Biomarkers have been considered a major step towards early diagnosis and a less invasive method for detecting diseases. Since 1847, when the first biomarker called Immunoglobulin Free Light Chain was discovered by Dr. Henry Bence Jones, the discoveries of biomarkers have only been increasing. Today, we have biomarkers for various conditions such as tumour markers for cancer, indicators for blood pressure, cholesterol etc.
Biomarkers are molecules that can be found in blood, tissues and other bodily fluids. They are used to detect certain conditions or diseases. They can also be used to monitor how the body responds to certain treatments. Biomarkers are being used to detect cancer, specifically solid cancer which is a mass of cancer cells that grow in an organ (for example breast cancer or lung cancer) and predicting the likelihood of further developments expected.
The major challenge faced in cancer treatment is the early detection which would significantly increase the chances of remission. Upcoming molecular biomarkers have shown promising signs of early diagnosis and might help in effective management of cancer treatment. Evidence shows that Extracellular Vesicles, that are small membrane bound vesicles derived from cells that are found in human body fluids, can be used as biomarkers. Cancer biomarkers are enzymes, RNA, DNA, produced or found in either tumor cells or by the host as an immune response to the cancer and they can be derived from blood or tissues.
Exosomes, a type of Extracellular Vesicle, are tiny vesicles that form when the membrane of late endosomes (which are small compartments within the cells), fold inwards and bud off. They represent the constituents of the cell from which they are secreted. These bodies are then transported to the cell’s surface, merge with the plasma membrane and they release exosomes into the extracellular space outside the cell. Exosomes play a vital role in cell communication as they carry and deliver molecules like protein and lipids to other cells. In addition to gene regulatory molecules, exosomes contain molecules that can be used to create vaccines. These characteristics make exosomes very suitable as biomarkers.
To improve cancer treatment, it's crucial to deliver drugs more accurately to tumor cells. Exosomes, naturally good at delivering substances, have been widely used to carry medications and functional RNA in cancer therapy. They can be taken up by cells and can safely transport drugs, like therapeutic microRNAs and proteins, to the target. They have special proteins on their surfaces that help them enter cells and deliver their contents effectively. In a study conducted in 2017 with mice, exosomes loaded with chemotherapy drugs were able to reach and treat tumor tissues effectively, stopping tumor growth without causing the usual side effects that come with free drugs. For instance, when exosomes were engineered to carry the drug doxorubicin (a type of chemotherapy drug), they delivered it more efficiently to tumor cells, which significantly enhanced the drug's ability to fight cancer.
Stem cell-derived exosomes have also been seen as a potential cancer treatment. In an experiment done in 2014, scientists Makiko Ono & Nobuyoshi Kosaka, co-cultured a specific type of aggressive breast cancer cells (called BM2) with bone marrow mesenchymal stem cells (BM-MSCs). The exosomes released by the BM-MSCs caused the cancer cells to enter a "dormant" state. This dormant state means the cancer cells grew more slowly, had fewer markers that are typically found on aggressive cancer cells, and became less sensitive to the chemotherapy drug docetaxel. The stem cell exosomes made the cancer cells less active.
While there are promising signs regarding the role of exosomes in cancer diagnosis and treatment, further research is crucial to fully bring out their potential. To do so, more in-depth studies are required to identify specific biomarkers associated with different types of cancer. Moreover, emerging evidence has shown a correlation between the size of exosomes and the progression of cancer, indicating that exosome size could play an important role in both the detection and understanding of cancer. This correlation highlights the importance of continued research, as understanding these nuances could lead to more precise approaches to cancer diagnosis and therapy.
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