Microfluidic, Label-Free Enrichment of Prostate Cancer Cells in Blood Based on Acoustophoresis

Abstract

Circulating tumor cells (CTC) are shed in peripheral blood at advanced metastatic stages of solid cancers. Surface-marker-based detection of CTC predicts recurrence and survival in colorectal, breast, and prostate cancer. However, scarcity and variation in size, morphology, expression profile, and antigen exposure impairs reliable detection and characterization of CTC. We have developed a non-contact, label-free microfluidic acoustophoresis method to separate prostate cancer cells from white blood cells (WBC) through forces generated by ultrasonic resonances in microfluidic channels. Implementation of cell pre-alignment in a temperature-stabilized (±0.5°C) acoustophoresis microchannel dramatically enhanced the discriminatory capacity and enabled the separation of 5-μm microspheres from 7-μm microspheres with 99% purity. Next, we determined the feasibility of employing label-free microfluidic acoustophoresis to discriminate and divert tumor cells from WBCs using erythrocyte-lysed blood from healthy volunteers spiked with tumor cells from three prostate cancer cell-lines (DU145, PC3, LNCaP). For cells fixed with paraformaldehyde, cancer cell recovery ranged from 93.6% to 97.9% with purity ranging from 97.4% to 98.4%. There was no detectable loss of cell viability or cell proliferation subsequent to the exposure of viable tumor cells to acoustophoresis. For non-fixed, viable cells, tumor cell recovery ranged from 72.5% to 93.9% with purity ranging from 79.6% to 99.7%. These data contribute proof-in-principle that label-free microfluidic acoustophoresis can be used to enrich both viable and fixed cancer cells from WBCs with very high recovery and purity.

Circulating tumor cell technologies

“…Acoustophoresis Chip Size Acoustic pre-alignment and separation (Antfolk et al, 2015a(Antfolk et al, , 2015bAugustsson et al, 2012) (continued on next page)…”

Acoustic Tweezing and Patterning of Concentration Fields in Microfluidics

“…By actuating the transducer at a resonance frequency of the cavity, an acoustic standing-wave field can be established in the channel cross section in the y-z plane, which is typically a few hundred micrometers in the width W and height H, leading to fundamental resonance frequencies on the order of 1-10 MHz. These systems are well characterized [4,[25][26][27][28] and are used in various biomedical applications, for example, the enrichment of circulating tumor cells in blood [14,29].…”

Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis

“…samples including blood, [20][21][22][23] raw milk, 24 circulating tumor cells, 25,26 and yeast. 27 For bulk acoustic waves (BAW) microchannel acoustophoresis is usually carried out in the 1-10 MHz frequency range and particles are focused along a single dimension.…”