Open-air human skin equivalent platform enabling photobiological studies and topical product testing.

Summary

The authors engineered an open-air HSE platform that preserves sterility and barrier function while allowing realistic UV exposure and topical product application. The model showed a ~1.5-fold tanning response to UV and dose-dependent suppression by commercial sunscreens, maintaining viability and function under natural sunlight and wind.

Key Findings

• A mechanically supported, barrier-integrated open-air HSE exposes only the cornified layer while maintaining sterility.
• UV irradiation elicited ~1.5-fold pigmentation increases, quantifying tanning responses.
• Commercial sunscreens suppressed pigmentation in a dose-dependent manner to near-baseline levels.
• The platform maintained tissue viability and barrier function under natural sunlight and wind.

Clinical Implications

Improved preclinical testing of sunscreens and topical agents may reduce reliance on in vivo testing, de-risk clinical development, and enhance consumer safety by identifying ineffective or irritating products earlier.

Limitations

• In vitro tissue lacks vascular and full immune components, limiting extrapolation to in vivo responses.
• Product types and endpoints tested were limited; long-term photostability and irritation assessments were not reported.

Future Directions

Integrate immune cells/appendages, expand to broader product classes, and correlate platform readouts with clinical tanning and sunburn protection outcomes to establish predictive validity.