Slanted spiral microfluidics for the ultra-fast, label-free isolation of circulating tumor cells

Abstract

The enumeration and characterization of circulating tumor cells (CTCs), found in the peripheral blood of cancer patients, provide a potentially accessible source for cancer diagnosis and prognosis. This work reports on a novel spiral microfluidic device with a trapezoidal cross-section for ultra-fast, label-free enrichment of CTCs from clinically relevant blood volumes. The technique utilizes the inherent Dean vortex flows present in curvilinear microchannels under continuous flow, along with inertial lift forces which focus larger CTCs against the inner wall. Using a trapezoidal cross-section as opposed to a traditional rectangular cross-section, the position of the Dean vortex core can be altered to achieve separation. Smaller hematologic components are trapped in the Dean vortices skewed towards the outer channel walls and eventually removed at the outer outlet, while the larger CTCs equilibrate near the inner channel wall and are collected from the inner outlet. By using a single spiral microchannel with one inlet and two outlets, we have successfully isolated and recovered more than 80% of the tested cancer cell line cells (MCF-7, T24 and MDA-MB-231) spiked in 7.5 mL of blood within 8 min with extremely high purity (400-680 WBCs mL(-1); ~4 log depletion of WBCs). Putative CTCs were detected and isolated from 100% of the patient samples (n = 10) with advanced stage metastatic breast and lung cancer using standard biomarkers (CK, CD45 and DAPI) with the frequencies ranging from 3-125 CTCs mL(-1). We expect this simple and elegant approach can surmount the shortcomings of traditional affinity-based CTC isolation techniques as well as enable fundamental studies on CTCs to guide treatment and enhance patient care.

Circulating tumor cell technologies

“…ClearCell Ò FX (Clearbridge Biomedics) combines the inertial migration of particles with secondary flow from curved channels to isolate CTCs (Hou et al, 2013;Warkiani et al, 2014). In curved channels, a secondary "Dean's" flow arises as a consequence of differences in flow velocity between the center and walls of the channel.…”

“…No RBC lysis required, captures viable cells, easy to manufacture, clusters observed (Sollier et al, 2014) ClearCell Ò FX RBC lysis required, 1e1.5 mL/min, captures viable cells, easy to manufacture (Khoo et al, 2015(Khoo et al, , 2014Warkiani et al, 2014) Biophysical e Electrophoresis Separates cells based on their electrical signature using an applied electric field. (Carpenter et al, 2014;Fabbri et al, 2013;Fernandez et al, 2014;Manaresi et al, 2003;Peeters et al, 2013;Polzer et al, 2014) Biophysical e Acoustophoresis Separates cells based on acoustophoretic mobility, which is size dependent, by exposing them to acoustic waves.…”

Monolithic 3D labs- and organs-on-chips obtained by lithography-based ceramic manufacture

“…Nanometric details can even help to interact with micro-organisms, not just at a cellular, but also at a molecular level. Potential applications include the development of enhanced organson-chips, the manufacture of biological traps and the development of selective filters capable of capturing bacteria, viruses and pathogens for subsequent studies [29][30][31]. The optimal biological properties of ceramic materials may result in improved performance, as our cell culture results, detailed further on, help to put forward.…”

High‐Throughput Inertial Focusing of Micrometer‐ and Sub‐Micrometer‐Sized Particles Separation

“…The resulting hydrodynamic drag enhances the lateral migration of particles across the channel. There are two major classes of curved channels: a spiral geometry18, 25, 26 and a serpentine channel geometry with asymmetric14, 15, 27 or symmetric configurations 28, 29. In this design, a serpentine channel is used to reduce the number of focused particle streams.…”