Stress creёert pluripotente stam cellen

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Samenvatting

RIKEN, de grootste japanse researchorganisatie voor fundamenteel en toegepast onderzoek, heeft de ontwikkeling bekend gemaakt van Stimulus Triggered Acquisition van Pluripotente (STAP) cellen. Deze cellen verkrijgen hun pluripotentie door extracellulaire stress, bijvoorbeeld wanneer lichaamscellen in vitro worden blootgesteld aan zure omstandigheden Deze procedure maakt geen gebruik van genetische manipulatie. STAP cellen die ingebracht zijn in muizen leveren embryonale cellen die zich vermenigvuldigen en maar ook cellen die in de placenta groeien

Extracellular stress makes somatic cells into pluripotent cells

Summary

RIKEN announced development of Stimulus-Triggered Acquisition of Pluripotency cells (STAP cells). STAP cells obtained pluripotency by receiving extracellular stress such as acidic condition to somatic cells in vitro. This procedure did not require genetic manipulation. STAP cells planted in mice were able to rise not only embryonic cells but also extraembryonic cells such as placental tissue.

Details

Joint work by Dr. Haruko Obokata of RIKEN, Dr. Charles Vacanti of Harvard University, and other researchers was published in Nature on January 30, 2014 on the development of the Stimulus-Triggered Acquisition of Pluripotency cells (STAP cells). The technology of creating of STAP cells with induced pluripotency needed extracellular stress to somatic cells in a tube.

The research group used mouse splenic CD45^+* cells as somatic cells. These cells were exposed to low-pH solution, pH 5.7, at 37 ℃ for 30 min and then cultured in a solution with leukemia inhibitory factor (LIF). LIF is a factor to maintain pluripotency. After 2 days, cells started to express Oct4, gene specific for pluripotent cells. Expression of Oct4 was observed through GFP that illuminates associated with the expression of Oct4 gene. Oct4-expressed cells were small and tended to make aggregates after 7 days of the treatment.

To eliminate the possibility of contamination of the culture, real time observation to follow the development of the stress-treated cells to Oct4-expressed cells was used. Furthermore, gene analysis of Oct4-expressed cells was conducted because splenic CD45⁺ shows the unique recombination of genes of T cell receptor through their differentiation. These observations showed the Oct4-expressed cells originated from the stress-exposed mouse splenic CD45⁺ cells.

Furthermore, the Oct4-expressed cells also expressed genes specific for pluripotent cells such as Sox2**, SSEA1, Nanog***. In addition, methylation status was not characteristic for a lymphocytes but a pluripotent cell.

Oct4-expressed cells showed the ability to form a chimera embryo as well as placental tissues in a blastocyst injection assay. ES cells and iPS cells are known to form chimera embryos but not placental tissues, which indicates the Oct4-expressed cells further “undifferentiated” compared to ES cells and iPS cells. When STAP cells were treated with Fibroblast Growth Factor 4 (FGF4), a growth factor, the tendency to differentiate to placental tissues increased.

Compared to iPS cells, the self-renewal capacity of STAP cells was limited. If STAP cells were cultured with the solution containing adrenocorticotropic hormone (ACTH) that RIKEN developed, the self-renewal capacity increased. However, differentiation to the placental tissues did not occur for these cells, while a chimera mouse was formed.

Other types of somatic cells were also tested whether they showed pluripotency through exposure to low-pH. Cells from brain, skin, lung, liver, skeletal muscle, adipose tissue, and heart muscle showed that they obtained pluripotency on one level or another.

Other types of sublethal extracellular stress such as mixing and exposure to streptolysin O to make holes on the membrane also induced STAP cells.

Dedifferentiation of somatic cell to STAP cells occurred fast. It took only 2 days to start expressing signs of differentiation. In addition, nuclear transfer and genetic manipulation were not required in the process. It is expected that this technology can be used for human cells as well as for understanding the mechanisms of dedifferentiation.

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