The heterogeneous nature of cancer has resulted in the use of combinatorial therapeutics designed to focus on multiple molecular targets. Monitoring the effectiveness of these tandem therapeutic combinations requires an analytical approach capable of high-throughput single cell screening. This approach provides a deeper understanding of drug treatments efficacies. Traditional approaches require performing replicate measures for each target in series or the incorporation of expensive antibodies to simultaneously track the different inputs. The goal of this work is to combine a suite of spectrally independent rare earth (RE)-doped nanoparticles with a three-input droplet microfluidic platform capable of high-throughput screening of the single cell response to increasing concentration of established drugs. This platform offers fast and accurate screening of encapsulated single cells in 70-micron aqueous droplet chambers that contain both fluorescent viability stains and luminescent RE-doped nanoparticles for droplet tracking. The triple-input microfluidic droplet trapping array was confirmed to achieve ~99% droplet trapping efficiency coupled with ~40-50% single cell encapsulation using GFP-expression HeLa cells. The result is a platform able to analyze approximately 500 cells for each of the three inlet conditions for a total of 1500 cells screened. As a proof of concept of the method, dynamic drug studies were performed to screen three different doses of two different cancer drugs: the proteasome inhibitor Bortezomib against myeloma-derived OPM2 cells and Paclitaxel against the triple negative breast cancer line MDA-MB-231. Image analysis of the encapsulated single cells was performed using a custom Python algorithm capable of distinguishing between nanoparticle trackers and fluorescent cells. The microfluidic platform confirmed that increasing the dose of a drug decreased cellular viability; however, the single cell approach confirmed a heterogeneous response in the population of cells with some cells exhibiting a resistance drug treatment. This platform can offer versatile drug studies, using patients’ samples in order to reach a suitable combined drug treatment that fits the unique needs of each individual patient diagnosed with cancer.

Simultaneous determination of drug efficacy in single cells using a multiplexed droplet trapping array

255th National Meeting (2018)

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