Deep-freezing testicular tissue produces healthy baby mice
For many boys who undergo cancer treatment, infertility can be one of the most adverse side effects. But a new study reveals how deep-freezing testicular tissue may be a promising technique to preserve fertility in these patients.
The research team, including Dr. Takehiko Ogawa of Yokohama City University in Japan, recently published their findings in the journal Nature Communications.
According to the American Childhood Cancer Organization, advances in cancer treatments in recent decades have meant that more and more children are surviving the condition. At present, there are more than 270,000 survivors of childhood cancers living in the US, and a 2003 study found that 1 in 640 patients between the ages of 20 and 39 are survivors of childhood cancers.
Because of the increase in survival rates, the research team notes that infertility has become an increasing concern for pediatric cancer patients and their families. The patients may wish to have children as they grow older, but the cancer treatment they have received - whether radiation, chemotherapy or removal of one of the testicles - may have deemed them infertile.
Cryopreservation - a process whereby cells or whole tissues subject to damage are cooled and stored at sub-zero temperatures - is already used to preserve semen for male cancer patients who wish to have children later in life. But although useful, the researchers point out that it cannot be used in patients who have not yet reached puberty.
With this in mind, the researchers set out to see whether cryopreservation of testicular tissue could be effective in preserving the fertility of boys who are due to undergo treatment for cancer.
Eight healthy mice produced using cryopreserved testicular tissue and spermatogenesis
For their study, Dr. Ogawa and colleagues used cryopreservation to store the testicular tissue of newborn mice. The tissue was cryopreserved using either slow-freezing or vitrification - a fast-freezing method.
Through cryopreserving testicular tissue and using an organ culture system that triggered spermatogenesis, the team was able to produce eight healthy baby mice. These mice were able to mate naturally and produce healthy offspring themselves.
In past research, the team created an organ culture system that triggered complete spermatogenesis - the process in which the testicles produce sperm - in mice. "In this previous work," say the researchers, "we found that spermatogenesis could be induced even in frozen tissues."
As such, the team thawed the testicular tissue after more than 4 months and applied the spermatogenesis technique, which successfully produced sperm.
Using an assisted reproduction technique called "microinsemination" - a method whereby sperm is delivered directly into immature egg cells - the team was able to produce eight healthy baby mice. These mice were able to mate naturally and produce healthy offspring themselves.
The researchers say although it will be a long time before this method can be applied to humans, their results show promise. They add:
"Although they may not be easy and require further investigation, organ culture methods for the spermatogenesis of other animals including humans are expected to be successful in the future.
When this goal is realized, testis tissue cryopreservation will become a practical means to preserve the reproductive capacity of pre-pubertal male cancer patients. The present data support developing this strategy for future clinical application."
Medical News Today recently reported on a study suggesting that the outcome of fertility treatment using sperm donors may not be dependent on the donor's age, but the quality of their sperm.
Written by Honor Whiteman
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