Spermatogonial stem cell transplantation through ultrasound guided rete testis injection and testicular tissue grafting will be performed for participants who have frozen testicular tissue prior to gonadotoxic therapy. The purpose of this study is to test the safety and feasibility of these transplant technologies and restore fertility for these participants.

Azoospermia (no sperm in ejaculated semen) impacts 1% of men in the general population and 15% of infertile men, which translates to 645,000 males between the ages of 20 and 50 (prime reproductive years) in the United States. Spermatogenesis arises from a population of spermatogonial stem cells in the testes that maintain continuous sperm production throughout a man's post-pubertal life. Diseases or medical treatments that compromise the stem cell pool and/or prevent the stem cells from differentiating can cause infertility. Adult men have the option to cryopreserve a semen sample prior to therapy but this is not an option for prepubertal patients who are not yet producing sperm. This study will test the safety and feasibility of two approaches to restore sperm production using previously cryopreserved testicular tissues, which contain spermatogonial stem cells.

The first approach is autologous transplantation of testicular cells, including spermatogonial stem cells, into the testis using ultrasound-guided rete testis injection. The second approach is autologous grafting of intact pieces of testicular tissue under the skin in the scrotum.

Inclusion Criteria:

• Male participant at least in Tanner stage 3
• Previously cryopreserved and stored testicular tissue/cells (frozen due to an infertility-risking diagnosis or treatment such as chemotherapy or radiation) available for autologous transplantation and grafting
• Healthy enough to undergo anesthesia
• Written clearance for the procedure from the patient's hematologist or oncologist to confirm the patient has finished treatment for primary condition and are clear to undergo autologous stem cell transplant

Exclusion Criteria:

• Participants considered to be high risk for surgical complications
• Participants with a history of leukemia, lymphoma or testicular cancer or a cancer that likely involved testicles at the time of testicular tissue collection
• Diagnosed with psychological, psychiatric, or other conditions which prevent giving fully informed consent.

The investigators will publish individual participant data, after deidentification. The investigators will also report each individual participants data back to them. Participants will be identified with unique ID numbers. No identifiable information will be shared.

Beginning 9 months and ending 36 months following article publication.

Researchers who provide a methodologically sound proposal. Proposals should be directed at korwig@mwri.magee.edu