Exosomes derived from adipose tissue-derived stem cells alleviated H2O2-induced oxidative stress and endothelial-to-mesenchymal transition in human umbilical vein endothelial cells by inhibition of the mir-486-3p/Sirt6/Smad signaling pathway
Authors: Li Yan , Xiao Yujie , Shang Yage , Xu Chaolei , Han Chao , Hu Dahai , Han Juntao , Wang Hongtao 
Published: May 2024

Hypertrophic scar (HS) is characterized by excessive collagen deposition and myofibroblasts activation. Endothelial-to-mesenchymal transition (EndoMT) and oxidative stress were pivotal in skin fibrosis process. Exosomes derived from adipose tissue-derived stem cells (ADSC-Exo) have the potential to attenuate EndoMT and inhibit fibrosis. The study revealed reactive oxygen species (ROS) levels were increased during EndoMT occurrence of dermal vasculature of HS. The morphology of endothelial cells exposure to H2O2, serving as an in vitro model of oxidative stress damage, transitioned from a cobblestone-like appearance to a spindle-like shape. Additionally, the levels of endothelial markers decreased in H2O2-treated endothelial cell, while the expression of fibrotic markers increased. Furthermore, H2O2 facilitated the accumulation of ROS, inhibited cell proliferation, retarded its migration and suppressed tube formation in endothelial cell. However, ADSC-Exo counteracted the biological effects induced by H2O2. Subsequently, miRNAs sequencing analysis revealed the significance of mir-486-3p in endothelial cell exposed to H2O2 and ADSC-Exo. Mir-486-3p overexpression enhanced the acceleration of EndoMT, its inhibitors represented the attenuation of EndoMT. Meanwhile, the target regulatory relationship was observed between mir-486-3p and Sirt6, whereby Sirt6 exerted its anti-EndoMT effect through Smad2/3 signaling pathway. Besides, our research had successfully demonstrated the impact of ADSC-Exo and mir-486-3p on animal models. These findings of our study collectively elucidated that ADSC-Exo effectively alleviated H2O2-induced ROS and EndoMT by inhibiting the mir-486-3p/Sirt6/Smad axis.

Graphical Abstract

A schematic diagram summarizing the impact of ADSC-Exo on oxidative stress and endothelial-to-mesenchymal transition in endothelial cells was presented in this study. ADSC-Exo effectively alleviated the accumulation of ROS in endothelial cells induced by H2O2 and suppressed the pro-fibrotic function through modulation of the mir-486-3p/Sirt6/Smad signaling pathway. ADSC-Exo attenuated the up-regulation of mir-486-3p in endothelial cells exposure to H2O2, establishing a target relationship between mir-486-3p and Sirt6. Overexpression of Sirt6 inhibited the occurrence of endothelial-to-mesenchymal transition, thereby suppressing collagen deposition and myofibroblasts activity by the regulation of Smad2/3 phosphorylation. Consequently, this led to a reduction in hypertrophic scar formation.

Graphical Highlights

1. The occurrence and development of ROS and endothelial-to-mesenchymal transition promoted hypertrophic scar fibrosis;

2. H2O2 induced oxidative stress and EndoMT of endothelial cells, whereas ADSC-Exo ameliorated the process;

3. Mir-486-3p was crucial for H2O2-induced EndoMT and the improvement of ADSC-Exo;

4. Mir-486-3p directly targeted Sirt6 to facilitate EndoMT by regulating Smad signaling pathway.