An estimated 2,000 U.S. boys and young men each year receive treatments or have cancers or blood disorders that place them at risk for infertility. While older youths who have undergone puberty can bank their sperm prior to undergoing sterilising doses of chemotherapy or radiation, there have been scant fertility preservation options for younger boys.
However, some older adolescents and young men are too sick or stressed to bank sperm. For patients with no sperm to a bank or who are too sick or stressed to bank sperm, the experimental procedure of freezing testicular tissue in anticipation that future cell- or tissue-based therapies can generate sperm is the only option.
Recent research in experimental models indicates that such testicular tissue biopsies contain stem cells, blank slate cells, hinting at the potential of generating sperm from biopsied tissue.
"This study demonstrates that undifferentiated stem and progenitor spermatogonia may be recovered from the testicular tissues of patients who are in the early stages of their treatment and have not yet received an ablative dose of therapy. The function of these spermatogonia was not tested," wrote lead author Hanna Valli-Pulaski, research assistant professor at the University of Pittsburgh.
Right now, haematologists and oncologists discuss future treatment options with patients and families, as well as possible long-term side effects, including infertility.
"This study is unique in that there is definitely a potential direct patient benefit. One of the reasons the study is compelling is that it presents a message of hope to the families. It's a message of survivorship We are optimistic we can help your child get through this and think about long-term issues, like having their own families," said Michael Hsieh, director of transitional urology at Children's National.
In this phase of the study, testicular tissue was collected from centres in the U.S. and Israel from January 2011 to November 2018 and cryopreserved.
Patients designated 25 per cent of the tissue sample to be used for the research study; 75 per cent remains stored in liquid nitrogen at temperatures close to absolute zero for the patient's future use. The fertility preservation patients ranged from 5 months old to 34 years old, with an average age of 7.9 years.
Thirty-nine per cent of patients had started medical treatment prior to requesting fertility preservation. 16 per cent received non-alkylating chemotherapy while 23 per cent received alkylating chemotherapy, which directly damages the DNA of cancer cells.
The research team found that the number of undifferentiated spermatogonia per seminiferous tubule increases steadily with age until about age 11, then rise sharply.
"We recommend that all patients be counselled and referred for fertility preservation before beginning medical treatments known to cause infertility," said Dr Hsieh.