Oxidative Stress-induced Changes in Fertility Status Of Cryopreserved Sperm: A Diagnosis Based on Sperm Chromatin Dispersion Assay

BACKGROUND: Cryopreservation introduces iatrogenic damage to sperm cells due to excess production of reactive oxygen species (ROS) that can damage sperm macromolecules and alter the physiochemical properties of sperm cells. These altered properties can affect the biological potential of sperm cell towards fertility. OBJECTIVE: The study was designed to assess the role of oxidative stress in sperm DNA damage upon cryopreservation. MATERIALS AND METHODS: Semen samples (160) were classified into fertile and infertile on the basis of Computer Assisted Semen Analysis (CASA), and cryopreserved. Thawed samples were analyzed for 8OHdG marker, sperm chromatin dispersion (SCD)-based DNA fragmentation index (SCD-DFI) and ROS levels. Receiver Operating Characteristics (ROC) was performed to find the specificity and sensitivity of SCD-DFI in assessing the sperm DNA integrity. Principle component analysis (PCA) was performed to group semen parameters. RESULTS: SCD-DFI significantly correlates with 8OHdG in infertile samples (r=0.73, p<0.0001) and moderately in fertile samples (r=0.52, p<0.001). Among SCD-DFI, ROS and 8OHdG values, SCD-DFI possess a higher area under the curve (0.83) in ROC, suggesting its potential in representing sperm DNA damage. PCA analysis extracted SCD-DFI and sperm progressive motility as two independent parameters, differentiating fertile and infertile cryopreserved semen. CONCLUSION: The study proves that SCD can potentially represent ROS-induced sperm DNA damage in infertile semen upon cryopreservation.