Miniaturization Of Bioartificial Liver/Kidney And Their Application In Predicting Drug Clearance

Predicting the absorption (A), distribution (D), metabolism (M) and excretion (E) properties of candidate drugs at an early phase of drug discovery is becoming increasingly important since the ADME of given drugs determined their toxicity and pharmaceutical efficiency. The pharmaceutical industry has therefore directed great efforts to develop fast and reliable in vitro methods for detection of drug ADME. In particular, it is very important to predict hepatic and renal clearance in vivo because most drugs are predominantly eliminated from the body by hepatic metabolism and renal excretion. However, the application of liver/kidney models is often limited by their imperfect simulation of in vivo situations. Therefore, the current paper aimed to establish miniaturized bioartificial liver/kidney for application as an in vitro alternative method in measuring hepatic/renal clearance. To this goal, the culture conditions of miniaturized bioartificial livers (gel entrapment culture of rat hepatocytes) which has been established in our past experiments will be optimized and the bioartificial kidney will be constructed.In our past experiments, gel entrapped rat hepatocytes have been proved useful in prolonging cell viability and preserving phase I and phase II enzyme acitivities. This paper further optimized its culture conditions and explored its application in the investigation of phase III metabolism. When cultured under optimal conditions, i.e., a collagen concentration of 0.6 g/L and the regular Williams’E medium supplemented with epidermal growth factor (EGF), the hepatocytes repolarized after 5-d incubation, and possessed a much higher hepatic transporter activities and a more accurate prediction of in vivo biliary clearance than conventional sandwich culture. Besides, gel entrapped hepatocytes could reflect the inhibition effect of efflux transporters on methotrexate and erythromycin induced hepatotoxicity.Furthermore, we established miniaturized bioartificial kidney by culturing rat proximal tubular cell (RPTC), Madin-Darby canine kidney (MDCK), and human kidney cell line (HK-2) inside a polysulfone hollow fiber. After 7-d incubation, renal cells formed in-vivo-like confluence, possessed lower MTT and GSH level, while higher levels of differential indexs including Mrp2, y-GT, CYP3A and AP than monolayer culture.Finally, we applied miniaturized bioartificial liver/kidney in prediction of in vivo clearance. For either hepatic clearance (CLh), renal clearance (CLr) or total clearance (CLtot), miniaturized bioartificial liver/kidney well provided a prediction with a high correlation coefficient squared (R2) of 0.92 for CLh,0.76 for CLr and 0.94 for CLtot, which were more accurate than conventional in vitro models.In conclusion, miniaturized bioartificial liver/kidney better predicted the drug clearance than conventional in vitro models and is suggested to be a relevant tool in drug development. Besides, the hollow fiber configuration of miniaturized bioartificial liver/kidney could benefit the construction of multiorgan combinational model.