USE OF PLACENTAL CORD SERUM IN CULTURES OF HUMAN FETAL HEPATOCYTES - ITS ASSESSMENT WITH CARBAMYL-PHOSPHATE SYNTHETASE AND ARGININOSUCCINATE LYASE AS MARKER ENZYMES

Isolated human fetal hepatocytes could be successfully cultured in Dul becco's modified Eagle's medium (DMEM) supplemented with placental cor d serum, which is a rich source of various growth factors. These cultu red 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 argininosuccina te lyase (ASL), was studied in isolated and cultured hepatocytes from human fetuses of different gestational age classified as Group I: 17-2 0 weeks, Group II: 21-24 weeks, Group III: 25-28 weeks, Group IV: 29-3 2 weeks, and Group V: 33-36 weeks. We found that on culture the activi ties of the two enzymes increased for a period of 4-6 days. Hepatocyte s 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 b y the 5th day of culture. In the case of ASL the maximum levels were s een by the 4th day of culture, after which the activities of both enzy mes 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 tha t isolated hepatocytes undergo reversible changes and that on culture for 4-6 days, liver cell functions recover with enhanced enzyme activi ties. Cultured human fetal hepatocytes of Group III gestation would ap pear to be more suitable for transplantation than isolated hepatocytes .