Following on from studies published last week, an independent team reports the generation of fertile adult mice derived entirely from induced pluripotent stem (iPS) cells. A comparison of the different methods used by each team will reveal important information about the cellular state of pluripotency. The study, published online in Nature, serves to firmly establish that cells reprogrammed in the lab can be as pluripotent as embryonic stem cells.
Kristin Baldwin and colleagues generated 6 iPS cell lines from mouse fibroblasts, using different amounts of each of the four factors that are needed to reprogram the cells to a pluripotent embryo-like state. They then tested the ability of each of the lines to form an embryo by injection into a tetraploid blastocyst -- groups of cells from fused embryos that form the placental tissue to support embryo growth, but cannot become part of the embryo itself. Live mice were successfully generated from 4 of the 6 lines, with similar efficiencies to that reported using embryonic stem cells in the same assay. Mice created from two of the lines also went on to produce offspring of their own, a final testament to the pluripotency of the original cells used.
With so many factors that can be tweaked in the recipe, research to identify the 'right' conditions for pluripotency is difficult and painstaking. Each study adds a bit more to this endeavour and allows researchers to refine their methods and improve efficiency.
Kristin Baldwin (The Scripps Research Institute, La Jolla, CA, USA)
Abstract available online.
(C) Nature press release.
Message posted by: Trevor M. D'Souza