Men who are HIV+ cannot father children without running the risk of passing the virus onto the unborn fetus. Current sperm freezing techniques do not separate sperm from plasma, so the virus may be passed into the egg upon fertilization, making cryogenics useless for HIV+ men. New freezing technologies may solve this problem by spinning sperm to remove plasma before freezing.

Presented at the World Congress of Fertility and Sterility, researchers have perfected a technique of sperm freezing that increases motility and decreases or eliminates the risk of HIV transmission. The HIV connection is a by-product of the new sperm freezing technology.

Researchers explained that sperm is spun to remove plasma during the first stage of preparation. After spinning, sperm is placed in a sucrose solution and fast frozen with liquid nitrogen. After freezing, sperm is stored until needed for IVF.

When sperm are thawed using this new method, sperm retains 77% of motility compared to 29% motility using current freezing technology. The process is called sperm vitrification. Egg vitrification and embryo vitrification are already in use. When motility is maintained, more sperm remains viable for implantation during IVF and quality of sperm is improved.

As a secondary benefit, the removal of plasma from sperm also removes the risk of blood-borne illnesses like HIV and Hepatitis B. Professor Ian Cooke of the International Federation of Fertility Sciences states, "This looks a very exciting technique, as it is much faster than the conventional slow-freeze procedure. In addition, the prospect of use with HIV+ patients has great potential, although we'd want to confirm the absence of residual HIV in sperm samples before going ahead.”

Source: International Federation of Fertility Sciences. 15 September 2010.