Shannon Stott, PhD, assistant professor of medicine at Harvard Medical School and assistant in genetics at Massachusetts General Hospital, is currently using microfluidic technologies to isolate circulating tumor cells (CTC) and extracellular vesicles (EVs) from patients with brain tumors. She’s working with Mass General neurosurgeon Brian Nahed, MD, to develop microfluidic blood tests that can use CTC and EVs as substitutions for glioma biopsies.

Microfluidic devices are chip-based networks that can collect a patient’s biomarkers, perform a drug screen, monitor a patient or create a summary of physiological mechanisms. Dr. Stott believes that these microfluidic technologies could complement existing procedures to provide greater accuracy from blood tests.

The technology could be especially helpful in neuro-oncology. Biopsy tissue removed from the brain provides limited information, and current technologies sometimes provide misleading images that can lead to misdiagnoses. But Dr. Stott says with this method she and Dr. Nahed can isolate tumor products with a high degree of specificity.

Aside from improved accuracy in diagnoses, Dr. Stott and Dr. Nahed hope to see two other outcomes as well:

  • An improved referral process that matches cancer patients with clinical trials
  • Expanded application of the technique so it can be used for brain injury and other neurological diseases


The two doctors face one big challenge: isolating CTCs properly. The ratio of CTCs to other cells in the blood can be one in a billion, making them the proverbial needle in the haystack. Dr. Stott and Dr. Nahed work around this by using negative selection, which essentially removes the white blood cells, red blood cells and platelets, making it easier to see the CTCs.

As for isolating the EVs, that’s a slightly more straightforward process. EVs are released from almost every cell in the body, but cells found in brain tumors carry unique proteins which can help isolate the EVs once they are identified.

All the processing steps for both technologies (isolating CTCs and isolating EVs) are incorporated on a single chip. Dr. Stott says they prefer to avoid harsh measures like centrifuging blood samples so they can maximize their biomarker yield. This process also provides high-quality RNA and could even lead to lab-grown cancer cells.

Drs. Stott and Nahed hope that in the future, this process can be applied to other neurological diseases as well as traumatic brain injuries.

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