Biopsies are a sure way to find out if a patient really has a neoplastic tissue in the body. While highly accurate, biopsies are only useful if one has a lesion to sample. Many tumors are well hidden and difficult to reach, making traditional biopsies effectively impossible. But, tumors tend to shed cells that end up swimming in the blood stream. While these cells are very problematic, as they cause metastasis, they are also perfect biomarkers that point to the existence of cancer within the body. Spotting them within a drawn blood sample is known as a “liquid biopsy,” and many research groups around the world have been working to make such biopsies a common way to screen for cancer.
Now researchers at Duke University, MIT and Nanyang Technological University in Singapore are reporting in journal Small that they’ve developed a way to pull out circulating tumor cells (the ones that tumors shed) from whole blood samples using nothing but sound. They managed to achieve 86% efficiency when sifting through 7.5-mL of a blood sample in under an hour. This is very impressive, as circulating tumor cells are extremely rare and therefore take a while for most other methods to identify.
Circulating tumor cells tend to be larger and stiffer than most other cells present within blood. By creating a standing wave within a small microfluidic device, a stream of blood can be separated based on cell size and rigidity. Ultrasound that is similar in frequency and strength to that used in imaging is what is used to setup the special standing wave. The wave has such a structure that it pushes on some cells more than others, creating a filtration effect.
Here’s a video that shows off the technology:
Study in journal Small: Circulating Tumor Cell Phenotyping via High‐Throughput Acoustic Separation…