Detection of Exosomal Cargoes by Plasmonic Biosensing Technology
Extracellular vesicles (EVs) are like tiny packages that cells release into the space around them. There are three kinds of these EVs - exosomes, microvesicles, and apoptotic bodies. Exosomes are released by almost all cell types, while microvesicles come from the plasma membrane of cells that have been activated, and apoptotic bodies are from cells that are dying.
These tiny EVs play a lot of different roles in our bodies. They help cells talk to each other, help fix damaged tissue, and help manage our immune system. These tiny packages are filled with all sorts of things like proteins, fats, and even genetic material. When they are sent from one cell to another, they can carry important information that can change how genes work, how the immune system responds, or even how cells move around. In the future, we might be able to use these EVs as a way to treat different diseases. Exosomes seem really promising. They could be used to help diagnose diseases, figure out how severe a disease is, and even be used as a treatment for various diseases, including glioma cancer.
Exosomes are tiny, bubble-like structures, about 30-200 nm, that are released by both healthy and sick cells. They carry a mix of proteins, fats, genetic material, and other molecules. We can find these mini bubbles in body fluids like blood, which makes them super handy for something we call liquid biopsies, a non-invasive way of diagnosing diseases like cancer. The exosomes released from cancer cells have special proteins and genetic info that we can use to identify and keep track of cancer's growth. These mini bubbles are even smaller than cells, so they can zip through blood vessels and get around the body fast, which makes them great for use in these liquid biopsies. Moreover, exosomes carry different types of genetic material including messenger RNA and microRNA. Looking at these can show us how genes are behaving in tumor cells, which helps doctors be more accurate in their diagnoses and plan more effective treatments. So, these tiny exosomes are a big deal for diagnosing and treating cancer through liquid biopsies.
Detecting these tiny packages from cells, the EVs, isn't easy, but we've got several techniques that help us do it. These include things like nanoparticle tracking and dynamic light scattering, methods that look at how light behaves when it hits these tiny particles. One of the most promising plasmonic biosensors known as Surface Plasmon Resonance (SPR), which is being widely studied to detect molecules found on cell membranes, like proteins and carbohydrates. This could be a game-changer in diagnosing diseases early and tracking how they develop.
SPR is like a high-tech sensor that can spot tiny changes in light when a molecule binds to something else. It's used a lot in biology because it's sensitive and precise and doesn't need any special labels to spot these binding events. It's versatile, being used in everything from drug discovery to detecting microbes and biofilms, and it can measure how fast these binding events happen under different conditions. It has the potential to see and measure interactions between proteins on cells and exosomes, giving us a direct look at these processes happening in real time. This makes it a potentially powerful tool for medical applications.
We've developed several types of SPR devices that are particularly good at detecting specific proteins that are important in a type of brain cancer called glioma. Glioblastoma is a very aggressive form of glioma with a poor outlook. We found that a byproduct made by cancer cells, lactate, ramps up a protein called CD44 and encourages the release of exosomes. Using a kind of SPR device, we were able to detect CD44 in these exosomes. We also ran tests in mice with glioblastoma, which showed the potential of using this SPR device to detect increased levels of CD44 in exosomes from blood and cerebrospinal fluid, a liquid found in and around the brain and spine. This could pave the way for less invasive tests for glioblastoma in the future. We've also looked at changes in cancer cells that cause them to make more of two other proteins, MCT1 and CD147, which help the cancer cells get rid of lactate. These proteins were also found to boost the release of exosomes loaded with molecules that can help the cancer grow. Another type of SPR device was able to detect these two proteins in the exosomes, offering another potential way to track how glioma develops. Furthermore, we've created a different SPR device to detect a specific protein on exosomes that come from glioma cells, called EGFRvIII. This could help us use blood and cerebrospinal fluid samples to diagnose and monitor glioma.
Understanding the difference between types of EVs is mostly down to their size and shape. Advanced techniques, including the use of SPR, can help us see and measure these differences. SPR is very sensitive and can detect a variety of biological molecules, making it a promising tool in diagnosing and monitoring diseases. Overall, the potential for SPR to detect different types of EVs in complex biological samples underlines the key role it could play in diagnosing and monitoring of medical oncology.
References
Minciacchi, V. R., Freeman, M. R., and Di Vizio, D. (2015). Extracellular Vesicles in Cancer: Exosomes, Microvesicles and the Emerging Role of Large Oncosomes. Semin. Cell Dev. Biol. 40, 41–51. doi: 10.1016/j.semcdb.2015.02.010.
Qiu, G., Thakur, A., Xu, C., Ng, S., Lee, Y., and Wu, C. L. (2019a). Detection of Glioma‐Derived Exosomes with the Biotinylated Antibody‐Functionalized Titanium Nitride Plasmonic Biosensor. Adv. Funct. Mater. 29, 1806761. doi: 10.1002/adfm.201806761.
Qiu, G., Thakur, A., Xu, C., Ng, S., Lee, Y., and Wu, C. L. (2019b). Sensors/Biosensors: Detection of Glioma‐Derived Exosomes with the Biotinylated Antibody‐Functionalized Titanium Nitride Plasmonic Biosensor (Adv. Funct. Mater. 9/2019). Adv. Funct. Mater. 29, 1970056. doi: 10.1002/adfm.201970056.
Thakur, A., Ke, X., Chen, Y.-W., Motallebnejad, P., Zhang, K., Lian, Q., et al. (2022a). The mini player with diverse functions: extracellular vesicles in cell biology, disease, and therapeutics. Protein Cell 13, 631–654. doi: 10.1007/s13238-021-00863-6.
Thakur, A., Parra, D. C., Motallebnejad, P., Brocchi, M., and Chen, H. J. (2022b). Exosomes: Small vesicles with big roles in cancer, vaccine development, and therapeutics. Bioact. Mater. 10, 281–294. doi: 10.1016/j.bioactmat.2021.08.029.
Thakur, A., Qiu, G., NG, S.-P., Guan, J., Yue, J., Lee, Y., et al. (2017a). Direct detection of two different tumor-derived extracellular vesicles by SAM-AuNIs LSPR biosensor. Biosens. Bioelectron. 94, 400–407. doi: 10.1016/j.bios.2017.03.036.
Thakur, A., Qiu, G., NG, S.-P., Wu, C.-M. L., and Lee, Y. (2017b). Detection of membrane antigens of extracellular vesicles by surface plasmon resonance. J. Lab. Precis. Med. 2, 98–98. doi: 10.21037/jlpm.2017.12.08.
Thakur, A., Qiu, G., Xu, C., Han, X., Yang, T., NG, S. P., et al. (2020). Label-free sensing of exosomal MCT1 and CD147 for tracking metabolic reprogramming and malignant progression in glioma. Sci. Adv. 6. doi: 10.1126/sciadv.aaz6119.
Thakur, A., Xu, C., Li, W. K., Qiu, G., He, B., Ng, S.-P., et al. (2021). In vivo liquid biopsy for glioblastoma malignancy by the AFM and LSPR based sensing of exosomal CD44 and CD133 in a mouse model. Biosens. Bioelectron. 191, 113476. doi: 10.1016/j.bios.2021.113476.
Yáñez-Mó, M., Siljander, P. R.-M., Andreu, Z., Bedina Zavec, A., Borràs, F. E., Buzas, E. I., et al. (2015). Biological properties of extracellular vesicles and their physiological functions. J. Extracell. Vesicles 4, 27066. doi: 10.3402/jev.v4.27066.