Tattoos are notorious for being difficult to remove. A group of French researchers may have figured out the reason why tattoos last so long.
According to Statistic Brain, 14% of Americans have at least one tattoo on their body, with the majority of those being adults under the age of 40 years. While they were once thought as a symbol of rebellion and criminality, tattoos have now become largely mainstream, with many young adults and pop culture icons now embracing tattoo culture.
But what makes tattoos last so long? Skin cells die and become sloughed off every day, but the ink can seemingly last forever. Published in the Journal of Experimental Medicine, a group of French researchers think they may finally have the answer.
When tattoo ink is deposited on to the skin, the pigment becomes engulfed by nearby macrophages, a type of white blood cell. These cells are part of the body’s first line of defence and engulf foreign particles to keep them from damaging other cells. It’s thought these macrophages can persist in the skin for decades, which gives the tattoo its permanence.
But when researchers went to test this theory by killing off all the macrophages on a tattooed mouse, they found that the ink remained. Instead of the pigments being trapped in the dead macrophages and removed from the body, researchers found the ink was released from the cells when they died. These pigments were then quickly re-absorbed by other nearby macrophages.
The research teams believe this could explain why tattoos are so notoriously difficult to remove. Even when laser-treatments are used to fragment pigment molecules, they simply get reabsorbed by surviving cells, never actually leaving the skin. Multiple rounds of laser treatment are typically needed to achieve tattoo removal, and even then, may not fade completely.
The authors suggest that by combining laser treatments with other methods which selectively kill macrophages, scientists may be able to improve the tattoo removal process.
Written by Calvin J. Chan, B.Sc.
References:
(1) Baranska, A. et al. (2018). Unveiling skin macrophage dynamics explains both tattoo persistence and strenuous removal. Journal of Experimental Medicine. Doi: 10.1084
(2) Statistic Brain (August 13, 2016 ) Tattoo Statistics. Retrieved Mar 27, 2018 from https://www.statisticbrain.com/tattoo-statistics/
