Everything You Need to Know about Exosome Therapy/Treatment
What are Exosomes?
Exosomes are cell-based vesicles found in many and maybe even all eukaryotic fluids. They’re about 30 to 100 nm in diameter.
Vesicles are fluid-filled blisters or cysts. Eukaryotic fluids include blood, urine, and the cultured medium of cell cultures.
In other words, an exosome is like a tiny fluid-filled bubble released from a cell.
Why are Exosomes Important?
Science discovered the exosome decades ago, but for a long while, researchers didn’t think it was particularly important. That began to change when, in 2007, Jan Lotvall from the University of Gottenburg proved that some cells use exosomes to transfer genetic material from one to another.
Specifically, an exosome can transfer microRNAs to control the expression of a gene, and messenger RNAs to manufacture proteins. They also transfer proteins themselves, lipids, and DNA.
That meant exosomes play a significant role in health, notably, the functioning of the immune system, disease, and might even be useful to treatment and therapy for disease.
How are Exosomes Involved in Disease?
A series of studies have shown that, just as exosomes transfer RNA for healthy bodily functioning, they can also spread metabolic problems like obesity and diabetes and diseases like cancer. A recent study even implicated them in the distribution of a plaque-forming protein that accumulates in the brains of Alzheimer’s patients.
Once scientists understood the role of exosomes in the development of disease, they began to consider the possibility that exosomes might also have the power to spread molecules that fight disease.
How do Doctors Isolate Exosomes?
Of course, before scientists could use exosomes for either basic research or clinical applications, they first had to find a way to work with them. Generally speaking, scientists isolate them via high-speed centrifugation of animal or cellular supernatant fluids. The result is an enriched preparation that can then be studied via biochemistry, electron microscopes, or mass spectrometry.
How do Doctors use Exosomes?
As mentioned above, scientists hypothesize a number of therapeutic uses for exosomes. It’s important to remember, though, that by and large, this research is still in its early stages. The results of various animal studies are promising. The results from human studies are only just beginning to emerge although cancer exosome diagnostics are already available.
It’s possible that, as a signaling or messenger system between cells, the exosome can be used to convey drugs to parts of the body that are otherwise difficult to reach, like the brain. They could, in theory, be used for the delivery of therapies involving small molecules, viral genes, RNA, proteins, and even CRISPR gene editing tools.
Studies with mice have shown that exosomes can be used to deliver interfering RNA that blocked production in the brain of a protein associated with Alzheimer’s and also provided therapy for cancer cells. Exosomes allowed the suppression of the mutant protein KRas, a cancer target notoriously difficult to drug, and provided a better therapy delivery system than lipid nanoparticles without triggering an immune response.
Other researchers are exploring the usefulness of mixtures of natural exosomes and synthetic liquid nanoparticles to deliver therapy to hard-to-reach targets like the sensory cells in the inner ear.
Some scientists even believe that, in addition to operating as an efficient drug delivery system, exosomes themselves, when derived from stem cells, may have therapeutic applications.
Doctors attempting to find a way to treat lung damage in newborn babies used human mesenchymal stem cells (MSCs). They were thus able to reduce inflammation and repair lung tissue in mice.
Eventually, though, the scientists discovered that the MSCs themselves couldn’t be responsible for the therapeutic improvement. They didn’t stay around long enough. After years of further study, the researchers found it was actually exosomes released by the stem cells that were helping the mice.
Similarly, efforts are underway to use exosomes derived from stem cells that were in turn derived from heart tissue to provide therapy for cardiac problems and inflammatory and trauma-related conditions.
Using pig and rodent subjects, researchers investigated the therapeutic effect of exosomes derived from human neural stem cells and MSCs on stroke. They found that recovery of motor movement improved and so did the preservation of brain cells.
Key Issues in Exosome Therapy
Based on exosome diagnostics, exosome therapy research is still in its early stages. With exosomes diagnostics, it’s fair to say that scientists have, at most, only a very limited understanding of the mechanism that makes stem cell-derived exosomes therapeutic. Indeed, there isn’t even universal agreement on what marker differentiates an exosome from some other sort of vesicle.
It’s also a difficult process just to produce exosomes in sufficient quantities for study, and the diversity of vesicles present in the body complicates research and the interpretation and replication of results.
For these and other reasons, patients should understand that exosome therapy is hardly a cure-all and be leery of exaggerated claims about its benefits. At the same time, early findings of exosome diagnostics suggest that its future could be very bright indeed.