Antigen-independent cell sorting begins by tagging the white cells in a blood sample with magnetic beads. The blood sample is then passed into the CTC-iChip microfluidic system, which first removes red cells, plasma and free magnetic beads and then sorts out tagged white blood cells, leaving a purified solution of circulating tumor cells. ( Emre Ozkumur, Mass. General Hospital Center for Engineering in Medicine)
Circulating tumor cells (CTCs) are shed by primary tumors and allow the cancer to metastasize to the distant sites. While this is a devastating tool in cancer’s war chest, it offers clinicians a marker through which to diagnose and monitor progress of the disease. Since the discovery of CTCs over a hundred years ago, researchers have been developing ever more sensitive methods of capturing them since they’re extremely rare in whole blood.
With this component of the CTC-iChip, a solution containing both white blood cells and circulating tumor cells enters on the left side of the chip and is then focused into a single-file through a microfluidic channel at the top section of chip. The solution then moves through a magnetic field that deflects out magnetically tagged cells (right section of the chip). Separated cells leave the device through different exits at the end of magnetic deflection channel.(Berkin Cilingiroglu)
Now a team from Massachusetts General Hospital has reported in journal Science Translational Medicine further refinements of their CTC-iChip that we initially reported three years ago. The new iteration of the device can process 107 cells per second and is applicable to just about any cancer type. Importantly, the CTC-iChip does not require using tumor-specific target molecules, perhaps allowing it to be used as a cancer screening tool. So far its ability to detect CTCs has been shown in epithelial and nonepithelial cancers of the lung, prostate, pancreas, breast, and melanoma.
From the study abstract:
The sorting of CTCs as unfixed cells in solution allows for the application of high-quality clinically standardized morphological and immunohistochemical analyses, as well as RNA-based single-cell molecular characterization. The combination of an unbiased, broadly applicable, high-throughput, and automatable rare cell sorting technology with generally accepted molecular assays and cytology standards will enable the integration of CTC-based diagnostics into the clinical management of cancer.
Flashback: CTC-chip Identifies Circulating Tumor Cells in Cancer Patients
Study in Science Translational Medicine: Inertial Focusing for Tumor Antigen–Dependent and –Independent Sorting of Rare Circulating Tumor Cells
MGH press release: Third-generation device significantly improves capture of circulating tumor cells
