Circadian rhythm and variation in small extracellular vesicles

Exosomes have been an ongoing interest for several years. Beginning with my PhD in Edinburgh and continuing in my current position I have published several articles on exosomes. The field is also maturing with a growing appreciation for the complexities of exosomes and related vesicles. Exosomes are formed and released by a specific mechanism from cells. Once released exosomes are difficult to distinguish from other sources of similar vesicles. In many experimental settings it would be difficult to confirm an exosomal origin. To reflect this uncertainty the use of the term small extracellular vesicles was suggested following a broad consultation by the International Society for Extracellular vesicles.

We have recently published an article on two related investigations:

  1. the circadian pattern of small extracellular vesicle release in the urine
  2. possible methods for normalizing biomarkers derived from small extracellular vesicles

Circadian patterns, or rhythms, are natural oscillations in biological processes that repeat roughly every 24 hours. They are widely seen in biological systems but little is known about variations in exosome, or small extracellular vesicle, release. A circadian rhythm is just one source of variation that may contribute to the wide variability seen in biomarker studies of small extracellular vesicles. In this article we suggest that normalization by small extracellular vesicle number may help correct for some of the variability encountered.