1994 年 17 巻 3 号 p. 133-139
Isolated human fetal hepatocytes could be successfully cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with placental cord serum, which is a rich source of various growth factors. These cultured hepatocytes were found to maintain their viability, morphological integrity, and detoxifying capacity. The expression of two urea-cycle enzymes, i.e., carbamyl phosphate synthetase (CPS) and argininosuccinate lyase (ASL), was studied in isolated and cultured hepatocytes from human fetuses of different gestational age classified as Group I: 17-20 weeks, Group II: 21-24 weeks, Group III: 25-28 weeks, Group IV: 29-32 weeks, and Group V: 33-36 weeks. We found that on culture the activities of the two enzymes increased for a period of 4-6 days. Hepatocytes of Group I and Group II showed maximum expression of CPS by the 6th day of culture, whereas those of Groups III, IV, and V showed theirs by the 5th day of culture. In the case of ASL the maximum levels were seen by the 4th day of culture, after which the activities of both enzymes decreased. CPS activity in cultured hepatocytes was about 1.4-4.7 times higher whereas that of ASL was about 1.2-1.6 times higher, when compared with that of freshly isolated cells.
This study indicates that isolated hepatocytes undergo reversible changes and that on culture for 4-6 days, liver cell functions recover with enhanced enzyme activities. Cultured human fetal hepatocytes of Group III gestation would appear to be more suitable for transplantation than isolated hepatocytes.
