The DNA of sperm taken directly from the testicles of infertile men is as healthy as that of sperm ejaculated by fertile men, suggests a new study.
In contrast, once the sperm have left the testes and been ejaculated in infertile men, there is a significant increase in DNA damage, the researchers suggest.
'What this means is that the DNA in sperm from the testicles of infertile men are better quality than sperm from their ejaculates,' said Professor Sheena Lewis, emeritus professor at Queens University Belfast. 'This opens the way to taking sperm directly from the testes of men who have highly fragmented ejaculated DNA and failed cycles of treatment, and trying to achieve fertility with these testicular sperm.'
UK scientists analysed sperm from 63 infertile men taken both directly from their testes, and in ejaculated samples. The men had previously been unsuccessful with the fertility treatment ICSI (intracytoplasmic sperm injection).
The team also examined ejaculated sperm from 76 fertile volunteers.
The DNA of the sperm was analysed for damage, in particular for breaks to the single or double-strands of DNA.
'When we looked at ejaculated sperm, we found that the extent of sperm DNA damage was much higher in infertile men than in fertile men, with roughly 15 percent in fertile men, but 40 percent in infertile men,' said researcher, Mr Jonathan Ramsay, a consultant urologist at Imperial College London.
'What we didn't expect was the consistency in these results when we looked at sperm taken directly from the testicles of infertile men, we found that it was of similar quality to that of ejaculated, fertile sperm.'
The study was presented at the European Association of Urology (EAU) Congress in Barcelona, Spain. Professor Maarten Albersen at UV Leuven in Belgium, and a member of the EAU Scientific Congress Office who was not involved in the work, said the results might help with 'decision-making' on whether on not to use sperm taken directly from the testicles rather than ejaculated sperm 'to enhance success rates of assisted fertilisation in infertile men with signs of DNA damage'.
He added: 'However, improved fertilisation rates and baby take-home rates would need to be confirmed before adopting this alternate strategy.'