Abstract
Achieving high embryo quality following IVF and ICSI procedures is a key factor in increasing fertility outcomes in human infertile couples. While the male factor is known to underlie infertility in about 50% of cases, studies performed in human infertile couples have not been able to define the precise effect of sperm affectations upon embryo development. This lack of consistency is, in most cases, due to the heterogeneity of the results caused by the multiple male and female factors that mask the concrete effect of a given sperm parameter. These biases can be reduced with the use of animal gametes, being a good approach for basic researchers to design more homogeneous studies analyzing the specific consequences of a certain affectation. Herein, we conducted a systematic review (March 2020) that assessed the relationship between sperm oxidative stress alterations and IVF/ICSI outcomes in nonhumans mammals. The review was conducted according to PRISMA guidelines and using the MEDLINE-PubMed and EMBASE databases. Thirty articles were included: 11 performed IVF, 17 conducted ICSI, and two carried out both fertilization methods. Most articles were conducted in mouse (43%), cattle (30%) and pig models (10%). After IVF treatments, 80% of studies observed a negative effect of sperm oxidative stress on fertilization rates, and 100% of studies observed a negative effect on blastocyst rates. After ICSI treatments, a positive relationship of sperm oxidative stress with fertilization rates (75% of studies) and with blastocyst rates (83% of studies) was found. In conclusion, the present systematic review shows that sperm oxidative stress is associated with a significant reduction in fertilization rates and in vitro embryo development.
Highlights
Infertility is defined as the failure to achieve a clinical pregnancy after 12 months of regular unprotected intercourse [1]
In order to help human infertile couples, assisted reproductive techniques (ART) were developed decades ago; nowadays, all intrauterine insemination (IUI), in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are methods with the potential to result in a pregnancy and a healthy newborn
The inclusion and exclusion criteria defined in the PICOS (Population, Intervention, Comparator, Outcome, Study) design structure (Supplementary Table S1) led to a comprehensive list of keywords and Medical Subject Headings (MeSH) terms, which were combined with keywords related to oxidative stress and IVF/ICSI outcomes, all them resulting in the design of the search strategy (Appendix A)
Summary
Infertility is defined as the failure to achieve a clinical pregnancy after 12 months of regular unprotected intercourse [1]. In order to help human infertile couples, assisted reproductive techniques (ART) were developed decades ago; nowadays, all intrauterine insemination (IUI), in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are methods with the potential to result in a pregnancy and a healthy newborn. Because of that, they are currently accepted worldwide as having a routine medical use. Procedures involving artificial fertilization (i.e., IVF or ICSI) are the most frequent ART, with more than 541,000 cycles a Biology 2020, 9, 178; doi:10.3390/biology9070178 www.mdpi.com/journal/biology
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