Using Optical Imaging Methods to Assess Laser-Tissue Interactions

Abstract

Recent years have seen an explosive increase in the use of lasers for medical applications, particularly in the field of dermatology where they are commonly used to achieve aesthetic, surgical, and therapeutic clinical objectives. Effective cutaneous laser procedures are achieved by tailoring the operating parameters of the laser to the physical and optical properties of the skin. Ideal laser parameters are selected to optimize therapeutic efficacy while minimizing unwanted side effects and tissue damage. Laser-induced tissue injury is known to occur via oxidative, photothermal, photomechanical, and photochemical mechanisms. However, the specific cellular and molecular pathways that initiate and govern these mechanisms are poorly understood. The primary objective of this research was to develop skin models and in vivo molecular imaging techniques to investigate laser-skin interactions. In this work, human skin cells, skin equivalent models, and animal models were developed to assess cellular damage associated with aesthetic, ablative, and therapeutic laser procedures. Thermal damage was assessed using a reporter gene system in which the activation of a thermo-responsive gene (hsp70A1) acts like an “on-off” switch for the expression and production of light emitting reporter genes. The models were used in this study to: (1) evaluate sublethal cellular damage in aesthetic laser procedures, (2) assess collateral damage in laser surgical ablation procedures, and (3) develop a therapeutic laser preconditioning protocol to enhance cutaneous wound repair. The use of skin models in conjunction with a thermally responsive reporter is a useful strategy for assessing sublethal thermal damage and is a valuable tool for improving medical laser procedures.