iPS Cells

iPS Cells

What are iPS cells? The unlimited cell resource for future regenerative treatments, and a powerful toolkit for disease modeling!

Human induced pluripotent stem (iPS) cells highly resemble embryonic stem (ES) cells in having the potential to differentiate to all cell types of the human body. Human iPS cells can be generated from different types of somatic cells by ectopic expression of pluripotency-related transcription factors. The process in which specialized somatic cells unlock their developmental potential and revert to an embryonic-like pluripotent state is called “reprogramming”. The ‘classic’ transcription factor reprogramming cocktail, coined collectively the “Yamanaka factors”, includes, Oct4, Sox2, Klf4 and c-Myc. There are many variants of reprogramming cocktails that often include Nanog and Lin28a. The HMGU iPSC Core Facility produces human iPS cell lines by reprogramming cells obtained from biopsies of patients and of healthy individuals. The primary reprogramming methods used by the Core Facility utilize cocktails of five or six factors delivered to the cells by non-viral techniques, which offer the advantage of producing genetically unmodified reprogrammed cells. In addition to routine production of human iPS cell lines, the Core Facility provides assistance to researchers in establishing differentiation protocols for derivation of tissue progenitor-like populations from iPS cells, and differentiation of the progenitor cells into a wide array of specialized cell types. The Core’s scientists also conduct experiments related to personalized medicine, disease modeling and drug discovery.

Figure 1. Overview of reprogramming methods and comparison of differentiation potential of pluripotent stem cells: induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs)

Four main methods for delivering reprograming factors exist (listed top to bottom in Figure 1), including, transduction by i) viral vectors, ii) integrating and non-integrating plasmids, iii) RNA molecules and iv) recombinant proteins. Following the introduction of reprogramming factors, somatic cells exhibit two phases of morphological transformations, named the “reprogramming waves”. Fibroblasts initially undergo mesenchymal to epithelial transformation and subsequently give rise to colonies resembling ESCs. Further passaging produce stable human iPS cell clones.