I am pleased to present to you Alternative Sources of Human Pluripotent Stem Cells, a White Paper of the President’s Council on Bioethics.Since the publication of our report, Monitoring Stem Cell Research, in January of 2004, the Council has continued to ponder and discuss the ethical challenges posed by human embryonic stem cell research and the demands of scientists to develop new human embryonic stem cell lines. While they may well in the future prove to be of considerable scientific and therapeutic value, new human embryonic stem cell lines cannot at present be obtained without destroying human embryos. As a consequence, the worthy goals of increasing scientific knowledge and developing therapies for grave human illnesses come into conflict with the strongly held belief of many Americans that human life, from its earliest stages, deserves our protection and respect.

Seeking to advance biomedical science while upholding ethical norms, the Council has taken a keen interest in recent suggestions that science itself might provide a way around this ethical dilemma. Accordingly, we have been looking into ways of obtaining pluripotent, genetically stable, and long-lived human stem cells (the functional equivalent of human embryonic stem cells) that do not involve creating, destroying, or harming human embryos. We have found that there are, broadly speaking, four such possible approaches: stem cells might be obtainable from dead embryos; from living embryos, by non-destructive biopsy; from bioengineered embryo-like artifacts; and from reprogrammed adult somatic cells. In this White Paper, we introduce each of these four approaches and offer a preliminary analysis of their strengths and weaknesses, ethical, scientific, and practical.