Stem cell
3/23/2009
Methods Mol Biol.
2010;636:207-18. Department of Chemistry, The
Scripps Research Institute, La Jolla, CA, USA. Induction of pluripotent stem
cells from somatic cells by defined factors was shown to be possible only
recently, but already several laboratories have made tremendous strive
toward improving and understanding the process. Originally, Oct4, Sox2,
Klf4, and cMyc were identified as being the combination of genes necessary
to induce reprogramming. It was later shown that cMyc was dispensable;
however, in its absence the process was less efficient and took a
considerably longer period of time to occur. Furthermore, others have shown
that the combination of Oct4, Sox2, Nanog, and Lin28 could also induce
reprogramming. One major caveat associated with these techniques remains
the need for overexpression of several genes using viral systems. Until
very recently, most studies were done using integrating viruses such as
retroviruses and lentiviruses. This method ensured that the protein of
interested would be expressed at a high concentration and for an adequate
period of time necessary to induce reprogramming. Up to date, others have
now been able to use different nonintegrative method such as adenovirus and
plasmid transfection to induce reprogramming. Furthermore, piggyBac
transposition was successfully used to induce reprogramming of murine
cells. Most importantly, it was recently published that reprogramming can
be induced in the absence of virus, with proteins and small molecules. All
of the later methods are appealing since they do not require the
integration of the virus or plasmid to exert its effect. However, one
avenue that would be all the more therapeutically appealing would be to
induce reprogramming in the absence of gene overexpression systems, using
small molecules to modulate signaling pathways in the somatic cells. A few
molecules have already been identified with the ability to either improve
the process or replace one or two of the genes deemed necessary for
reprogramming. We have screened successfully for compounds that can replace
some of these factors, and share the methods developed following these
screens. PMID:
20336525 [PubMed - in process]
Using small molecules to
improve generation of induced pluripotent stem cells from somatic cells.
Abstract
