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Scientists have designed a biomedical tattoo that changes color when calcium in the blood is too high — a tool that they say could one day be used to monitor for the earliest signs of disease.

Some types of cancer increase the amount of calcium in the blood before symptoms appear. So researchers engineered cells that turn dark like a tattoo when calcium is too high. They published a proof-of-concept paper on the work Wednesday in Science Translational Medicine.

“Whenever the spot comes up, it would be a very early sign to go to the doctor and get checked,” said Martin Fussenegger, a professor of bioengineering at Swiss Federal Institute of Technology in Zurich.


When calcium levels are higher than normal, the cells produce melanin, a dark pigment that’s already found in the skin. Fussenegger and his colleagues suspended their engineered cells in gelatin and injected them into the skin of mice.

They implanted the biomedical tattoos in mice who had cancers that either increased calcium levels or didn’t affect them. The tattoos showed up only on the skin of mice with raised calcium levels during the 38-day experiment.


The idea would still need to be studied further in animals and in patients before it could ever be used in the clinic. If it worked in humans, Fussenegger said the tool might be useful for monitoring people at an increased risk of certain types of cancer that change calcium levels or in cancer survivors to monitor for new tumors.

And, Fussenegger pointed out, the idea isn’t just limited to cancer detection.

“You could link it to any type of biomarker,” he explained. “Potentially, such a tattoo could be linked to something that is slowly developing, like a neurodegenerative disorder such as Parkinson’s.”