TUNEL assay to characterize acute histopathological injury following treatment with the active and deep FX fractional short-pulse CO₂ devices

Background: This is a report of the histopathological evaluation of the acute damage profile in human skin following treatment with two novel short-pulsed fractional carbon dioxide resurfacing devices used independently and in combination in vivo. Methods: The panni of eight abdominoplasty patients were treated with either the Active FX, the Deep FX (Lumenis Ltd., Yokneum, Israel), or a combination of the two (Total FX) prior to the start of the excisional surgical procedure. Multiple combinations of energies, pulse widths, and densities were evaluated for each device. After surgical removal (two to five hours), each pannus was immediately biopsied and samples were processed for histopathological evaluation. Results: The Active FX system resulted in extensive epidermal injury with wide shallow ablation craters that, at higher fluences, extended through the basement membrane of the epidermis into the papillary dermis. The Deep FX fractional treatment caused deep microcolumns of ablation penetrating up to 3 to 4 mm from the epidermal surface into the deep reticular dermis with a variable rim of coagulated collagen surrounding each ablation column. Conclusions: The in vivo histopathological evaluation of these devices furthers our understanding of the fundamental laser/tissue interaction following treatment with each device independently and in combination.