Induction of spermatogenesis by grafting neonatal mouse testicular tissue into epididymal fat of castrated adult mouse

Chemotherapy treatment used for childhood cancer can cause irreversible infertility in many cancer survivors. Also, it has been known that epididymal fat is necessary for spermatogenesis. In this study, spermatogenesis development was evaluated after grafting of fresh and frozen-thawed neonatal mice testicular tissue fragments to epididymal fat of bilaterally castrated adult mice. Neonatal male mice as the donor and adult male mice as the recipient were used. After bilateral castration of recipient’s mice, fresh or frozen-thawed neonatal testis tissue fragments were grafted into recipient epididymal fat. Eight weeks after implantation, grafted testicular tissue were evaluated by hematoxylin and eosin staining, real time PCR, immunofluorescence staining and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). The blood of the recipient mice was collected to measure Testosterone, FSH and LH levels. Eight weeks after implantation, a gradient of different types of germ cells from spermatogonia up to the elongated spermatids were seen. The meiotic and post-meiotic genes and proteins were upregulated in both fresh and frozen grafted groups and they confirmed the meiosis and post-meiotic progression in grafted tissues. The expression of apoptosis and necrosis genes showed no significant differences between the grafted and non-grafted control groups. There were no significant differences in hormonal assessments between control and experimental groups. Epididymal fat is an area with optimal hormonal and temperature conditions, which could support spermatogenesis in grafted immature testicular tissue. This method of grafting may pave a way for fertility preservation in childhood cancer survivors.