title: Functional Integrity of the Chimeric (Humanized) Mouse Liver: Enzyme Zonation, Physiologic Spaces, and Hepatic Enzymes and Transporters.
abstract: Chimeric mouse liver models are useful in vivo tools for human drug metabolism studies; however, liver integrity and the microcirculation remain largely uninvestigated. Hence, we conducted liver perfusion studies to examine these attributes in FRGN [Fah(-/-), Rag2(-/-), and Il2rg(-/-), NOD strain] livers (control) and chimeric livers repopulated with mouse (mFRGN) or human (hFRGN) hepatocytes. In single-pass perfusion studies (2.5 ml/min), outflow dilution profiles of noneliminated reference indicators ((51)Cr-RBC, (125)I-albumin, (14)C-sucrose, and (3)H-water) revealed preservation of flow-limited distribution and reduced water and albumin spaces in hFRGN livers compared with FRGN livers, a view supported microscopically by tightly packed sinusoids. With prograde and retrograde perfusion of harmol (50 µM) in FRGN livers, an anterior sulfation (Sult1a1) over the posterior distribution of glucuronidation (Ugt1a1) activity was preserved, evidenced by the 42% lower sulfation-to-glucuronidation ratio (HS/HG) and 14% higher harmol extraction ratio (E) upon switching from prograde to retrograde flow. By contrast, zonation was lost in mFRGN and hFRGN livers, with HS/HG and E for both flows remaining unchanged. Remnant mouse genes persisted in hFRGN livers (10%-300% those of FRGN). When hFRGN livers were compared with human liver tissue, higher UGT1A1 and MRP2, lower MRP3, and unchanged SULT1A1 and MRP4 mRNA expression were observed. Total Sult1a1/SULT1A1 protein expression in hFRGN livers was higher than that of FRGN livers, consistent with higher harmol sulfate formation. The composite data on humanized livers suggest a loss of zonation, lack of complete liver humanization, and persistence of murine hepatocyte activities leading to higher sulfation.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: Edwin C Y
authors.initials: EC
authors.lastname: Chow
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: Jason Z Ya
authors.initials: JZ
authors.lastname: Wang
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: Holly P
authors.initials: HP
authors.lastname: Quach
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: Hui
authors.initials: H
authors.lastname: Tang
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: David C
authors.initials: DC
authors.lastname: Evans
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: Albert P
authors.initials: AP
authors.lastname: Li
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.).
authors.forename: Jose
authors.initials: J
authors.lastname: Silva
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada (J.Z.W., H.P.Q., H.T., K.S.P.); Pharmacokinetics, Dynamics & Metabolism, Janssen Pharmaceuticals Inc., Spring House, Pennsylvania (D.C.E., J.S.); and In Vitro ADMET Laboratories, Columbia, Maryland (A.P.L.) ks.pang@utoronto.ca.
authors.forename: K Sandy
authors.initials: KS
authors.lastname: Pang
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000276:immunology; D015239:Arylsulfotransferase / Q000378:metabolism; D002678:Chimera; D004798:Enzymes / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000201:enzymology*; D051379:Mice; D008833:Microcirculation; D000099148:UGT1A1 Enzyme
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D015239:Arylsulfotransferase; D004798:Enzymes; D014453:Glucuronosyltransferase; D000099148:UGT1A1 Enzyme; C117544:SULT1A1 protein, human