PT  - JOURNAL ARTICLE
AU  - Albert P. Li
AU  - Ming-Chih David Ho
AU  - Kirsten Amaral
AU  - Carol Loretz
TI  - A novel in vitro experimental system for the evaluation of drug metabolism: Cofactor-supplemented permeabilized cryopreserved human hepatocytes (MetMax™ Cryopreserved Human Hepatocytes)
AID  - 10.1124/dmd.117.079657
DP  - 2018 Jan 01
TA  - Drug Metabolism and Disposition
PG  - dmd.117.079657
4099  - http://dmd.aspetjournals.org/content/early/2018/01/23/dmd.117.079657.short
4100  - http://dmd.aspetjournals.org/content/early/2018/01/23/dmd.117.079657.full
AB  - We report here a novel experimental system - MetMax™ cryopreserved human hepatocytes (MMHH), for in vitro drug metabolism studies. MMHH consist of cofactor-supplemented permeabilized cryopreserved human hepatocytes. The use procedures for MMHH are significantly simplified from that for conventional cryopreserved human hepatocytes (CCHH): 1. Storage at -80o C instead of in liquid nitrogen; 2. Usage directly after thawing without centrifugation and microscopic evaluation of cell density and viability and cell density adjustment. In this study, we compared MMHH and CCHH in CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2D6, CYP2E1, CYP3A4, CYP2J2, monoamine oxidase A, aldehyde oxidase, flavin-containing monooxygenase, UGT, SULT, NAT-1, and acetaminophen glutathione (GSH) conjugation activities based on LC/MS-MS quantification of substrate metabolism. MMHH were prepared from CCHH consisted of hepatocytes pooled from 10 individual donors. The DME activities of both CCHH and MMHH were cell concentration and time-dependent, with specific activities of MMHH ranged from 43.24% (aldehyde oxidase) to 234.21% (acetaminophen GSH conjugation) of that for CCHH. As observed in CCHH, sequential oxidation and conjugation was observed in MMHH for coumarin, 7-ethoxycoumarin, and acetaminophen. 7-hydroxycoumarin conjugation results showed that metabolic pathways in MMHH could be selected via the choice of cofactors, with glucuronidation but not sulfation observed in the presence of UDPGA and not PAPS and vice versa. Results with non-cytotoxic and cytotoxic concentrations of acetaminophen showed that drug metabolism was compromised in CCHH but not in MMHH. Our results suggest that the MMHH system represents a convenient and robust in vitro experimental system for the evaluation of drug metabolism.