by hearingearly hearingearly

I. What are exosomes

Exosomes are small vesicles secreted by cells, with a diameter of 30-150 nm, which contain cell-specific proteins, liposomes, and complex RNA, which naturally exist in body fluids and can be transmitted to other cells as signal carriers to change the function of other cells, so as to regenerate cells. Exosomes were first identified in sheep reticulocytes in 1983, and were named “exosome” by Johnstone in 1987. In 2013, three scientists from the United States and Germany discovered the “regulatory mechanism of exosome transport” and won the 2013 Nobel Prize in Physiology or Medicine.

II. The formation and composition of exosomes

Many kinds of cells can secrete exosomes in normal and pathological state. The production process of exosomes is as follows: the membrane invaginates to form endosomes, then forms polyvesicles, and then the polyvesicles fuse with the cell membrane and are released outside the cell to form exosomes. The rate of exosome production in different cells is different, and the size and composition of exosomes are highly heterogeneous, and the composition is closely related to the source cell.

III. the role of exosomes

1. Intercellular information transmission of exosomes

Exosomes are widely present and distributed in various body fluids, just like postmen, carrying multiple “letters”, such as proteins, mRNA, miRNA and lipids, etc. As important signaling molecules, exosomes form a new cell-cell information transmission system, which can participate in cell communication, cell migration, angiogenesis and tumor cell regulation and other processes.

Specific to the application of treatment, such as: can effectively promote the healing of fractures, protect and repair kidney damage, myocardial weakness and hind limb ischemia treatment, as well as regulate and promote the regeneration of skin, muscle, hair follicles and other tissues and organs.

2. Immune system regulation of exosomes

The study of exosomes began with the study of immunology-related mechanisms, and it was found that exosomes are particularly closely related to immune regulation: exosomes are loaded with various immune-related molecules, through which the immune response is regulated.

Exosomes derived from immune cells contain antigenic peptides – MHC complexes and various antigens, which can significantly inhibit tumor growth, activate T cells and B cells, and may also promote the expansion of CD4+T cells.

Similar properties could be used to develop novel immunotherapies that could eventually lead to a cure for cancer.

Exosomes, which promote immunosuppression, can effectively inhibit inflammatory factors and have strong anti-inflammatory ability, which can be applied to the treatment of patients with inflammation or autoimmune diseases.

3. Exosomes are used as drug carriers

Exosome – extracellular vesicle drug delivery system has the advantages of high biocompatibility, low immunogenicity, intracellular targeting, and easy chemical and genetic manipulation. It can be used as an integrated platform for multiple drugs or therapeutic strategies to synergistically activate multiple steps of the tumor immune cycle, thus being widely used to amplify the anti-cancer immune response.

Exosomal drug delivery technology surpasses the technical barriers existing in traditional T cell-mediated cellular immunity (tumor antigen release, antigen presentation by antigen presenting cells (APC), T cell activation, recruitment and penetration of T cells in tumors, and recognition and killing of tumor cells by T cells).

4. Exosomes are used in disease diagnosis

The mechanism of exosome production suggests that by analyzing the composition of exosomes, it can help identify the cell type from which they originate. This property has been used to develop molecular diagnostic methods for cardiovascular diseases, central nervous system diseases, and tumors, and has also been valued in the diagnosis of liver, kidney, and lung-related diseases. Other studies have shown that tumor-derived DNA fragments carried in exosomes can help detect tumor-associated DNA mutations.

In addition, exosome-related mirnas have high value in tumor diagnosis, such as miR-100, miR-21, etc. In addition to mirnas, some exosomal proteins may also be used for molecular diagnostics.

In recent years, the clinical research of exosomes by Chinese researchers has shown explosive growth, showing great application potential in disease treatment, and the progress of modern biomedicine represented by exosomes has been unstoppable.