Unfertilized Eggs Might Produce Stem Cells

Japanese researchers said human eggs from fertilization clinics that would otherwise be discarded might be capable of producing embryonic stem cells.

The finding, which is based on work in mice cells, could provide a way around some of the ethical quandaries surrounding therapeutic cloning and embryonic stem cell research, said researchers from the RIKEN Center for Developmental Biology.

During human in vitro fertilization, a proportion of egg cells, or oocytes, fail to become fertilized and are often discarded. But experiments with mice oocytes that did not become fertilized showed that they could still give rise to embryonic stem cells after their nucleus was removed and replaced by a nucleus from a different cell, the RIKEN researchers report in the Feb. 20 issue of Current Biology.

None of the resultant mouse embryos was capable of developing to full term.