Sperm turn out to do such a great job of packing in and coating their DNA that they can be dried, sealed, and stored at room temperature for use in In Vitro Fertilization (IVF)
Madrid, Spain: A novel method of preserving sperm through air drying is showing initial promise and has the potential to revolutionize sperm storage, allowing men awaiting in vitro fertilization (IVF) to take care of their sperm at home.
Dr Daniel Imoedemhe, a consultant in reproductive medicine and endocrinology, working in Saudi Arabia, told the annual meeting of the European Society of Human Reproduction and Embryology, that for the first time studies on human embryos fertilized with air-dried sperm have shown that the new technique does not impair the early stages of embryo cell division.
Dr Imoedemhe, from Erfan and Bagedo Hospitals, Centre for Assisted Reproduction, Jeddah, said that in the past it was believed that sperm "died" when allowed to dry in air because they were no longer motile and therefore unable to penetrate an egg. "But with the technique intracytoplasmic sperm injection (ICSI), the loss of motility doesn't necessarily mean the loss of ability to fertilize an egg, since this is largely dependent on the DNA (genetic material) that is tightly packed into the sperm head. We believe our study confirms that sperm DNA is resistant to damage by air drying."
Current techniques for freezing sperm are expensive.
Sperm are stored in large liquid Nitrogen tanks that require regular top-ups to ensure that they remain in the desired condition. The tanks are expensive, large and occupy a great deal of laboratory space. In the current system, in order to prevent mis-identification during recovery from storage tanks, a rigorous labelling and coding system is required.
"These methods are time-consuming and cumbersome compared to our simple technique of air-drying that just requires re-suspension before use," said Dr Imoedemhe. "The process can be further simplified by allowing patients to take responsibility for storing their air-dried sperm at home."
The new air-drying technique involves smearing a sample pellet of washed sperm on to a glass slide and then leaving it to dry for two to three hours in a laminar flow cabinet that allows a directional flow of filtered air to ensure that the sample remained uncontaminated by airborne dust or micro-organisms. The dried sperm can then be stored at normal room temperature or in a normal refrigerator and do not seem to require any other special storage conditions. Just prior to injection by ICSI into an egg, the sperm film can be re-suspended with a large drop of special biological medium (similar to that in which the eggs are held in order to avoid osmotic changes).
This technique has not yet been tested using eggs that were of the same quality as the eggs typically used for IVF techniques. Therefore the poorer results with the air-dried sperm are at least partially attributable to the poorer quality eggs used for those experiments.
But although drying did not seem to interfere with fertilization, it was found that 72 hours after sperm injection, the therapeutic group (eggs fertilized with fresh un-dried sperms) had significantly more embryos advancing to the eight or more cell stage than the experimental group (air dried sperm) – 50.5% versus 18.2%.
However Dr Imoedemhe believes this may have more to do with the differences in experimental procedure necessitated by the difficulty of acquiring fresh mature eggs for the experimental group, than the effects of air-drying. In the treatment group all the eggs were mature (at metaphase II), whereas in the air-dried group the eggs were immature (at metaphase I) and had to be matured outside before ICSI. It is thought that such immature eggs may have less potential for development after fertilization compared to normally matured eggs.
If this becomes cheap and easy to do one can easily imagine why some men will arrange to have it done just as an insurance policy against the possibility of disease or injury.
This also opens up greater possibilities for sperm theft. If the sperm can more easily be stored then there will be greater incentive for a woman to get sperm from someone they have a brief affair with and arrange to have the sperm air dryed and then kept for later fertilization. A woman could easily build up a large collection from all the men she ever slept with and then go thru and, once DNA sequencing is cheap, sequence a part of each sample and then choose which man's sperm she wants to use for making a baby on her own.
Update: Dr. Nikolaos Sofikitis, professor of urology at Ioannina University in Greece, has taken germ cells from healthy testicles of men who had testicular cancer in the other testicle and transplanted the germ cells back into the testicular area after cancer treatment was completed. This restored sperm production in the cancer patients.
The new technique preserves the "germ cells" which make sperm, which are frozen and then transplanted back into the man when he is given the all-clear from the disease.
Remarkably, the frozen cells then "re-colonise" the testicle, and start producing enough sperm to allow fertility doctors to extract it from semen.
The germ cells included stem cells and those cells were able to recolonize the healthy testicle.
The germ cells were then thawed and injected back into the healthy testicles of three of the men.
Thirteen months later, the scientists found the testicles had been successfully recolonized with germ cells that produce sperm.
|Share |||Randall Parker, 2003 July 02 09:52 AM Biotech Reproduction|