25 / 2026-03-13 08:27:26

Pluripotent Cells Exhibit Greater Resistance to Totipotent Reprogramming than Somatic Cells

SCNT,cell reprogramming,early embryos,Totipotency

During mammalian embryogenesis, cell fate is progressively specified from totipotency to pluripotency and ultimately to terminally differentiated somatic state. Somatic cell nuclear transfer (SCNT) technique has demonstrated that the differentiated nuclei retain totipotent potential. Based on the prevailing assumption that a higher degree of differentiation corresponds to the lower reprogramming efficiency, embryonic stem cells—being developmentally closer to early embryos—have been widely regarded as superior donor cells for nuclear transfer. However, the underlying mechanisms remain poorly understood.

In this study, we used extended pluripotent stem cells (EPSCs) and highly differentiated fibroblasts as nuclear donors to generate cloned embryos. Unexpectedly, EPSC-derived embryos exhibited lower developmental competence than those derived from somatic cells. Integrated transcriptomic and epigenomic analyses revealed that H3K27me3 inheriting from EPSCs were partially retained in cloned embryos, thereby suppressing the activation of key pioneer transcription factors, including NR5A2 and members of the PRD-like homeobox family, and impairing the establishment of the totipotent program. Furthermore, EPSC-derived cloned embryos displayed significant defects in the establishment of H3K9me3 and H3K27me3 at the 4-cell stage, as well as impaired deposition of H3K4me3 and H3K27me3 within H3K4me3/H3K9me3/H3K27me3 trivalent regions at the blastocyst stage. These aberrant chromatin configurations may lead to unfaithful activation of ERVL-MaLR and LINE1 elements, consequently hindering the transition from totipotency to pluripotency. Notably, utilizing differentiated EPSCs as nuclear donors significantly improved the developmental competence of cloned embryos.

Collectively, although pluripotent stem cells originate from embryonic lineages, they encounter stronger epigenetic barriers for cell reprogramming from pluripotency to totipotency when compared with somatic cells. These findings suggest that the developmental trajectory from totipotency to pluripotency and terminal differentiation is not simply reversible, but instead follows a cyclic model constrained by stage-specific epigenetic regulation of cell identity.