In vivo wound healing and dermal matrix remodelling in response to fractional CO2 laser intervention: Clinicopathological correlation in non-facial skin

Abstract

Purpose: Ablative fractional photothermolysis is a new concept for treatment of aged skin. Despite the low frequency of side effects there are now several reports about scarring, especially in non-facial regions like the neck. Our study aimed to investigate the in vivo wound healing process and remodelling in an area prone to scarring using a fractional ablative CO2 laser with three different energy protocols.Materials and methods: Six patients with photo-damaged skin received a single fractional ablative treatment using a 250-µm scanning CO2 laser. Three areas on the neck were treated with 50, 100 and 300 mJ/microbeam at densities of 200, 150 and 100/cm2, respectively. Biopsies were taken from untreated skin (control) and 10 minutes, 3 days, 14 days, 21 days and 28 days post-intervention.Results: Fractional ablation with higher energies resulted in increased total thermal damage. Overall, 50 mJ was effective up to the superficial dermis, 100 mJ up to the mid-dermis, and 300 mJ resulted in deep dermal ablation. The intensity of lymphocytic inflammation and dermal remodelling correlated with the total amount of thermal damage. At 300 mJ, granuloma was present and persisted for at least 4 weeks as opposed to clinical healing, which was completed < 2 weeks.Conclusions: With the above-mentioned low and medium parameter settings, ablative fractional photothermolysis is safe and effective in non-facial skin. However, dermal remodelling continues for up to 4 weeks, which should be the minimum space between treatment sessions. Higher energies may induce granuloma formation, possibly a sign of an overstrained remodelling capacity.