Efficient induction and sustenance of pluripotent stem cells from bovine somatic cells

Although derivation of naive bovine embryonic stem cells is unachieved, the possibility for generation of bovine induced pluripotent stem cells (biPSCs) has been generally reported. However, attempts to sustain biPSCs by promoting self-renewal have not been successful. Methods established for maintaining murine and human induced pluripotent stem cells (iPSCs) do not support self-renewal of iPSCs for any bovid species. In this study, we examined methods to enhance complete reprogramming and concurrently investigated signaling relevant to pluripotency of the bovine blastocyst inner cell mass (ICM). First, we identified that forced expression of SV40 large T antigen together with the reprogramming genes (OCT4, SOX2, KLF4 and MYC) substantially enhanced the reprogramming efficacy of bovine fibroblasts to biPSCs. Second, we uncovered that TGF beta signaling is actively perturbed in the ICM. Inhibition of ALK4/5/7 to block TGF beta/activin/nodal signaling together with GSK3 beta and MEK1/2 supported robust in vitro self-renewal of naive biPSCs with unvarying colony morphology, steady expansion, expected pluripotency gene expression and committed differentiation plasticity. Core similarities between biPSCs and stem cells of the 16-cell-stage bovine embryo indicated a stable ground state of pluripotency; this allowed us to reliably gain predictive understanding of signaling in bovine pluripotency using systems biology approaches. Beyond defining a high-fidelity platform for advancing biPSC-based biotechnologies that have not been previously practicable, these findings also represent a significant step towards understanding corollaries and divergent aspects of bovine pluripotency.

Automated summary

Despite the lack of success in deriving naive bovine embryonic stem cells, the generation of bovine induced pluripotent stem cells (biPSCs) has been reported. Enhancing reprogramming efficacy and inhibiting TGF beta signaling have been found to support robust self-renewal of biPSCs. The findings contribute to advancing biPSC-based biotechnologies and understanding bovine pluripotency.