The Effect of an Er:YAG Laser Combined with a 755 nm Picosecond Laser on Tattoo Removal in a Rat Model

Laser tattoo removal is an effective technique, but multiple rounds of treatment are required to eliminate tattoos, which can be a challenge for patients who do not have the time. Additionally, there is relatively limited research on the mechanisms of laser tattoo removal, necessitating further in-depth studies. This study aimed to investigate the efficacy of an Er:YAG laser combined with a 755-picosecond laser for tattoo removal and the changes in skin diffuse reflection, pigment particle size, macrophage recruitment, and inflammatory factor levels during combined laser treatment. Our experiments used three sets of lasers-an Er:YAG laser, a 755 nm picosecond laser, and an Er:YAG laser combined with a 755 nm picosecond laser-for tattoo removal. The effects of tattoo removal at different time points were evaluated. Moreover, the mechanisms were explored using HE staining, immunohistochemistry, diffuse reflectance measurements, in vitro gel tests, mass spectrometry, and ELISA experiments. The combined treatment was more effective for tattoo removal in rats. The combined laser treatment effectively reduced diffuse reflection from the skin, thereby increasing the effective laser power, reducing the size of the pigment particles, allowing for easier removal of the pigment, and increasing the recruitment of dermal macrophages and the release of inflammatory factors, thus increasing the rate of tattoo removal in vivo.