Scientists Create First Stem Cells Using CRISPR Technology

In a scientific first, a research team led by Gladstone Institutes scientists turned mouse skin cells into so-called induced pluripotent stem cells by activating a specific gene using CRISPR technology. The results appear in the journal Cell Stem Cell.

Liu et al demonstrate that induced pluripotency can be achieved through targeted activation of endogenous Oct4 or Sox2 genes. With CRISPR activation, the promoter and enhancer are specifically remodeled, Oct4 or Sox2 is derepressed in fibroblasts, and reprogramming is triggered toward pluripotency. Image credit: Liu et al, doi: 10.1016/j.stem.2017.12.001.

Pluripotent stem cells can be turned into virtually any cell type in the body. As a result, they are a key therapeutic resource for currently incurable conditions, such as heart failure, Parkinson’s disease, and blindness.

They also provide excellent models to study diseases and important tools to test new drugs in human cells.

In 2006, Gladstone Institutes’ Dr. Shinya Yamanaka discovered he could make stem cells — called induced pluripotent stem cells (iPSCs) — by treating ordinary skin cells with four key proteins.

These proteins, called transcription factors, work by changing which genes are expressed in the cell, turning off genes associated with skin cells and turning on genes associated with stem cells.

Building on this work, Gladstone Institutes’ Dr. Sheng Ding and co-authors previously created iPSCs not with transcription factors, but by adding a cocktail of chemicals to the cells.

The latest study offers a third way to turn skin cells into stem cells by directly manipulating the cells’ genome using CRISPR gene regulation techniques.

“Having different options to make iPSCs will be useful when scientists encounter challenges or difficulties with one approach,” Dr. Ding said.

“Our approach could lead to a simpler method of creating iPSCs or could be used to directly reprogram skin cells into other cell types, such as heart cells or brain cells.”

The researchers targeted two genes that are only expressed in stem cells and known to be integral to pluripotency: Sox2 and Oct4.

Like transcription factors, these genes turn on other stem cell genes and turn off those associated with different cell types.

The team discovered that with CRISPR, they could activate either Sox2 or Oct4 to reprogram cells.

In fact, the authors showed that targeting a single location on the genome was enough to trigger the natural chain reaction that led to reprogramming the cell into an iPSC.

For comparison, four transcription factors are typically used to create iPSCs using the original method.

What’s more, one transcription factor typically targets thousands of genomic locations in the cell and changes gene expression at each location.

“The fact that modulating one site is sufficient is very surprising,” Dr. Ding said.

“Now, we want to understand how this whole process spreads from a single location to the entire genome.”

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Peng Liu et al. CRISPR-Based Chromatin Remodeling of the Endogenous Oct4 or Sox2 Locus Enables Reprogramming to Pluripotency. Cell Stem Cell, published online January 18, 2018; doi: 10.1016/j.stem.2017.12.001