PSCDGs of mouse multipotent adult germline stem cells can enter and progress through meiosis to form haploid male germ cells in vitro.

Spermatogonial stem cells (SSCs) provide the basis for spermatogenesis throughout adult life by undergoing self-renewal and differentiation into sperm. SSC-derived cell lines called multipotent adult germline stem cells (maGSCs) were recently shown to be pluripotent and to have the same potential as embryonic stem cells (ESCs). In a differentiation protocol using retinoic acid (RA) and based on a double selection strategy, we have shown that ESCs are able to undergo meiosis and produce haploid male germ cells in vitro. Using this differentiation protocol we have now succeeded to generate haploid male germ cells from maGSCs in vitro. maGSCs derived from a Stra8-EGFP transgenic mouse line were differentiated into stable spermatogonial stages and further cultured. These cells were transfected with a postmeiotic specific promoter construct Prm1-DsRed to monitor retinoic acid (RA) induced differentiation into haploid male gametes. Our protocol is another approach for the production of pluripotent stem cell derived gametes (PSCDGs) and is an alternative for the investigation of mammalian spermatogenesis, germ line gene modification and epigenetic reprogramming. If reproducible with pluripotent cell lines derived from human SSCs, it could also be used as a therapeutic approach for the treatment of male infertility.