Characterization of a perfusion reactor utilizing mammalian cells on microcarrier beads

Our overall objective is to develop a cell culture analogue bioreactor (CCA ) that can be used together with a corresponding physiologically based phar macokinetic model (PBPK) to evaluate molecular mechanisms of toxicity. The PBPK is a mathematical model that divides the body into compartments repres enting organs, integrating the kinetic, thermodynamic, and anatomical param eters of the animal. The CCA bioreactor is a physical replica of the PBPK; where the PBPK specifies organs, the CCA bioreactor contains compartments w ith a corresponding cell type that mimics some of the characteristic metabo lism of that organ. The device is a continuous, dynamic system composed of multiple cell types that interact through a common circulating cell culture medium. The CCA bioreactor and the model can be coupled to evaluate the pl ausibility of the molecular mechanism that is input into the model. This pa per focuses on the design, development, and characterization of a CCA biore actor to be used in naphthalene dose response studies. A CCA bioreactor pro totype developed previously is improved upon by culturing the cells on micr ocarrier beads. Microcarrier beads with cells attached can form packed beds with cell culture medium perfusing the beds. In this study, two packed bed s of cells, one with L2 cells (rat lung) and one with H4IIE cells (rat hepa toma), are linked in a physiologically relevant arrangement by a common rec irculating cell culture medium. Studies of this CCA bioreactor presented he re include mixing profiles, effect of reactor environment on cell viability and intracellular glutathione, naphthalene distribution profile, and initi al naphthalene dosing studies. Unlike the prototype system there is no dete ctable response to naphthalene addition; in a companion paper we show that this discrepancy can be explained by differences in liquid residence times in the organ compartments. The perfusion reactor design is shown to have si gnificant operating improvements over prototype designs.