Label-free enrichment of rare unconventional circulating neoplastic cells using a microfluidic dielectrophoretic sorting device

Abstract

Technologies that facilitate analyses of circulating biomarkers from blood for cancer detection are powerful tools for improving patient outcomes. Circulating biomarkers derived directly from the primary tumor have been identified including circulating tumor cells (CTCs) and circulating hybrid cells (CHCs), described to harbor phenotypes of both tumor cells and leukocytes. CHCs are present in higher numbers than CTCs which support their translational potential. Methods for isolation of CHCs do not exist and are restricted to low-throughput, time consuming, and biased methodologies. Here, we report development of a label-free dielectrophoretic (DEP) microfluidic platform facilitating enrichment of CHCs in a high-throughput and rapid fashion. Unlike other methods, depletion of healthy peripheral blood mononuclear cells (PBMCs) drives enrichment of CHCs. We analyzed DEP differential response of PBMCs and cancer cells and demonstrated up to 96.5% depletion of PBMCs resulting in 18.6-fold enrichment of cancer cells. In PBMCs from pancreatic adenocarcinoma patients, the platform enriched for neoplastic cells identified by their KRAS mutant status using droplet digital PCR from only 2 mL of whole blood with one hour of processing. Enrichment was achieved in 75% of the clinical samples analyzed, establishing this approach as a promising way to non-invasively analyze tumor cells from patients.