The microfluidic capture of single breast cancer cells for multi-drug resistance assays.

Utilizing the microfluidic single-cell technique enables us to study the inhibition of multidrug resistance due to drug efflux on a single triple-negative breast cancer cell. This method examines drug efflux inhibition on a single cell in a microfluidic chip using a conventional optical detection system constructed from an inverted microscope and a microphotometer. More importantly, the integration of single-cell selection, dye and drug loading, and fluorescence measurement for intracellular drug accumulation is all conducted on a single microfluidic chip. By using a microfluidic chip and the adherent nature of the cancer cell lines, a single breast cancer cell could be selected and retained near the cell retention structure in the chip. This enabled us to detect dye accumulation in the MDR breast cells in the presence of cyclosporine A (CsA). CsA and rhodamine 123 (Rh123) were used as the P-glycoprotein (P-gp) inhibitor and fluorescent dye, respectively. Furthermore, Paclitaxel, a commonly known chemotherapeutic used in breast cancer patients, was administered in the presence of both reagents. During the entirety of the experiment fluorescence measurement was used to monitor the fluctuating levels of intracellular Rh123 levels, and an optical imaging system was used to monitor the shape and size of the cell. The results showed that the Rh123 fluorescence signal in a single-cell increased dramatically over its same-cell control due to the competitive inhibition of paclitaxel and the non-competitive inhibition subjected by CsA.

Development of a microfluidic platform for size-based hydrodynamic enrichment and PSMA-targeted immunomagnetic isolation of circulating tumour cells in prostate cancer.

Efforts to further improve the clinical management of prostate cancer (PCa) are hindered by delays in diagnosis of tumours and treatment deficiencies, as well as inaccurate prognoses that lead to unnecessary or inefficient treatments. The quantitative and qualitative analysis of circulating tumour cells (CTCs) may address these issues and could facilitate the selection of effective treatment courses and the discovery of new therapeutic targets. Therefore, there is much interest in isolation of elusive CTCs from blood. We introduce a microfluidic platform composed of a multiorifice flow fractionation (MOFF) filter cascaded to an integrated microfluidic magnetic (IMM) chip. The MOFF filter is primarily employed to enrich immunomagnetically labeled blood samples by size-based hydrodynamic removal of free magnetic beads that must originally be added to samples at disproportionately high concentrations to ensure the efficient immunomagnetic labeling of target cancer cells. The IMM chip is then utilized to capture prostate-specific membrane antigen-immunomagnetically labeled cancer cells from enriched samples. Our preclinical studies showed that the proposed method can selectively capture up to 75% of blood-borne PCa cells at clinically-relevant low concentrations (as low as 5 cells/ml), with the IMM chip showing up to 100% magnetic capture capability.