Scientists have now developed a gel that boosts the ability of normal cells to revert into stem cells by simply "squeezing" them into shape. Published in Nature Materials, the new technique can also be easily scaled up to produce stem cells for various applications on an industrial scale.
There are different types of stem cells, but the ones that are of particular medical interest are the so-called "induced pluripotent stem cells" or iPSCs. These are derived from mature, adult cells that have been genetically reprogrammed to behave like stem cells (which is why they are "induced"). iPSCs can then be regrown into a whole range of different cells types, e.g. liver, pancreatic, lung, skin etc.
There have been many attempts to design a standardized method for generating such stem cells. But even the most successful methods turn out to not be very effective, especially for use on a large scale. A major issue is that existing techniques use the two-dimensional environment of a petri dish or cell culture flask, whereas cells in the body exist in a three-dimensional world.
Researchers have now developed a new method that may help to overcome these challenges. The approach uses a three-dimensional cell culture system. Normal cells are placed inside a gel that contains normal growth nutrients.
The researchers discovered that they could reprogram the cells faster and more efficiently than current methods by simply adjusting the composition - and hence the stiffness and density - of the surrounding gel. As a result, the gel exerts different forces on the cells, essentially "squeezing" them.
As a new phenomenon, this is not entirely understood. However, the scientists propose that the three-dimensional environment is key to this process, generating mechanical signals that work together with genetic factors to make the cell easier to transform into a stem cell.
"Each cell type may have a 'sweet spot' of physical and chemical factors that offer the most efficient transformation," says the author. "Once you find it, it is a matter of resources and time to create stem cells on a larger scale."
The greater impact of this discovery is possibly quantity. The technique can be applied to a large number of cells to produce stem cells on an industrial scale.