PT  - JOURNAL ARTICLE
AU  - Patrik Lundquist
AU  - Gunilla Englund
AU  - Cristine Skogastierna
AU  - Johan Loof
AU  - Jenny Johansson
AU  - Janet Hoogstraate
AU  - Lovia Afzelius
AU  - Tommy B. Andersson
TI  - Functional ATP-binding Cassette (ABC) Drug Efflux Transporters in Isolated Human and Rat Hepatocytes Significantly Affect Assessment of Drug Disposition
AID  - 10.1124/dmd.113.054528
DP  - 2014 Jan 06
TA  - Drug Metabolism and Disposition
PG  - dmd.113.054528
4099  - http://dmd.aspetjournals.org/content/early/2014/01/06/dmd.113.054528.short
4100  - http://dmd.aspetjournals.org/content/early/2014/01/06/dmd.113.054528.full
AB  - Freshly isolated hepatocytes are considered the gold standard for in vitro studies of hepatic drug disposition. To ensure a reliable supply of cells, cryopreserved human hepatocytes are often used. ABC-super family drug efflux transporters are key elements in hepatic drug disposition. These transporters are often considered lost after isolation of hepatocytes. In the present study the expression and activity of ABC transporters BCRP, BSEP, P-gp, MRP2, MRP3, and MRP4, in human and rat cryopreserved hepatocytes were investigated. In commercially available human cryopreserved hepatocytes all drug efflux transporters except human BCRP (hBCRP) exhibited similar expression levels as in fresh liver biopsies. Expression levels of hBCRP were 60% lower in cryopreserved human hepatocytes than in liver tissue, which could lead to, at most, a 2.5-fold reduction in hBCRP-mediated efflux. Fresh rat hepatocytes showed significantly lower levels of rat BCRP (rBCRP) compared to liver expression levels, expression levels of other ABC transporters were unchanged. ABC-transporters in human cryopreserved cells were localized to the plasma membrane. Functional studies could demonstrate P-gp and BCRP activity in both human cryopreserved and fresh rat hepatocytes. Inhibiting P-gp mediated efflux by elacridar in in vitro experiments significantly decreased fexofenadine efflux from hepatocytes, resulting in an increase in apparent fexofenadine uptake. The results from the present study clearly indicates that ABC-transporter mediated efflux in freshly isolated as well as cryopreserved rat and human hepatocytes should be taken into account in in vitro experiments used for modeling of drug metabolism and disposition.