Scientists have managed to reprogram human skin cells directly into cells that look and act like embryonic stem (ES) cells. The technique makes it possible to generate patient-specific stem cells to study or treat disease without using embryos or oocytes–and therefore could bypass the ethical debates that have plagued the field. “This is like an earthquake for both the science and politics of stem cell research,” says Jesse Reynolds, policy analyst for the Center for Genetics and Society in Oakland, California.
Since the key concept behind this was reported for mice in June, “earthquake” strikes me as overstating the case a bit. Translating the mouse tech to human cells is an engineering problem, and not a very challenging one at that.
On a practical level Kevin Drum argued that no technique involving virus DNA transfer will be approved for people. Given the discouraging rash of patient deaths gene therapy I can see his point, but for two reasons I think that he’s off the mark on this one. First it’s important to note that even patient deaths have only put gene therapy on hold rather than killed it. Stem cell therapy has already produced astonishing medical advances, which is nothing compared to the magic tricks like limb and brain injury regeneration that researchers feel increasingly confident in promising. If deadly viruses can’t kill gene therapy outright then the stiffer wind at the back of stem cell treatment will keep clinical work moving forward.
Second, I doubt that the debate will even be necessary. I will drop in details after the break, but suffice to say that tech exists to do virus cloning without worrying about down-the-road infectivity.
How’s that, you say? Biologists trying to shuttle genes often use a two-stage virus trick that retains the monster DNA transfer rate of viruses but never produces a “live” virus capable of copying itself in a host cell. The two parts of this trick are (1) a “packaging” line of mammalian cells that produces the virus coat proteins but no virus DNA, and (2) a stretch of external DNA (a plasmid) containing the gene that you want to shuttle around plus some extra sequence that fools the virus coat into packing the plasmid inside as if it was the virus’s own DNA. Slip the external DNA into the packaging cell line using old-fashioned non-virus techniques and the cells will start to produce “viruses” that shuttle DNA just as well as wild adenoviruses, but instead of virus DNA they insert whatever gene you designed them to carry. Without virus genes the host cell will never produce new virus particles.