Pluripotent stem cells (PSCs) provide a unique tool to investigate early development and to generate animal models through chimera formation. Establishing robust chimerism in non-rodent species such as rabbits and non-human primates is particularly valuable to (i) assess the developmental potential of PSCs across all somatic and germline lineages, (ii) model embryogenesis using PSCs carrying defined mutations, and (iii) generate germline chimeras for disease modeling.

In cynomolgus monkeys, we identified two signaling pathways—MEK and PI3K/AKT—whose sustained activity is essential for PSCs to survive following blastocyst injection and to compete effectively with host pluripotent cells. In parallel, in rabbits, we established naïve induced PSCs by reprogramming with KLF2, ERAS, and PRMT6. These cells exhibited remarkable embryo colonization capacity, including contribution to the germline. Strikingly, iPSC-derived female gametes outcompeted host gametes, yielding germline chimeras with transmission efficiencies reaching up to 100% in female rabbits.

Together, these results establish rabbit and monkey chimeras as powerful models to interrogate PSC potency, dissect cell–cell competition during development, and provide proof-of-concept for germline transmission in non-rodent species.