Abstract
Background: Cryopreservation of human sperm has long been a successful method for managing male fertility and for storing and preserving donor spermatozoa. Boron is one element used in this particular procedure. The primary objective of this study was to conduct a thorough assessment of existing evidence regarding the impact of boron extenders on sperm parameters.
Methods: The databases PubMed, Scopus, Embase, ProQuest, and the Web of Science were searched up until January 2023 without time or language restrictions, using specified keywords and index terms. The keywords included: ((((“reproduction”[MeSH Terms]) OR (“reproduction”[Title/Abstract])) OR (“reproductive”[Title/Abstract])) OR (((“infertility”[MeSH Terms]) OR (infertile*[Title/Abstract])) OR (Sperm [Title/Abstract]))) AND ((“boron”[MeSH Terms]) OR (boron [Title/Abstract])). The methodological validity of the quantitative papers selected for inclusion in the systematic review was assessed by two independent reviewers using the standardized ARRIVE Essential 10: Compliance Questionnaire appraisal tools.
Results: Out of 1602 citations, only five studies met the eligibility criteria to be included in the study. All five studies were conducted in Turkey and used a case-control design with varying samples, including Angora goats, bulls, brown trouts, Merino rams, and Ankara bucks. Freezing semen using boron-added extenders, specifically extenders 1c and 1d, showed the highest motility values in Angora goats. In bulls, different boron doses in extenders were evaluated, with the group containing the lowest boron content exhibiting the best sperm parameters. Incorporating boron into semen extenders improved post-thaw sperm quality, especially in motility. For brown trout sperm, two freezing profiles were tested, revealing that boron improved post-thaw sperm characteristics, with 0.4 mM yielding the best results. In addition, boron supplementation in Merino ram sperm demonstrated that 0.25 mM boron with trehalose improved motility, mitochondrial activity, viability, and acrosome integrity, and reduced DNA damage at 1 mM boron. Moreover, 0.25 and 1 mM boron protected sperm plasma membrane, acrosome integrity, and mitochondrial membrane activity after freeze-thawing, with all boron concentrations offering better cryoprotective benefits than the control group.
Conclusion: Overall, the findings suggest that boron positively impacts sperm cryopreservation outcomes and could be a valuable addition to semen extenders for enhancing fertility preservation in various animal species.