A low shear stress modular bioreactor for connected cell culture under high flow rates

Abstract

A generic "system on a plate" modular multicompartmental bioreactor array which enables microwell protocols to be transferred directly to the bioreactor modules, without redesign of cell culture experiments or protocols is described. The modular bioreactors are simple to assemble and use and can be easily compared with standard controls since cell numbers and medium volumes are quite similar. Starting from fluid dynamic and mass transport considerations, a modular bioreactor chamber was first modeled and then fabricated using "milli-molding," a technique adapted from soft lithography. After confirming that the shear stress was extremely low in the system in the range of useful flow rates, the bioreactor chambers were tested using hepatocytes. The results show that the bioreactor chambers can increase or maintain cell viability and function when the flow rates are below 500 microL/min, corresponding to wall shear stresses of 10(-5) Pa or less at the cell culture surface.

Design Criteria for Generating Physiologically Relevant In Vitro Models in Bioreactors

“…This value is now considered as an overestimation. In fact, we more recently report that a shear stress of about 2 × 10 −5 Pa exerts deleterious effects on the viability and function of sandwich cultured primary rat hepatocytes [31]. In a fluidic bioreactor system, shear stress and oxygen delivery are closely related: reducing the flow rate will reduce the shear stress on cells and, as a consequence, shear induced damage, but it will also reduce the oxygen delivery to hepatocytes.…”

“…As a result, in most academic and industrial research laboratories, the standard cell culture is still represented by cell monolayers cultured on Petri dishes or multi-well plates. Table 2 summarises the advantages and disadvantages of micro-and milli-fluidic systems [31]. …”

Environmental Control in Flow Bioreactors

“…LB1 is a single flow transparent bioreactor with an internal hydrodynamic design which ensures a low wall shear stress for high fluid turnover rates. The bioreactor is an upgrade of the MCmB (multi-compartmental modular bioreactor), which has been successfully used with hepatocytes [21,22]. The geometry of LB1 differs slightly from the MCmB, to increase the optical transparency of the system and enable optical imaging during the experiment.…”

“…The shear stress on the surface of a non-porous tissue construct depends linearly on the density and the viscosity of the culture medium used. In our model, the culture medium was considered an essentially aqueous media at body temperature characterized by the following constants: T = 310.15 K, ρ = 993 kg/m 3 , and η = 0.7 × 10 −3 Pa·s [2,22]. As boundary conditions, the inflow velocity v in was set to 2.12 × 10 −3 , 4.24 × 10 −3 , 6.36 × 10 −3 , and 10.6 × 10 −3 m/s (corresponding to 100, 200, 300, and 500 µL/min, respectively), on the basis of previous experiments with similar bioreactors.…”

Assessment of AMBR<sup>TM</sup> as a model for high-throughput cell culture process development strategy

“…Recent literature have demonstrated availability of various designs of micro-scale reactors from a simpler standard plate with integrated sensors called Microtiter plate based bioreactors (MTB) [6][7][8][9][10][11][12] to more advanced cell culture systems such as the Stirred Mini Bioreactors (MBR) with control capabilities close to bench-top bioreactors for high throughput cell culture screening and optimization studies [13][14][15][16][17]. MBRs possess the advantage of being able to closely mirror the bench-scale bio-reactors in their monitoring and control capabilities and hence are considered as a preferred alternative vessel over shake flasks or MTBs for early stage process development.…”