Isolation of circulating tumor cells using a microvortex-generating herringbone-chip

TLDR

Rare circulating tumor cells in cancer patients offer a minimally invasive source for detection, characterization, and monitoring of non‑hematological malignancies. The study aims to present a high‑throughput herringbone‑chip microfluidic device that enhances isolation of circulating tumor cells. The HB‑Chip employs passive microvortex mixing to increase interactions between CTCs and antibody‑coated surfaces, was validated with spiked cancer cells and prostate cancer specimens, and its transparent design permits imaging with standard histopathology and immunofluorescence. In 15 metastatic prostate cancer patients, 14 (93%) yielded detectable CTCs (median 63 cells/mL, mean 386 ± 238 cells/mL), TMPRSS2‑ERG translocation was identified by RT‑PCR, and low‑shear conditions revealed previously unappreciated CTC microclusters.

Abstract

Rare circulating tumor cells (CTCs) present in the bloodstream of patients with cancer provide a potentially accessible source for detection, characterization, and monitoring of nonhematological cancers. We previously demonstrated the effectiveness of a microfluidic device, the CTC-Chip, in capturing these epithelial cell adhesion molecule (EpCAM)-expressing cells using antibody-coated microposts. Here, we describe a high-throughput microfluidic mixing device, the herringbone-chip, or “HB-Chip,” which provides an enhanced platform for CTC isolation. The HB-Chip design applies passive mixing of blood cells through the generation of microvortices to significantly increase the number of interactions between target CTCs and the antibody-coated chip surface. Efficient cell capture was validated using defined numbers of cancer cells spiked into control blood, and clinical utility was demonstrated in specimens from patients with prostate cancer. CTCs were detected in 14 of 15 (93%) patients with metastatic disease (median = 63 CTCs/mL, mean = 386 ± 238 CTCs/mL), and the tumor-specific TMPRSS2-ERG translocation was readily identified following RNA isolation and RT-PCR analysis. The use of transparent materials allowed for imaging of the captured CTCs using standard clinical histopathological stains, in addition to immunofluorescence-conjugated antibodies. In a subset of patient samples, the low shear design of the HB-Chip revealed microclusters of CTCs, previously unappreciated tumor cell aggregates that may contribute to the hematogenous dissemination of cancer.