Written by Angeline A. De Leon, Staff Writer. Vitamin C treatment of semen samples prior to cryopreservation by vitrification preserved sperm chromatin integrity and prevented DNA fragmentation.
For men undergoing chemotherapy and/or surgical operations associated with testicular failure, cryopreservation of sperm has become a common way of preserving fertility 1. Although several methods of cryopreservation exist, including slow freezing and rapid freezing, these approaches are associated with reduced quality of preserved spermatozoa (damaged mitochondria following thawing), limited efficiency, and high cost, warranting the need to develop alternative strategies 2,3. Vitrification, a cryopreservation method based on ultrarapid freezing, appears to be safer and more cost-effective by comparison 2. However, it is also associated with increased levels of reactive oxygen species (ROS) in the sperm cytoplasm, which increases risk of DNA damage 4. Considered a cryopathogenic factor, elevated levels of ROS in sperm cells can lead to DNA fragmentation, cellular damage, and morphological defects 5,6. Although research on the efficacy of specific cryoprotectants for spermatoza is limited 7, experimental work has shown that supplementation with antioxidants like zinc, for example, can significantly improve the quality of cryopreserved spermatoza and prevent loss of sperm function 8. More specifically, some research shows that vitamin C, one of the most potent ROS scavengers, can improve sperm quality and sperm performance 9. To further explore this, a 2018 study 10 published in the Taiwanese Journal of Obstetrics and Gynecology tested the effects of vitamin C treatment on various sperm parameters, quality of chromatin (complex of DNA and protein), and apoptosis (cell death) in sperm samples undergoing the vitrification process.
A total of 40 normozoospermic semen samples were collected from men aged 25 to 45 years and were divided into five different groups: a control sample of fresh semen (Group 1); semen samples that were processed (sperm selected based on motility and swimming ability) and then vitrified (Group 2); neat semen samples that were vitrified (Group 3); semen samples that were treated with vitamin C (600 µm), processed, and then vitrified (Group 4); and neat semen samples that were treated with vitamin C and then vitrified (Group 5). Sperm analysis was carried out for each sample to assess sperm count, morphology, motility, and viability, and sperm chromatin/DNA integrity was evaluated using staining methods to detect chromatin abnormalities, apoptosis, and DNA fragmentation.
Analyses revealed a significant decrease on all sperm parameters for experimental groups, compared to the control sample, following vitrification (p < 0.05 for all parameters). A significant increase in DNA fragmentation of sperm was also apparent for the groups after vitrification (p < 0.05). However, vitamin C treatment of spermatozoa attenuated the adverse effects of vitrification on sperm parameters in Groups 4 and 5. Vitamin C-treated sperm samples also exhibited reduced rates of chromatin abnormality and DNA damage (showing improved sperm chromatin condensation, lower DNA fragmentation, and apoptosis), compared to other groups, with the strongest effects detected for Group 4.
Overall, data from the current trial confirms the detrimental effects of vitrification on sperm parameters and DNA integrity of semen, highlighting the risks associated with fertility strategies employing cryopreservation. In line with previous research, findings suggest that freezing procedures like vitrification may be accompanied by lower sperm count, poorer motility and viability, and higher rates of DNA fragmentation and chromatin defects 4 . However, results also indicate that vitamin C may be an effective cryoprotectant, improving the recovery of sperm parameters and diminishing the rate of DNA damage and chromatin abnormalities in neat and prepared semen samples post-vitrification. One study limitation of note is the failure to measure ROS levels in sperm samples following the vitrification process. Future studies should also examine the effects of vitamin C treatment in human spermatozoa both prior to and following vitrification.
Source: Magnoli E, Talebi AR, Anvari M, et al. Vitamin C attenuates negative effects of vitrification on sperm parameters, chromatin quality, apoptosis, and acrosome reaction in neat and prepared normozoospermic samples. Taiwanese Journal of Obstetrics and Gynecology. 2018; 57: 200-204. DOI: 10.1016/j.tog.2018.02.006.
© 2018 Taiwan Association of Obstetrics & Gynecology. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Click here to read the full text study.
Posted December 15, 2020.
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