Automated Immunomagnetic Enrichment and Optomicrofluidic Detection to Isolate Breast Cancer Cells: A Proof-of-Concept towards PoC Therapeutic Decision-Making

Abstract

In breast cancer research, immunomagnetic enrichment of circulating tumor cells (CTCs) from body fluids has impressively evolved over the last decades. However, there is growing interest in further singularizing these pre-enriched rare cells to decrease signal-to-noise ratio for downstream molecular analysis, e.g., to distinguish between hormone receptor-associated tumor subtypes. This can be done by a combinatory principle to link magnetic cell separation with flow cytometry and single cell dispensing. We have recently introduced an automated benchtop platform with a microfluidic disposable cartridge to immunomagnetically enrich, fluorescence-based detect and dispense single cells from biological samples. Herein, we showcase the fine-tuning of microfluidic cell isolation in dependency of bead-binding on the cell surface. We implemented a gating function for the cytometer subunit of the benchtop platform to selectively dispense cells instead of autofluorescent objects. Finally, we developed a simplified qPCR protocol without RNA purification targeting breast cancer-relevant progesterone and estrogen receptor, Muc-1, Her-2, EpCAM and CXCR4 transcripts. In conclusion, the presented results markedly demonstrate a future diagnostic and therapy-accompanying semi-automated workflow using immunomagnetic enrichment, fluorescence-based isolation and dispensing of circulating tumor cells to achieve tumor subtyping by means of rapid, simple and immediate molecular biological examination of single cells.