Special report: Stem cell research advances by fits and starts

Stem cell research continues morphing into new areas. Stem cells were once theorized to be a therapy in and of itself--a way to directly treat diseases or restore people's health from debilitating conditions. But scientists are now exploring how to use the cells indirectly to generate tissue or immune responses that can achieve the same goals. Scientists, for example, are increasingly using pluripotent stem cells from different parts of the body that can be tested as treatments, drug therapy targets or as ways to build models of disease on which to test drugs for toxicities. And they offer some of the advantages of embryonic stem cells without the political baggage. Report