Prepubertal boys who are at risk of becoming infertile because of chemotherapy might have healthy testicular tissue removed and frozen beforehand.
The treatment of Krebs is increasingly successful in children, but it means that many prepubertal boys suffer from reduced fertility or are completely infertile later in life. One chemotherapy used to treat cancer can kill stem cells in the testicles that sperm to produce. Adults can freeze semen samples prior to this treatment, but this is not an option for children who are not yet in the puberty are.
One possible treatment would be to remove, freeze and replant testicular tissue that contains stem cells. But for prepubertal boys with cancer, reimplantation may not be possible until a decade or more following collection, raising questions regarding how long frozen spermatogenic stem cells (SSCs) can remain viable.
Die cryopreservation refers to a gentle and complex procedure for freezing germ cells (egg cells and sperm cells). This is a computer-controlled process that takes several hours until the germ cells are finally stored in liquid nitrogen at around -196°C. In this “cold sleep” the germ cells are capable of surviving for several years. For example, many women have their egg cells frozen for later use. Due to the extremely low temperatures, there is practically no metabolism in the egg cell and therefore no aging process.
To investigate this question, the researchers thawed spermatogenic stem cells from rats that had been cryopreserved in their laboratory for more than 23 years and implanted them into mice previously treated with medication were rendered sterile and one defective immune system had so that they might not reject the transplant. HERE let’s go to the study.
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They compared the ability of the long-frozen SSCs to produce viable sperm with stem cells frozen for just a few months and with freshly harvested SSCs. It turned out that the 23-year-old stem cells survived their time in the ice and formed new sperm-producing cells in the testicles. These cell groups from the implanted stem cells then produced mature ones spermbut only regarding a third as much as with implants of fresh or briefly frozen cells.
Nevertheless, the study by Whelan and his colleagues gives cause for optimism. “Our study showed that 23-year-frozen rat spermatogonia stem cells transplanted into an infertile recipient animal might regenerate the ability to produce sperm – albeit at a reduced rate. This might represent a method of restoring fertility in prepubertal boys who die because of cancer were treated.” A human study is pending.
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