Keratinocyte and Fibroblast Wound Healing In Vitro Is Repressed by Non-Optimal Conditions but the Reparative Potential Can Be Improved by Water-Filtered Infrared A.

It is a general goal to improve wound healing, especially of chronic wounds. As light therapy has gained increasing attention, the positive influence on healing progression of water-filtered infrared A (wIRA), a special form of thermal radiation, has been investigated and compared to the detrimental effects of UV-B irradiation on wound closure in vitro. Models of keratinocyte and fibroblast scratches help to elucidate effects on epithelial and dermal healing. This study further used the simulation of non-optimal settings such as infection, chronic inflammation, and anti-inflammatory conditions to determine how these affect scratch wound progression and whether wIRA treatment can improve healing. Gene expression analysis for cytokines (, , ), growth (, ) and transcription factors (, ), heat shock proteins (, , ), keratinocyte desmogleins (, ), and fibroblast collagen (, ) was performed. Keratinocyte and fibroblast wound healing under non-optimal conditions was found to be distinctly reduced in vitro. wIRA treatment could counteract the inflammatory response in infected keratinocytes as well as under chronic inflammatory conditions by decreasing pro-inflammatory cytokine gene expression and improve wound healing. In contrast, in the anti-inflammatory setting, wIRA radiation could re-initiate the acute inflammatory response necessary after injury to stimulate the regenerative processes and advance scratch closure.