Researchers from the University of Missouri were able to isolate adult stem cells from blood that can be turned into five types of cells. One of the main arguments in favor of embryonic stem (ES) cell research is that ES cells are pluripotent, that is, they are able to become any number of different cells. However it is becoming increasingly evident that adult stem cells have the same potential. The big difference is that, because ES cells are so young, they are harder to control and have lead to tumor formation in many or most of their animal studies. AS cells, being more mature, typically do not have this problem.