Can you please introduce yourself and tell us what inspired your latest research?
Dr. Fei Liu is a professor of Biomedical Engineering at Wenzhou Medical University in China.
Dr. Luke P. Lee is Professor of Medicine at Harvard Medical School, Harvard University.
The eyes reflect the health conditions and emotions of the human body. Lacrimal extracellular vesicles (EVs) carrying proteins, RNA, DNA, etc., are secreted from different cells in tears. We hope to explore the secret of diseases and emotions by isolating, purifying and investigating these biological particles at the nanoscale using the iTEARS platform and incorporating this with proteomics and sequencing technologies.
Currently, disease diagnoses are based on the assessment of the patient’s symptoms, which may not always be accurate in the early stages and may often be underreported. What problems does this create and how does your new iTEARS platform help overcome these challenges?
Clinical symptoms usually help to diagnose the disease at a later stage; however, the underlying molecular mechanisms need to be further explored for early stage detection and subtype classification.
Tears are relatively pure samples with low potential contaminant interference, which correlate directly with circulating fluids such as blood. Tear sample collection is quick and non-invasive, which attracts a lot of attention in point-of-care studies. However, studies based on tear samples are limited compared to other body fluids (eg, urine and blood) due to practical limitations in sample handling and analytical performance of tear exosomes.
Thus, we use the iTEARS platform to uncover the secrets of eye disorders and systemic diseases. We isolated exosomes rapidly with high throughput and purity from a few tears (∼10 μL) within 5 min for quantitative detection and biomarker discovery by proteomic and transcriptomic analysis.
Image Credit: T.Photo/Shutterstock.com
Analyzing exosomes helps improve disease accuracy, but current methods used to isolate them from samples such as urine are challenging. Why is this?
Exosomes (small extracellular vesicles) have been widely found in body fluids, including blood, urine, tears, saliva, and cerebrospinal fluid. Despite the different sample volumes and biological compositions among various body fluids, iTEARS can help produce more pure exosomes from clinical samples, which should be strongly encouraged. As we demonstrated in our study, we obtained more nanoparticles than UC or SEC methods, which are the most commonly used strategies in EV studies.
Your iTEARS platform is able to use tears, analyzing them for disease biomarkers. Can you please tell us more about how this platform was designed and works?
iTEARS is based on our EXODUS device, which consists of a sample reservoir coupled with a double nanoporous membrane and two outlets connected to the negative pressure oscillation system.
To achieve rapid exosome isolation, a periodic change of negative pressure is applied to two sides of the device, which can drive the sample, trap the larger-sized exosomes, release the small fragments (e.g., proteins, acids nucleic acids) and reduce bio- aggregates in the membranes, thereby speeding up the processing time and expanding the processing volume range. Purified exosomes can be extracted for downstream analysis, including proteomics, sequencing, PCR or ELISA.
Image credit: ACS Nano 2022
Your platform is based on using tears as a sample. Despite their often low volumes, what makes tears a good choice for this analysis?
As one of the crucial liquid resources of exosomes, tears are required to maintain normal physiological activities of the eyes and share parts of blood components through vascular penetration, indicating a prominent role in understanding ocular disorders and systemic diseases.
Unlike other ocular fluids, tears are highly accessible for biomarker analysis using the Schirmer strip, allowing us to discover molecular signatures of disease and establish a non-invasive diagnostic method. Tear studies are not a “hot topic” compared to other body fluids (eg urine and blood), but it is time to recognize the importance of molecular diagnostics.
How accurate is iTEARS in diagnosing diseases?
In this work, we aim to establish a new platform that can facilitate studies based on tear exosomes both in the diagnosis of the disease and in the pathogenesis. We have demonstrated the diagnostic potential of exosomal levels and their burdens in ocular diseases, and hope to show more detailed applications with large-scale cohorts in future work.
Your platform combines biology and nanotechnology. How important is it to have a multidisciplinary research approach when making discoveries? What are the advantages of this?
The integrated platform allows us to simplify the experimental processes, shorten the time consumed, and recover more exosomes with relatively high purity. Using iTEARS, we have shown the protein and miRNA compositions within tear exosomes and their dynamics in disease classifications or during disease development. In addition to medical studies, applications of the multidisciplinary research approach could also be extended to the broad field of natural sciences.
What would be the benefits of using this iTEARS platform not only for clinical settings but also for patient care?
We identified extracellular vesicle protein biomarkers to classify different types of dry eye diseases and miRNA biomarkers to monitor the development of diabetic retinopathy. We look forward to further developing point-of-care technology for patient healthcare.
Image credit: sruilk/Shutterstock.com
Currently, iTEARS has only been used in the diagnosis of eye conditions such as dry eye disease and diabetic retinopathy. Are you hopeful that with continued research, it can also be used to diagnose diseases in other areas of the body?
Tear components have been shown to relate to body organs such as the brain and chest. We hope to conduct further research not only on eye diseases but also on cancers, neurological and psychotic disorders, etc.
What’s next for you and your research?
We plan to further explore biological communications in the development or pathogenesis and precision molecular diagnosis of different diseases, as well as molecular quantifications of emotional conditions or molecular consequences of psychological stress through human tears.
We hope to provide a clinical translational method for tear-based molecular diagnosis and prognostication not only of eye-related diseases, but also of cancers, diabetes mellitus, neurological diseases, and the biological functions of emotional tears.
Where can readers find more information?
About Dr. Fei Liu
Dr. Fei Liu is a professor of Biomedical Engineering at Wenzhou Medical University. He received his Ph.D. in Chemical and Biomolecular Engineering from Korea Advanced Institute of Science and Technology (2012). His current research focuses on exosome-based clinical diagnostics and therapeutics.
About Dr. Luke P. Lee
Dr. Luke P. Lee is Professor of Medicine at Harvard Medical School, Harvard University.
His current research focuses on exosomics, exosome particle biophysics, molecular diagnostics, brain organoids on a chip, and quantum biological electron transfer.