Rapid thawing enhances tissue destruction in a mouse model of cutaneous cryoablation: Insights into oxidative stress and neutrophil activation.

Abstract

Background: Cryoablation is an integral therapeutic approach in dermatology for eliminating viral warts and benign tumors by damaging tissue through freeze-thaw cycles. Rapid thawing of the frozen area by warming it with fingertips during cryoablation is a common technique in Japan; however, its efficacy has not been elucidated.

Objective: This study aimed to evaluate the effect of rapid thawing on cryoablation-treated skin and clarify the underlying mechanisms using cryoablation model mice.

Methods: Cryoablation was performed on the dorsal skin of mice using a liquid nitrogen-soaked cotton swab, followed by rapid thawing by warming with fingertips or natural thawing without treatment. The effects on skin ulcers, immune cell infiltration, and oxidative stress were assessed.

Results: Rapid thawing enlarged cryoablation-induced skin ulcers. The numbers of cryoablation-induced CD3⁺ T cells, neutrophils, neutrophil extracellular traps (NETs), and TUNEL⁺ cells increased with rapid thawing. Visualization of oxidative stress in OKD48 transgenic mice showed that oxidative stress signals in the cryoablation-treated area were enhanced with rapid thawing. Real-time PCR analysis of mouse skin demonstrated that cryoblation-induced levels of NOX2 and HO-1 were significantly elevated with rapid thawing. In mouse melanoma tumors treated with cryoablation, rapid thawing significantly inhibited tumor growth and increased the infiltration of neutrophils, NETs, and TUNEL⁺ cells compared to the group without rapid thawing.

Conclusion: Rapid thawing during cryoablation enhances neutrophil and lymphocyte infiltration, increases oxidative stress, and induces cell death, leading to greater tissue destruction in mice. Dermatologists should consider employing rapid thawing techniques during cryoablation when higher therapeutic intensities are required.