Benefits versus Potential Harms of Exosome Therapies
Extracellular vesicles secreted by cells are divided into types by size, in the absence of greater knowledge that would allow functional classification. Exosomes are one of these size classes, and a popular choice as a basis for therapies intended to replace the transplantation of stem cells. Stem cell therapies produce benefits via the signaling generated by transplanted cells, a sizeable fraction of that signaling is carried in extracellular vesicles, and it is logistically much easier to harvest, store, and use exosomes than it is to use cells in therapy. As researchers here note, exosomes are not universally beneficial. Like all cell communications, context matters, and stem cell derived exosomes can produce potential harms, such as promotion of cancerous growth or undesirable immunomodulation that dampens the response to infection.
Exosomes are nanosized extracellular vesicles (30-150 nm) with a bilayer lipid membrane that encapsulates proteins, lipids, and nucleic acids, first identified in the 1960s and expanded in application from disease diagnostics to targeted therapeutics. They are intercellular communicators with roles in physiological regulation and pathological progression, which have a large applications in gene therapy, drug delivery, tissue regeneration, and disease diagnostics. Their unique biological properties have attracted considerable attention for applications in regenerative medicine, targeted drug delivery, gene therapy, and disease diagnosis.
This review highlights the dual biological nature of exosomes by discussing their beneficial 'Elixir' and detrimental 'Trojan Horse' functions. Exosomes activate signaling pathways such as Wnt/β-catenin and PI3K/Akt, deliver anti-aging molecules, and promote angiogenesis, owing to their properties such as biocompatibility, ability to cross the blood-brain barrier, and use as vectors for selective cargo delivery. Conversely, the same mechanisms that promote regeneration can also lead to undesired outcomes like tumor progression, drug resistance, immune responses suppression, and pathogenic factors spread underscore their "Trojan horse" potential. The exosome's dual nature can presents challenges.