The Stem Cell

Eric Chiao’s post about model systems reveals how important these new iPS discoveries could be for hundreds of stem cell laboratories. He says (with tongue firmly in cheek) that disease-specific lines can be made quickly, in as little as a few weeks. The beauty of the Yamanaka and Thomson methods are that they use standard gene manipulation techniques, which means not only do they go quickly, but they can be rapidly adopted and replicated by laboratories anywhere. I figure that research directors have already handed off the papers and supporting materials to graduate students and postdoctoral fellows with these simple instructions: “try it, and get it to work here.”

This means that in short order (assuming all goes well and the methods can be repeated) we’ll see a profusion of reprogrammed lines using every imaginable kind of cell: different cell types and ages, along with normal and diseased cells—even cells from specific genetic populations. The problem facing embryonic stem cell research is that embryonic lines are in short supply. This problem is sidestepped by putting iPS lines in many labs, and then comparing them across research projects.

No one knows whether these new cells will be as useful as embryonic stem cells. Researchers will have to compare them to existing lines, and we know that even embryonic stem cells lines differ (See TSC’s Three Reasons for More Lines). They have to prove their usefulness in the laboratory—they may be good for some experiments but not for others. It is quite possible that iPS lines may not behave the same from one lab to another. And, the technical hurdles must be overcome before they can be used in the clinic. The lines were made using genes and retroviruses that can cause cancer in humans (see TSCs Gene Therapy and Stem Cells). This might be solved by putting the genes into a skin cell, reprogramming the cell to an embryonic state (or other desired cell type), and then taking the genes out with a technique called Cre-Lox.

The fact that we’ve got a new kind of cell to work with only underscores why we must push forward with embryonic stem cells and do the experimental comparisons. Embryonic stem cells are the gold standard. Good science dictates that we use that—and no other—before we declare a new standard.