This device can help diagnose diseases of your tears

ByLance T. Lee

Jul 22, 2022
Credit: Wikimedia Commons.

Some people are so afraid of going to the doctor that they might cry. Well, you might actually be encouraged to do that on a date in the future. Researchers have developed a nanomembrane system that analyzes extracellular vesicles called exosomes found in human tears and looks for signs of potential disease. It is a non-invasive solution that could provide reliable medical diagnosis for a number of eye-related conditions, but also for other conditions that may affect other parts of the body, not just the eyes. .

“Through our eyes, we can see, feel and communicate. Our tears generally maintain eye health, reflect our bodily conditions, and express emotions. In this work, we hope to provide a new way to uncover the secret of diseases and reflect emotions from tear extracellular vesicles combined with proteomics and sequencing technologies. We are interested in studying vesicle-based extracellular multi-biomarkers from teardrops for clinical diagnosis. Since the lacrimal glands secrete tears into the eyelids by filtration from blood plasma, which circulates throughout the body collecting exosomes from organs and tissues, it is time to recognize that tears contain rich clinical information. on different parts of our body,” lead authors Dr. Luke P. Lee of Harvard Medical School and Dr. Fei Liu of Wenzhou Medical University said. ZME Science.

Credit: ACS.

Exosomes carry nucleic acids, proteins, lipids and metabolites, components that may not only mirror their cell of origin, but also offer a means of detecting disease. They are released from many cell types, such as dendritic cells (DCs), lymphocytes, platelets, mast cells, epithelial cells, endothelial cells, and neurons, and can be found in most body fluids, including including blood, urine, saliva, amniotic fluid, breast milk and, as you now know, tears.

Until not too long ago, exosomes were thought to simply serve as “garbage bags” for cells to get rid of their unwanted constituents. However, recent research has shown that exosomes are not just biological containers, but rather play an important role in cell-to-cell communication and influence physiological and pathological processes. These properties make exosomes ideal for diagnosis. For example, exosomes can contain nucleic acids and proteins linked to cancer, as well as neurodegenerative, metabolic, infectious and other diseases.

The new system, dubbed “Integrated Tear Exosome Analysis via Rapid Isolation System,” or simply iTEARS for short, can separate exosomes from tear samples in just five minutes, as opposed to the hours or even days required by conventional approaches. traditional methods, such as ultracentrifugation (UC) and size exclusion chromatography (SEC), which involve complex multi-step processes and require large sample volumes.

The secret to these fast readings is a nanoporous membrane with oscillating pressure flow that effectively reduces clogging. The system allowed researchers to tag proteins with fluorescent probes for tracking and later transfer to other instruments for further analysis, as well as extract nucleic acids for analysis.

“Using our established method, an 18.4-fold and 2.3-fold elevation in particle amounts could be found compared to UC and SEC, respectively. Our approach shows a fast processing time (less than 5 minutes) and high recovered yield with relatively high purity, which enables us to get more proteins and miRNAs through tear extracellular vesicles per drop than from urine or blood and achieve the purpose of medicine precision based on tear exosomes (i.e. molecular diagnosis),” the researchers told us in an email.

In a demonstration, using iTEARS, researchers were able to identify dry eye and diabetic retinopathy in samples taken from healthy controls and patients. But the tears could be used to diagnose a range of diseases that affect the body, not just the eyes, researchers say. Together with blood and urine, tears could thus become viable samples that doctors could collect in order to make non-invasive and rapid diagnoses or to follow the progression of the disease.

“Previous reports have also demonstrated the relationship between tear components and body organs such as the brain and breast. Studies based on tear samples are limited compared to other bodily fluids (eg, urine and blood). However, tears are relatively pure with little potential interference from contaminants, directly correlated to circulating fluids such as blood. Collection of tear samples is rapid and non-invasive, which is attracting great attention in point-of-care studies.

Next, the researchers plan to use iTEARS to explore a range of disease diagnostics. They also want to see if iTEARS can be used to spot signs of stress and other markers of mental health problems.

“We hope to provide a clinical translation method for tear-based molecular diagnostics and prognoses, not only for eye diseases, but also for cancers, diabetes mellitus, neurological diseases and the biological functions of emotional tears.

The results are published in the journal ACS Nano.

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