The isolation of circulating tumor cells is essential to diagnostics and metastasis studies. Since these cells are rare compared to the whole cell content of blood, the isolation process poses a challenge. There are several widespread methods of analysis and isolation of circulating tumour cells, from direct analysis of blood by marking tumor cells selectively, to blood processing through flow cytometry and magnetophoresis, that are based on EpCAM expression by tumor cells. However, circulating tumor cells from cancers of non-epithelial origin and cells that go through epithelial to mesenchymal transition do not have EpCAM. Therefore, these approaches have the tendency to lose rare cells.
To overcome this issue, a research team from Boston, Massachusetts has developed microfluidic methods that allow gentle and sensitive capture of circulating tumor cells from patients’ blood using tumor antigen independent enrichment. To improve the isolation of tumor cells from whole blood, this technique uses a modified CTC-iChip architecture with two consecutive separate chips. This method allows a primary separation of blood based on size to eliminate red blood cells and platelets. The remaining leukocytes are marked with anti-CD45 and anti-CD66b magnetic microbeads and then go through a two stage microfluidic magnetophoresis to deplete marked cells. This method results in a 97% yield of rare cells and is compatible with cytopathological and RNA-based characterization, genotyping analysis and culture methods.
The development of innovative methods for the isolation of circulating tumor cells based on immunomagnetic separation is of the uttermost importance for diagnosis and treatment of cancer. This group developed a solution for research that is easy to manufacture and highly efficient.
Microfluidic, marker-free isolation of circulating tumor cells from blood samples. Karabacak, N. M., Spuhler, P. S., Fachin, F., Lim, E. J., Pai, V., Ozkumur, E., … Toner, M. Nature Protocols, 9(3), 694–710 (2014).
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