An Innovative Bioengineering Approach to Investigate the Response of Melanin-Rich Cells to Intense Pulsed Light (IPL).

Light-based therapies are becoming increasingly = more mainstream, not only within the medical science space, but also within the fields of cosmetic dermatology and personal grooming. Intense Pulsed Light (IPL) harnesses the ability of the natural chromophore-melanin to absorb light energy, which is translated into heat energy and consequently results in targeted thermolysis of cells rich in melanin. This mechanistic pathway lends itself to a wide range of applications, including long-term hair removal, skin rejuvenation, the treatment of unwanted pigmentation, and the treatment of ophthalmic conditions. The development of home use devices (HUDs) for the delivery of IPL-mediated hair removal has facilitated the self-administration of photothermal treatments and reduced reliance on clinical settings. In this study, we demonstrate a pioneering approach to model aspects of IPL-induced thermal induction and selective thermolysis in a complex human skin tissue equivalent. Our approach utilised a deactivated HUD with disabled safety features that allowed for the exposure of tissue constructs to high-fluence IPL. We demonstrate an increase in biomarkers consistent with increased cellular temperature, induction of apoptosis, and increased pro-inflammatory cytokine release following extreme treatment regimens, all of which correlate with an increased fluence and/or increased number of IPL pulses delivered. This method allowed for the identification of cellular events evoked by increasing fluence and extreme-exposure regimes.