Generation of functional rat spermatozoa in sterile mice utilizing blastocyst complementation with pluripotent stem cells [bulk RNA-seq]

Pluripotent stem cells (PSCs) provide a powerful tool to produce transgenic animals for biomedical research. However, impaired PSC contribution to chimerism and most notably the germline oftentimes impedes production of genetically modified animals, rendering techniques that expediate PSC contribution to the germline highly desirable. Blastocyst complementation denotes a technique which purposes to generate organs, tissues or cells in animal chimeras via microinjection of PSCs into genetically compromised blastocyst-stage embryos. Here we report on successful blastocyst complementation of the male germline in adult chimeras following microinjection of mouse or rat PSCs into mouse blastocysts mutated for Tsc22d3, an essential gene for spermatozoa production. Microinjection of mouse embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) into Tsc22d3-KnockOut (KO) blastocyst-stage embryos gave rise to intraspecies chimeras embodying functional spermatozoa, which were solely derived from microinjected PSCs. Furthermore, microinjection of rat ESCs into Tsc22d3-KO mouse embryos gave rise to viable mouse-rat chimeras that exhibited extensive contribution of rat cells to various organs. Notably, multiple mouse-rat chimeras showed contribution of rat ESCs to the male germline, solely harboring rat spermatids and spermatozoa that were rat ESC-derived and could fertilize rat oocytes. Collectively, this study reports a method for exclusive production of functional germ cells of one species in another via blastocyst complementation with PSCs. Implications of this study extend to development of transgenic rats via sterile mice, and may further assist efforts to generate xenogeneic gametes from endangered animal species. Sample 1 ordered from RRRC line 464, confirmed rat embryonic stem cell. Sample 2-4 biological replicates, rat tail tip fibroblasts