COURTESY RICARDO ROSSELLOPotent stem cells
The ability to reprogram skin cells to pluripotent stem cells by a simple gene-expression formula opened up a world of new experiments. This year, researchers continued to push ahead with better and faster methods to reinvent the identity of cells. Several months ago, scientists in Israel found a way to overcome one of the biggest limitations of inducing stem cells—the technique’s inefficiency. Typically, just about one out of every 10 cells prodded toward pluripotency actually do what researchers want it to, but Jacob Hanna from Israel’s Weizmann Institute of Science and his colleagues disabled a gene that represses pluripotency and voilà: near-perfect efficiency. “I never believed we’d get to 100 percent,” Hanna told The Scientist in September. “This shows that the process of reprogramming need not be random and inefficient.”
The induction of pluripotent stem cells reached new lows, as it were, in 2013. Researchers were able to generate in vivo more primitive forms of stem cells that had been accomplished before. Another group reprogrammed cells from animals lower on the tree of life than mammals, including birds, fish, and insects. And yet another team skirted the usual step of inserting genes into cells and instead used small molecules to coax cells into a pluripotent state.