Plasmid protocol for mouse iPS cells
February 12, 2010 - The ability to induce pluripotency in somatic cells through reprogramming represents a technological breakthrough of fundamental interest and great promise, but concerns remain about the safety and stability of cells generated through the original method for generating induced pluripotent stem (iPS) cells, which relies on retroviral vectors to introduce the transgenes needed to effect the transformation.
In 2008, Shinya Yamanaka's team in the Kyoto University Center for iPS Cell Research and Application (CiRA) published a report of a new iPS method that substitutes bacterial chromosomal loops known as plasmids as an alternative to viral vectors for gene delivery. By inserting the genes Oct3/4, Sox2, Klf4, and c-Myc into circular strands of bacterial DNA, the team was able to bypass the use of retro– or adenoviruses. This plasmid system enabled them to establish novel iPS lines from mouse embryonic fibroblasts without the risk of insertional mutagenesis or reactivation of transgenes that are characteristic of retrovirally-induced iPS cells.
Now, the full protocol for the generation of mouse iPS cells using plasmid vectors has been published by Keisuke Okita et al. in Nature Protocols, providing detailed instructions for this method to a wider community of scientists interested in iPS cell technology. The availability of such alternative methods should help to broaden the spectrum of research into induced pluripotency, leading to new insights into stem cell properties and applications.