Optimized Hepatocyte-Like Cells with Functional Drug Transporters Directly-Reprogrammed from Mouse Fibroblasts and their Potential in Drug Disposition and Toxicology.

BACKGROUND/AIMS: To develop a suitable hepatocyte-like cell model that could be a substitute for primary hepatocytes with essential transporter expression and functions. Induced hepatocyte-like (iHep) cells directly reprogrammed from mice fibroblast cells were fully characterized. METHODS: Naïve iHep cells were transfected with nuclear hepatocyte factor 4 alpha (Hnf4α) and treated with selected small molecules. Sandwich cultured configuration was applied. The mRNA and protein expression of transporters were determined by Real Time PCR and confocal. The functional transporters were estimated by drug biliary excretion measurement. The inhibition of bile acid efflux transporters by cholestatic drugs were assessed. RESULTS: The expression and function of p-glycoprotein (P-gp), bile salt efflux pump (Bsep), multidrug resistance-associated protein 2 (Mrp2), Na+-dependent taurocholate cotransporting polypeptide (Ntcp), and organic anion transporter polypedtides (Oatps) in iHep cells were significantly improved after transfection of hepatocyte nuclear factor 4 alpha (Hnf4α) and treatment with selected inducers. In vitro intrinsic biliary clearances (CLb,int) of optimized iHep cells for rosuvastatin, methotrexate, d8-TCA (deuterium-labeled sodium taurocholate acid) and DPDPE ([D-Pen2,5] enkephalin hydrate) correlated well with that of sandwich-cultured primary mouse hepatocytes (SCMHs) (r2 = 0.984). Cholestatic drugs were evaluated and the results were compared well with primary mice hepatocytes. CONCLUSION: The optimized iHep cells expressed functional drug transporters and were comparable to primary mice hepatocytes. This study suggested direct reprogramming could provide a potential alternative to primary hepatocytes for drug candidate hepatobiliary disposition and hepatotoxicity screening.

Opposite regulation of hepatic breast cancer resistance protein in type 1 and 2 diabetes mellitus.

Previous studies on diabetes have reported controversial results with regard to transporters in liver. The present study aimed to explore changes in hepatic breast cancer resistance protein (BCRP) expression and functions, as well as the possible underlying mechanisms, in type 2 diabetic patients, type 1 (streptozotocin-induced), and type 2 (Goto Kakizaki) diabetic rats. Protein and mRNA levels of human (h) and rat (r) BCRP were investigated using Western blot and quantitative polymerase chain reaction analyses. Functions of liver rBCRP were evaluated using rosuvastatin. Sandwich cultured rat hepatocytes (SCRH) were cultured with d-glucose, insulin, or oleic acid for 72 h, and rBCRP mRNA was detected. The effect of oleic acid on rBCRP function in SCRH was also investigated using rosuvastatin. Results showed that liver rBCRP mRNA levels decreased to 20% in type 1 diabetic rats, whereas that in diabetic patients and GK rats significantly increased threefold and twentyfold, respectively. No changes were observed in h/rBCRP protein levels of type 2 diabetic patients and GK rats. The functions of rBCRP significantly declined in type 1 diabetic rats but showed no significant changes in GK rats. The data from SCRH indicated that d-glucose decreased rBCRP mRNA level to 60%. Oleic acid increased rBCRP mRNA in SCRH by approximately eightfold but decreased rBCRP function to 50%. Therefore, h/rBCRP expression and functions were oppositely regulated in type 1 and type 2 diabetes mellitus subjects. Alternations in d-glucose, insulin, and free fatty acid levels in plasma might contribute to the changes in h/rBCRP expression and functions.

Development and validation of a sensitive quantification method for hematoporphyrin monomethyl ether in plasma using high-performance liquid chromatography with fluorescence detection.

A rapid, sensitive, precise and specific method for determination of hematoporphyrin monomethyl ether (HMME), a novel photodynamic therapy (PDT) drug, was developed and validated using high-performance liquid chromatography (HPLC) with fluorescence detection. HMME was isolated from the plasma by a single-step liquid-liquid extraction with ethyl acetate. The analyte and internal standard fluorescein were baseline separated on a Diamonsil C(18) analytical column (4.6 x 150 mm, 5 microm) and analyzed using a fluorescence detector with the excitation and emission wavelengths set at 395 and 613 nm, respectively. The method was linear in the concentration range 0.025-5 microg/mL with a lower limit of quantitation (LLOQ) of 10 ng/mL. The inter- and intra-day accuracies and precisions were all within 10% and the mean recoveries of HMME and fluorescein were 95 +/- 3.7 and 90 +/- 2.3%, respectively. The analyte was stable during all sample storage, preparation and analysis periods. This method was successfully applied to a pharmacokinetic study after a single-dose intravenous administration of HMME (5 mg/kg) to beagle dogs. This method was reproducible and sensitive enough for the pharmacokinetic study of HMME. Based on the results of the pharmacokinetic study, we suggest that a rather long light-avoiding time is essential for patients under HMME therapy.