Sperm identification could improve male fertility

May 29th, 2010 - 5:28 pm ICT by IANS  

Washington, May 29 (IANS) Researchers have discovered a method to select sperm with the highest DNA integrity that is likely to improve male fertility.
The method is comparable to that of the egg’s natural selection abilities, says a new study.

“Our results could help address the fact that approximately 40 percent of infertility cases can be traced to male infertility,” said study co-author Gabor Huszar, senior research scientist in obstetrics, gynaecology and reproductive sciences at Yale School of Medicine.

Huszar said that past semen analysis focused on sperm concentration and motility (ability to move spontaneously and actively). It was assumed that if a man had a high sperm count and active sperm he was fertile.

But there was no information on the sperm’s fertility or its ability to attach to its mark, the female gamete.

In an ideal case, the egg naturally selects the optimal sperm, but during in-vitro (test tube) fertilisation treatment of men who had only a few sperm, clinicians did not know whether they were injecting the correct sperm into the egg for fertilisation.

“We have now found a biochemical marker of sperm fertility so that we can select sperm with high genetic integrity,” Huszar said.

Huszar and his colleagues tested the idea that binding sperm to hyaluronic acid selects sperm with high DNA integrity.

They studied semen samples from 50 men, and a part of the sperm in the semen was allowed to bind to hyaluronic acid. These sperm were isolated, and the DNA chain integrity was compared to the original sperm in semen.

The team used a reagent that stained sperm with high DNA integrity green, whereas sperm with fragmented DNA, and diminished DNA integrity were stained red.

“The sperm with fragmented DNA work like scratched CDs,” Huszar said. “They seem to be operational, but when you play them, some of the information is missing.”

“These damaged sperm may also carry chromosomal aberrations that could be related to genetic diseases,” Huszar added, according to an Yale release.

Other Yale authors included Artay Yagci, William Murk and Jill Stronk. These findings are slated for publication in the June/July issue of the Journal of Andrology.

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