Engineered atopic dermatitis models for recreating hypoxic conditions in atopic dermatitis microenvironments.

Atopic dermatitis (AD) is a chronic inflammatory condition with severe itching. The complex physiology and diverse pathogenesis of AD complicate the prediction of clinical outcomes. Therefore, it is essential to develop preclinical models closely mimicking features of AD. Herein, gelatin-based in situ crosslinkable hydrogel AD models are engineered replicating the characteristics of AD tissue. First, public data of patients with AD is used to confirm the following, using single-cell RNA sequencing analysis: (1) collagen type VI alpha 5 chain (COL6A5+) fibroblast expression in patient tissues, (2) cell interaction with dorsal root ganglions that induce itching, and (3) overexpression of hypoxia-related factors in AD tissues. Based on these characteristics, an artificial AD model is developed using gelatin-based in situ crosslinked hydrogels. 3D cell culture systems are fabricated by encapsulating cells within hydrogels, supporting 3D cell survival and growth. These models exhibit a hypoxic (pO2 < 5 %) environment within the hydrogels, with upregulated expression of hypoxia-related genes. In these hydrogel-based skin models, the AD microenvironment is recreated, inducing immune responses and chronic hypoxia through IL-4 treatment and controlled oxygen concentration. Overexpression of itch-related factors, evaluation of drug response to treatment, and gene upregulation under hypoxic and immune conditions are also analyzed in the models. Our platforms are potential preclinical models for drug screening and fundamental research.