Derivation and characterization of chimera-competent eXtra-Embryonic eNdoderm (XEN) cells from pig blastocysts

We report for the first time, the derivation and characterization of extra-embryonic endoderm (XEN) cells from primitive endoderm (PrE) of porcine (p) embryos. The pXEN cells can be reliably and reproducibly generated from parthenogenic, in vitro or in vivo derived embryos, and express canonical PrE or XEN cell genes (GATA4, GATA6, SOX17, SALL4, FOXA2, and HNF4A). Transcriptome analysis of pXEN cells revealed close resemblance to yolk sac than any other embryonic or extraembryonic tissue. When introduced into blastocyst stage embryo, the pXEN cells contributed to wide-spread chimerism including visceral yolk sac, chorion, as well as embryonic gut and liver primordium in the fetus. The pXEN cells were shown to be an efficient nuclear donor for generating cloned offspring. Taken together, pXEN cells fulfil a longstanding need for a stable, chimera-competent, and nuclear transfer-compatible porcine embryonic cells with applications for genome editing in livestock.