Study summary

A man received his own frozen sperm stem cells for the first time

First stem cell transplant · One man, age 26 · Transplant November 2023; reported 2025

What was tested

Sperm-forming stem cells frozen before childhood cancer treatment were injected back into the same man's testis as an adult, at the University of Pittsburgh.

What they found

• The injection was reported as safe and simple to perform.
• The report had not yet been peer reviewed.
• The team expects any sperm production to be small, so IVF would still be needed.
• Earlier work showed the approach can produce working sperm in monkeys.

What it means

This helps men who banked tissue before treatment. For men with non-obstructive azoospermia from other causes there is usually no healthy stem cell supply to transplant, so the benefit is indirect: it proves the technique.