Multiphoton Microscopy of Collagen Structure in Ex Vivo Human Skin Following Electrochemical Therapy.

[OBJECTIVES] Injury to healthy dermis and the dermoepidermal junction initiates a robust healing process consisting of fibrous tissue overgrowth, collagen deposition, and scar formation. The conventional management of scars and other skin injuries has largely relied upon surgical soft tissue transfer to resurface and/or replace damaged and dysmorphic tissue with new skin. However, these strategies are invasive, expensive, and may further exacerbate integumentary injury. In this study, we examine the creation of in situ redox generated pH changes in fresh human skin. We believe this process of "electrochemical therapy" (ECT) leads to changes in collagen matrix structure. Our objective is to map local tissue pH landscapes and image changes in collagen structure of non-injured skin following ECT.

[STUDY DESIGN] Ex vivo human study involving ECT of human skin.

[METHODS] Remnant fresh ex vivo human facial skin from facelift operations was enveloped in saline-soaked gauze for a maximum of 2 hours prior to ECT and imaging. ECT was performed by inserting platinum-plated needle electrodes connected to a DC power supply. Voltage (4, 5, or 6 V) and time (3, 4, or 5 minutes) were varied systematically. High frequency ultrasound (25 MHz) was performed immediately after ECT on each sample. Treated samples were also imaged using multiphoton microscopy (MPM) with second harmonic generation (SHG) to specifically visualize collagen fibers in the dermis. The pH landscapes were mapped using indicator dyes in bisected specimens and the MPM images were compared with histologic findings.

[RESULTS] Above 4 V and 3 minutes, a profound reduction in dermal collagen SHG signal was observed at the anode. Although there was less blunting of SHG signal seen at the cathode, a decrease in the fluorescence of the dermoepidermal junction was observed. The pH application suggests ECT spatial selectivity and a direct relationship between voltage and application time. Ultrasound demonstrated gas formation between the anode and cathode, which is consistent with ECT's mechanism of action. Importantly, these electrochemical changes occurred without disrupting dermal and epidermal histologic architecture.

[CONCLUSION] ECT alters tissue pH leading to dermal collagen structural change. These results offer additional insight into the translational potential of ECT to locally remodel the soft-tissue matrix. Future directions aim to expand into a skin injury model to determine if similar collagen effects are observed in vivo. ECT is incredibly inexpensive (~$5) and may be a means to treat soft tissue injuries using simple needle-based devices and DC battery power supplies. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.