reprogramming-mouse-embryonic-fibroblasts-with-transcription-factors

Reprogramming Mouse Embryonic Fibroblasts with Transcription Factors to Induce a Hemogenic Program

This protocol details the induction of a hemogenic program in mouse embryonic fibroblasts (MEFs) via overexpression of transcription factors (TFs). We ...

Icahn School of Medicine at Mount Sinai

Patient-specific induced pluripotent stem cells (iPSCs) are considered a versatile resource in the field of biomedicine. As iPSCs are generated on an individual basis, iPSCs may be the optimal cellular material to use for disease modeling, drug discovery, and the development of patient-specific cellular therapies. Recently, to gain an in-depth understanding of human pathologies, patient-specific iPSCs have been used to model human diseases with some iPSC-derived cells recapitulating pathological phenotypes in vitro. However, complex multigenic diseases generally have not resulted in concise conclusions regarding the underlying mechanisms of disease, in large part due to genetic variations between disease-state and control iPSCs. To circumvent this, the use of genomic editing tools to generate perfect isogenic controls is gaining momentum. To date, DNA binding domain-based zinc finger nucleases and transcription activator-like effector nucleases have been utilized to create genetically defined conditions in patient-specific iPSCs, with some examples leading to the successful identification of novel mechanisms of disease. As the feasibility and utility of genomic editing tools in iPSCs improve, along with the introduction of the clustered regularly interspaced short palindromic repeat system, understanding the features and limitations of genomic editing tools and their applications to iPSC technology is critical to expending the field of human disease modeling.

Genomic editing tools to model human diseases with isogenic pluripotent stem cells.

The ability of cells to count and remember their divisions could underlie many alterations that occur during development, aging, and disease. We tracked the cumulative divisional history of slow-cycling hematopoietic stem cells (HSCs) throughout adult life. This revealed a fraction of rarely dividing HSCs that contained all the long-term HSC (LT-HSC) activity within the aging HSC compartment. During adult life, this population asynchronously completes four traceable symmetric self-renewal divisions to expand its size before entering a state of dormancy. We show that the mechanism of expansion involves progressively lengthening periods between cell divisions, with long-term regenerative potential lost upon a fifth division. Our data also show that age-related phenotypic changes within the HSC compartment are divisional history dependent. These results suggest that HSCs accumulate discrete memory stages over their divisional history and provide evidence for the role of cellular memory in HSC aging.

Article	Year
Genomic editing tools to model human diseases with isogenic pluripotent stem cells. Stem cells and development\| PubMed ID: 25075441	2014
Hematopoietic Stem Cells Count and Remember Self-Renewal Divisions. Cell\| PubMed ID: 27839867	2016

Jeffrey M. Bernitz

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