Spermatogonial Stem Cells in Domestic Animals: Current Insights and Future Directions with a Focus on Dogs

The growing interest in improving the fertility-rate of livestock species, considering their high economic value, has prompted the development of new methodological approaches using male germline stem cells. Spermatogonial stem cells' (SSCs) potential to self-renew and differentiate into mature spermatozoa holds promise for their transplantation into testicular tissue and use in new biotechnological methodologies. Moreover, SSCs' ability to convey genetic information to the next generation is a property that could be exploited for gene targeting. The review provides an update on the main aspects of SSC biology, focusing on the genetic regulators of self-renewal and differentiation processes and different isolation methods. In addition, recent advancement in the cryopreservation of SSCs from domestic animals and their transplantation into recipients' testes are also discussed. Finally, a section focused on canine SSCs (cSSCs), their biological aspects, and their potential clinical application in the field of reproduction is included. This represents an effective animal model for human reproduction, development, and disease, given that the reproductive anatomy and physiology of canine species and human are similar. We then report on the potential clinical transplantation of SSCs into recipient testicular tissue and suggest future topics to explore for significant advances in fertility preservation.