The ethical dimension of embryonic stem cell research looms so large in the public consciousness that the underlying science often gets taken for granted. But within the ESC research community, realism has overtaken early euphoria as scientists realize the difficulty of harnessing ESCs safely and effectively for clinical applications. After earlier papers in 2000 and 2001 identified some possibilities, research continued to highlight the tasks that lie ahead in steering cell differentiation and avoiding side effects, such as immune rejection and tumorigenesis.
In 2001, several seminal papers laid much of the groundwork, and this issue's Hot Papers were particularly influential. Nadya Lumelsky at the National Institutes of Health and colleagues described the generation of cells expressing insulin from murine ESCs.1 Lumelsky's group, unlike the researchers of the other two Hot Papers, was precluded from using human ESCs under NIH funding rules.
The second paper by Su-Chun Zhang and researchers at ...
