Thursday September 12 2013
Stem cells offer huge potential for "regenerative medicine"
A “breakthrough” study in which stem cells were created from living adult tissue means that damaged and diseased organs could eventually be regenerated inside the bodies of living patients, The Daily Telegraph has reported. The Independent said the experiment could one day end the need for organ transplants.
The media’s excitement over this study is over-the-top.
This was an experiment that genetically engineered mice in a way that aimed to make their cells “re-programmable” into stem cells if treated with a specific drug. Previously, cells had to be taken out of the mice’s bodies and treated in the lab to induce them to become stem cells.
The experiment worked, and scientists were able to induce some of the cells in the mice’s bodies to become stem cells just by giving them the drug in their drinking water. However, they weren’t able to “direct” these cells to repair tissues or form new organs, and instead some of the cells formed tumours.
The field of stem cell research is fast moving, and this study proves that generating stem cells within a living animal is possible. The genetic engineering used in this study means that the technique is not going to be directly applicable to humans. However, it could help researchers to better understand stem cell biology, and this in itself may help in the future development of human treatments.
Where did the story come from?
The study was carried out by researchers from the Spanish National Cancer Research Centre in Madrid and was funded by the same. The study was published in the peer-reviewed scientific journal, Nature.
The Telegraph and The Independent both called this a “breakthrough” study, stressing its potential benefit in being able to regenerate damaged organs within patients’ bodies. The study is reportedly the first to have created stem cells within living animals (rather than in a petri dish).
But this research is at a very early stage and required genetic engineering that would not be feasible in humans. Researchers have also not yet worked out how to direct these stem cells to do what they want them to do in the body. Any human applications of such a technique, if they do materialise, are a long way off.
What kind of research was this?
This was an animal study in mice in which scientists attempted to use genetic technology to reprogramme adult cells within the mice’s bodies back to their embryonic state, as stem cells. Embryonic stem cells are primitive cells, produced when an egg is first fertilised, that are capable of dividing indefinitely and developing into all the specialised cell types of the body – for example, into cells of the brain, heart, muscles and skin. Most adult cells lose this ability.
In 2006, stem cells were generated for the first time in the laboratory from adult cells – an achievement for which scientist Shinya Yamanaka was awarded the Nobel prize in Physiology or Medicine in 2012. He injected ordinary adult cells in the lab with four genetic factors that “reprogrammed” them back to their embryonic state. These stem cells are called induced pluripotent stem (iPS) cells.
The Spanish scientists aimed to achieve the same result but within living mice – without taking the cells out of their bodies.
What did the research involve?
The researchers genetically engineered mice so that all of their cells carried extra copies of the four genetic factors needed to induce them to become stem cells. They did this in a way that meant that these extra copies could be “switched on” by a specific drug. They then gave the mice this drug in their drinking water and analysed what happened to cells from different mouse organs.
What were the basic results?
The scientists found that after treating the genetically engineered mice with the drug that switched on their “reprogramming” genetic factors:
- some of the cells in the mice’s stomachs, intestines, pancreas, kidneys, bone marrow and bloodstream became induced stem cells (iPS cells)
- in some mice, these iPS cells went on to develop into tumours called teratomas in these organs
- the iPS cells that developed in the mice’s bodies were at an earlier, more primitive stage of development (more like the very earliest cells in the embryo) than iPS cells generated in the laboratory
How did the researchers interpret the results?
The researchers concluded that reprogramming living adult tissue into stem cells is feasible, and results in a cell that is more like the earliest cells in the embryo than those that have been created in the laboratory.
They say that this discovery could be relevant for reprogramming in human regenerative medicine.
This study is the first to induce stem cells within the body of an adult mouse, without the need to take the cells out of the body. The way that the researchers achieved this required the use of genetically engineered mice whose cells all had the genetic capacity to “reprogramme” into stem cells when treated with a specific drug. When these mice were given the drug, some of their cells “reprogrammed”, and some of these went on to form tumours.
The technique used in this study is clearly not something that can be directly applied to humans – who cannot be genetically engineered in the way laboratory mice can be. Researchers did not have the ability to stop the reprogrammed cells from forming tumours within the mice’s bodies, or to “direct” the cells to repair specific tissues or develop into specific organs. Doubtlessly this study will prompt further research into seeing if this is possible.
Although the study is an advance, it seems like the approach is better suited to helping scientists to understand stem cell biology through animal experiments rather than forming the basis of potential new treatments. Greater understanding of stem cell biology is in itself useful in helping researchers to develop stem cell-based treatments.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.