Induced Pluripotent Stem Cells: Progress and Future Perspectives in the Stem Cell World

Abstract

Pluripotent stem cells (PSCs) have the potential to differentiate into many cell types and therefore can be a<br><br>valuable source for cell therapy. Embryonic stem cells (ESCs), which are derived from the inner cell mass (ICM)<br><br>of the blastocyst, are representative of PSCs. However, use of these cells has some limitations, especially ethical<br><br>restrictions and immune response. As a result, researchers have been looking for other cell sources or strategies<br><br>to overcome these limitations. One kind of cellular reprogramming is the process of guiding mature cells into a<br><br>state of gene expression similar to PSCs. It has been demonstrated that somatic cells can be reprogrammed by<br><br>various methods, including somatic cell nuclear transfer (SCNT) and cell fusion with ESCs or treatment with<br><br>their extracts. This implies that some factors in oocytes and ESCs are able to initiate the reprogramming process.<br><br>Accordingly, induced pluripotent stem cells (iPSCs) have been derived from somatic cells by ectopic expression<br><br>of some transcription factors. This discovery has resulted in raising several important questions about the<br><br>mechanisms by which these factors influence the reprogramming and epigenetic status of the cells. iPSCs hold<br><br>great promise for regenerative medicine, developmental biology, and drug discovery because they circumvent<br><br>problems associated with both ethical issues and immunological rejection. Here we review the experiments<br><br>involved in the discovery of iPSCs, important factors in their reprogramming, and their future perspectives in<br><br>cell therapy.