Advances in Reprogramming Somatic Cells to Induced Pluripotent Stem Cells

Abstract

Traditionally, nuclear reprogramming of cells has been performed by transferring somatic cell nuclei into oocytes, by combining somatic and pluripotent cells together through cell fusion and through genetic integration of factors through somatic cell chromatin. All of these techniques changes gene expression which further leads to a change in cell fate. Here we discuss recent advances in generating induced pluripotent stem cells, different reprogramming methods and clinical applications of iPS cells.Viral vectors have been used to transfer transcription factors (Oct4, Sox2, c-myc, Klf4, and nanog) to induce reprogramming of mouse fibroblasts, neural stem cells, neural progenitor cells, keratinocytes, B lymphocytes and meningeal membrane cells towards pluripotency. Human fibroblasts, neural cells, blood and keratinocytes have also been reprogrammed towards pluripotency. In this review we have discussed the use of viral vectors for reprogramming both animal and human stem cells. Currently, many studies are also involved in finding alternatives to using viral vectors carrying transcription factors for reprogramming cells. These include using plasmid transfection, piggyback transposon system and piggyback transposon system combined with a non viral vector system. Applications of these techniques have been discussed in detail including its advantages and disadvantages. Finally, current clinical applications of induced pluripotent stem cells and its limitations have also been reviewed. Thus, this review is a summary of current research advances in reprogramming cells into induced pluripotent stem cells.

Induced Pluripotent Stem Cells and Their Implication for Biomedical Sciences

“…However, adenovirus is generally rather poor at gene transfer. It is also very difficult to control the level of gene expression infected cell (Lai et al, 2011;Patel and Yang, 2010).…”

“…Theoretically, with the transplantation of specific cells created from autologus iPS cells, the cells that lacking can be replenished and replace by cells with the defects corrected, thereby relieving a patient`s symptoms. The mostly use somatic cells are fibroblasts, but different groups generated also iPS cells from other somatic cells providing evidence that is possible to reprogram cells of different origins (Deng, 2010;Ebben et al, 2011;Patel and Yang, 2010;Uemura et al, 2012;Vitale et al, 2011;Walia et al, 2012;Wong and Chiu, 2011;Zeng and Zhou, 2011). Other sources of iPSCs that can be easily reprogrammed are human keratinocytes (Aasent et al, 2008;Petit et al, 2012), oral mucosa fibroblasts (Miyoshi et al, 2010), dermal papilla cells (Tsai et al, 2010), pancreatic beta cells (Stadtfeld et al, 2008), neural stem cells (Kim et al, 2009), mature B lymphocytes (Hanna et al, 2008), liver and stomach cells (Aoi et al, 2008) and cord blood cells (Cai et al, 2010;Takenaka et al, 2009).…”

“…This discovery caused a paradigm shift in developmental biology. However, the process was very inefficient and the reprogramming incomplete leading to Dolly's premature death and early onset of a number of degenerative disease (Kang et al, 2010;Patel and Yang, 2010). This reprogramming method also has proved successful for several species, but there are technical issues in applying this approach to human cells (Feng et al, 2009).…”

Application of Human Pluripotent Stem Cells in T Cell Based Cancer Immunotherapy

“…While initial reports on iPS generation utilized recombinant viral vectors to deliver reprogramming factors, several different methodologies are now available to generate iPS cells by non-viral methods [31], addressing concerns associated with the clinical application of recombinant viral vectors. The availability of the technical know-how to derive iPS cells offer a unique opportunity not only to study the hPS cells without any moral or ethical constraints, the development of donor specific iPS lines as the source material for the cell replacement therapy (CRT) would also address the issue of immune rejection associated with allogenic hES derived immune-incompetent cells, therefore, making it feasible to harness the therapeutic potential of hPS cells.…”

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“…Therefore, generation of patient specific pluripotent stem cells from somatic cells is not associated with immune rejection or ethical controversy and holds promise for regenerative medicine and biomedical research. 5 Reprogramming of somatic cells to pluripotent ES cell-like cells, named IPS cells, has been attained by expression of defined transcription factors, including the combination of OCT4, Klf4, Sox2, and c-Myc or OCT4, Sox2, Nanog, and Lin28. 6 The microRNAs (miRNAs or miRs) are a type of small noncoding RNAs with 18 to 24 nucleotides which were first described as a part of a cascade resulting in posttranscriptional gene silencing in Caenorhabditis elegans > 15 years ago.…”