The advance is expected to benefit transplant medicine, drug discovery and basic developmental biology. Doctors may use it in the future to treat victims of heart disease, diabetes, Parkinson's and Alzheimer's diseases, spinal cord injuries and some kinds of cancers.

James Thomson, a developmental biologist at the University of Wisconsin at Madison, headed an international research team that included Joseph Itskovitz, an Israeli in-vitro fertilization specialist and a member of the medical faculty at the Technion-Israel Institute of Technology in Haifa. Itskovitz provided the study with embryos and research assistance.

"We are searching now for a way to control the differentiation of the cells," Itskovitz said. "We cannot direct the cells changing into other human tissue cells — it happens on its own randomly."

With so many scientific hurdles to cross, Thomson does not expect his labs to create specialized cells and tissues overnight. It will be at least 10 to 15 years before any treatments go to trial on humans.