Background/Objectives
The role of extracellular vesicles (EVs) in the regeneration of mammalian model systems is the subject of many studies. However, from an evolutionary perspective, it is unclear whether this effect is an adaptive response to injury or merely a physi- ological by-product of transplanted EVs. Here, we investigated the role of EVs in the regeneration of Schmidtea mediterranea, a species capable of whole-body regeneration mediated by adult pluripotent stem cells.
Methods
After isolating EVs from planarians, we characterized their morphology using transmission electron microscopy (TEM) and ana- lyzed their protein profile using label-free mass spectrometry. To address the potential role of planarian EVs in regeneration, we investi- gated changes in the proteomic profile following amputation in the region adjacent to the wound (blastema and postblastema, BL/PBL) and in the rest of the body, which undergoes extensive repatterning but is not directly involved in the regeneration process (rest of the body, ROB).
Results
Planarian EVs exhibited cup-shaped structures typical of mammalian exosomes and showed significant enrichment of exosome protein markers including CD63, CD9, alix and flotillin-1. At three days post-amputation (3 dpa), a substantial number of significantly enriched proteins were identified in the BL/PBL region compared to intact animals, with gene ontology analysis revealing involvement in key regenerative processes including cell communication, cell cycle regulation, and development. The EV protein profile changed dynamically during regeneration, exhibiting the greatest diversity at 3 dpa, which corresponds to the most critical time point in planar- ian regeneration. Comparative analysis of EV protein profiles isolated from BL/PBL and ROB regions revealed distinct protein signatures, highlighting spatial differences in protein enrichment during regeneration.
Conclusion
Our results indicate that EVs have a conserved role in regeneration in a non-mammalian organism, exhibiting temporal and spatial dynamics that potentially correspond with cellular and molecular regenerative processes. This study positions EVs as promising candidates for future research on the evolution of regeneration, potentially revealing whether EVs serve as important molecular evolu- tionary triggers.
Keywords
Extracellular Vesicles (EVs), Planarian, Regeneration, Evolution
Funding/Acknowledgments
We gratefully acknowledge the scholarship from the Erasmus Mundus Master Programme in Evolutionary Biology (MEME), which made this research and academic journey possible.
