The cellular response to extracellular vesicles is dependent on their cell source and dose

Extracellular vesicles (EV) have been established to play important roles
in cell-cell communication and have shown promise as therapeutic agents.
However, we still lack a basic understanding of how cells respond upon
exposure to EVs from different cell sources at various doses. Thus, we
treated fibroblasts with EVs from twelve different cell sources at doses
between 20 and 200,000 per cell, analyzed their transcriptional effects,
and functionally confirmed the findings in various cell types in vitro,
and in vivo using single-cell RNA-sequencing. Unbiased global analysis
revealed EV dose to have a more significant effect than cell source, such
that high doses downregulated exocytosis and upregulated lysozomal
activity. However, EV cell source-specific responses were observed at low
doses, and these reflected the activities of the EV’s source cells.
Finally, we assessed EV-derived transcript abundance and found that immune
cell-derived EVs were most associated with recipient cells. Together, this
study provides important insight into the cellular response to EVs.

细胞外囊泡（Extracellular vesicles, EV）已被证实可在细胞间通讯中发挥关键作用，且作为治疗制剂展现出可观的应用潜力。然而，目前学界对于细胞暴露于不同细胞来源、不同剂量EV后的应答机制，仍缺乏基础认知。为此，我们以每细胞20至200000个EV的剂量梯度，用12种不同细胞来源的EV处理成纤维细胞（fibroblasts），分析其转录效应，并通过体外多种细胞类型实验以及体内单细胞RNA测序（single-cell RNA-sequencing）技术对研究结果进行了功能验证。无偏全局分析结果显示，EV剂量对细胞应答的影响程度显著高于细胞来源：高剂量EV可下调胞吐作用相关基因表达，并上调溶酶体活性。然而，在低剂量条件下可观测到EV来源细胞特异性的应答反应，且该应答特征与EV供体细胞的活性状态相符。最后，我们对EV来源的转录本丰度进行了评估，发现免疫细胞来源的EV与受体细胞的关联程度最高。综上，本研究为解析细胞对EV的应答机制提供了重要的理论参考与实验依据。