A U.S. firm that recently said it may have a way to make stem cells without hurting embryos now says no embryos survived its research.

Advanced Cell, based in Alamed, Calif., admitted this week that none of the embryos used in its experiments done to create the stem cells survived the process, said a report Friday in the Wall Street Journal.

The company is now facing criticism that it didn’t make that caveat clear when it released its study, the report said, the results of which appeared in the journal Nature.

However, Advanced Cell CEO William Caldwell said his company was not misleading about the experiment because its method of removing individual cells from embryos is used in the field of diagnostic testing and so “in principle, it could also be used to create stem cells without harming embryos,” WSJ reported.