Published online Mar 26, 2015. doi: 10.4252/wjsc.v7.i2.315
Peer-review started: July 17, 2014
First decision: August 14, 2014
Revised: December 3, 2014
Accepted: December 16, 2014
Article in press: December 18, 2014
Published online: March 26, 2015
Processing time: 247 Days and 13.4 Hours
Pluripotent stem cells are unspecialized cells with unlimited self-renewal, and they can be triggered to differentiate into desired specialized cell types. These features provide the basis for an unlimited cell source for innovative cell therapies. Pluripotent cells also allow to study developmental pathways, and to employ them or their differentiated cell derivatives in pharmaceutical testing and biotechnological applications. Via blastocyst complementation, pluripotent cells are a favoured tool for the generation of genetically modified mice. The recently established technology to generate an induced pluripotency status by ectopic co-expression of the transcription factors Oct4, Sox2, Klf4 and c-Myc allows to extending these applications to farm animal species, for which the derivation of genuine embryonic stem cells was not successful so far. Most induced pluripotent stem (iPS) cells are generated by retroviral or lentiviral transduction of reprogramming factors. Multiple viral integrations into the genome may cause insertional mutagenesis and may increase the risk of tumour formation. Non-integration methods have been reported to overcome the safety concerns associated with retro and lentiviral-derived iPS cells, such as transient expression of the reprogramming factors using episomal plasmids, and direct delivery of reprogramming mRNAs or proteins. In this review, we focus on the mechanisms of cellular reprogramming and current methods used to induce pluripotency. We also highlight problems associated with the generation of iPS cells. An increased understanding of the fundamental mechanisms underlying pluripotency and refining the methodology of iPS cell generation will have a profound impact on future development and application in regenerative medicine and reproductive biotechnology of farm animals.
Core tip: The generation of an induced status of pluripotency in somatic cells by ectopic expression of core transcription factors allows to extending advanced genetic modifications and reproductive techniques to species, for which the derivation of genuine embryonic stem cells was not successful till now. The commonly employed viral gene transfer may be genotoxic and therefore non-viral methods for iPS cell derivation are intensively studied. In this review, we focus on the mechanisms of cellular reprogramming and current methods used to induce pluripotency.