To explore the effects and mechanisms of bone marrow mesenchymal stem cell exosomes (BMSC-exo) on endometriosis (EMS) in mice.

Mouse endometrial epithelial cells (mEECs) were divided into the BMSC-exo group (co-cultured with 25 μg/mL) and phosphate buffer saline (PBS) group (co-cultured with equal volume of PBS) . The EdU method was used to detect cell proliferation rate. Cell scratch and Transwell assays were employed to assess cell migration ability. RT-qPCR was used to detect the relative expression levels of Interleukin-1β (IL-1β) , interleukin-6 (IL-6) , chemokine 2 (Ccl-2) , and tumor necrosis factor alpha (TNF-α) in mEECs. BALB/c mice were divided into sham-operated, EMS model, and BMSC-exo groups (n = 7) . EMS and BMSC-exo groups were used to construct EMS models. Mice in the BMSC-exo group received weekly tail vein injections of BMSC-exo at a dose of 3 μg/g for 4 weeks. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of EMS lesion tissue in mice. Enzyme-linked immunosorbent assay (ELISA) was used to detect inflammatory factors IL-1β, IL-6, Ccl-2, and TNF-α in serum and cell supernatants. Western blot was used to detect the expression of TLR4 and NF-κB p65 in endometrial tissue. Comparisons between two groups were performed using the independent sample t-test. Comparisons among multiple groups were performed using one-way analysis of variance (ANOVA) , with post-hoc pairwise comparisons conducted using Dunnett's t-test. For data not following a normal distribution, comparisons between two groups were performed using the Wilcoxon signed-rank test. For the analysis of repeated measures factors between two groups, the two-way repeated measures ANOVA was used.

Compared with PBS group, the proliferation rates[ (41.00 ± 3.61) % vs (59.67 ± 2.52) %], cell scratch healing rates [ (22.00 ± 3.00) %vs (65.33 ± 5.51) %], the number of migration cells (82.00 ± 19.31 vs 145.00 ± 9.85) of mEECs, the expression of IL-1β mRNA (0.18 ± 0.05 vs 1.00 ± 0.01) , IL-6 mRNA (0.30 ± 0.09 vs 0.99 ± 0.01) , Ccl-2 mRNA (0.27 ± 0.08 vs 1.00 ± 0.02) , TNF-α mRNA (0.33 ± 0.08 vs 1.00 ± 0.06) and the concentrations of IL-1β[ (1 083.00 ± 67.68) vs (1 507.00 ± 131.10) pg/mL], IL-6[ (878.70 ± 19.50) vs (1 127.00 ± 75.59) pg/mL], Ccl-2 [ (1 046.00 ± 56.72) vs (1 298.00 ± 52.52) pg/mL] and TNF-α[ (1 069.00 ± 114.80) vs (1 470.00 ± 165.90) pg/mL] in cell supernatants in the BMSC-exo group were significantly decreased (P < 0.05) , were significantly decreased (all P < 0.05) . Compared with the sham-operated group, the pathological damageof endometrium in EMS group was significantly, with increased concentrations of serum inflammatory factors IL-1β [ (2 034.00 ± 165.50) vs (1 083.00 ± 125.80) pg/mL], IL-6 [ (3 292.00 ± 232.30) vs (1 505.00 ± 126.20) pg/mL], Ccl-2 [ (1 300.00 ± 64.50) vs (939.30 ± 56.45) pg/mL] and TNF-α [ (545.00 ± 34.70) vs (344.00 ± 41.33)  pg/mL] (all P < 0.01) , as well as a significantly upregulated expression of TLR4 (1.44 ± 0.06 vs 0.38 ± 0.06) and NF-κB p65 (1.18 ± 0.03 vs 0.29 ± 0.04) (all P < 0.001) . Compared with the EMS group, the BMSC-exo group showed a reduction in EMS tissue lesions, with a decrease in the expression of serum inflammatory factors IL-1β [ (1 488.00 ± 202.50) vs (2 034.00 ± 165.50)  pg/mL], IL-6 [ (2 543.00 ± 317.20) vs (3 292.00 ± 232.30) pg/mL], Ccl-2 [ (1 058.00 ± 57.95) vs (1 300.00 ± 64.50) pg/mL], TNF-α [ (415.00 ± 13.00) vs (545.00 ± 34.70) pg/mL] (all P < 0.05) , and TLR4 (0.81 ± 0.03 vs 1.44 ± 0.06) , NF-κB p65 (0.81 ± 0.06 vs 1.18 ± 0.03) expression (all P < 0.001) .

BMSC-exo inhibits TLR4/NF-κB signaling pathway to alleviate EMS in mice.