A new study conducted on the testicles of mice has paved the way for important, possible developments for the complete restoration of fertility after cancer in humans. Researcher Eoin Whelan of the School of Veterinary Medicine, University of Pennsylvania (USA) and his colleagues found that male testicular tissue cryopreserved of a mouse can be replanted even after more than 20 years, continuing to produce viable spermatozoa. Of course, the degree of fertility is not comparable to that obtained with tissue immediately transplanted or frozen for a shorter time. However, the results remain very promising, especially with regard to the treatment of boys and children with cancer. for which chemotherapy could be preceded by the withdrawal and by freezing the testicular tissue for a possible subsequent reimplantation.
The survival rate for childhood cancers has increased dramatically over the past few decades, but a serious side effect of treatment is decreased fertility later in life. One potential treatment would be to collect, freeze and replant the testicular tissue, which it contains stamina cells. But for prepubertal boys with cancer, replanting may not be feasible for a decade or more after harvest. Hence the question of how long frozen spermatogenic stem cells (SSCs) they can remain viable. To explore this question, the authors thawed rat SSCs that had been cryopreserved in their laboratory for more than 23 years old and implanted them in so-called naked mice, which lack an immune response that would otherwise repel foreign tissue. They compared the ability of long-frozen SSCs to generate viable sperm with SSCs frozen for only a few months and freshly harvested SSCs, all from a single rat colony maintained for several decades. The results were as previously mentioned: spermatogenic stem cells (SSCs) from long frozen testicular tissue were able to colonize the mouse testis and generate all cell types necessary for successful sperm production, albeit not with the efficacy of SSCs from more recently collected tissue samples.
Although the long-frozen SSCs had similar profiles of changes in gene expression than the other samples, they produced fewer elongated spermatids, which go on to form the swimming sperm. However, the researchers believe it may be possible to identify and mitigate the key factors of the loss of vitality, in order to improve the fertility of children whose tumors, in childhood, are treated successfully. Whelan said: “Our study showed that rat spermatogonial stem cells can be successfully frozen for over 20 years, transplanted into a sterile recipient animal and regenerate the ability to produce sperm, albeit at a reduced rate. This could provide a method for recovering the loss of fertility in prepubertal boys being treated for cancer. “
Gianmarco Pondrano Altavilla