April 24, 2013
Induce Pluripotent Stem Cell
Induction of Pluripotent stem cells is one of the most controversial topics that many Biology scientists want to discover. In the article titled “Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors,” scientists do the research on how to develop the pluripotent stem cells from somatic cells (Takahashi et al. 2007). Induction of Pluripotent Stem cells is the process that reprograms human somatic cells into pluripotent stem cells so that they may be forced to maintain the properties of embryonic cells.
They first generated pluripotent stem cells from human dermal fibroblasts by transducing Oct3/4, Sox2, c-Myc, and Klf4 by retrovirus. As the result, they can prove that pluripotent stem cells can be produced from somatic cells. However, they want to see whether it works on human cells. Therefore, they took human dermal cells to test it out. And the result showed that the induced pluripotent stem cells had similar properties with embryonic cells as well.
The differentiation of induced pluripotent stem cells into three different germ layers plays an important role because the induced pluripotent stem cells can possibly be cultured into any type of cells. As shown in the article, about two weeks after the transduction, they harvested some colonies but not resembled human embryonic stem cells in morphology. Nevertheless, over 30 days, induced pluripotent stem cells then appeared highly similarity to human embryonic stem cells in morphology. In addition, there was a disadvantage which shown that human induced pluripotent stem cells carried out the specific surface antigens such as SSeA-4, tumor-related antigen (TRA)-1-60, TRA-1-81 and TRA-2-49/6E, and NANOG protein.
The expression of human embryonic stem cell in human induced pluripotent stem cells was then performed by RT-PCR ananlysis showing that the selected genes Oct3/4, Sox2, and Nanog were active in both induced pluripotent stem cells and human embryonic stem cells but inactive in human dermal fibroblast. Moreover, in the experiment of analysis of promoter regions of specific genes in human induced pluripotent stem cells, the data showed that the transcriptional activities were highly expressed in human embryonic stem cells but not in human dermal fibroblast. In addition, the data also indicated that induced pluripotent stem cells had high levels of telomerase activity and high development rate resembling to human embryonic stem cells.
In the second article titled iPS Cells Can Support Full-Term Development of Tetraploid Blastocyst-Complemented Embryos, there is a similar research where induced pluripotent stem cells could be reprogramed by forcing the expression of four factors such as Oct4, Sox2, Klf4 and c-Myc (Kang et al. 2009). This research endeavors to support the idea of making induced pluripotent stem cells of the first research by two different experiments to test the generation of induced pluripotent stem cells by producing full-term mice. However, human somatic-derived cells into induced pluripotent stem cells did not clearly become fully pluripotent as normal human embryonic stem cells. Therefore, to give the best