The effect of myo-inositol antioxidant activity on human sperm parameters and DNA damage in ultra-rapid and conventional freezing methods

Male fertility preservation is still challenged by cell damage induced during sperm cryopreservation and impaired sperm structure and function. Sperm ultra-rapid freezing, despite a higher protective effect compared to conventional freezing method, is still associated with suboptimal sperm cryosurvival and needs to be modified to increase its efficiency in sperm protection. Sperm freezing media supplemented with antioxidants can improve sperm parameters following freezing-warming process. In this study, we aimed to investigate the effect of employing ultra-rapid freezing and myo-inositol on sperm cryosurvival. Thirty semen samples with normal sperm parameters were collected and each one was divided into four portions to cryopreserve by conventional freezing, ultra-rapid freezing, conventional freezing + myo-inositol 2 mg/ml, and ultra-rapid freezing + myo-inositol 2 mg/ml. Sperm samples warmed after at least 24 h of freezing and sperm cryosurvival were analyzed by evaluation of sperm motility, viability, morphology and DNA fragmentation index (DFI). Freezing method had a significant influence on post-thaw sperm DFI and morphology (p < 0.05) and the interaction between freezing method and antioxidant supplementation significantly affected sperm morphology (p < 0.05). The highest percentage of sperm normal morphology and minimal DFI was achieved using ultra-rapid freezing supplemented by myo-inositol antioxidant compared to other groups (P < 0.05). The highest sperm DNA damage after freezing-warming was observed following the conventional freezing method. In conclusion, sperm freezing method was identified as factor strongly influencing sperm DFI and morphology after thawing/warming. Sperm samples can be rapidly frozen using the modified freezing media supplemented by myo-inositol without impacting sperm DNA and morphology.