Meet the Exosomes
Exactly a decade ago, a seminal paper revealed the role exosomes play in the body. Read on for Exopharm’s guide on what exosomes are, and why they’re beginning to create a buzz in medical circles.
Human cells are a gregarious bunch – otherwise we would fall apart. They continually message each other, letting neighbours near and far know what they’re up to and how they are.
This constant communication is not idle chatter; it is key to the function of a multicellular organism. It means cells under stress can call for help, for example, and responder cells can mount a coordinated response.
Ten years ago this month, writing in Nature Cell Biology, a research team in Sweden published a remarkable new mechanism of cell-to-cell communication1. Cells don’t just send each other status updates. They exchange genetic directives: sections of RNA, wrapped inside nano-sized packages called exosomes. What’s more, the team showed, these snippets of genetic instruction were taken up by recipient cells and reprogrammed that cell’s behaviour.
In the decade since this discovery, rapid progress has been made to decipher exosome function. Read on to discover why exosomes represent the next frontier of regenerative medicine.
What is an exosome?
An exosome is a small packet of biologically active molecules released by a cell2. Exosomes range between 40 and 200 nanometres in diameter. Since the seminal discovery that exosomes carry RNA, we have since discovered that lipids and proteins also form part of their cargo. The contents is enclosed in a bi-layer fatty membrane called a phospholipid, the same stuff cell membranes are made of.
Where do exosomes come from?
Many types of cells release exosomes, including muscle cells, brain cells, immune cells, epithelial cells, tumour cells and stem cells. The contents of an exosome varies according to the type of cell it was released from. Exosomes are found in virtually every biofluid, including blood, milk and saliva.
What do exosomes do?
Exosomes are a key line of cell-to-cell communication.
The more research that is done into exosomes, the more we discover the pivotal role this form of communication plays in maintaining health, in the processes of aging, and in disease.
Exosomes are one mechanism by which immune cells coordinate their response to an infection, for instance. More generally, exosomes help coordinate a whole-body response to tissue damage and disease.
As we age, the balance of exosomes found circulating in the body changes; the number of inflammatory exosomes rises, while the number of regenerative exosomes declines.
Why are exosomes causing a buzz in medical circles?
For the past decade or more, there has been a lot of activity around the therapeutic potential of stem cells; regenerative cells thought to be capable of replacing diseased cells. It has recently become clear that the exosomes that stem cells release, rather than the cells themselves, are the real source of health benefit3.
The cargo of RNA, lipids and proteins the exosomes carry appear to activate self-repair mechanisms in recipient tissues. Potential applications range from Alzheimer’s disease to heart disease to arthritis.
Treating patients with regenerative exosomes has the potential to be considerably less expensive, simpler and safer than treating them with living cells.
What’s the next step in exosome therapy?
Though several small-scale clinical trials have demonstrated the safety and efficacy of exosome therapy, the critical bottleneck has been the lack of a reliable, scalable method for producing and harvesting exosomes.
This barrier has now been overcome. Exopharm has developed a proprietary stem cell exosome production and purification technology called LEAP. The exosomes produced by this system, Exomeres™, will pave the way for the rapid translation of this technology into clinical trials for many indications.
To learn more about exosomes go to www.exopharm.com
1. Valadi, H., et al. Exosome-mediated transfer of mRNAs and microRNAs is a novel mechanism of genetic exchange between cells. Nature Cell Biology 9, 654 – 659 (2007)
2. Lerner, T., et al. Applying Extracellular vesicles based therapeutics in clinical trials – an ISEV position paper. Journal of Extracellular Vesicles 4, 30087 (2015)
3. Andaloussi, S. E. L., et al. Extracellular vesicles: biology and emerging therapeutic opportunities. Nature Reviews Drug Discovery 12, 347-357 (2013)