Infertility is a serious public health problem. One pair in 6 is barren in all of Europe1, and male infertility is currently the largest cause of couples seeking treatment. It is known that sperm DNA damage is the main cause of male infertility and reduces the chances of a couple having a family.
The new study shows the journey of sperm from the testicles along long series of conduits before ejaculation, and also shows how sperm DNA can suffer serious damage, some of which is caused by oxidative stress.
In a new study, presented at the European Association for Urological Congress in Barcelona, British scientists suggest that sperm DNA from many infertile men is as good as the semen of fertile men. This can explain the remarkable cause of male infertility and opens the probability of using semen specifically collected from these men's testicles; overcome their infertility.
Researchers collected sperm samples from 63 infertile men and used them for embossed semen samples produced by the same men. In these infertile men, the earlier treatment of fertility (intradermal sperm injection, ICSI) was unsuccessful.
Researchers also examined spermatozoa for two types of DNA strand breaks (single and double strand break), each in testicular sperm and ejaculation. A group of 76 fertile volunteers also gave ejaculated sperm to compare.
They then measured DNA damage using the Comet2 test, which is able to measure the double and single strand breaks separately.
According to the researcher, Jonathan Ramsay (consultant urologist, Imperial College, London):
"When we looked at spurted sperm, we found that the degree of sperm DNA damage was significantly higher in infertile men than infertile men, from about 15% of infertile men, but 40% in infertile men. It was no surprise that I saw more damage to the DNA in the ejaculates of infertile men. What we did not expect was the consistency of these results, when we looked at the semen taken directly from the testicles of infertile men, we found it to be of similar quality to ejaculate sperm, fertile sperms. "
Most DNA damage caused by the journey from the testicles to the ejaculate is caused by oxidative stress, which causes a single, but not double, DNA rupture. This happens when sperms are exposed to a bad lifestyle, such as a terrible eating routine, sitting at a computer all day or smoking. Diseases, for example Crohn's disease and type 2 diabetes, also cause oxidative stress.
Professor Sheena Lewis, retired professor at Queens University Belfast and founder of ExamenLab Ltd:
"This means that DNA in sperm of testes of infertile men is of better quality than spermatozoa from their ejaculates. This opens the way to the collection of sperm directly from the testicles of men who have highly fragmented DNA ejaculation and unsuccessful treatment cycles and try to achieve fertility with these testicular sperm. We also noticed in the subgroup that the number of more serious double-stranded DNA breaks was lower in semen collected from the testicles, so the use of these sperm can lead to improved fertility in men. "
"We must be aware of what this study does and does not show. We can not yet prove that sperm DNA damage is the main cause of male infertility or ART failure in these men, or that the direct use of testicular sperm would help to increase their chance of getting pregnant, but the work certainly indicates this direction. "
Commenting, Professor Maarten Albersen (UV Leuven, Belgium.) A member of the EAU Scientific Congress Office, said:
"Couples who face an unfulfilled child's desire for male infertility often have to resort to assisted reproduction techniques such as in vitro fertilization (IVF) or intra-uterine sperm injection (ICSI). Indicators of the success of these techniques on the cycle are rather low, and these factors are influenced by various factors. In many European countries, one or a small number of cycles are refunded, which means that couples should optimize their chances of success. In this study, a London group shows that the integrity of DNA in infertile men is higher in testicular sperm than in ejaculate sperm. "
"Because DNA integrity is thought to play a role in assisted reproduction indicators, these results can help in making decisions, or rather refer to testicular biopsy / aspiration, than using sperm ejaculation to increase the success rate of assisted fertilization in infertile men with signs of DNA damage. However, before the adoption of this alternative strategy, the improvement of fertilization rates and the rate of admission of children should be confirmed.