Gamete preservation before chemotherapy
A big group of people in the reproductive age group are diagnosed with cancer or other such diseases. Oncological patients undergoing chemotherapy or radiotherapy run the risk of losing their reproductive potential. An important part of post chemotherapy in both men and women is to maximise quality of their life which includes their reproductive life . Gamete preservation or embryo preservation offers the best fertility preserving technique foe oncological patients.
As humans we produce two different types of gametes . Each individual produces only one type. Females produce the larger gamete – the ovum. Males produce the smaller tadpole like gamete – the sperm. Artificial or invitro gametes are derived from stem cells. The best method to preserve gametes is through cryopreservation.
What is Cryopreservation?
Cryopreservation is a process in which any biological content which is susceptible to damage by unregulated chemical kinetics are preserved by cooling to very low temperatures(-80°c using solid carbon dioxide or -196°c using liquid nitrogen). At such low temperatures any enzymatic or chemical activity that may cause harm ceases. Any damage that can be caused by the cooling process due to the formation of ice is negated by the addition of cryoprotectants.
Cryoprotectants are generally coated on the biological material before preserving. Freezing and then thawing are done taking care not to cause any damage to the gametes. Some of the common cryopretectants used are dimethylsulfoxide(dmso) and ethylene glycon. Their presence leads to the lowering of the freezing point of the solution. Selection of the cryoprotectant depends on the cell type.
Sperms are preserved in specialised cryovials and can be later used for the desired treatment . Oocytes are cryopreserved using a process called vitrification. It is a rapid and simple procedure based on solidification of the cells and the surrounding solution thus preventing the formation of ice crystals which might damage the structure of the gamete.
The collection of the gametes from the individual is done after screening the patient for HIV and Hep B and C . The gametes are then used at a minimum of 6 months from collection and the individuals are tested again to confirm seronegativity. Once this is confirmed the gametes can then be used for the desired process. In conclusion the method of gamete preservation through cryopreservation done before chemotherapy can provide these individuals with high chances of leading a qualitative reproductive life.