Date of Award


Degree Name

MS in Biomedical Engineering


Biomedical and General Engineering


Lily Laiho


Ultraviolet (UV) radiation has been demonstrated in numerous studies to be a major risk factor for non-melanoma skin cancer development. Despite the emergence of current UV-preventative strategies, such as sunscreens and skin-protective clothing, the incidence of non-melanoma skin cancer has continued to rise. This has encouraged investigations on alternative methods for UV prevention. In particular, bovine milk sphingomyelin has been studied for its potential in protecting human skin against UV photodamage. While the previous studies have suggested that sphingomyelin exhibits UV-protective properties in a human skin equivalent model, the exact mechanisms behind sphingomyelin’s photoprotective effects are yet unknown.

This thesis aims to further investigate the UV-protective effects of sphingomyelin in normal human epidermal keratinocytes, using nuclear p21 expression as a marker for UV photodamage. Keratinocytes were incubated for 24 hours in a 0.1% sphingomyelin solution and then exposed to 40mJ/cm2 of 302nm UV radiation. After 24 hours of post-UV incubation, nuclear p21 expression was evaluated using immunofluorescence. Confocal images were analyzed for their mean nuclear p21 fluorescence intensity measured in grayscale (0-255). Keratinocytes treated with sphingomyelin showed approximately a 50% decrease in UV-induced mean nuclear p21 intensity compared to keratinocytes with no sphingomyelin treatment (via Tukey’s test; p