Cryopreserved testicle tissue has been used to produce live mouse offspring for the first time, reports a paper in Nature Communications this week. This indicates that the cryopreservation of testicle tissue may be a realistic measure for preserving fertility.

Infertility is one of the adverse effects of certain cancer treatments. As cure rates for paediatric cancers increase, fertility has become an important concern for patients and their families. Since semen cryopreservation is applicable only for postpubescent patients, alternative measures are necessary for younger patients.

Ogawa and colleagues previously developed an organ culture system that can induce complete spermatogenesis-the process by which sperm is produced by the testes-in mice. In their latest research they cryopreserved the testicular tissues of new-born mice, either by slow-freezing or vitrification-a specialised fast-freezing technique. After thawing, the tissues were cultured and showed spermatogenesis as efficient as that in unfrozen control tissues.

Microinsemination-sperm deposition directly into immature egg cells-was performed from tissues cryopreserved for more than four months and this lead to eight offspring in total. The offspring grew healthily and were able to reproduce. This strategy presents a potential method for preservation of fertility but will require further work before it can be translated into humans.