June 14, 2013
Using Scent To Detect Skin Cancer
redOrbit Staff & Wire Reports - Your Universe Online
Unique odors from human skin cells can be used to identify melanoma, the deadliest form of skin cancer, and may lead to early, non-invasive detection and diagnosis of the disease, according to new research from the Monell Center and the University of Pennsylvania published in the Journal of Chromatography B.
The researchers also demonstrated that a nanotechnology-based sensor could reliably differentiate melanoma cells from normal skin cells.
Melanoma is a tumor affecting melanocytes, skin cells that produce the dark pigment that gives skin its color. The disease is responsible for about 75 percent of skin cancer deaths, with chances of survival directly related to how early the cancer is detected.
Current methods of detection typically rely on visual inspection of the skin, which is highly dependent on individual self-examination and clinical skill.
The current study used the fact that human skin produces numerous airborne chemical molecules known as volatile organic compounds (VOCs), many of which have an odor.
"There is a potential wealth of information waiting to be extracted from examination of VOCs associated with various diseases, including cancers, genetic disorders, and viral or bacterial infections," said George Preti, PhD, an organic chemist at Monell who is one of the paper's senior authors.
In conducting their study, the researchers used sophisticated sampling and analytical techniques to identify VOCs from melanoma cells at three stages of the disease, as well as from normal melanocytes. All the cells were grown in culture.
They used an absorbent device to collect chemical compounds from air in closed containers containing the various types of cells. Gas chromatography-mass spectrometry techniques were used to analyze the compounds and identified different profiles of VOCs emitting from melanoma cells relative to normal cells.
They found both the types and concentrations of chemicals were affected.
Melanoma cells produced certain compounds not detected in VOCs from normal melanocytes and also more or less of other chemicals. Furthermore, the different types of melanoma cells could be distinguished from one another.
Because the translation of these results into the clinical diagnostic domain would require a reliable and portable sensor device, the researchers went on to examine VOCs from normal melanocytes and melanoma cells using a nano-sensor.
Constructed of nano-sized carbon tubes coated with strands of DNA, these tiny sensors can be bioengineered to recognize a wide variety of targets, including specific odor molecules.
The researchers were able to demonstrate that the nano-sensor could distinguish differences in VOCs from normal and several different types of melanoma cells.
"We are excited to see that the DNA-carbon nanotube vapor sensor concept has potential for use as a diagnostic. Our plan is to move forward with research into skin cancer and other diseases," said A.T. Charlie Johnson, Professor of Physics at the University of Pennsylvania, who led the development of the olfactory sensor.
Together, the findings provide a proof-of-concept regarding the potential of the two analytical techniques to identify and detect biomarkers that distinguish normal melanocytes from different melanoma cell types.
"This study demonstrates the usefulness of examining VOCs from diseases for rapid and noninvasive diagnostic purposes," said Preti. "The methodology should also allow us to differentiate stages of the disease process."
Researchers are currently analyzing VOCs from tumor sites of patients diagnosed with primary melanoma.