Devices and Systems for Point-of-Care Liquid Biopsy Cancer Diagnostics
Michael Heller,
Distinguished Scientist - Knight Cancer Institute, Center for Cancer Early Detection and Research (CEDAR),
Oregon Health & Science University (OHSU)
New AC dielectrophoretic (DEP) microarray/chip devices now allow 15-20-minute isolation of cancer related ccf-DNA, RNA and exosome biomarkers from 20-50ul of blood, plasma or serum. Circulating cell free (ccf) DNA, RNA and exosomes have now become important biomarkers for liquid biopsy cancer diagnostics and hold great promise for early cancer detection. Until recently, the isolation of these biomarkers from patient samples required relatively complex, time consuming and expensive procedures which greatly limits their use for point of care (POC) cancer diagnostic applications. Now using new AC DEP devices for isolation of these biomarkers, specific fluorescent dyes can be used first to simultaneously detect the different biomarker levels directly on the chip (in-situ). In a subsequent step, immunofluorescent analysis can be carried out to identify specific protein biomarkers on the exosomes. Finally, the ccf-DNA and RNA (mRNAs and miRNAs release from the exosomes) can be eluted from the DEP chip, and PCR and sequencing analysis carried out to identify the cancer-related point mutations and other polymorphisms, as well as to further verify the tissue origin of the biomarkers. In the case of our Chronic Lymphocytic Leukemia clinical studies, final PCR and DNA sequencing results for the CLL related ccf-DNA isolated by DEP were found to be exactly comparable to two much more complex and time consuming “gold standard” procedures. In the case of glioblastoma exosomes isolated from plasma, exosome-specific surface and interior proteins CD63 and TSG101 could be detected by immunofluorescence, and mutated EGFRvlll mRNA was detected by RT-PCR. Finally, the exosomal related protein biomarker Glypican-1 could be isolated from pancreatic cancer patient plasma samples by DEP and detected on-chip by immunofluorescence. Thus, DEP represents a powerful new minimally invasive technology for cancer diagnostics.
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