Shimaoka S, Nakamura T, Ichihara A
Division of Enzyme Pathology, University of Tokushima, Japan.
Exp Cell Res. 1987 Sep;172(1):228-42. doi: 10.1016/0014-4827(87)90109-1.
DNA synthesis of adult rat parenchymal hepatocytes alone in primary culture can be stimulated only by the addition of humoral growth factors to the culture medium. However, when parenchymal hepatocytes were cocultured with nonparenchymal liver cells from adult rats, their DNA synthesis was markedly stimulated in the absence of added growth factors or calf serum. DNA synthesis of parenchymal hepatocytes was not stimulated by conditioned medium from nonparenchymal liver cells and was greatest when the parenchymal cells were plated on 24-h cultures of nonparenchymal liver cells. A dead feeder layer of nonparenchymal cells was almost as effective as a feeder layer of viable nonparenchymal cells. These results suggest that the stimulation of DNA synthesis in parenchymal hepatocytes was not due to some soluble factors secreted by nonparenchymal liver cells but to an insoluble material(s) produced by the nonparenchymal liver cells. This insoluble material(s) was collagenase- and acid-sensitive, suggesting that it was a protein containing collagen. The effect of nonparenchymal liver cells was specific: coculture with hepatoma cells, liver epithelial cells, or Swiss 3T3 cells did not stimulate DNA synthesis in parenchymal hepatocytes. Added insulin and epidermal growth factor showed additive effects with nonparenchymal cells in the cocultures. These results suggest that DNA synthesis in parenchymal hepatocytes is stimulated not only by various humoral growth factors but also by cell-cell interaction between parenchymal and nonparenchymal hepatocytes, possibly endothelial cells. This cell-cell interaction may be important in repair of liver damage and liver regeneration.
原代培养中单独培养的成年大鼠实质肝细胞的DNA合成，只有在向培养基中添加体液生长因子时才能被刺激。然而，当实质肝细胞与成年大鼠的非实质肝细胞共培养时，在不添加生长因子或小牛血清的情况下，它们的DNA合成会受到显著刺激。非实质肝细胞的条件培养基不会刺激实质肝细胞的DNA合成，当实质细胞接种在非实质肝细胞的24小时培养物上时，DNA合成最为显著。非实质细胞的死亡饲养层几乎与活的非实质细胞饲养层一样有效。这些结果表明，实质肝细胞中DNA合成的刺激不是由于非实质肝细胞分泌的某些可溶性因子，而是由于非实质肝细胞产生的一种不溶性物质。这种不溶性物质对胶原酶和酸敏感，表明它是一种含胶原的蛋白质。非实质肝细胞的作用具有特异性：与肝癌细胞、肝上皮细胞或瑞士3T3细胞共培养不会刺激实质肝细胞的DNA合成。在共培养中，添加的胰岛素和表皮生长因子与非实质细胞表现出相加作用。这些结果表明，实质肝细胞中的DNA合成不仅受到各种体液生长因子的刺激，还受到实质肝细胞与非实质肝细胞（可能是内皮细胞）之间的细胞间相互作用的刺激。这种细胞间相互作用可能在肝损伤修复和肝再生中起重要作用。
