Exosomes: Stem Cells 2.0?

Many in the field of regenerative therapy have strived to use stem cells as a promising strategy to repair human tissue; nevertheless, exosomes (packed vesicles secreted from cells) have shown more intriguing possibilities in recent years. Exosomes produced from stem cells, in particular, have shown a high potential for therapeutic potential. They are secreted by cells in a paracrine manner to resist cellular stress. As a result, there are numerous medical advantages that stem cell-derived exosomes can provide. If exosomes could be efficiently isolated from stem cells and combined with specific regenerative products, disorders like neurodegenerative diseases, cardiovascular diseases, osteoarthritis, and others might be treated using cell-free regenerative medicine via exosomes.

Extracellular vesicles are produced by a variety of cell types, including neurons, tumours, and immune cells. They’re also found in bodily fluids like the serum, saliva, cerebrospinal fluid, sperm, breast milk, and urine.

Exosomes are excellent therapeutical models due to their physiochemical resilience in the body and multidimensional packaging; stem cell-derived exosomes deliver a strategy to provide cell-free regenerative medicine. Exosomes can be produced easily in the laboratory by subjecting stem cells to a certain level of stress. Here are some of the clinical applications of exosomes in treating various diseases:

Applications of Exosomes

Whilst a huge number of ongoing exosome-based clinical trials are conducted to identify diagnostic or prognostic biomarkers, a growing number of trials are also looking into exosomes as therapeutic agents in a variety of diseases such as immunomodulation, cancer, neurodegeneration, and various infectious diseases like Covid-19.

• Cancer: Exosomes may travel to distant places and generate a pro-tumour environment to harbour metastatic niches due to their durability, selective tissue absorption, and ability to deliver miRNA and proteins to destination cells. Exosomes may also have an immune suppression profile, promoting tumour escape mechanisms to avoid the immune response. Overall, these properties underscore the importance of exosomes not only as suitable vaccines for cancer therapy, as previously thought but also as natural liposomes for biologic delivery, offering various chances for establishing novel cancer treatment alternatives.
• Neurodegenerative Diseases: Exosomes have been postulated as unique players throughout normal nervous system development and physiology, operating as cell-cell communication and serving functional activities not just during development but also during neuron regeneration. Exosomes are named “the trojan horse of neurodegeneration” due to their capability of transporting toxic substances from unhealthy neurons to their neighbouring cells.
• Cardiovascular Diseases: Exosomes have pro-angiogenesis, pro-coagulant, pro-and/or anti-inflammatory properties, as well as a negative impact on vascular tone and the vessel wall. These properties of exosomes are most likely due to their ability to transport and transfer proteins, mRNAs, and miRNAs. Exosomes are moving vesicles with the potential to transport a wide variety of chemicals, and because of the selectivity of their surface proteins, they have been pushed as specialised therapeutic carriers for cardiovascular disorders.
• Infectious Disease: Microvesicles, particularly exosomes, have been implicated in a variety of pathways in viral infections, depending on the type of virus, its life span, and the type of infected cell. Exosomes, for instance, participate in the transfer of proteins and RNA (miRNA and sRNA) from infected to non-infected cells, delivering these substances even to distant cells. Exosomes released in response to infection are involved in a variety of infection biology mechanisms. To restrict the spread of the infection, exosomes extracted from infected cells may be modulated to eliminate or reduce virulence.
• Pregnancy: Pregnancy is an immunological event in which the semiallogeneic foetus is not rejected due to immune tolerance. Exosomes with immunosuppressive properties were discovered to be more abundant in pregnant women than in non-pregnant women. Furthermore, exosomes separated from sera of women with full-term pregnancies are found in considerably higher amounts than those isolated from pregnancies that deliver prematurely.

Considering the significance of exosomes in both normal and pathobiological circumstances, microvesicles are being researched for potential therapeutic applications. They are being studied as biomarkers for medical diagnosis and follow-up, immunomodulators to inhibit or activate the immune system, vectors for drug delivery, and therapeutic agents in general.

Future Prospects of Exosomes

Exosomes are of major interest due to the vital biological and pathobiological processes in which they are implicated. Furthermore, because of their qualities that are employed to identify, alleviate, or cure serious disorders, they open up a plethora of new therapeutic possibilities.

Despite these potential perks of using exosomes for therapeutics that have been outlined, some concerns such as the purity of the exosome preparation, the co-expression of various molecules within the microvesicle (proteins and RNAs that may intrude with the biological process required), and the method of administration to accomplish the targeted delivery and the desired impact have yet to be resolved.

Future research should focus on improving the procedures for isolating pure exosomes in order to separate them from many other types of microvesicles and better comprehend the mechanism by which they perform. These accomplishments will aid in the advancement of early diagnosis, control, prevention, and therapy.