ABSTRACT
Stem cells are viewed as an important target for gene therapy because of their ability to
self-renew at least for the lifetime of the individual and to give rise to a large number of
differentiated progenies. Thus, the transfer of a therapeutic gene to stem cells has the poten-
tial to provide long-lasting correction of a number of acquired or inherited disorders. Most
research in stem cells has focused on either embryonic or adult stem cells. Embryonic
stem cells are isolated from early embryos and generally possess enormous proliferative
capacity and the potential to differentiate into multiple lineages (1,2). They are more versatile
when used for the regeneration or repair of different tissues because of their multipotentiality.
However, ethical and technical concerns limit the use of those cells due to the need to use
human embryos for their derivation and in the form of an allograft, unless therapeutic
cloning techniques are utilized to generate autologous embryonic stem cells (3).
