Exosomes: From “Dust” to Design in Proteome Medicine

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Four properties define exosomes. First, they are tiny bodies–as small as 35 nm in diameter, 1,000 times less than the width of a human hair—that perform key assignments in cell signaling and other biological processes. Second, their size aids in transiting hard-to-navigate tissue boundaries in the body, such as the brain–blood barrier and the gut–blood barrier, optioning an oral administration of therapy in some instances. Third, since they can convey protein peptides, nucleic acids, and small molecule drugs, they represent an amalgam of proteomic, genomic, and lipidomic concepts in biomedicine. And fourth, it is conceivable, exosomes can address any human disease—many of which cannot be accessed today—even using material from other species. Two research groups—in St. Louis and Montreal—first characterized them almost simultaneously in 1984, offering an explanation of how immature red blood cells lost their iron-transporting transferrin receptor when they matured. Their role as intercellular communicators grew in 1996 when researchers at the University of Utrecht showed how exosomes induced a powerful immune response that caused cancerous tumors to regress. They travel in every body fluid: blood, lymph, urine, tears, saliva, cerebrospinal, and mother’s milk. Originally seen in electron micrographs and thought to be inconsequential, they now have a presence in biotechnology as a new platform for diagnostics and therapy, broadly representing proteome medicine. As yet, they have not reached a critical mass for clinical adoption, though their prospects are tantalizing. This piece ends with a prediction—that by 2034, the 50th anniversary of the term exosome, proteome medicine will have several generally recognized as safe and effective exosome-based prescriptions, with China leading the way.