Use of cryopreserved human hepatocytes in sandwich culture to measure hepatobiliary transport.

Fresh hepatocytes cultured in a sandwich configuration allow for the development of intact bile canaliculi and the ability to measure hepatic uptake and biliary clearance. A disadvantage of this model is its dependence upon hepatocytes from fresh tissue. Therefore, the ability to use cryopreserved human hepatocytes in this model would be a great advantage. Multiple variables were tested, and the recommended conditions for culturing cryopreserved human hepatocytes in a sandwich configuration in 24-well plates are as follows: BioCoat plates, a cell density of 0.35 x 10(6) cells/well in 500 microl, an overlay of Matrigel and InVitroGRO media. These conditions resulted in good hepatocyte morphology and the formation of distinct bile canaliculi. The function of multiple uptake and efflux transporters was tested in multiple lots of cryopreserved and fresh human hepatocytes. For taurocholate [Na+ taurocholate cotransporting polypeptide/organic anion transporting polypeptide (OATP) uptake/bile salt export pump efflux], the average apparent uptake, apparent intrinsic biliary clearance, and biliary excretion index among five cryopreserved hepatocyte lots was high, ranging from 11 to 17 pmol/min/mg protein, 5.8 to 10 microl/min/mg protein, and 41 to 63%, respectively. The corresponding values for digoxin (OATP-8 uptake/multidrug resistance protein 1 efflux) were 0.69 to 1.5 pmol/min/mg protein, 0.60 to 1.5 microl/min/mg protein, and 37 to 63%. Both substrates exhibited similar results when fresh human hepatocytes were used. In addition, substrates of breast cancer resistance protein and multidrug resistance-associated protein 2 were also tested in this model, and all cryopreserved lots showed functional transport of these substrates. The use of cryopreserved human hepatocytes in 24-well sandwich culture to form intact bile canaliculi and to exhibit functional uptake and efflux transport has been successfully demonstrated.

Simple strategies for reducing sample loads in in vitro metabolic stability high-throughput screening experiments: a comparison between traditional, two-time-point and pooled sample analyses.

Higher-throughput ADME programs in early drug discovery are becoming common throughout the pharmaceutical industry as companies strive to reduce their compound attrition in later-stage development. Many of the ADME assays developed into higher-throughput formats rely on LC/MS analyses. Since the biological aspects of the assay are amenable to parallel processes using dense plate formats, the number of samples generated from these assays produce a large analysis load for serial LC/MS. Presented in this report are two novel strategies, including a sample pooling method and a two time-point method, that could be used in drug discovery to reduce the number of samples generated during multiple time-point in-vitro ADME assays. One hundred and sixty-three compounds were subjected to human microsomal incubations with full time-point method samples taken at t = 0, 5, 15, 30, and 45 min. The ER data correlation (R(2)) between the full time-point method and the pooling method and two time-point methods were 0.98 and 0.97, respectively. Both methods have the potential to: 1. produce data of similar quality to traditional high throughput ADME assays, 2. be easily implemented, 3. shorten analytical run times, and 4. be reproducible and robust.