Walkerville, MD (LifeNews.com) -- American and Russian scientists say they have been able to obtain embryonic stem cells from an unfertilized egg in an advancement that may help reduce the ethical concerns over using the cells. Pro-life advocates oppose embryonic stem cell research because human embryos must be killed in the process.

The scientists published their work in the latest issue of Cloning and Stem Cells and Jeffrey Janus, president of Lifeline and an author of the study, talked about the work.

He said the embryonic stem cells were obtained after first stimulating unfertilized eggs.

Previously, scientists have used a cloning process that involves taking DNA from the patient and inserting it into an unfertilized egg. That creates an embryo that is destroyed for the stem cells.

Janus' team tried a new approach: stimulating a woman's unfertilized egg to begin embryonic development. The scientists believe this development cannot continue long enough to produce a baby, but still allow the embryonic stem cells to develop and be obtained.

Janus and colleagues report producing six lines of embryonic stem cells, one of which had abnormalities.

However, the Rev. Tad Pacholczyk, of the National Catholic Bioethics Center in Philadelphia, says the process doesn't avoid the moral pitfalls that plague the research.

"My view is that if these grow as organized embryos for the first few days and then arrest, they may just be very short-lived human beings," he told the Associated Press.

"One is very possibly dealing with a defective human being. And at a minimum, the benefit of the doubt should be given here, and these embryos should not be created for the purposes of destroying them," the leading bioethicst added.