A team of scientists from Chile and Germany found that fast-freezing sperm preserves its ability to swim towards an egg far more efficiently than the slow-freezing method currently in use.
The method, according to the scientists, also offers the chance to cancer patients and HIV-infected men to become father without passing on the disease to the newborn, the Daily Mail reported.
In the existing slow-freezing techniques, the sperm only retains 30 to 40 per cent of activity. But rapid freezing — also known as vitrification — allows that figure to rise to almost 80 per cent, the scientists said.
Vitrification is already used to quick-freeze eggs and embryos with success, allowing spare ones to be used in IVF at a later date. Following thawing, more eggs and embryos survive with vitrification than with older, slower cooling techniques.
In vitrification, cryopreservation agents are added to lower the water content in cells and prevent ice crystals building up.
In the latest study, the researchers separated and removed plasma and placed the sperm in a sucrose solution before plunging them into liquid nitrogen to fast-freeze.
When sperm was rethawed, it regained motility (77 per cent versus 29 per cent with slow cooling) and showed less damage, the researchers found.
The removal of plasma means HIV and other viruses can also be removed, giving HIV positive men the chance of fathering a child without the likelihood of passing on the virus to mother or baby, they said.
Men with a low sperm count and whose sperm is deteriorating in quality over time would also benefit from the technique, they said.
Some men with low sperm counts fail to produce a good enough sample when it is time for IVF. The new technique could also allow several samples to be put together as one.
Lead researcher Professor Raul Sanchez, from La Frontera University in Chile, said: “This work shows that we can preserve functional sperm via vitrification, which gives a greater chance of success for patients with low sperm counts.
“The other great advantage of this technique is that it can eliminate potential sources of infection such as Aids or hepatitis B, which are present in seminal plasma.
“It (also) has the potential to allow HIV positive men to have children without worrying about transmitting the virus.”
The Times of India