# Comparative Profiling of Mouse and Human Microglial Small Extracellular Vesicles Reveals Conserved Core Functions with Distinct miRNA Signatures

## TL;DR

Mouse and human microglial extracellular vesicles share core functions but differ in miRNA content, affecting translational research.

## Contribution

The study provides the first integrated cross-species blueprint of microglia-derived extracellular vesicles, highlighting conserved and species-specific features.

## Key findings

- Mouse and human microglial extracellular vesicles share core functional effects on Schwann cells.
- Human and mouse vesicles show distinct miRNA signatures, with human miRNAs favoring regenerative pathways and mouse miRNAs favoring inflammatory signaling.
- Human extracellular vesicles provide stronger protection against oxidative stress compared to mouse vesicles.

## Abstract

What are the main findings?
Mouse and human microglial cell lines secrete small extracellular vesicles that exert shared core functional effects on human Schwann cells while displaying distinct molecular signatures.Cross-species miRNA profiling identifies a large, shared miRNA core with distinct, species-biased enrichment patterns.

Mouse and human microglial cell lines secrete small extracellular vesicles that exert shared core functional effects on human Schwann cells while displaying distinct molecular signatures.

Cross-species miRNA profiling identifies a large, shared miRNA core with distinct, species-biased enrichment patterns.

What are the implications of the main findings?
Divergent microglial sEV cargo between species highlights limitations when extrapolating rodent sEV data to human biology.This study provides a controlled cross-species framework for interpreting microglia-derived sEV function in human-relevant systems.

Divergent microglial sEV cargo between species highlights limitations when extrapolating rodent sEV data to human biology.

This study provides a controlled cross-species framework for interpreting microglia-derived sEV function in human-relevant systems.

Microglia-derived small extracellular vesicles (MGEVs) are key mediators of neuroimmune communication, yet their cross-species comparability and translational relevance remain poorly defined. Here, we establish a harmonized framework to compare the molecular and biochemical signatures of sEVs derived from immortalized mouse (BV2) and human (HMC3) microglial cells as well as assess their bioactivity on a human Schwann cell (HuSC) line. MGEVs were isolated via MISEV-aligned size-exclusion chromatography (SEC) and characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and immunoblotting for canonical EV markers CD9, CD63, CD81, TSG101. Human and mouse MGEVs exhibited similar morphology but displayed distinct membrane tetraspanin protein enrichment patterns. Functionally, mouse and human MGEVs attenuated HuSC migration while enhancing HuSC proliferation and their resistance to H2O2-induced oxidative stress, with human MGEVs providing stronger protective effects, suggesting they retain similar core functional properties. Short, non-coding-miRNA sequencing analysis identified 196 shared miRNAs (Spearman ρ = 0.72) with species-specific enrichment: human MGEVs-derived miRNAs favored regenerative and metabolic pathways, whereas mouse MGEVs-derived miRNAs aligned more so with inflammatory signaling. This study delivers the first integrated cross-species blueprint of MGEVs, revealing conserved neuroprotective actions alongside species-biased miRNA cargo that define translational boundaries and highlight human-relevant MGEV signatures for therapeutic innovation, therefore contributing to the importance of considering these differences in translational research.