Background and Objective: Lasers based on the theory of selective photothermolysis can selectively destruct pigment cells, but repigmentation unexpectedly occurs and the mechanism is unknown. We investigated selective photothermolysis and regeneration of melanocytes in zebrafish skin following laser ablation.
Study Design/Materials and Methods: The caudal peduncles of zebrafish were exposed to 1064 nm Q-switched Nd:YAG laser. Changes in melanocytes were investigated under transmission electron microscopy and apoptosis was studied by TUNEL stain, depending on the laser ablation energy levels.
Results: Selective photothermolysis of melanocytes was induced 1 week after laser ablation, but repigmentation occurred after 2 months. Regeneration of melanocytes and apoptosis showed clear energy dependency, but in the opposite direction. As laser ablation energy was increased, regeneration of melanocytes was more suppressed, but apoptosis was enhanced.
Discussion: We suggest that higher laser ablation energy induces greater apoptosis, and apoptosis destructs melanocyte precursor cells. This explains why regeneration of melanocytes is more suppressed at higher laser ablation energy levels in zebrafish skin.