Ultrasound-Guided Rete Testis Approach to Sperm Aspiration and Spermatogonial Stem Cell Transplantation in Patients with Azoospermia

BackgroundAzoospermia, characterized by the absence of sperm in the ejaculate, impacts 1% of men globally. Surgical approaches to retrieve sperm from the testis are effective in some cases but can be invasive and expensive. Here we described a noninvasive ultrasound-guided rete testis (UGRT) approach to retrieve sperm from the testes or infuse stem cells into the testes of men with azoospermia. MethodsUltrasound was used to guide insertion of a 25-gauge hypodermic needle through the base of the scrotum and into the rete testis space that is contiguous with all seminiferous tubules. Medium was infused into the rete testis and aspirated to retrieve sperm from monkeys and men (NCT03291522) with azoospermia. A peripubertal patient with osteosarcoma of the femur cryopreserved a testicular cell suspension to safeguard his future fertility (NCT02972801). He returned as a young adult (21-25 yo) survivor for autologous transplantation of his cryopreserved testicular cells, including spermatogonial stem cells, using the UGRT approach (NCT04452305). FindingsSperm were successfully aspirated from four of six monkeys with radiation-induced azoospermia and three of three patients with obstructive azoospermia, demonstrating proficiency with the UGRT approach. Sperm were not recovered from the testes of seven patients with nonobstructive azoospermia. Semen analysis confirmed that the adult survivor of childhood cancer was azoospermic. His cryopreserved testis cells were transplanted back into one testis, with no adverse effects. After transplantation, the testicular parenchyma had a normal homogeneous appearance. Testosterone, Follicle Stimulating Hormone, and Luteinizing Hormone levels were normal. Inhibin B levels were low. The patient remains azoospermic one year after transplantation. InterpretationWe describe a platform for proficiency training in UGRT flushing, aspiration, or injection. This provides a noninvasive option for sperm retrieval and infusing stem cells or other therapeutics into the testis. FundingThe Eunice Kennedy Shriver National Institute for Child Health and Human Development HD100197 and the UPMC Magee Center for Reproduction and Transplantation.