Enhancement of the predicted drug hepatotoxicity in gel entrapped hepatocytes within polysulfone-g-poly (ethylene glycol) modified hollow fiber

Abstract

Collagen gel-based 3D cultures of hepatocytes have been proposed for evaluation of drug hepatotoxicity because of their more reliability than traditional monolayer culture. The collagen gel entrapment of hepatocytes in hollow fibers has been proven to well reflect the drug hepatotoxicity in vivo but was limited by adsorption of hydrophobic drugs onto hollow fibers. This study aimed to investigate the impact of hollow fibers on hepatocyte performance and drug hepatotoxicity. Polysulfone-g-poly (ethylene glycol) (PSf-g-PEG) hollow fiber was fabricated and applied for the first time to suppress the drug adsorption. Then, the impact of hollow fibers was evaluated by detecting the hepatotoxicity of eight selected drugs to gel entrapped hepatocytes within PSf and PSf-g-PEG hollow fibers, or without hollow fibers. The hepatocytes in PSf-g-PEG hollow fiber showed the highest sensitivity to drug hepatotoxicity, while those in PSf hollow fiber and cylindrical gel without hollow fiber underestimated the hepatotoxicity due to either drug adsorption or low hepatic functions. Therefore, the 3D culture of gel entrapped hepatocytes within PSf-g-PEG hollow fiber would be a promising tool for investigation of drug hepatotoxicity in vitro.

Introduction

The development of liver tissue engineering has promoted the emergence of new devices for potential use as bioartificial liver (Diekmann et al., 2006) as well as in evaluation of drug hepatotoxicity in vitro (Khetani and Bhatia, 2008). The central element of the tissue engineered devices is 3D cultured hepatocytes with similar morphology and functions as in liver.

Collagen gel-based 3D cultures of hepatocytes are the most extensively used models for sustaining hepatic functions and reflecting drug behaviors in vitro. Such 3D cultures include sandwich (Farkas and Tannenbaum, 2005) and gel entrapment culture with (Nyberg et al., 1993) or without (Beken et al., 1997, deSmet et al., 1997) hollow fibers. The sandwich culture of hepatocytes between two collagen gel layers was the most accepted platform for drug investigation (Marion et al., 2007), while the entrapment culture of hepatocytes was designed as a simplified sandwich culture within a discal (Beken et al., 1997, deSmet et al., 1997) or cylindrical (Nyberg et al., 1992, Wu et al., 1995) collagen gel. Though being reportedly superior to gel entrapment culture in biotransformation of drugs (Beken et al., 1997, deSmet et al., 1997), sandwich culture could not preserve the CYP 2E1 expression for several days (Farkas and Tannenbaum, 2005). Another gel entrapment culture within hollow fibers initially developed for bioartificial liver could sustain high hepatocyte viability, biotransformation and synthesis activity for more than 7 days (Nyberg et al., 1993) but was not convenient for high-content drug evaluation.

Recently, we have scaled down the gel entrapment culture of hepatocytes in hollow fibers for high-content drug screening (Meng et al., 2006). This miniaturized gel entrapment culture not only expressed high liver-specific functions but also well reflected the hepatotoxicity of 20 selected drugs in vivo (Meng, 2010). By contrast to the frequently underestimated drug hepatotoxicity in traditional monolayer culture, the gel entrapment cultures of hepatocytes exhibited the high sensitivity to drug hepatotoxicity as in vivo. However, this culture model was found to underestimate the hepatotoxicity of hydrophobic drug like amiodarone due to its significant adsorption onto chemically synthetic hollow fibers and cylindrical gel entrapment without hollow fibers was used as an alternative (Shen et al., 2010). Such severe adsorption has elicited adverse effect on hemodialysis (Tsuruoka et al., 2004), bioartifical liver (Unger et al., 2001) and drug testing platform of Caco-2 cells (Palmgren et al., 2006). Moreover, whether the hollow fibers are necessary for maintenance of cell functions or only serve as a scaffold has never been addressed.

In this paper, we fabricate the PSf-g-PEG hollow fiber for hepatocyte entrapment culture and examine its impact on liver-specific functions as well as drug hepatotoxicity.