The whole journey from skin cell to epithelial stem cell takes, broadly, two steps. First, the scientists, a team from the University of Pennsylvania and the New Jersey Institute of Technology, transformed adult skin cells into pluripotent stem cells. Pluripotent stem cells are those powerful, early-stage stem cells that are found in developing embryos. Scientists figured out how to make them from adult cells in 2004 and have been refining their techniques since. From there, the Pennsylvania-New Jersey team guided the pluripotent stem cells into becoming epithelial stem cells by controlling when they fed the cells certain chemicals called growth factors.