Human umbilical cord mesenchymal stem cell-derived exosomes alleviate endometrial injury rats by suppressing the HMGB1/TLR4/NF-κB signaling pathway

Endometrial injury is the main cause of intrauterine adhesion (IUA), with dysregulated inflammatory signaling promoting fibrosis and dysfunction. Human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-Exos) show potential for endometrial repair, but their molecular mechanisms remain unclear. This study isolated and characterized hUCMSCs and hUCMSC-Exos. We found that hUCMSC-Exos transplantation effectively reversed rat endometrial injury by restoring endometrial thickness, increasing gland number, attenuating inflammation and fibrosis, and upregulating proliferation marker expression. Moreover, hUCMSC-Exos enhanced proliferation, reduced pro-inflammatory cytokine levels, and increased anti-inflammatory/anti-fibrotic factor expression in Endometrial stromal cells (ESCs). Mechanistic studies confirmed that hUCMSC-Exos significantly downregulated mRNA expression of HMGB1, TLR4, and NF-κB while upregulating IκBα mRNA. Meanwhile, hUCMSC-Exos inhibited the protein expression and phosphorylation of HMGB1, TLR4, p-IκBα, and p-p65, upregulated IκBα protein. Additionally, Ethyl pyruvate(EP) and Ammonium pyrrolidinedithiocarbamate (PDTC) potentiated hUCMSC-Exos-mediated inhibition of the above pathway molecules’ expression and phosphorylation, whereas recombinant high-mobility group box 1 (rHMGB1) significantly reversed this inhibitory effect. The results indicate that hUCMSC-Exos may modulate inflammation via the HMGB1/TLR4/NF-κB signaling pathway, which suggests a potential role of this pathway for endometrial injury repair.