Enhancing Hair Follicle Regeneration by Nonablative Fractional Laser: Assessment of Irradiation Parameters and Tissue Response

In 2015, a study was conducted on eight-week-old female C57BL/6 mice to investigate the effects of a 1,550-nm fractional laser on hair follicle regeneration. The results indicated that laser irradiation could stimulate hair growth by inducing the active growth phase of hair follicles, known as anagen entry. However, the intensity and duration of inflammation caused by the laser were critical. Moderate, short-term inflammation could induce hair regeneration without causing ulcers, while intense and persistent inflammation led to ulcer formation and scarring. The study also found that the beam density required to induce anagen entry was less than the beam density that induced ulcers. The researchers concluded that to minimize direct thermal injury to hair follicles and to avoid ulcers, lower beam energy and density and fewer treatment sessions should be considered. The exact number of subjects was not specified.