.

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Various sugar derivatives having carboxylic acid group, e. g., D-glucuronic acid, D-galacturonic acid, D-mannuronic acid, sialic acids,3-deoxy-D-manno-2-ocutulosonic acid (KDO), Lipopolysaccharides (LPSs), lactobionic acid, and Nacetylmuraminic acid were immobilized on aminomethylated polystyrene dishes, and murine macrophage cell line TME9 cells or murine peritoneal exudate cells were cultured on the immobilized dishes. In the supernatants of those cells, high productions of tumor necrosis factor (TNF), interleukin- I (IL-I), IL-6, granulocyte-macrophage-colony stimulating factor (GM-CSF), and granulocytestimulating factor (G-CSF) were detected. TME9 cells released TNF, IL-6, and GMCSF at the early stage of the culture, and IL- I at the second stage.

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Various proteoglycan (PG) molecules have been identified in the liver ECM. Large part of the hepatic PGs belongs to a group of heparan sulfate PGs, which mainly exist in association with plasma membrane of the hepatic cells. While a family of chondroitin sulfate (CS) PGs takes only a small part of the hepatic PGs and were mainly found in association with fibril collagens of insoluble ECM. Decorin and biglycan, both of which belong to small CS/DS-PGs, were recently isolated from hepatic insoluble ECM. These small CS/DS PGs inhibited the formation of monolayer of hepatocytes when immobilized on the culture dish, resulted in inducing the formation of multicellular spheroids in the primary culture. The multicellular spheroid appeared to be a tridimensional assembly of biologically active hepatocytes which retained various differentiated morphological features and functions. While HS-PG derived from EHS sarcoma did not show the spheroid forming ability, Similar difference in spheroid forming ability between CS and HS was found also with proteoglycan analogs of synthetic GAG-phospholipid. In this article we described about the difference in a biological aspect of CS- and HS-PGs proteoglycans with a special interest on the spheroid formation.

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[in Japanese]

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The neural tube consisting of neural precursor cells gives rise to the central nervous system. A simple enzymatic method has been established to isolate precursor cells. In primary culture, precursor cells proliferate and differentiate. Immortaliza tion of precursor cells made it possible to establish lines which proliferate and produce differentiated cells. Two different methods were taken to immortalize precursor cells. The first is to introduce oncogenes into precursor cells in culture, and the second is to isolate lines from tumors developed in transgenic mice. These lines will be powerful tools to study developmental biology, bio chemistry, molecular biology and electrophysiology of the central nervous system.

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