The ‘ultimate’ stem cell

In the earliest moments of a mammal’s life, the developing ball of cells formed shortly after fertilisation ‘does as mother says’ – it follows a course that has been pre-programmed in the egg by the mother. Extraordinary as this is, what happens then is even more remarkable.

 

Capturing ES cells is like stopping the developmental clock at the precise moment before they begin to turn into distinct cells and tissues
   - Austin Smith

Just before implantation in the uterus, the ball of cells, called a blastocyst, gains the capacity to generate all of the cell types of the subsequent adult – a feature called pluripotency. It is at this moment when everything is possible, when the history of the previous generation has been wiped clean and when the embryo begins its unique course of development.

But, although these ‘naive’ stem cells have been isolated in mice – and mouse cells at a later stage of development can be manipulated to take them back to full naivety – the same has not been convincingly accomplished for humans.

In fact, in an assessment earlier this year, Cambridge researchers Professor Roger Pedersen and PhD student Victoria Mascetti concluded that the existence of naive human stem cells required confirmation by other stem cell research groups: “Like Higgs’ Boson to the field of particle physics,” they explained, naivety in human stem cells “was predicted from considerations of symmetry and conservation, [but] we are yet to unlock its potential."

Now researchers led by the Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute have managed to induce a ground state by rewiring the genetic circuitry in human embryonic stem (ES) cells and in adult cells that have been induced into a pluripotent state. Their ‘reset cells’ share many of the characteristics of authentic naive ES cells isolated from mice, suggesting that they represent the earliest stage of development.

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Image: Mouse blastocyst at the pluripotent stage, when cells have the capacity to generate all of the cell types of the adult
Credit: Jenny Nichols


Reproduced courtesy of the University of Cambridge
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Mouse blastocyst at the pluripotent stage, when cells have the capacity to generate all of the cell types of the adult

Credit: Jenny Nichols

- See more at: http://www.cam.ac.uk/research/news/the-ultimate-stem-cell#sthash.m8vDKtGL.dpuf


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