Scientists at Johns Hopkins University School of Medicine believe exosomes may hold the key to powerful, targeted drug therapies, biomarkers for clinical laboratory treatments, and precision medicine.
Not to be confused with exomes, which are part of the human genome and used in whole exome sequencing (WES), exosomes are tiny vesicles excreted by cells that were once thought to be little more than cellular refuse.
However, exosomes do have purpose. They deliver proteins and genetic information between cells and may be able to courier drug therapies throughout the body as well.
Critical for Normal Bodily Functions
Scientists are proving that exosomes have specialized functions within the body and that they play a role in many critical processes, such as:
- coagulation;
- intercellular signaling; and,
- waste management.
Exosomes are found in nearly all eukaryotic fluids in the body including: blood, urine, saliva, semen, vaginal fluid, breast milk, and amniotic fluid. They range from 30 to 100 nanometers in size and transfer Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), and proteins between cells in the body.
“They are just a ubiquitous fact of our biology,” Stephen J. Gould, PhD, Professor of Biological Chemistry at the Johns Hopkins University School of Medicine, told Chemical and Engineering News (CEN).
The existence of exosomes has been known for decades. But in 2007, Jan Lötvall, MD, PhD, a professor at the University of Gothenburg in Sweden and an industry expert in exosomes and extracellular vesicles, discovered that some cells use exosomes to transfer genetic material to other cells.
“Lötvall changed the way people think about exosomes,” Doug Williams, President and CEO of Codiak BioSciences, told CEN. “It’s become clear that this is a very important and ancient messenger system.”
Codiak BioSciences, headquartered in Cambridge, Mass., is just one of many biotech companies hoping to cash in on new developments surrounding exosomes. “It seems like all cells make exosomes, and all cells can take them up,” Williams told CEN. “Exosomes are amenable to every therapeutic area.”
Exosomes are even implicated in the spread of:
- cancer;
- diabetes;
- obesity; and;
- Alzheimer’s disease.
Since exomes can carry molecules that spread diseases, the scientists theorize that they could effectively deliver drugs throughout the body as well. Perhaps even targeting delivery of drugs to specific cells, which would be a boon to precision medicine.
Some scientists, however, have expressed concerns. Raj Kishore, PhD (above) professor of pharmacology and translational medicine at the Lewis Katz School of Medicine at Temple University in Philadelphia, and Director of the school’s stem cell therapy program, leads a team studying exosomes derived from stem cells for heart repair. He feels that the science may be expanding a little too rapidly. “We should try to understand the mechanism a little more and not rush the therapies,” he told CEN. “I don’t want to see this field die like the stem cell therapy field, which took a setback from not understanding how the mechanisms work.” [Photo copyright: Lewis Katz School of Medicine at Temple University.]
Ongoing Investment in Exosome Drug Delivery Research
Despite concerns, biomedical developers are forging ahead. Exosomes may even be useful for transferring drugs into cells that are traditionally difficult to reach—such as the brain.
Steven Stice, PhD, co-founder and Chief Scientific Officer at ArunA Biomedical, believes “the field of exosomes is growing exponentially as pharmaceutical and biotech companies seek ways to enhance the delivery of drugs throughout the body.”
His company has raised $5.3 million to develop a neural exosome therapeutic platform. “We are well positioned to move ahead with our plans to leverage the therapeutic potential of our proprietary exosomes to treat patients with a range of neurological disorders,” he stated in a news release.
Evox Therapeutics in Oxford, Great Britain, also is developing exosome-based treatments for rare diseases. The pharmaceutical treatment company is developing cell-targeted, exosome-based approaches to deliver nucleic acid-based drugs directly into brain cells.
And, Freehold, N.J.-based Avalon Globocare (NASDAQ: AVCO) and its subsidiary Genexosome Technologies announced in January “the discovery and development of the world’s first saliva-based exosomal microRNA biomarker, miR-185, as a dual diagnostic and therapeutic target for oral cancer,” noted a press release.
Their research involves the topical application of exosomes from genetically modified human stem cells combined with miR-185 to deter the progression of pre-malignant oral leukoplakia into full blown oral cancer.
“Exosomes are enriched in the tumor microenvironment and growing evidence has demonstrated that exosomes can mediate cancer progression. Given the important biological roles played by these nanovesicles in cancer initiation and progression, exosomes and their content can be used as ideal, non-invasive biomarkers in detecting and monitoring tumors as well as therapeutic targets,” said Yu Zhou, MD, PhD, co-CEO of Genexosome Technologies, in their press release. “In addition to oral cancer, genetic engineering of exosomes provides opportunities to develop a new ‘medicine’ for treatment of cancer and other diseases.”
Stem cell companies also are adding exosomes to their research. Capricor Therapeutics is using exosomes derived from stem cells to try to treat cardiac and inflammatory conditions. Their next-generation exosome therapeutic platform—CAP-2003—consists of microvesicles derived from proprietary cardiosphere-derived cells made from donor heart tissue.
Because of their compatibility with the human body, biomedical researchers will likely continue to study ways exosomes can be useful in drug therapies.
“It speaks to the fact that they are important in almost every aspect of biology and medicine,” Gould told CEN. “The potential here is huge.”
Exosomes have a unique, critical role in human physiology and may prove to be a key element in targeted precision medicine treatments for cancer and other chronic diseases. Exosomes are a rising star in medical research and might even become valuable biomarkers for clinical laboratory testing.
—JP Schlingman
Related Information:
Meet the Exosome, the Rising Star in Drug Delivery
Exosomes—The Next Small Thing: A Mini Documentary Series
Capricor and USAISR Announce Collaboration to Investigate Exosome Platform to Treat Injured Troops
