Strategies for the derivation of pluripotent cells from farm animals.

Recent experiments demonstrated that forced expression of few critical genes drives conversion of a somatic into a pluripotent cell state. These induced pluripotent cells (iPS) were first generated from murine fibroblasts by Shinya Yamanaka's laboratory in 2006. By using retroviral vectors to express combinations of stemness genes, they identified Oct4, Sox2, Krueppel-like factor 4 and c-Myc as essential factors for reprogramming of somatic cells. Subsequent experiments applied this technology to human and rat fibroblasts, as well as other cell types and several groups showed that iPS can be generated by an even smaller number of transcription factors. The efficiency of conversion and maintenance of a pluripotent state can be supported by small molecules, such as valproic acid and specific pharmacological inhibitors. This technology is a milestone for a basic understanding of cell potency, cell fate and pathogenesis, as well as for development of cell therapies and potential applications in animal breeding.