Cell and molecular biology of testicular stem cells

Human spermatogonial stem cells (SSCs) are one subtype of the population of spermatogonia, which form the foundation of spermatogenesis as they can self-renew or differentiate into sperm. A better understanding of the properties of SSCs is crucial as these cells have the potential to be used for fertility preservation approaches, for instance in pre-pubertal cancer survivors who often become infertile following cancer treatment and do not have the opportunity to cryopreserve sperm prior to treatment.

 

Schematic representation of seminiferous tubules in human testes. The undifferentiated spermatogonia (dark blue) are located along the basement membrane and have the ability to self-renew and to give rise to differentiating germ cells. Elongated spermatids as the most differentiated germ cell type are located closest to the lumen of the seminiferous tubules (modified from Heckmann et al., 2018).

In recent years, we have successfully set up approaches for the isolation and characterization of human spermatogonia focusing on expression and methylation changes during development and in infertility. Moreover, comparative single cell RNA sequencing analyses have demonstrated hitherto unknown properties of these cells, which were masked by previous bulk analyses.