Dead Embryos and Stem Cells

The Boston Globe reports today that it is possible to retrieve usable stem cells from an embryo that had stopped developing naturally and was considered dead. This would seem to surmount ethical objections. On the other hand, Robin Lovell-Badge of the Medical Research Council's National Institute for Medical Research in London observed that there is no way to prove that an arrested embryo would have stopped growing if it had been put into a woman's womb rather than a lab dish, leaving open the possibility that lab conditions halted its growth. I take it Lovell-Badge maintains that labs have a duty to place embryos in women as soon as possible. Does the moral objection to stem cells depend upon the assumption that embryos are ensouled? Assuming the use of stem cells would otherwise be problematic, is there a moral objection to using stem cells from dead embryos? Is the “stopped developing naturally” criterion a proper one to determine the death of an embryo? If not, what is? The story is at http://www.boston.com/news/nation/articles/2006/09/23/stem_cells_from_dead_embryo/