These so-called stem cells, the foundation source of the body's tissue, have been identified as a way to make new skin, liver and other organs. But in previous research the cells were harvested from embryos, a technique that set off a storm of ethical objections. The new research suggests that even mature stem cells, such as from the adult brain or bone marrow, can change into the progenitor cells for other types of tissue. If such a technique also worked in humans, embryos may not be needed for such research. As a concept, I don't see any problem in adult stem cells being used to make new skin, for instance.
Stem cells are the mortar and brick for growing all of the body's tissues.
In a developing embryo, they produce the cells that become the body parts. After birth, some stem cells are specially programmed to replenish some tissues such as blood and skin. Researchers earlier had isolated stem cells from human embryos or from aborted fetuses, and grew the cells in a lab. When treated with specific proteins, the cells began to grow different types of tissue cells. That work set off a frenzy of studies.