Sheep embryonic stem cells derivation and characterization under defined conditions

Sheep ESCs with characteristics similar to those described for rodents and primates have not been produced. We report the derivation of sheep ESCs under a chemically defined culture system containing fibroblast growth factor 2 and a tankyrase inhibitor. We also show that several culture conditions used for stabilizing naive pluripotency state in humans and mice were unsuitable to maintain ovine pluripotency. These cells display a dome morphology, and they maintain an euploid karyotype and stable expression of the transcriptome and pluripotency markers after more than 40 passages. This study demonstrates that inhibition of tankyrase activity and FGF2 are essential for the maintenance of an undifferentiated state in sheep ESCs, with other naive culture conditions incapable of maintaining pluripotency. The ovine ESCs derived here represent stable cell lines from sheep blastocysts and a promising step towards understanding pluripotency in livestock species and developing novel biotechnologies. Additionally, these cells have important biomedical and agriculture implications, such as the development of transgenic animal models.