Table 1.
Comparison of CTC enrichment techniques
| Enrichment Method | Advantages | Disadvantages |
|---|---|---|
| Cell density | ||
| Ficoll-Hypaque or similar | Easy, low cost, availability of cells for additional studies, EpCAM-positive and – negative tumor cells are retained | Low specificity, due to high contamination with leukocytes, Low CTC recovery, limited data for clinical validation |
| OncoQuick® | Easy, improved depletion of leukocytes, availability of cells for additional studies, EpCAM-positive and –negative tumor cells are retained | Low CTC recovery, limited data for clinical validation |
| Cell Size | ||
| ISET® | Easy procedure, availability of cells for additional studies, EpCAM-positive and – negative tumor cells are retained | Low specificity, large leukocytes are retained, CTCs are fixed, requires an automated filtration system, limited data for clinical validation |
| ScreenCell® | Easy, low cost, live cells can be retrieved for culture purposes, different kits available for cell enumeration, immunolabeling, and molecular biology studies, Ep-CAM-positive and –negative tumor cells are retained | High sensitivity, low specificity due to potential leukocyte contamination, limited data for clinical validation |
| Antibody-based magnetic platforms | ||
| MACS® Dynabeads® | Cell integrity preserved, flexible (antibodies available for positive and negative selection) | False positive results due to retention of non-tumor cells expressing same antigens, CTCs depleted of specific antigens (i.e., EpCAM) can be lost, limited data for clinical validation |
| CellSearch® | Semiautomated system, high reproducibility, High purity, can be used for molecular profiling and flow cytometry, FDAapproved for predicting the prognosis and monitoring of clinical outcome in certain cancers | Mutiple steps, non-viable cells, modest cell recovery, only EpCAM-positive CTCs detected Expensive |
| MagSweeper | Automated, flexibility in the starting sample volume and the process scalability, high purity, high recovery, purified cells can be used for biochemical analysis | Only EpCAM-positive CTCs detected Limited data for clinical validation |
| Antibody-based microfluidic platforms | ||
| CTC-Chip Herringbone-Chip | Very sensitive, with almost 100% detection rate, single step separation procedure, no pre-processing of blood necessary, low volumes of blood are used, cell viability is maintained, can be used for molecular profiling | Cells cannot be collected for tissue culture Only EpCAM-positive CTCs detected Limited data for clinical validation |
| High-throughput microsampling unit (HTMSU) | Very sensitive, single step separation procedure, low volumes of blood are used, no pre-processing of blood necessary, no cell staining or microscopic visualization needed, can be used for molecular profiling | Only EpCAM-positive CTCs detected, no data for clinical validation |
| “Nano-Velcro” microfluidic chip | Very sensitive, single step separation procedure, fast, no pre-processing of blood necessary, low cost | Cells are fixed, only EpCAM-positive CTCs detected, no data for clinical validation |