Technological Overview of iPS Induction from Human Adult Somatic Cells

Abstract

The unlimited proliferation capacity of embryonic stem cells (ESCs) combined with their pluripotent differentiation potential in various lineages raised great interest in both the scientific community and the public at large with hope for future prospects of regenerative medicine. However, since ESCs are derived from human embryos, their use is associated with significant ethical issues preventing broad studies and therapeutic applications. To get around this bottleneck, Takahashi and Yamanaka have recently achieved the conversion of adult somatic cells into ES-like cells via the forced expression of four transcription factors: Oct3/4, Sox2, Klf4 and c-Myc. This first demonstration attracted public attention and opened a new field of stem cells research with both cognitive – such as disease modeling - and therapeutic prospects. This pioneer work just received the 2012 Nobel Prize in Physiology or Medicine. Many methods have been reported since 2006, for the generation of induced pluripotent stem (iPS) cells. Most strategies currently under use are based on gene delivery via gamma-retroviral or lentiviral vectors; some experiments have also been successful using plasmids or transposons-based systems and few with adenovirus. However, most experiments involve integration in the host cell genome with an identified risk for insertional mutagenesis and oncogenic transformation. To circumvent such risks which are deemed incompatible with therapeutic prospects, significant progress has been made with transgene-free reprogramming methods based on e.g.: sendaï virus or direct mRNA or protein delivery to achieve conversion of adult cells into iPS. In this review we aim to cover current knowledge relating to both delivery systems and combinations of inducing factors including chemicals which are used to generate human iPS cells. Finally, genetic instability resulting from the reprogramming process is also being considered as a safety bottleneck for future clinical translation and stem cell-therapy prospects based on iPS.

Directed differentiation protocols for successful human intestinal organoids derived from multiple induced pluripotent stem cell lines

“…However, the retro-virally reprogrammed cells produced more robust HIO epithelial cell marker expression and this may be relevant for their use as translational 3D models of the gut physiology and pathophysiology. While retrovirally reprogrammed cell lines have been essential for the initial characterization of iPSCs relative to embryonic stem cell lines, they are incompatible with therapeutic applications, as genomic integration of reprogramming factors introduces a risk of insertional mutation that can potentially disrupt cellular stability and function [19]. High expression of pluripotent markers was evident in E2055A, which showed deviations from ideal ESlike morphology within maintenance cultures.…”

“…These two observations suggested to us that changes in handling and localization of structures, could drive the outcome to successful differentiated HIO, maybe as much as the differentiation growth factor protocols. Finally, iPSC lines can be produced by the forced expression of reprogramming transcription factors (e.g., Oct4, Sox2, Klf4, and c-Myc) by means of retroviral transduction [1] although this can potentially disrupt cellular stability and function [19]. Thus, to compare the robustness of intestinal differentiation, five cell lines were contemporaneously differentiated and their morphology and a number of markers of differentiation through HIO tracked.…”

Human Induced Pluripotent Stem Cells as a Platform for Personalized and Precision Cardiovascular Medicine

“…Reprogramming efficiency (i.e., the number of starting somatic cells which transition to hiPSCs) has been reported to be significantly enhanced by addition of supplementary pluripotency factors (12) or epigenetic modifiers (160) to the reprogramming mix. Rais et al (225) and Lujan et al (168) also demonstrated in both human and mouse cells that almost 100% of cells in a differentiated population are capable of reprogramming following depletion of Mbd3, a core member of the Mbd3/NuRD (nucleosome remodeling and deacetylation) repressor complex.…”

Pluripotent stem cells and their use in hearing loss

“…iPS cells are obtained by the reprogramming of body somatic cells with some gene transcription factors. They were first produced from mice dermal fibroblast cells by the retroviral gene transfer method with Oct3/4, Sox2, Klf4, and cMyc (OSKM) factors, also known as the Yamanaka factors (Figure) (Takahashi and Yamanaka, 2006;Bayart and Cohen-Haguenauer, 2013). iPS cells were obtained from human dermal fibroblasts a year later by the same authors (Takahashi et al, 2007).…”