Novel approaches select best sperm for IVF
Progress Educational Trust11 July 2008
Two independent studies presented at a European fertility meeting this week highlight new techniques for selecting those sperm most likely to result in successful pregnancies following IVF using intra-cytoplasmic sperm injection (ICSI). The first, by Italian scientists, uses high-powered microscopy to choose the healthiest-looking sperm for fertilisation, while the second, by US scientists, uses fluorescence microscopy to distinguish which 'healthy-looking' sperm are in fact harbouring DNA damage, which can decrease the chances of achieving pregnancy.
The Italian group, lead by Dr Monica Antinori, of RAPRUI clinic in Rome, used a microscope five times more powerful than standard microscopes to select sperm with the best genetic quality on the basis of their size and shape. When these sperm were each injected directly into an egg, they found that the overall pregnancy rate rose from 26.5 per cent in patients treated using standard methods, to 39.2 per cent in those treated with the new approach, known as intra-cytoplasmic morphologically-selected sperm injection (IMSI).
'By treating this kind of patient with this technique, we offer them an opportunity to solve their fertility problems. As you can see from the results, the group that has had two or more IVF failures can get more than twice the opportunity to have a pregnancy with this new technique', Dr Antinori told the Times newspaper. But, being about twice as expensive as ICSI, which costs between £3,000 and £5,000 in the UK, the treatment does come at a price, warned Dr Antinori.
Meanwhile, the US group, led by Mr Conrado Avendano, of the Jones Institute for Reproductive Medicine in Virginia, found that 20-66 per cent of the sperm selected using conventional methods - which analyse size and shape using much lower power microscopy than the IMSI method - turned out to be harbouring DNA damage, suggesting that appearances can be deceptive and should therefore not be solely relied on.
'DNA-damaged sperm has a highly deleterious effect on the ability to achieve a pregnancy. Even if damaged sperm are used and the woman becomes pregnant, the chances of miscarrying are significantly higher', said Mr Avendano, speaking at the annual meeting of the European Society for Human Reproduction and Embryology (ESHRE).
While these studies have the potential to bring dramatic benefits to infertile males, they also highlight the need for further research to evaluate the various methods available for identifying the sperm most likely to result in pregnancy.
Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.