Endocrine Abstracts

The testes develop from a bipotential gonad upon the presence of the Y chromosome and activation of the male genetic cascade. Much of what we currently know of sex determination and testis development stem from in vivo studies and cases of Differences of Sex Development (DSD). Yet, the gonads develop at embryonic stages, where the amount of biological material that can be retrieved, and accessibility, pose a major limitation to understanding sex determination and gonad development. Developing an in vitro stem cell-derived testis organoids could promote our mechanistic understanding of sex determination in health and disease. We have previously developed stem cell-derived differentiation protocol enabling to get Sertoli cells upon combination of defined media and forced expression of transcription factors. We also developed primary in vitro embryonic and pre-pubertal testis organoids able to recapitulate the in vivo testis. Here, we refined and improved our previous protocol and now able to generate all the somatic lineages of the testis: Sertoli, Leydig and Peritubular Myoid cells in a single protocol relying solely on defined media and 3D scaffolding. Our stem cell-derived testis organoids are highly similar to in vivo testis, and the protocol mimics the in vivo developmental trajectories. Transcriptomic analysis confirms their high resemblance to in vivo counterparts. Culturing these cells in 3D, they are able to organise in a manner resembling the in vivo testis. Future applications of this system to better explore sex determination under normal and pathological conditions will be discussed.