(579b) Design and Fabrication of High-Throughput Microfluidic 3-Dimensional Cell Culture Systems

3-dimensional (3D) cell cultures play a key role in tissue engineering. Furthermore, increasing evidence indicates that 3D cell cultures also create superior in vitro models for toxicity studies, and even provide novel platforms for bioprocessing, such as cell expansion and biomolecule production. For many of these applications, screening and testing for either different biological entities or cell culture conditions, based on cell growth kinetics and phenotypic responses, constitute the major exploratory tasks. Therefore, the need for iterative experiments makes high-throughput platforms desirable. Microfabrication provides the enabling techniques for making high-throughput cell culture devices. For 3D cell cultures, due to intrinsically high cell density, nutrient transport is a critical factor for maintaining cells. Therefore, perfusion culture over a relatively long period of time via microfluidic operation provides a feasible solution. As a result, the design and fabrication of high-throughput microfluidic 3D cell culture systems create some unique challenges for engineering. We adopted a bilayer design and assembly strategy for making the devices. Each device was composed of multiple chambers as microbioreactors and different channels to define the fluid flow distribution, either incorporating interactions between different chambers or excluding the interference from other chambers. We used photolithography and replica molding to make devices of poly(dimethylsiloxane) (PDMS). Simple bonding method for the bilayer was used to assemble the device for fluid flow studies. Fluid ports connecting the microchip and the macroworld were also engineered for prolonged use, which well stand the conditions of autoclave and the strains from multiple tubing assembly and disassembly. A frame-assisted assembly method was also devised to package the device for convenient cell seeding of different types and easy access to cells at any time of the culture process. The 3D culture was achieved by incorporating tissue engineering scaffold in each microbioreactor. Poly(ethylene) terephthalate (PET) fibers were used as a model scaffold in our studies, while the device can provide a platform for many types of 3D cultures. A colon cancer cell line, HT29, which was engineered to constitutively express green fluorescence protein, was used to test the culture systems under different conditions and operation modes. In addition, computational fluidic dynamics were also studied with FluentTM, and compared with experiment observations. Our work identified some interesting challenges in building high-throughput microfluidic 3D cell culture systems, and provided feasible solutions for further development.