Category: Assay Development and Screening
While combination drug therapy is emerging as an effective strategy for the cancer treatments, there is a controversial issue about which is more efficient between simultaneous- and sequential-combination. The previous common view was that simultaneous combinations have better anti-cancer effects, but larger side-effects, and sequential combinations have the opposite characteristics. But, recently it has been revealed that sequential combination can have even better anti-cancer effect than simultaneous combinations in some cases. This is because cell signaling network can be dynamically rewired during the therapy. Especially, the use of a sequential drug combination has been shown to be effective in the treatment of triple negative breast cancer (TNBC), which is considered as an incurable disease, a need to find an effective sequential drug pairs have begun to emerge. However, it is hard to find potent sequential drug pairs among numerous drug candidates with conventional well plates and pipetting because such screening platforms require high reagent cost and laborious works. Therefore, it is required to develop more convenient and cost-effective method to perform high-throughput screening for sequential drug pair discovery.
Here, we present a novel platform to perform high-throughput sequential drug combination assay with a single pipetting of encoded drug-laden microparticles (DLPs). Thousands of heterogeneous encoded microparticles with different kinds of loading drugs are delivered to a “particle chip”, which has numerous microwells on it, by just one-step pipetting. Next, those DLPs are self-assembled into microwells one-by-one by several sweeping. Automated imaging and decoding system can identify which drug is in which microwell. By combining the “particle chip” with the “cell chip”, which have microwells seeded with cells, drug molecules in the DLPs are released to the microwell of the cell chip at the corresponding location. High-throughput assay of sequential drug combination can be conducted by sequentially replacing the “particle chip” assembled with different kinds of DLPs.
To make this platform available from a practical standpoint, we fabricated all chips with polystyrene (PS) injection molding, which enables mass production and introducing of 3-dimensional align-key. The cell chip and the particle chip each have 1600 microwells, so it is possible to carry out up to 1600 different kinds of assays on a single chip. To increase the reliability of our platform, we firstly proposed uniform drug loading method into microparticles based on freeze-drying of solvent from drug solution mixed with microparticles. Using our platform, we performed a sequential combination screening against TNBC cell line BT-20 within 45-drug pairs and various concentration. We identified that erlotinib followed by mitoxantrone is the most effective drug pairs among our treatment libraries.
We expect that our platform can help individual laboratories to more efficiently conduct high-throughput bio-assay in terms of cost and work-load.
Seo Woo Song– Ph.D. candidate, Seoul National University, Seoul, Seoul-t'ukpyolsi, Republic of Korea
Seoul National University
Seoul, Seoul-t'ukpyolsi, Republic of Korea
My research background is development of a platform for bio-medical researches. Currently I am working on developing high-throughput cell-based assay platform requiring no expensive equipment (i.e. robotic pipetting machine) and low labor. In addition, I am interested in the fabrication of functional polymer composites using photocurable polymers and applications using them.