Efficient derivation of stable sheep embryonic stem cells opens a new avenue for agricultural and biomedical application.

INTRODUCTION: Embryonic stem cells (ESCs), capable of generating all adult cell types, hold transformative potential for agriculture and biomedicine. However, stable sheep ESCs derivation remains challenging, limiting their application in further research. OBJECTIVES: We aimed to establish stable sheep ESCs using a simplified protocol, validate their pluripotency, and demonstrate genome editing utility. METHODS: Sheep ESCs were derived from blastocyst inner cell masses via an IWR-1-containing culture system (termed TePR). Pluripotency was assessed through long-term culture (>100 passages), trilineage differentiation, transcriptomic analysis (E0-E6 embryos), and cross-species comparisons. ATAC-seq and WGBS mapped chromatin accessibility and methylation patterns, respectively. Genome editing utilized PiggyBac transposition and CRISPR/Cas9. RESULTS: Sheep ESCs derived under TePR condition (termed TePR-sESCs) exhibited stable morphology and trilineage differentiation. Transcriptomics showed TePR-sESCs resemble 8-cell/morula embryos, consistent with sheep genome activation timing. ATAC-seq revealed accessible chromatin at pluripotency loci (e.g., POU5F1, NANOG). WGBS identified hypomethylation in pluripotency-associated regions. Efficient mCherry integration and MSTN knockouts confirmed editing compatibility. CONCLUSION: The TePR system enables robust derivation of sheep ESCs with embryonic-like pluripotency. TePR-sESCs' editing proficiency supports applications in livestock trait engineering and biomedical modeling, overcoming a major barrier in ungulate stem cell research.