U.S. must lead in stem-cell research

Today I will join a bipartisan group of senators to reintroduce legislation that would make it a crime to attempt to clone a human being and would also promote ethical stem-cell research.

I realize this is controversial territory. The ongoing debate over embryonic stem-cell research forces us to confront fundamental questions: When does life begin? How do we promote groundbreaking science while preserving our core values?

These are difficult questions, but we should not run away from them. We have faced similar decisions in the past — whether to allow in vitro fertilization, for example — and our courage and wisdom made it possible to give life to more than a million children throughout the world. In vitro fertilization now seems so commonplace that it's easy to forget the fierce debate we had about the morality of fertilizing an egg in a Petri dish.

Embryonic stem cells appear to have the amazing potential to transform themselves into any of the more than 200 types of cells that form the human body. These cells could be the key to understanding much about human health and disease and may yield new diagnostic tests, treatments and cures for diseases such as diabetes, cancer, heart disease, Parkinson's, autoimmune diseases and so many others.

Experts believe that a promising source of stem cells may be derived from a process called nuclear transplantation. In this process, scientists remove the normal 23 chromosomes in a human egg cell and replace them with the full complement of 46 chromosomes that are present in mature human cells, without fertilizing the egg with sperm. Some scientists suggest that nuclear transplantation could overcome the problem of tissue or organ rejection, as well as allow the study of disease progression.

If cells derived from nuclear transplantation were implanted in a woman's womb, it is theoretically possible to reproduce, asexually, a human. Most of us believe this is morally wrong and should be outlawed. Creating a cloned human being violates the divinely appointed means of bringing children into the world.