1 Introduction
2 Current use of CTCs
2.1 Trends in CTC enrichment techniques
2.2 Markers for CTC enrichment
Device | Feature for isolation | Technology | Comments | Clinical studies | |
---|---|---|---|---|---|
Positive enrichment | CellSearch (Veridex) | EpCAM | FDA approved, ferromagnetic beads labeled with EpCAM-antibodies, stained for CK+, CD45−, DAPI+ | No detection of EMT, single marker, expensive, no further downstream analysis | |
GILUPI CellCollector | EpCAM | In vivo metal probe with anti-EpCAM antibodies on surface, high sensitivity | Invasive 30-min insertion, no detection of EMT, single marker, no further downstream analysis | NCT03071900, NCT02507778 | |
IsoFlux (Fluxion Biosciences) | EpCAM and optional additional markers | Antibody based magnetic separation by flow cytometry, additional markers available | Based on cell surface antigen presence, automated identification, incorporates Next Generation Sequencing | [19] | |
Herringbone CTC-Chip | EpCAM | Antibody micropost capture, microfluidic device | Increased interactions with antibody surface, based on cell surface antigen presence, single marker, no detection of EMT | [20] | |
MAC MicroBead Technology (Miltenyi) | EpCAM | Superparamagnetic nano-sized beads | No differentiation of low and high expression levels [21], single marker, no detection of EMT | [22] | |
BD FACScanto II | EpCAM and CKs | Flow-cytometry antibody fluorescent separation | No detection of EMT, based on cell surface antigen presence | ||
GEDI | EpCAM | Microfluidic device with EpCAM-antibody labeled obstacles, stained for CD45−, DAPI+, Pdx-1+ | No detection of EMT, single marker, no further downstream analysis | [25] | |
EPISPOT | Many cell surface proteins | CD45 depletion followed by immunofluorescence using fluorochrome labeled secondary antibodies | Utilize CTC secreted proteins for enrichment, protein characterization possible | [26] | |
Negative enrichment | RosetteSep CTC Enrichment Cocktail/ CD45 Depletion Cocktail (STEMCELL) | Density | RBC lysis with or without CD45 depletion followed by density gradient to remove lymphocytes and other unwanted cells | Requires downstream analysis to confirm CTC status | NCT02349867 |
ApoStream | Dielectric property | Dielectrophoresis field-flow that repels blood cells into eluent | Takes advantage of CTC phenotypic and dielectric properties | NCT02349867 | |
MAC MicroBead Technology (Miltenyi) | CD45 | Superparamagnetic nano-sized beads deplete CD45+ leukocytes | No differentiation of low and high expression levels [21] | ||
Size-based | CellSieve (Creatv Microtech) | Size | Biocompatible polymer filter with 7-μm diameter pores | Loss of small diameter CTCs, high leukocyte retention | |
ISET | Size | Polycarbon membrane with 8-μm diameter pores | Loss of small diameter CTCs, high leukocyte retention | NCT01776385 | |
Viator Therapeutic Oncophoresis System | Size and deformability | Ex vivo extracorporeal fluid circuit, cross-flow filtration, returns other blood elements back to the body | Time-consuming, patient compliance with procedure, loss of small diameter CTCs | NCT01943500 | |
Parosotix System (ANGEL) | Size and deformability | Microfluidic device, separates cells when flowing through steps of the cassette | NCT02490800, NCT03427450, NCT02785731 | ||
CanPatrol (SurExam) | Size | RBC lysis followed by filtration in an 8-μm diameter porous membrane | Loss of small diameter CTCs, high leukocyte retention | NCT02951897 | |
ScreenCell Cyto Filtration | Size | 8-μm diameter porous membrane | [30] | ||
Density-based | Ficoll-Paque | Density | Reagent separates peripheral blood mononuclear cells for downstream analysis of CTCs | Requires downstream analysis to confirm CTC status | [31] |