The Niche
Gene-free reprogramming in human cells
A new paper in Cell Stem Cell describes how scientists reprogrammed human cells to pluripotency without using any DNA at all. Instead, reprogramming proteins were engineered so that they could enter the nucleus. These proteins were produced in cultures of mammalian cells and secreted into the culture media. When fibroblasts derived from newborns were exposed to those cell extracts, the cells reprogrammed to teratoma-producing induced pluripotent stem (iPS) cells, a big first for human cells.