A New Scientist story published today highlights work by Swedish researchers to identify the basic molecular structure of the skin layer that forms our body's watertight barrier. The findings may help further efforts to develop new technology to deliver drugs directly through the skin.
In the (small) study, researchers shaved a layer of skin from volunteers' arms, cooled the tissue to below -140 Celsius in a high-pressure freezer and then sliced the skin samples into layers 25-50 nanometers thick. The tissue was then examined using an electron microscope. Helen Thomson writes:
What the researchers saw surprised them. Lipids have a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. Normally, the two tails point in the same direction, giving the molecule a hairpin-like appearance.
A group of lipid molecules typically arrange themselves into a two-layered sheet - or bilayer - with all of the tails pointing inwards. However, the lipid molecules in between the cells of the stratum corneum are splayed outwards so that the two tails of each molecule point in opposite directions.
...
This uniquely structured fatty layer prevents any water from getting past in either direction - except where the skin layer is modified to form pores. "There's no water present within this extracellular space," says [study author Lars Norlen, MD, PhD.] "It cannot perturb the barrier so it's completely robust to hydration, which is necessary for the changing environment that we live in."
The research team now plans to use the findings to create a computer model to use in developing a method for screen drugs that could potentially be administered through the skin.
Photo by Monik Markus
