Semen cryopreservation which is more commonly known to us as sperm freezing or sperm banking. As can be understood from the name, this is a procedure of preserving the sperm cells. This can be extremely useful for the treatment of infertility. It would be extremely surprising to know that the longest successful reporting of human sperm storage is 24 years. The stored sperm cells can come very handy for donation where the receiver actually wants the treatment in other location or time. This procedure is basically a means of preservation of fertility for the males who have undergone vasectomy or any other treatments which affects their fertility such as radiation therapy, chemotherapy or surgery.
The experts at KARE, make use of the procedure for the purpose of stabilisation of the sperm cells at temperatures known as cryogenic temperatures and the procedure is referred to as cryopreservation. Glycerol is the most common cryoprotectant used for semen. Many a times, sucrose or different trisaccharides are added to the solution of glycerol. The doctors at KARE may use additional cryoprotectants in the solution for the purpose of increasing the rates of viability and fertility after freezing. The doctors also treat the sperms with heparin binding proteins before carrying on with the process of cryopreservation for decreasing the chances of cryoinjury and the generation of ROS.
Usually, there are two main cryopreservation methods for conventional freezing which are as listed below.
1. Slow Freezing – This technique of slow freezing involves a progressive cooling of the sperm over a time duration of two to four hours in a total of two or three steps. The steps are either carried on manually or with the help of a semi programmable freezer.
The manual procedure is carried out by a simultaneous decrease in the temperature of semen while the addition of a cryoprotectant in a stepwise manner after the transferring of the semen samples into liquid nitrogen. The initial rate of cooling from room temperature to 5 degree Celsius is 0.5 to 1 degree per minute. Later the cooling rate is about 1 to 10 degree per minute while freezing from 5 degree to -80 degree Celsius. Then the sperm specimen is transferred to liquid nitrogen at -196 degree Celsius.
Semi Programmable Freezers
In the manual technique, the reproducibility of the process might give rise to some problems for which the semi programmable freezers are used. The freezers make use of a plate for holding the straws which are cooled by liquid nitrogen that is held under the plates. Liquid nitrogen is filled in the tank and then the machine is programmed. The machine uses data logging software for obtaining cooling from 20 degree to – 80 degree Celsius first at the rate of 1.5 degree Celsius per minute and then at 6 degree Celsius per minute.
2. Rapid Freezing – In this technique of sperm freezing, there is direct contact
between the straws and the vapours of nitrogen for about 8 to 10 minutes and ultimately immersion of the straws in the liquid nitrogen at -196 degree Celsius.
The process of semen cryopreservation is carried out by highly trained and vastly experienced professionals at KARE so that successful results can be obtained.