Summary: | Freezing decreases sperm quality, ultimately affecting fertilizing ability. The repair of freeze-damaged sperm is considered crucial for improving post-thaw viability and fertility. We investigated the effects of exosomes derived from canine adipose-derived mesenchymal stem cells on dog sperm structure and function during cryopreservation. The pooled ejaculate was diluted with buffer, without (Control), or with exosomal proteins (25, 50, or 100 µg/mL). Using fresh semen, the determined optimal exosomal protein concentration was 50 µg/mL (Group 2) which was used in further experiments. Post-thaw sperm treated with exosomes were superior to control (<i>p < 0.05</i>) in terms of motility (56.8 ± 0.3% vs. 47.2 ± 0.3%), live sperm percentage (55.9 ± 0.4% vs. 45.4 ± 0.4%), membrane integrity (55.6 ± 0.5% vs. 47.8 ± 0.3%), and acrosome integrity (60.4 ± 1.1% vs. 48.6 ± 0.4%). Moreover, expression of genes related to the repair of the plasma membrane (<i>ANX 1</i>, <i>FN 1</i>, and <i>DYSF</i>), and chromatin material (<i>H3</i>, and <i>HMGB 1</i>) was statistically higher in exosome-treated sperm than control, but the expression of the mitochondrial reactive oxygen species modulator 1 gene was significantly higher in control. Therefore, exosomal treatment may improve the quality of post-thaw dog semen through initiating damaged sperm repair and decreasing reactive oxygen species production.
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