Microfluidic isolation of platelet-covered circulating tumor cells

Abstract

The interplay between platelets and tumor cells is known to play important roles in metastasis by enhancing tumor cell survival, tumor-vascular interactions, and escape from immune surveillance. However, platelet-covered circulating tumor cells (CTC) are extremely difficult to isolate due to masking or downregulation of surface epitopes. Here we describe a microfluidic platform that takes advantage of the satellite platelets on the surface of these “stealth” CTCs as a ubiquitous surface marker for isolation. Compared to conventional CTC enrichment techniques which rely on known surface markers expressed by tumor cells, platelet-targeted isolation is generally applicable to CTCs of both epithelial and mesenchymal phenotypes. Our approach first depletes unbound, free platelets by means of hydrodynamic size-based sorting, followed by immunoaffinity-based capture of platelet-covered CTCs using a herringbone micromixing device. This method enabled the reliable isolation of CTCs from 66% of lung and 60% of breast cancer (both epithelial) patient samples, as well as in 83% of melanoma (mesenchymal) samples. Interestingly, we observed special populations of CTCs that were extensively covered by platelets, as well as CTC-leukocyte clusters. Because these cloaked CTCs often escape conventional positive and negative isolation mechanisms, further characterization of these cells may uncover important yet overlooked biological information in blood-borne metastasis and cancer immunology.

AFM-compatible microfluidic platform for affinity-based capture and nanomechanical characterization of circulating tumor cells

“…The reversible physical bonding easily peels off of the PDMS chip for further AFM analysis of the captured intact CTCs residing on the glass substrate. While HB-based microfluidic devices have been widely used to isolate CTCs from blood samples of patients with epithelial (such as prostate 12 and breast 13 ) as well as nonepithelial (such as bone marrow 14 and lymphocytic leukemia 15 ) cancers, reversible microfluidic device assembly-which allows direct measurements of AFM tip-cell surface interactions with no restrictions on the external access of captured CTCs-to the best of our knowledge is novel.…”

Circulating tumour cell enumeration does not correlate with Miller-Payne grade in a cohort of breast cancer patients undergoing neoadjuvant chemotherapy

“…In this study, we define clusters as >3 CTCs but we have also conducted analyses using the other cut-offs of >1 cell and we did not find any significance with our clinicopathological details or response to neoadjuvant chemotherapy. Clusters are more aggressive than single CTCs [18,19] and a lot of effort is now focussed on methods for isolation and characterisation of CTC clusters [20,21]. We have previously reported the importance of platelets in cancer metastasis, which are a major component of these clusters and microemboli [28] and may explain the increased aggressiveness observed.…”

“…CTC clusters/microemboli have been associated with a worse clinical outcome in breast and lung cancer [17][18][19]. Current technologies underestimate CTC clusters because few specialized devices exist for the detection of CTC clusters and microemboli [20,21].…”

Recent Advances in Microfluidic Platforms Applied in Cancer Metastasis: Circulating Tumor Cells' (CTCs) Isolation and Tumor‐On‐A‐Chip

“…Furthermore, the OncoBean chip via affinity‐based capture methods provided feasibility of ultra‐high‐throughput processing even without blood dilution, and multiplexing separations. Jiang and co‐workers employed the platelet‐targeted isolation to capture mesenchymal and epithelial phenotypic CTCs from blood samples of lung, breast, and melanoma cancer patients via a herringbone‐based microfluidic platform . With the aid of hydrodynamic size–based sorting and affinity‐based capture methods, reliable captures of 66% and 60% CTCs (epithelial) were achieved from lung and breast cancer specimens, respectively, while 83% of CTCs (mesenchymal) were isolated from melanoma blood samples.…”