The Q-switched alexandrite laser's effects on tattoos in guinea pigs and harvested human skin

Background.: Developmental work in tattoo removal is currently carried out in animal models whose skin has different optical and mechanical properties from human skin. Objective.: To observe laser effects on tattoos in a new human skin model and that of in vivo guinea pig skin. Methods.: A comparison of the efficacy of the Q-switched Alexandrite laser (750 nm, 100-120 nanoseconds) in tattooed harvested human skin and guinea pig skin was performed. Visual assessments as well as histologic and electron microscopy evaluation before and after treatment are reported. Results.: Mild to moderate clearing of black tattoo pigment, as judged by visual assessment, was found after one laser treatment in both the in vitro human skin model and guinea pig skin. Blue and green ink showed similar results to black ink in human skin whereas red and yellow ink did not respond in our model. Conclusion.: Possible mechanisms of tattoo lightening and the usefulness of the in vitro human skin model are discussed.