Stem cells created in living mice

 September 12 2013

It’s positive news to hear that researchers in Spain have succeeded in reprogramming cells inside living mice that behave like embryonic stem-cells. This is another step forward on the long road to find a way to use stem cells to regenerate lost or damaged tissues in people. However it doesn’t mean that stem-cell therapies are around the corner.

Stem cells are cells that are able to divide and turn themselves into other cell types (this process is called ‘differentiation’) and thus have the potential to create the different tissue and cell types used in different parts of the body. The stem cells present in embryos are  able to produce all the cells in the body. However after birth, the body retains just a few stem cells that are able to produce only a limited range of cell types.

Being able to regenerate and replace lost cells safely would clearly have a huge benefit for many degenerative conditions, such as A-T.

Up to now, researchers have been able to take ordinary cells, such as skin cells, and re-programme them to become stem cells with the capacity, like embryonic stem cells, to turn into a wide range of cell types (these are known as induced pluripotent stem cells iPSCs) – but only in the laboratory.  What the team of Dr Manuel Serrano, a cancer researcher at the Spanish National Cancer Research Centre in Madrid, have done, is to do this in living mice.

However, to do this they had to breed mice genetically engineered to have four genes which produce proteins that are used to create pluripotent stem cells in the laboratory. The genes were engineered so that they could be turned on or off when researchers gave the mice a particular type of antibiotic.

Turning the genes on at a high level quickly killed the mice, but at lower levels researchers found evidence of the production of multiple cell types within the body. In addition, the stem-cells they found were more similar to real embryonic stem cells than the induced pluripotent stem-cells produced in the laboratory.

However, with these cells being expressed all over the body, this was still bad for the mice and they were found to be full of teratomas — disorganised tumours containing multiple cell types.

Serrano’s team are now looking at ways to make the cells take on new identities without producing tumours. And of course there is a huge amount of work to do to be able to control where this happens and what sort of cells are produced.

Nevertheless, this is a step forward. Speaking on the BBC Today programme, stem-cell expert Professor Chris Mason likened it to humans first leaping off a hill with wings and realising they could fly – a necessary starting point for today’s rapid and controlled aircraft. But there are still many, many years of work before we can hope to be testing therapies in people.


Picture of induced pluripotent stem cells in Mouse


Induced pluripotent stem cells in a mouse.