Biology: Comparison of Two Stem Cells Research Papers

Topics: Stem cell, DNA, Developmental biology Pages: 5 (1622 words) Published: May 13, 2013
Induced pluripotent stem cell, iPSC, can be generated from somatic cells(Wiki 2007-2012). These iPSC cells the potential to be closed as embryonic stem cell (ESCs) which can develop and differentiate into three germ layers. Somatic cells(Wiki 2007-2012) or adult cells will introduced four transcription factors; OCT3/4, SOX2, c-Myc, and Klf4. The expectation of this process is to be able to reverse ESCs to embryonic cell that can lead to understanding of disease mechanism, which help prevent stage 3 of cancers, develop effective drugs, and etc. The scientists tried to find the best and effective way to reprogram somatic cells by adding certain chemical compound with four transcription factors; OCT3/4, SOX2, c-Myc, and Klf4. As a result, some were not able to successfully obtain iPSC, some were very close to achiev their goals, but support data were not reliable and reasonable enough.

Induction of pluripotent stem cells from adult human fibroblast was experimented by Japanese researchers. Mouse embryonic cell(MES) and human dorsal fibroblast were target cells. They claimed to be able to generate iPSC from woman adult cell by optimizing retroviral (Takahashi et al 2007) transduction that is located on human fibroblast and protocol in certain conditions. Overall result, non-ESCs-like colonies appear mixed with hESCs-like colonies after 25 days of incubation periods. These non-ESCs-like colonies(Takahashi et al 2007) were unidentified further in their experiment. H-iPSCs were test for potential different type of gene expressions, only four transcription factors will be mainly observed. Some of the methods are RT-PCR analysis and western blot, this marker gene shows iPSC markers as negative control, ESCs is positive control ,HDF is also negative control. As a result of these two methods, negative control, iPSCs give similarity markers as ESCs markers. Almost all the markers of iPSC were presented at the equivalent level to those in hES cells, except hTERT marker. hTERT gene that is indicated to telomerase reverse transcriptase. According to data, the expression of this gene is iPSC cells appeared to be lighter than ESCs. The expression level of NANOG and endogenous OCT4(Takahashi et al 2007) between ES Cs and iPSCs present in equivalent but not for iPSCs and HDF pattern. OCT3/4, NANOG, and SOX were turned on in iPSCs only, there is no expression of gene present in HDF area. Methylation status analysis(Wiki 2007-2012) is the method to determine if the promoters of CpG region of pluripotent work on DNA(gene) or not. As a result, OCT4 and NANOG show only few circle of methylate, which means the promoters in the region were active compare to HDF, which had about 50% of methylation present. Unfortunately, researchers did not provide the information for ESCs, thus the data for this method was undependable. Some of the methods that determined the direct differentiation of hiPSCs only provided negative data controls, and there was no explanation of appearance of MEF2C on HDF marker. GFAP gene refers as neuron makers(Takahashi et al 2007). According to their data, there was no expression of GFAP, which is irrelevant to their claim that hiPSC could differentiate into neuron cells.

Researchers were not successfully accomplished with the experiments. They claimed to be able to induced HDF to hiPSCs that meet all criteria of ESCs. Base on their data, there is not enough to support the conclusion. Furthermore, the absent of positive control result in, ESCS in some of the methods will cause misinterpretation for the readers, he/she will not be able to compare negative control which is iPSCs to positive control and analyze the difference. There are some errors during the experiments, they did not provide any explanation such as the present of unidentified non-hESC like. The second article is an extended research from the original papers by researchers from china. The researchers used human born marrow-derived mesenchymal stem cells...
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