Method for Investigation of Photobiological Effects of Light on Human Skin Cells In Vitro Using Visible and Near-Infrared Light.

Shaped by evolution, human skin cells have acquired a remarkable capacity to detect and react to sunlight photons through a wide array of photochemical processes. These reactions trigger intricate intracellular signaling cascades, ultimately resulting in photobiological effects that help regulate skin cell homeostasis. Some of these photobiological responses (also so-called photobiomodulation or low-level light therapy) are capable of initiating profound and beneficial therapeutic effects. To identify the regimes for these light-based therapeutic solutions, one needs to carefully decipher the physical, optical, biological, and chemical conditions that all need to be fulfilled to facilitate such positive photobiological effects. Here, we provide the protocols specifically developed to investigate multidimensional parameter space driving photobiological interactions triggered by light in the cells of human integumentary system. The approach also includes the so-called design of experiment (DoE), a statistical method, which allows for the investigation of multidimensional parameters landscapes. This goes hand in hand with sharing practical tips for the design of light-based devices for experimental work. We illustrate practical applications of our methods and light-based devices by sharing comprehensive experimental datasets, highlighting both the robustness and reproducibility of the results.