Summary

Extracellular vesicles are tiny particles that cells release to send signals to other cells. Exosomes are one type. Earlier animal studies found that vesicles from human bone marrow stem cells can calm inflammation and protect brain cells after an injury. This study asked a practical question: when the vesicles are given through the nose, how much of the brain do they reach, and does the brain have to be injured for them to get in?

What the researchers did

They placed 10 billion labeled vesicles in the left nostril of two groups of rats: healthy rats, and rats that had just been through two hours of prolonged seizures (status epilepticus), which injures the brain. Six hours later they examined the brain tissue under a microscope.

What they found

  • The vesicles were in virtually every region of the forebrain, on both sides, in healthy and injured animals alike.
  • They were inside neurons and inside microglia, the brain’s immune cells. In the hippocampus, about 10–21% of neurons and 40–54% of microglia had taken them up.
  • In the injured animals, more neurons took up the vesicles in three areas: part of the hippocampus called CA1 (36% of neurons, against 14% in healthy animals), the entorhinal cortex and the somatosensory cortex. CA1 and the entorhinal cortex are areas known to lose neurons after prolonged seizures.

What it means

The authors conclude that a dose in one nostril is enough to deliver vesicles to both sides of the forebrain, and that injured areas may draw in more of them. They suggest this could matter for future vesicle-based treatments for traumatic brain injury, stroke, multiple sclerosis and Alzheimer’s disease.

This was a study in rats that tracked where the vesicles went. It did not test whether they improved symptoms, and it did not involve people.

Source

Kodali M, Castro OW, Kim D-K, Thomas A, Shuai B, Attaluri S, Upadhya R, Gitai D, Madhu LN, Prockop DJ, Shetty AK. Intranasally Administered Human MSC-Derived Extracellular Vesicles Pervasively Incorporate into Neurons and Microglia in both Intact and Status Epilepticus Injured Forebrain. International Journal of Molecular Sciences. 2020;21(1):181. Open access under the CC BY 4.0 license.

Read the full article: https://pmc.ncbi.nlm.nih.gov/articles/PMC6981466/