Establishment of a BALB/c Mouse Model for Photoaged Skin: Insights into UV-Induced Dermatological Changes

Photoaging, primarily induced by prolonged ultraviolet (UV) radiation exposure, significantly alters skin structure and function, necessitating models for deeper understanding and intervention development. This study aims to establish a BALB/c mouse model for investigating photoaging, leveraging their haired skin and genetic consistency.

Six-week-old female BALB/c mice were subjected to repeated exposure to Ultraviolet A (315-400 nm) (UVA) and Ultraviolet B (280-315 nm) (UVB) radiation at doses corresponding to one and two minimal erythemal doses (MEDs), four times weekly for 12 weeks. Skin aging was evaluated through clinical observations of wrinkles, thickness, hydration, and elasticity, as well as histopathological analyses of epidermal and dermal thickness and collagen degradation. Additionally, gene expression was conducted for collagen Types I and III, and matrix metalloproteinases (MMPs) 1, 2, and 3.

UV-exposed mice exhibited significant increases in skin thickness and wrinkle formation, with concurrent decreases in hydration and elasticity compared to controls. Aging signs were more pronounced in the two MED-group than in the one MED-group. Histological assessment showed epidermal hyperplasia, dermal thickening, and collagen degradation. Furthermore, UV irradiation upregulated MMP-1, MMP-2, and MMP-3 expression while downregulating Collagen 1 and 3, indicating molecular pathways of skin aging.

The BALB/c mouse model effectively mimics human photoaging under chronic UV exposure using a two-MED protocol, which corresponds to a total dose of 51.8 J/cm² UVA and 5.53 J/cm² UVB. This practical model, which exhibits skin features comparable to those of humans, provides a closer approximation of human skin responses for comprehensive studies on the mechanisms and interventions of photoaging.