Clinical-Scale Cell-Surface-Marker Independent Acoustic Microfluidic Enrichment of Tumor Cells from Blood.

Enumeration of circulating tumor cells (CTCs) predicts overall survival and treatment response in metastatic cancer, but as many commercialized assays isolate CTCs positive for epithelial cell markers alone, CTCs with little or no epithelial cell adhesion molecule (EpCAM) expression stay undetected. Therefore, CTC enrichment and isolation by label-free methods based on biophysical rather than biochemical properties could provide a more representative spectrum of CTCs. Here, we report on a clinical-scale automated acoustic microfluidic platform processing 5 mL of erythrocyte-depleted paraformaldehyde (PFA)-fixed blood (diluted 1:2) at a flow rate of 75 μL/min, recovering 43/50 (86 ± 2.3%) breast cancer cell line cells (MCF7), with 0.11% cancer cell purity and 162-fold enrichment in close to 2 h based on intrinsic biophysical cell properties. Adjustments of the voltage settings aimed at higher cancer cell purity in the central outlet provided 0.72% cancer cell purity and 1445-fold enrichment that resulted in 62 ± 8.7% cancer cell recovery. Similar rates of cancer-cell recovery, cancer-cell purity, and fold-enrichment were seen with both prostate cancer (DU145, PC3) and breast cancer (MCF7) cell line cells. We identified eosinophil granulocytes as the predominant white blood cell (WBC) contaminant (85%) in the enriched cancer-cell fraction. Processing of viable cancer cells in erythrocyte-depleted blood provided slightly reduced results as to fixed cells (77% cancer cells in the enriched cancer cell fraction, with 0.2% WBC contamination). We demonstrate feasibility of enriching either PFA-fixed or viable cancer cells with a clinical-scale acoustic microfluidic platform that can be adjusted to meet requirements for either high cancer-cell recovery or higher purity and can process 5 mL blood samples in close to 2 h.