Unlocking the mystery of skin renewal

Everyday we shed the outermost layer of our skin and replace it from within with new skin cells. Scientists from Cambridge have looked at the way that skin is renewed.

By observing the skin of mice at the cellular level over a whole year, they have turned previous thinking about skin renewal on its head. Their research is published today on Nature Online.

Previously, it was thought that two types of cells were needed to regenerate skin: adult stem cells and short lived cells that soon stopped dividing. New research led by the MRC Cancer Cell Unit in Cambridge found that what actually happens is very different. The adult stem cells don't seem to do anything in normal skin. Their role is to help repair and replace injured skin. The MRC scientists found that the skin is actually regenerated by non stem cells behaving in a very surprising way. Most cells expand by doubling, producing 2, 4, 8, etc, daughter cells as they grow.

Dr Philip Jones who led the research explained: "Using a fluorescent genetic marker and 3D imaging, we found that the cells followed a 1, 2, 3, 4, 5 growth model, where one of the daughter cells stops growing after cell division while the other carries on. This means that regular, healthy skin maintains itself on its own without the skin adult stem cell population being involved. One of the implications of this is that these progenitor skin cells can also potentially go bad and cause skin cancer if they linger long enough."

Being able to track these cells in the actual animals at the cellular level over a year has allowed the scientists to develop mathematical models for predicting confidently what happens to skin long-term for the first time. These models may help to understand what genes do and inform our understanding of how cancer develops. They could also allow us to refine our drug testing procedures. This has led the team to patent this new mathematical tool for predicting skin growth.

"Our ultimate goal though is to be able to model the evolution of cancer from the single cell stage onwards so we can find better ways to tackling the disease. By using the right gene to label the cells, this might just be possible." said Dr Jones.