Breast cancer can be detected in your tears
Researchers from Kobe University and System Instruments Co have developed TearExo — a new chemical nanoprocessing technology that detects breast cancer using the exosomes found in small amounts of bodily fluids, such as tears, as biomarkers.
Described in the Journal of the American Chemical Society, TearExo demonstrates high sensitivity and smooth operability, without the need for pre-treatments and detection reagents. By enabling non-invasive testing to be conducted using tear fluid samples that can be easily self-collected by the patient, the technology has the potential to enable prompt cancer detection.
Currently, imaging-based screening methods such as mammography are used to detect breast cancer. However, these medical devices are often large and it takes time to obtain the results, as at least two specialists need to interpret the images. Liquid biopsies, where the extracellular vesicle exosomes found in patients’ bodily fluids are used as biomarkers to detect cancer, have now gained attention as a possible alternative, as they are non-invasive and reduce the burden on the patient.
Exosomes are considered to be extremely important markers for diagnosing cancer, as they are reported to be involved in cancer metastasis and malignant development. However, regular exosome analysis methods require cumbersome pre-processing. If a new, convenient and highly sensitive method for detecting cancer cell-related exosomes in bodily fluids were to be implemented, it would provide an extremely powerful cancer screening method.
TearExo consists of a fluorescent exosome sensing chip and an automatic exosome analyser — a highly sensitive assay to measure exosomes that enables bodily fluid tests to be conducted quickly and easily. The fluorescent exosome sensing chip was constructed by placing an antibody and a fluorescent reporter molecule in a 100 nm nanocavity formed on a glass chip. The antibody recognises the surface proteins of exosomes and the fluorescent reporter molecule can be used to read the exosomes’ binding with the antibody based on changes in the fluorescence. The automatic exosome analyser meanwhile enabled the researchers to achieve a rapid, ultrasensitive assay (about 1000 times more sensitive than current immunoassays) capable of detecting 50 exosomes in 100 µL of fluid in 10 min, without the need for the lengthy pre-treatment required in the past.
The technology was tested using tear fluid that was sampled from breast cancer patients and healthy donors via Schirmer tests, whereby a small strip of filter paper is used to collect the tear fluid. TearExo was used to measure the exosomes in these tear fluid samples and analyse the pattern of the surface proteins’ composition (principal component analysis).
A clear difference was found between the samples obtained from healthy donors and those from breast cancer patients, demonstrating that tear fluid can be used to detect breast cancer. The method could also be useful for monitoring patients who have undergone a mastectomy, as after surgery their exosome composition is the same as that found in healthy people.
Exosome analysis of clinical samples will be conducted on a larger scale to determine the specificity and sensitivity of this method of breast cancer diagnosis. After that, there are plans to establish a venture company and apply to Japan’s PMDA (Pharmaceuticals and Medical Devices Agency) for the approval of TearExo as an in vitro diagnostic device.
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