Stem cells at the dawn of the 21st century.

Abstract

It is rare that a field of scientific research can both have an enormous potential impact on human health and quality of life and be a fount of new basic research discovery. Stem cell biology is surely one such field, offering hope for curing scourges like diabetes, Parkinson's disease, neurological degeneration, and congenital heart disease, as well as bringing together many disciplines of cell and molecular biology. Five years ago, stem cell biology was an exciting but rather restricted area of science with growing basic science and clinical implications. Currently, the existence of stem cells is a matter of public discussion, with religious, ethical, political, and economic implications. A week does not go by without some new revelation, about either the politics or biology of stem cells in the general press. What has changed? Clearly we know more about the biology of these cells, but the public interest has been driven by their potential in the treatment of disease on the one hand and concerns for the ethical implications of their use on the other. Some of the arguments are semantic and can be resolved by making sure that everyone is using the same terms to discuss the topic. Other concerns are theoretical and religious, such as defining when human life begins, and reflect beliefs and philosophies rather than the facts and data that scientists are restricted to when formulating coherent models. Science relies on facts, and many of the extraordinary claims made about stem cells in the scientific and public domain need to pass the important test of independent verification. Stem cells are loosely defined as self-renewing progenitor cells that can generate one or more specialized cell type. In vertebrates, stem cells have been traditionally subdivided into …