Characterization of drug metabolizing activities in pig hepatocytes for use in bioartificial liver devices: comparison with other hepatic cellular models.
OBJECTIVE
The pig is considered the best donor of hepatocytes for bioartificial liver devices, but little is known about the metabolic capability of pig hepatocytes. Therefore, we have evaluated drug metabolizing activities in pig hepatocytes and liver microsomes and compared the results with those of man and other animal hepatic cellular models that are potential sources of cells for bioreactors, such as rat, rabbit and dog hepatocytes and hepatoma cell lines.


METHODS
Total cytochrome P450 levels, six phase 1 activities representative of the most relevant cytochrome P450 enzymes (7-ethoxycoumarin O-deethylase, 7-ethoxy-, 7-methoxy- and 7-benzoxyresorufin O-dealkylases, coumarin 7-hydroxylase and p-nitrophenol hydroxylase), two phase 2 activities (glutathione S-transferase and UDP-glucuronyltransferase) and CYP-dependent regioselective testosterone metabolism were evaluated in in vitro models of different species.


RESULTS
The pattern of specific cytochrome P450 activities and the metabolic profile of testosterone in intact hepatocytes were essentially the same as those measured in liver microsomes. Relatively low ethoxy-, methoxy-, and benzoxyresorufin O-dealkylation rates were found in pig liver microsomes and hepatocytes as compared to hepatic in vitro human models. However, in contrast with the other species studied, stereoselective testosterone oxidation profiles were practically identical in human and pig models. Finally, the metabolic capability of hepatoma cell lines was very limited in comparison with that of hepatocytes.


CONCLUSIONS
Pig hepatocytes are able to maintain in culture the phase 1 and phase 2 activities found in liver microsomes. The high metabolic similarities found between pig and human hepatocytes lend support to the use of pig hepatocytes in bioartificial liver devices.
Donato
M T
MT
Unidad de Hepatología Experimental, Centro de Investigación, Hospital Universitario La Fe, Valencia, Spain.
Castell
J V
JV
Gómez-Lechón
M J
MJ
D000818:Animals; D001711:Biotransformation; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004285:Dogs; D014453:Glucuronosyltransferase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D019164:Liver, Artificial; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013379:Substrate Specificity; D013552:Swine; D014407:Tumor Cells, Cultured
D004364:Pharmaceutical Preparations; D003577:Cytochrome P-450 Enzyme System; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase