4 
Recent Developments in Stem Cell 
Research and Therapy 
Research using human and animal stem cells is an ex- 
tremely active area of current biomedical inquiry. It is contrib- 
uting new knowledge about the pathways of normal and ab- 
normal cell differentiation and organismal development. It is 
opening vistas of new cell transplantation therapies for human 
diseases. Although the availability of a variety of human stem 
cells is relatively recent — ^the isolation of human embryonic 
stem cells * was first reported only in 1998 — much is happening 
in both publicly funded and privately funded research centers 
around the world. It is difficult for anyone to stay abreast of all 
the results now rapidly accumulating. 
To help us fulfill our mandate to "monitor stem cell re- 
search," the President’s Coimcil on Bioethics asked several 
experts to survey the recent published scientific literature and 
to contribute articles on various areas of stem cell research to 
this report (see articles by Drs. Gearhart,^ Ludwig and Thom- 
son,^ Verfaillie,^ Prentice,'^ Itescu,^'® and Jaenisch^ in the Ap- 
pendices). These reviews and the present chapter emphasize 
peer-reviewed, published work with human stem cells through 
July 2003. Interested readers should also consult the wide va- 
riety of other review articles that have appeared.® 
This chapter should be read in conjunction with the commis- 
sioned review articles cited above. It draws on their findings, 
as well as on the Council’s own monitoring activities, but it 
makes no attempt to summarize all the complexity of stem cell 
research or the vast array of results. Rather we offer here some 
* In this chapter, technical terms that are defined in the Glossary are under- 
lined v\7hen they are used for the first time. 
109 
