Affiliations: Escola Superior de Tecnologia, State University of Amazonas, Manaus, Brazil | Centre for Lasers and Applications, Nuclear and Energy Research Institute, São Paulo, Brazil | Instituto de Física “Gleb Wataghin”, State University of Campinas, Campinas, Brazil | São Paulo University, São Paulo, Brazil
Note:  Corresponding author: Denise Maria Zezell, Centre for Lasers and Applications, Nuclear and Energy Research Institute, Av. Prof. Lineu Prestes, 2242 – Cidade Universitária, São Paulo, Brazil. Tel.: +55 11 3133 9370; E-mail: firstname.lastname@example.org
Abstract: BACKGROUND: The techniques of second harmonic generation (SHG) and two-photon excitation of fluorescence microscopy (TPEFM) have shown as powerful tools to investigate collagen and extracellular matrix components. OBJECTIVE: The aim of this study is evaluate the feasibility of using femtosecond lasers of high intensity as an auxiliary treatment of burn patients using an in vivo model, monitoring and characterizing the healing process by histology and SHG+TPEFM. METHODS: Samples from three dorsum areas of Wistar rats anaesthetized were burned by water vapour exposure and treated by debridement and laser ablation at the third day post burned. To differentiating the healing process, skin fresh biopsies at four different days of study were evaluated by histology, TPEFM and SHG. RESULTS: Changes in the skin caused by vapour exposure were observed by histological images and characterized by TPEFM+SHG images. The healing process of burned skin was observed by regeneration of its morphology comparing histological images. The integrity of collagen and components of extracellular matrix are evidence of a normal skin detected by TPEFM+SHG. CONCLUSIONS: The methods used to characterize the tissue are useful to validate the femtosecond lasers ablation treatment of burned skin.