COMPARISON OF FRESH AND CRYOPRESERVED CYNOMOLGUS MONKEY HEPATOCYTE CYTOCHROME P450 LEVELS IN INDUCTION STUDIES

Limited information is available on the induction of cytochrome P450 enzyme activities in vitro in fresh and cryopreserved cynomolgus monkey (Macaca fascicularis) hepatocytes. In this study, fresh cynomolgus monkey hepatocytes (FCMH), cryopreserved cynomolgus monkey hepatocytes (CCMH) and fresh human hepatocytes (FHH) were plated on collagen-coated 48-well plates. After a 48-hour preincubation period in medium, hepatocyte monolayers were incubated for 48 hours with vehicle control, 8 μM 3-methylcholanthrene (3-MC), 33 μM β-naphthoflavone (BNF), 2 mM phenobarbital (PB), 25 μM rifampicin (RIF), or 50 μM omeprazole (OMEP). At the end of the 5-day incubation period, all plates had hepatocyte monolayers of 70% or greater confluence. After the induction period, hepatocytes were evaluated for 7-ethoxyresorufin Odeethylase (CYP1A) and testosterone 6β-hydroxylase (CYP3A) enzyme activities. CYP1A was induced greater than 2-fold in FCMH, CCMH, and FHH by BNF, 3-MC, and OMEP. RIF did not induce CYP1A activity in any of the hepatocyte monolayers. CYP3A was induced greater than 2-fold by RIF and PB in all hepatocyte monolayers, while CYP3A activity was not induced by 3-MC or BNF. OMEP significantly induced CYP3A in FHH but did not induce in CCMH or FCMH. Of the five compounds in this study, all except OMEP demonstrated a similar induction profile for both CYP1A and CYP3A in human and cynomolgus monkey hepatocytes. In addition, CCMH responded in the same manner as FCMH, demonstrating the utility of this cryopreserved non-human primate hepatocyte model.