title: Fluid Dynamic Modeling to Support the Development of Flow-Based Hepatocyte Culture Systems for Metabolism Studies.
abstract: Accurate prediction of metabolism is a significant outstanding challenge in toxicology. The best predictions are based on experimental data fromin vitrosystems using primary hepatocytes. The predictivity of the primary hepatocyte-based culture systems, however, is still limited due to well-known phenotypic instability and rapid decline of metabolic competence within a few hours. Dynamic flow bioreactors for three-dimensional cell cultures are thought to be better at recapitulating tissue microenvironments and show potential to improvein vivoextrapolations of chemical or drug toxicity based onin vitrotest results. These more physiologically relevant culture systems hold potential for extending metabolic competence of primary hepatocyte cultures as well. In this investigation, we used computational fluid dynamics to determine the optimal design of a flow-based hepatocyte culture system for evaluating chemical metabolismin vitro. The main design goals were (1) minimization of shear stress experienced by the cells to maximize viability, (2) rapid establishment of a uniform distribution of test compound in the chamber, and (3) delivery of sufficient oxygen to cells to support aerobic respiration. Two commercially available flow devices - RealBio®and QuasiVivo®(QV) - and a custom developed fluidized bed bioreactor were simulated, and turbulence, flow characteristics, test compound distribution, oxygen distribution, and cellular oxygen consumption were analyzed. Experimental results from the bioreactors were used to validate the simulation results. Our results indicate that maintaining adequate oxygen supply is the most important factor to the long-term viability of liver bioreactor cultures. Cell density and system flow patterns were the major determinants of local oxygen concentrations. The experimental results closely corresponded to thein silicopredictions. Of the three bioreactors examined in this study, we were able to optimize the experimental conditions for long-term hepatocyte cell culture using the QV bioreactor. This system facilitated the use of low system volumes coupled with higher flow rates. This design supports cellular respiration by increasing oxygen concentrations in the vicinity of the cells and facilitates long-term kinetic studies of low clearance test compounds. These two goals were achieved while simultaneously keeping the shear stress experienced by the cells within acceptable limits.
authors.affiliation: Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences , Research Triangle Park, NC , USA.
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Pedersen
authors.affiliation: Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA; ScitoVation, LLC, Research Triangle Park, NC, USA; Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Yoo-Sik
authors.initials: YS
authors.lastname: Shim
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina , Chapel Hill, NC , USA.
authors.forename: Vaibhav
authors.initials: V
authors.lastname: Hans
authors.affiliation: ScitoVation, LLC , Research Triangle Park, NC , USA.
authors.forename: Martin B
authors.initials: MB
authors.lastname: Phillips
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina , Chapel Hill, NC , USA.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Macdonald
authors.affiliation: Joint Department of Biomedical Engineering, North Carolina State University , Raleigh, NC , USA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Walker
authors.affiliation: Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA; ScitoVation, LLC, Research Triangle Park, NC, USA.
authors.forename: Melvin E
authors.initials: ME
authors.lastname: Andersen
authors.affiliation: Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA; ScitoVation, LLC, Research Triangle Park, NC, USA.
authors.forename: Harvey J
authors.initials: HJ
authors.lastname: Clewell
authors.affiliation: Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA; ScitoVation, LLC, Research Triangle Park, NC, USA.
authors.forename: Miyoung
authors.initials: M
authors.lastname: Yoon
keywords: QuasiVivo; RealBio; computational fluid dynamics; fluid dynamic modeling; hepatocyte culture; metabolism