Cell-Based Drug Combination Screening with a Microfluidic Droplet Array System

Abstract

We performed cell-based drug combination screening using an integrated droplet-based microfluidic system based on the sequential operation droplet array (SODA) technique. In the system, a tapered capillary connected with a syringe pump was used for multistep droplet manipulations. An oil-covered two-dimensional droplet array chip fixed in an x-y-z translation stage was used as the platform for cell culture and analysis. Complex multistep operations for drug combination screening involving long-term cell culture, medium changing, schedule-dependent drug dosage and stimulation, and cell viability testing were achieved in parallel in the semiopen droplet array, using multiple droplet manipulations including liquid metering, aspirating, depositing, mixing, and transferring. Long-term cell culture as long as 11 days was performed in oil-covered 500 nL droplets by changing the culture medium in each droplet every 24 h. The present system was applied in parallel schedule-dependent drug combination screening for A549 nonsmall lung cancer cells with the cell cycle-dependent drug flavopiridol and two anticancer drugs of paclitaxel and 5-fluorouracil. The highest inhibition efficiency was obtained with a schedule combination of 200 nM flavopiridol followed by 100 μM 5-fluorouracil. The drug consumption for each screening test was substantially decreased to 5 ng-5 μg, corresponding to 10-1000-fold reductions compared with traditional drug screening systems with 96-well or 384-well plates. The present work provides a novel and flexible droplet-based microfluidic approach for performing cell-based screening with complex and multistep operation procedures.

Microfluidics for cell-based high throughput screening platforms—A review

“…Furthermore, it is regarded as an effective way to increase the efficiency of drug discovery as most drug combinations are carried out using existing drugs which have passed through the strict clinical and safety examinations [70]. Based on the sequential operation droplet array (SODA) technique [71], Du et al [72] achieved multi-step operations for drug combination screening involving cell culture, medium changing, schedule-dependent drug dosage and stimulation, and cell viability testing in an oil-covered nanoliter-scale droplet array system, by using multiple droplet manipulations including liquid metering, aspirating, depositing, mixing, and transferring, as shown in Fig. 15.…”

High-throughput screening approaches and combinatorial development of biomaterials using microfluidics

“…Many of these systems are based on droplets, a rapidly growing subfield within microfluidics. Droplets are finely controlled emulsion objects generated by microfluidic stream breaks [131,132], existing either physically entrapped in arrays [133][134][135] or free in suspension [132,136,137]. As opposed to conventional methods to produce droplets, microfluidics-generated droplets can be highly monodisperse, easily engineered in geometry and content, and available for modular arrangements [131,132], owing to technical possibilities that allow precise generation, handling [138,139] and dispensing [140][141][142].…”

Electrical lysis of cells for detergent-free droplet assays

“…Droplet microfluidics breaks through this barrier by allowing single cells to be analyzed using soluble assays, such as enzyme catalysis, 5 detection of secreted products, 6–8 or presence of unique nucleic acid sequences 9,10 . The devices achieve this using tools for rapidly generating, 11 merging, 12 injecting, 13 and sorting droplets 14 for applications including single-cell sequencing, 15,16 directed evolution, 17,18 and drug screening 19 …”