The study of embryonic stem cells has been tangled up in politics almost from the start. Although a substantial majority of the US public supports research into their medical applications, a significant minority is uncomfortable with some of the ethical issues involved. The intersection between science and politics was very apparent today, as President Obama announced the lifting of Bush-era restrictions on federal funding of stem cell research. That move comes during a time when researchers have announced several major steps towards developing techniques that may some day eliminate the need to use embryonic stem cells.

First, the science. Human embryonic stem cells (hESCs) are derived shortly after fertilization, at a time when the cells are known to be capable of forming adult tissue. As such, they hold the promise of providing the raw material to repair tissue damage caused by injury or disease. Unfortunately, the cells won't be a precise genetic match with their recipients, raising the prospect that the body will mount an immune response to them.