Embryonic Stem Cells

It is fair to say that embryonic stem (ES) cells have taken their place beside the human genome project as one of the most discussed biomedical issues of the day. It also seems certain that as this millennium unfolds we will see an increase in scientific and ethical debate about their potential utility in society. On the scientific front, it is clear that work on ES cells has already generated new possibilities and stimulated development of new strategies for increasing our und- standing of cell lineages and differentiation. It is not naive to think that, within a decade or so, our overall understanding of stem cell biology will be as revolutionized as it was when the pioneering hemopoietic stem cell studies of Till and McCulloch in Toronto captured our imaginations in 1961. With it will come better methods for ES and lineage-specific stem cell identification, maintenance, and controlled fate selection. Clearly, ES cell models are already providing opportunities for the est- lishment of limitless sources of specific cell populations. In recognition of the gr- ing excitement and potential of ES cells as models for both the advancement of basic science and future clinical applications, I felt it timely to edit this collection of pro- cols (Embryonic Stem Cells) in which forefront investigators would provide detailed methods for use of ES cells to study various lineages and tissue types.