Semen cryopreservation
Encyclopedia
Semen cryopreservation
is a procedure to preserve sperm cells. Semen
can be used successfully indefinitely after cryopreservation. For human sperm, the longest reported successful storage is 21 years. It can be used for sperm donation
where the recipient wants the treatment in a different time or place, or for men undergoing a vasectomy
to still have the option to have children.
(10% in culture medium). Often sucrose
or other di-
, trisaccharides are added to glycerol solution. Cryoprotectant media may be supplemented with either egg yolk or soy lecithin, with the two having no statistically significant differences compared to each other regarding motility, morphology, ability to bind to hyaluronate in vitro, or DNA integrity after thawing.
Semen is frozen using either a controlled-rate, slow-cooling method (slow programmable freezing or SPF) or a newer flash-freezing process known as vitrification. Vitrification gives superior post-thaw motility and cryosurvival than slow programmable freezing.
, up to three cycles of freezing and thawing can be performed without causing a level of risk significantly higher than following a single cycle of freezing and thawing. This is provided that samples are refrozen in their original cryoprotectant
and are not going through sperm washing
or other alteration in between, and provided that they are separated by density gradient centrifugation or swim-up before use in assisted reproduction technology.
Cryopreservation
Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as 77 K or −196 °C . At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped...
is a procedure to preserve sperm cells. Semen
Semen
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...
can be used successfully indefinitely after cryopreservation. For human sperm, the longest reported successful storage is 21 years. It can be used for sperm donation
Sperm donation
Sperm donation is the provision by a man, , of his sperm, with the intention that it be used to impregnate a woman who is not usually the man's sexual partner, in order to produce a child....
where the recipient wants the treatment in a different time or place, or for men undergoing a vasectomy
Vasectomy
Vasectomy is a surgical procedure for male sterilization and/or permanent birth control. During the procedure, the vasa deferentia of a man are severed, and then tied/sealed in a manner such to prevent sperm from entering into the seminal stream...
to still have the option to have children.
Freezing
The most common cryoprotectant used for semen is glycerolGlycerol
Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...
(10% in culture medium). Often sucrose
Sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...
or other di-
Disaccharide
A disaccharide or biose is the carbohydrate formed when two monosaccharides undergo a condensation reaction which involves the elimination of a small molecule, such as water, from the functional groups only. Like monosaccharides, disaccharides form an aqueous solution when dissolved in water...
, trisaccharides are added to glycerol solution. Cryoprotectant media may be supplemented with either egg yolk or soy lecithin, with the two having no statistically significant differences compared to each other regarding motility, morphology, ability to bind to hyaluronate in vitro, or DNA integrity after thawing.
Semen is frozen using either a controlled-rate, slow-cooling method (slow programmable freezing or SPF) or a newer flash-freezing process known as vitrification. Vitrification gives superior post-thaw motility and cryosurvival than slow programmable freezing.
Thawing
Thawing at 40°C seems to result in optimal sperm motility. On the other hand, the exact thawing temperature seems to have only minor effect on sperm viability, acrosomal status, ATP content, and DNA.Refreezing
In terms of the level of sperm DNA fragmentationDNA fragmentation
DNA fragmentation is the separation or breaking of DNA strands into pieces. It can be intentional by laboratory personnel or the cells, or it can be spontaneous.-Intentional:Restriction digest is the intentional laboratory breaking of DNA strands....
, up to three cycles of freezing and thawing can be performed without causing a level of risk significantly higher than following a single cycle of freezing and thawing. This is provided that samples are refrozen in their original cryoprotectant
Cryoprotectant
A cryoprotectant is a substance that is used to protect biological tissue from freezing damage . Arctic and Antarctic insects, fish, amphibians and reptiles create cryoprotectants in their bodies to minimize freezing damage during cold winter periods. Insects most often use sugars or polyols as...
and are not going through sperm washing
Sperm washing
Sperm washing is a term used to describe the process in which individual sperms are separated from the seminal fluid. The sperms are then used in intrauterine insemination or in vitro fertilization ....
or other alteration in between, and provided that they are separated by density gradient centrifugation or swim-up before use in assisted reproduction technology.