Minimally invasive automated de-epithelization by precise ArF excimer laser ablation

Development of a robotic ArF excimer laser device with a three-dimensional (3D) pattern scanning sensor for the controlled de-epithelization of live mouse and xenografted epidermis.

The animal model could be adapted to humans for automated, minimally invasive de-epithelization of cutaneous areas and therefore is of interest for cutaneous gene therapy research.

Ablation thresholds of mouse, porcine, and human skin were measured by acoustic detection methods. These ablation thresholds were used as initial parameters for dosimetry measurements. De-epithelization of live mouse and xenografted epidermis was performed by laser ablation (ArF excimer laser, λ = 193 nm, t(p) = 20 nsec). The rectangular shape of the laser spot and a robotic arm displacement incorporating a three-dimensional patter scanning sensor allowed a polygonal tile floor irradiation of a 2-cm-diameter area. Ablated epidermis was subjected to histology.

SCID and nude mouse skin did not entirely reflect the de-epithelization of human skin because abundant pockets of dermal keratinocytes persist in the outer root sheath of hair and cysts providing competitive foci of re-epithelization. Automated de-epithelization of human and porcine skin xenografts resulted in precise removal of keratinocytes with subcellular precision, providing a smooth live surface where epidermal transplants might engraft with little endogenous competition from residual outer root sheath from rare hairs.

The displacement of the ArF excimer laser devices allows reproducible, smooth, and damage-free ablation of epidermal areas in the animal model.