But research on induced stem cells may be the real winner.
15 January 2013
he US Supreme Court’s decision last week to throw out a lawsuit that would have blocked federal funding of all research on human embryonic stem cells cleared the gloom that has hung over the field for more than three years. Yet the biggest boost from the decision might go not to work on embryonic stem (ES) cells, but to studies of their upstart cousins, induced pluripotent stem (iPS) cells, which are created by ‘reprogramming’ adult cells into a stem-cell-like state.
At first glance, iPS-cell research needs no help. Researchers flocked to the field soon after a recipe for deriving the cells from adult mouse cells was announced in 2006, partly because this offered a way to skirt the thorny ethical issues raised by extracting cells from human embryos. But the real allure of iPS cells was the promise of genetically matched tissues. Adult cells taken from a patient could be used to create stem cells that would, in turn, generate perfectly matched specialized tissues — replacement neurons, say — for cell therapy. Although the number of published papers from iPS-cell research has not yet caught up with that of ES-cell work (see ‘Inducing a juggernaut’), US funding for each approach is now roughly matched at about US$120 million a year.
But, as iPS cells crop up in ever more labs, ES cells — generally cheaper, better behaved and backed by an extra decade’s worth of data — promise to have an important supporting role. Ever since iPS cells were described, researchers have been trying to understand just how similar they are to ES cells. iPS cells begin with different patterns of gene expression, and they can also acquire mutations during the reprogramming process, which means that every iPS cell must be thoroughly evaluated before it can be used in any study. “Human ES cells will always be the standard to which other cells will be compared,” says Roger Pedersen, who studies how stem cells retain embryo-like states at the University of Cambridge, UK.