Human skin can smell itself as well as other odors, according to a new study that also determined a common and pleasant-smelling odor promotes skin healing.
The paper, published in the latest issue of the Journal of Investigative Dermatology, strengthens prior research that found olfactory receptors -- proteins specialized to detect odors -- don't just exist in the nose.
"Only a tiny little amount of odorants are used by our receptors in the nose," chemist Peter Schieberle of the Technical University of Munich told Discovery News. "Odor might have secondary functions in the human body."
Schieberle and his team discovered that the human heart, blood and lungs all possess olfactory receptors. Yet another research group, led by Ester Feldmesser of the Weizmann Institute of Science, theorized that these odor-detecting sensors could be all over, and in, the body.
Now, with the new study, Daniela Busse and her team provide the first direct evidence that such cells exist within the epidermis, which is the skin's outermost layer.
Busse, a researcher in the Department of Cellphysiology at Germany's Ruhr-University Bochum, and her team not only identified five different types of olfactory receptors in human skin keratinocytes (the predominant type of cell in the epidermis), but they also cloned one of them, called OR2AT4.
The scientists next exposed the target smeller cells to the compound Sandalore, which is a synthetic sandalwood odorant. Busse and her team focused on sandalwood because, for at least 4,000 years, oil from the East Asian sandalwood tree has been prized both as a perfume and as a medicinal agent for the skin.
Busse and colleagues explained that they used a synthetic sandalwood odorant because, "In the past years, the development of synthetic sandalwood molecules has led to a series of substitutes that are often used in cosmetics, deodorants and perfumes because the essential sandalwood oil obtained from the East Asian sandalwood tree is quite rare and is therefore an expensive substance."
The researchers found that Sandalore activated the cloned smeller cells in skin, thereby inducing a calcium-signaling cascade that dramatically increased the proliferation and migration of cells. This process is characteristic of wound healing.
Busse and her team are not exactly sure why the synthetic sandalwood appears to be so beneficially potent, but they suspect that it somehow facilitates interaction between the predominant human skin cells and neurons (nerve cells), also found within skin.
Yet another study released this week, published in the Archives of Biochemistry and Biophysics, found that in lab experiments East Indian sandalwood oil causes pre-cancerous cells in skin to die, leaving behind healthy skin.
Lead author Sally Dickinson of the Arizona Cancer Center at the University of Arizona and her colleagues explained that "sandalwood oils have many well-known health benefits due to their anti-inflammatory and antiseptic properties, among others."
Yet another fan of the woodsy scent is Chandradhar Dwivedi, head of the Department of Pharmaceutical Sciences at South Dakota State University. He has been conducting research on the fragrant oil for years.
"This product has been very effective in preventing skin cancer caused by chemicals and by UV radiation," Dwivedi said. "It smells nice, and at the same time, it prevents chemically-caused or UV-induced skin cancer."
Tests are ongoing, so no one is yet urging anyone to run out and buy sandalwood-scented products.
Nonetheless, the new research demonstrates how sensitive the body and even its skin are to odors, and it opens the door to possible new skin problem treatments with few side effects, so long as the individual does not, in this case, mind smelling like a tree.