The National Institutes of Health on Monday published final guidelines governing federal sponsorship of research on embryonic stem cells, rules that will have the effect of expanding scientists' access to existing stem cell lines and setting clear boundaries for creating eligible lines going forward. University research groups applauded the new rules, which the Association of American Universities said would "enable scientists to pursue groundbreaking research that will transform our understanding of human development and disease and lead to long-awaited and hoped-for cures and therapies."