Progress is slowly being made in controlling stem cell differentiation in both embryonic and adult stem cells. This is key to the reliable use of stem cells in regenerative therapies for age-related and other conditions. The Australian reports on recently published work: "Our experiments have shown adult stem cells isolated from the olfactory mucosa have the ability to develop into many different cell types if they are given the right chemical or cellular environment ... New nerve cells, glial cells, liver cells, heart cells, muscle cells -- all were grown in a dish from stem cells from the human nose." A methodology for obtaining and differentiating multipotent, easily extracted adult stem cells would certainly speed up many lines of research.
Link: http://www.theaustralian.news.com.au/common/story_page/0,5744,12616654%5E28737,00.html