Exosomes, ranging in size from 30 to 150 nanometers,[1] are membrane-bound extracellular vesicles (EVs) that are produced in the endosomal compartment of most eukaryotic cells.

[6][10][11] Enriched with a diverse array of biological elements from their source cells, exosomes contain proteins (such as adhesion molecules, cytoskeletons, cytokines, ribosomal proteins, growth factors, and metabolic enzymes), lipids (including cholesterol, lipid rafts, and ceramides), and nucleic acids (such as DNA, mRNA, and miRNA).

[18] Exosomes were shown to participate in selective removal of many plasma membrane proteins[19] as the reticulocyte becomes a mature red blood cell (erythrocyte).

[26][27] Therefore, scientists who are actively researching the role that exosomes may play in cell-to-cell signaling, often hypothesize that delivery of their cargo RNA molecules can explain biological effects.

Although functional nucleic acid exchange is well-documented in plants and nematodes, the mammalian context presents unique experimental challenges.

The mere presence of RNAs in extracellular vesicles does not necessarily imply biological function, as RNA degradation, passive release, and contamination from cellular debris can confound interpretations [33].

[47][29] In breast cancers, neratinib, a novel pan-ERBB inhibitor, is able to downmodulate the amount of HER2 released by exosomes, thus potentially reducing tumor dissemination.

[48] Urinary exosomes have also proven to be useful in the detection of many pathologies, such as genitourinary cancers and mineralocorticoid hypertension, through their protein and miRNA cargo.

"[49][15] With neurodegenerative disorders, exosomes appear to play a role in the spread of alpha-synuclein, and are being actively investigated as a tool to both monitor disease progression as well as a potential vehicle for delivery of drug and stem cell based therapy.

Hypothetically, exosomes can plant tumor information, such as tainted RNA, into new cells to prepare for cancer to travel to that organ for metastasis.

[56] Exosomes also mediate the cross talk between the embryo and maternal compartment during implantation.They help to exchange ubiquitous protein, glycoproteins, DNA and mRNA.

[57] Exosome formation starts with the invagination of the multi-vesicular bodies (MVBs) or late endosomes to generate intraluminal vesicles (ILVs).

[71] To isolate a pure population of exosomes a combination of techniques is necessary, based on both physical (e.g. size, density) and biochemical parameters (e.g. presence/absence of certain proteins involved in their biogenesis).

[67][72] The use of reference materials such as trackable recombinant EV will assist in mitigating technical variation introduced during sample preparation and analysis.

[75][76] Exosomes are small extracellular vesicles that play a crucial role in cell-to-cell communication by transporting proteins, lipids, microRNAs, and functional mRNAs.

Traditional methods for isolating exosomes are often hindered by low purity, inefficiency, lengthy processing times, and the need for substantial sample volumes and specialized equipment.

Microfluidic platforms not only improve the efficiency and purity of exosome isolation but also address the limitations of conventional methods, paving the way for their application in both research and clinical settings.

Well-known examples of assays to detect proteins in total populations of exosomes are mass spectrometry and Western blot.

These new systems include a microNMR device,[79] a nanoplasmonic chip,[80] and a magneto-electrochemical sensor[81] for protein profiling; and an integrated fluidic cartridge for RNA detection.

Recently, bioinformatics based analysis of RNA-Seq data of exosomes extracted from Trypanosoma cruzi has showed the association of these extracellular vesicles with various important gene products that strengthens the probability of finding biomarkers for Chagas disease.

[90] Exosome-mediated delivery of superoxide dismutase extends life-span in Caenorhabditis elegans, apparently by reducing the level of reactive oxygen species.

[93] These engineered exosomes can deliver drugs directly to tumors, thereby minimizing off-target effects while enhancing therapeutic efficacy .

Preclinical studies suggest that exosomes loaded with amyloid-beta-clearing enzymes or antibodies can reduce amyloid-beta plaques, offering a potential treatment for Alzheimer's .

Exosomes are also being investigated for their role in treating autoimmune conditions like multiple sclerosis and rheumatoid arthritis, where they can carry anti-inflammatory agents to regulate immune responses.

[96][97][98] Unapproved marketing of exosomes remains a persistent issue in the U.S., with some companies exploiting regulatory gaps and consumer confusion about these emerging therapies.

These companies often operate in a grey zone, marketing exosome products as "minimally manipulated" and thereby attempting to avoid strict FDA regulations.

In response, the FDA has increased its enforcement actions in recent years, emphasizing the need for exosome-based products to meet rigorous standards of safety and efficacy, similar to other biological drugs.

The FDA's warnings, particularly around exosome treatments for COVID-19, highlighted how some firms were capitalizing on the global pandemic to promote unverified therapies under the guise of immunity boosters or infection preventatives.

However, the FDA continues to assert that any use of exosomes, whether for cosmetic or therapeutic purposes, requires formal review and approval due to the potential biological effects of these extracellular vesicles.

Regulatory experts warn that such practices, if unchecked, could undermine the credibility of legitimate exosome research and therapeutics being developed through proper channels.