| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
Hepatocytes and non-parenchymal liver cells were isolated from adult rat liver and co-cultured for 48 hours as a monolayr. The ability of tyrosine aminotransferase (TAT), which is one of liver specific functions, in hepatocytes was greatly enhanced by non-parenchymal cells. Hepatocytes and non-parenchymal liver cells were immobilized within Ca-alginate gel. In immobilization state non-parenchymal cells also could stimulate the ability of hepatocytes.
A soluble factor was responsible for the enhancement, because conditioned medium prepared from non-parenchymal cells was also stimulatory. We tried to fractionate non-parenchymal cells using Percoll gradient to analyze which type of cells secrete the soluble factor. The co-culture with Kupffer cell-rich fraction enhanced the ability of TAT induction in hepatocytes. Therefore, Kupffer cells seems to be responsible for this enhancement. The conditioned medium prepared from non-parenchymal cells was treated with 1 N acetic acid, dithlothreitol (DTT), and heat (55ﾟC 30mln). These treatments are known to inactivate hepatocyte growth factor (HGF). The soluble factor in the conditioned medium was inactivated by the acid, but stable to DTT and heat treatments. These results indicated that the soluble factor is different from HGF.Conditioned media prepared from non-parenchymal cells treated with D-galactosamine (Ga-NPCM) and llpopolysaccharide (LPS-NPCM) had higher activities of enhancement than the medium from normal cells (NPCM). Both Ga-NPCM and LPS-NPCM were stable to those physicochemical treatments. Therefore, the soluble factors in Ga-NPCM and LPS-NPCM are different from the factor in NPCM.Three kinds of conditioned media inhibited the DNA synthesis measured with [3H] thymidine uptake. It might be possible that the factors stimulating the ability of TAT induction and inhibiting DNA synthesis are identical. Now the purification of the factors is underway.
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