Antibody-independent isolation of circulating tumor cells by continuous-flow dielectrophoresis

Abstract

Circulating tumor cells (CTCs) are prognostic markers for the recurrence of cancer and may carry molecular information relevant to cancer diagnosis. Dielectrophoresis (DEP) has been proposed as a molecular marker-independent approach for isolating CTCs from blood and has been shown to be broadly applicable to different types of cancers. However, existing batch-mode microfluidic DEP methods have been unable to process 10 ml clinical blood specimens rapidly enough. To achieve the required processing rates of 10(6) nucleated cells/min, we describe a continuous flow microfluidic processing chamber into which the peripheral blood mononuclear cell fraction of a clinical specimen is slowly injected, deionized by diffusion, and then subjected to a balance of DEP, sedimentation and hydrodynamic lift forces. These forces cause tumor cells to be transported close to the floor of the chamber, while blood cells are carried about three cell diameters above them. The tumor cells are isolated by skimming them from the bottom of the chamber while the blood cells flow to waste. The principles, design, and modeling of the continuous-flow system are presented. To illustrate operation of the technology, we demonstrate the isolation of circulating colon tumor cells from clinical specimens and verify the tumor origin of these cells by molecular analysis.

Three dimensional passivated-electrode insulator-based dielectrophoresis

“…This technique has been widely used in biological applications to characterize yeast, 2 bacteria, 3 and mammalian cells. [4][5][6][7] Electrode based DEP (eDEP) technique is normally used to generate non-uniform electric fields in the channel. 8,9 Micro-patterned electrodes in the channel generate highly localized electric fields and trapping is observed to be concentrated around the electrodes.…”

Increasing label-free stem cell sorting capacity to reach transplantation-scale throughput

“…10,29 Other goals have been to design DEP devices for clinical samples (needing eventual approval by the FDA) or to make them amenable to industrial scale up or mass production. 9,24,27 However, many labs are recognizing the need to simplify the operation of DEP sorters to make them more useful for biological separations. To this end, new generations of sorters have addressed issues such as improving cell recovery from DEP devices.…”

“…Impressive sorting rates of up to 17,000 cells/s have been demonstrated in mammalian cell separations such as the isolation of breast cancer cells from blood, 25,26 leukemia cells from blood, 22 and circulating colon tumor cells from blood. 27 Many of these separations were aided by labels 28 or a difference in size between the cells of interest and background cells. Here, we have accomplished a biologically relevant enrichment of astrocyte progenitor cells from a population of neural stem/progenitor cells that are homogeneous in size.…”

Automated electrorotation shows electrokinetic separation of pancreatic cancer cells is robust to acquired chemotherapy resistance, serum starvation, and EMT

“…Differences in the crossover frequency between the cancer cells and the white blood cells allow for a positive DEP selection. 15,20,54 because cells are forced to regions in the device where the field is weak, so DEP trapping experiments yield only partial spectra. 21 Additionally, near the crossover frequency, which is of greatest interest for cell separations, the DEP signal is necessarily weakest, making it more vulnerable to confounding effects.…”

“…Using DEP as the only separation mechanism has led to some success in CTC enrichment. [14][15][16] A proof-of-concept hybrid DEP-immunoaffinity device has shown promise of further improving capture. [17][18][19] Careful device design and frequency selection can attract CTCs while repelling contaminating white blood cells, and simulations have predicted capture efficiency increases of up to 400%.…”