"It doesn't have to be, you know, embryo stem-cell research or fetal or cloning, " Lott said.

CNN: Lott says he's opposed to federal funding of stem-cell research

Once you've got them, you don't need to destroy any more embryos, but each time you get a new one of these embryonic stem-cell lines, you need to destroy an embryo.

NPR: Ethical Guidelines for Stem Cell Research Proposed

Scientists using this method seek to persuade the cell to "forget" its current status and go back to the original stem cell state it was in during its time in the embryo.

BBC: Q&A: UK stem cell first

On Thursday a team of researchers at Newcastle University in the UK, which hopes to join South Korea in the forefront of stem cell research, also said they had successfully cloned an human embryo.

CNN: Cloning success hailed, feared

They used stem cells from a human embryo, which are capable of becoming any other type of cell in the human body from nerve to skin, muscle to kidney.

BBC: Deaf gerbils 'hear again' after stem cell cure

They would also like to push other stem-cell types, such as those found in the intestine, to the limit in their embryo experiments.

ECONOMIST: Stem cells