What are mesenchymal stem cell-derived exosomes?

"Exosomes" are small bubbles secreted by cells. Many cells secrete "exosomes" into the surrounding microenvironment. Recent studies have shown that "exosomes" play a role in intercellular communication and can even affect distant cells or tissues by being released into the blood circulation.

Cells are like logistics centers, and "exosomes" are vehicles for delivering goods, controlling the delivery of goods to the right place at the right time, including delivering to nearby or far-end cells or tissues.
These nanovesicles, about 30-150 nm in size, carry proteins like hormones or DNA, RNA, and miRNA that contain genetic information, and transmit these instructions to other cells, regulating the behavior of other cells.

So, what are the messages transmitted by cells in the body through "exosomes"? For example, when skin cells are abnormal, they will release "exosomes" to seek help from other cells, allowing healthy cells around them to repair the problem. There are more things that stem cells could use "exosomes" to perform, such as anti-inflammatory, cell proliferation, tissue repair and regeneration, inhibition of cell apoptosis, reduction of tissue fibrosis, etc.

In July 2020, the National Institutes of Health in Taiwan published a research paper on "New Breakthroughs in Neurogenesis". The team found that when the "exosomes" of stem cells were injected into the brain-damaged mice, the damaged nerve cells grew synapses again, and the number of nerve cells could be restored to 60% of the original. This research subverts the traditional cognition that "nerves cannot be regenerated", and diseases such as brain damage or neurodegeneration will have a chance to be cured in the future.

Dr. Shiaw-Min Hwang, the host of the Taiwan Stem Cell Bank Program, indicates that,  for example, human amniotic fluid stem cells belong to mesenchymal stem cells, and the "exosomes" secreted by them can activate the neuronal survival-promoting pathway and stop the apoptosis pathway. In other words, AF-MSCs are expected to change the problem of poor stroke prognosis by protecting neurons and controlling the process of neuronal cell death.

A number of studies have proved that the power of stem cells is not only the ability to differentiate, but also regulate the growth of specific cells and perform immune regulation through "exosomes", which play an important role as signal transduction in immune, cardiovascular, and neuronal cells.