Embryonic stem cells can be made from adult cells. Such cells are called iPSCs or induced embryonic stem cells, and they have all the characteristics of embryonic stem cells made by means of the destruction of embryos.
Lately, scientists have found a way to convert one type of adult cell into another type of adult without going through any embryonic step.
Qi Zhou and his colleagues from the Melton lab at Harvard were able to transform pancreatic enzyme-secreting cells (exocrine cells) into insulin-secreting cells by inserting three transcription factors (Ngn3, also known as Neurog3), Pdx1 and Mafa into the exocrine cells and they reprogrammed themselves into beta-cells (Nature 455, 627–32 (2008)). Also, Yechoor and his colleagues used a similar technique that placed neurogenin into liver cells in a live animal. These animals shows insulin-secreting cells into their livers, which showed that the liver cells had been reprogrammed into beta cells (V. Yechoor et al., Dev. Cell 16, 358–73 (2009)).
This shows that reprogramming is vastly superior and cheaper than making cloned embryos that we subsequently kill and use to make embryonic stem cells. This is the therapeutic way of the future.
Now, Jun Takeuchi and Benoit Bruneau at the Gladstone Institute of Cardiovascular Disease in San Francisco have found that adding cardiac-specific genes to developing mouse embryos can make even some extra-embryonic parts become beating heart cells. They made the cells from amnion, the thin layer that surrounds the embryo and fetus throughout development. This is the sac that breaks when we say that a mother’s water breaks. The amnion is normally medical waste, but can now be used to make heart cells.
See this link for the paper.