The questions of which type of stem cells are most likely to generate medical breakthroughs therefore include both methodological and ethical issues. Methodologically, for example, adult stem cells are seen by Fischbach (2003) as more readily available from such tissue samples of those found in adult bone marrow, which can be donated voluntarily by an adult for use in a specific medical treatment or in research.
Those who favor the use of ASCs do so in the belief that they are both as viable in research as are ESCs and, perhaps most significantly, are less likely to be acquired by unethical means. Conversely, those favoring ESCs argue that these stem cells are preferable to ASCs in that they are more viable and flexible, less differentiated than ASCs and therefore able to be used more effectively in a variety of applications, and better suited to research because of this attribute (Fischbach, 2003). On balance, given a regulatory environment that prevents unethical use of or access to ESCs, most researchers believe that these stem cells are preferable from a scientific standpoint (Korobkin & Munzer (2007).
There are some 60 established stem cell lines that are approved for use in research (NIH, 2008). NIH (2008) stated that this includes both embryonic and adult stem cells, the former obtained through voluntary donations. NIH (2008) reported thatPresident George W. Bush ruled that federal funds would be used for research only on the