Biotechnology and applied biochemistry | 2021
A continuous flow cell culture system for precision cell stimulation and time-resolved profiling of cell secretion.
Abstract
Cells absorb and secrete substances to-and-from their surroundings as part of metabolism, signaling, and other functions. These fluxes are dynamic, changing over time in response to external cues and internal programs. Static cultures are inadequate for measuring these dynamics because the environments of the cells change as substances accumulate or are depleted from medium, which affects cell behavior in unintended ways. Static cultures also offer limited time resolution due to the impracticality of frequent or prolonged manual timepoint sampling, and cannot expose cells to smooth, transient changes in stimulus concentrations. Perfusion cultures overcome these challenges by constantly replenishing medium to maintain cellular environments, while continuously sampling the effluent stream. However, many perfusion culture implementations are microfluidic devices, which cannot culture large tissue constructs and require specialized equipment and expertise to use. Previously published macrofluidic devices often use custom parts that are difficult to replicate, do not support both solute input control and measurement, and do not account for effects of dispersion on measured signals. In this study, a multiplexed macrofluidic perfusion culture platform was developed to measure secretion and absorption rates of substances by cells in a temporally controlled environment. The modular platform can handle up to 31 streams with automated sample collection using a fraction collector. This paper presents the assembly of this dynamic bioreactor and a method for quantitatively handling the effects of dispersion using residence time distributions. The system is then applied to monitor the secretion of a circadian clock gene-driven reporter from transfected cells. This article is protected by copyright. All rights reserved.