BY SARA GÓMEZ GARCÍA 04/21/2019
Semen analyses are needed to evaluate male infertility. However, about 15% of infertile men present sperm parameters regarded as normal and so these standard measures alone are insufficient in predicting male fertility potential. Therefore, additional tests become necessary.
The genetic information of the newborn is the result of the conjunction of both oocyte and sperm DNA. This should be intact, as any damage on the DNA may affect embryonic development. Consequently, sperm DNA fragmentation (SDF) has been under the scope for some time with increasing interest. This factor has been related to reduced fertilization and pregnancy rates, abnormal embryonic development and increased risks of miscarriage and of neonatal disease in the offspring.
HOW DOES SPERM DNA FRAGMENTATION OCCUR?
There are mainly two ways in which DNA strand breaks could occur.
1. Errors during spermatogenesis
Under normal circumstances, DNA nicks are generated and they are repaired during sperm maturation. If repair is impaired, sperm DNA can remain fragmented. In addition, aberrations in sperm development could be produced, which could make sperm DNA more vulnerable.
2. Oxidative Stress
Reactive Oxygen Species (ROS) are metabolites of oxygen and nitrogen, among others, and are highly reactive in that they readily oxidize other molecules. These metabolites are produced by sperm or external factors, and even though they play physiological roles in supporting sperm function, an imbalance in those levels may lead to DNA damage. Sperm contain antioxidant mechanisms to regulate this balance; however, an excess of ROS or defects in the antioxidant system can result in DNA damage.
WHAT ARE THE SOURCES OF SDF AND THE CURRENT INDICATIONS TO CARRY OUT SFD TEST?
Several studies suggest that SDF could have a variety of origins and, therefore, sperm DNA could be subjected to a multitude of damaging events.
Indications to carry out sperm DNA fragmentation test.
Poor embryo quality
Increase of time of conception
Several ART failures
HOW TO AVOID SPERM DNA FRAGMENTATION
Lifestyle modifications like stopping smoking, reducing alcohol intake and adopting a more balanced diet are the easiest way to improve SDF.
Several studies have demonstrated that the use of antioxidants like vitamin C, vitamin E, vitamin B, 𝛃-carotene, isoflavones, as dietary supplements can reduce oxidative DNA fragmentation or prevent oxidative stress. However, such positive effect is not observed in all patients, and so further research is needed.
Antioxidants added to culture media during sperm preparation have been demonstrated to reduce ROS levels produced by ART and so improve sperm parameters. Also, research on mice has shown that antioxidant inclusion during fertilization has led to improved embryo development.
Men with inflammatory diseases could be treated with medications to decrease the amount of ROS and, thus, to improve fertility outcomes. Patients suffering from varicocele can undergo varicocelectomy to decrease ROS levels.
Recurrent ejaculation leads to the discard of older sperm cells with more SDF. Similarly, testicular sperm, directly extracted by surgery from the testis, exhibit lower SDF.
Female infertility has historically been more widely studied than male factor. Male reproductive potential is evaluated by seminal parameters, like motility, morphology, volume, total sperm count…etc. However, these measures are insufficient as they do not assess the quality of sperm DNA. Nowadays, male factor has become a more interesting focus of attention, and so it is subjected to more and deeper research, such as SDF evaluation.
(my two cents - mike berkley): I have treated numerous men with severe sperm DNA fragmentation with acupuncture and herbal medicine and have been successful in reducing the percentage of DNA fragmentation to normal or more reasonable numbers.