Label-free Raman imaging defines distinct cell populations in human skin

Abstract Understanding cellular heterogeneity in human skin is crucial for regenerative medicine and tissue engineering. In this study, we applied label-free Raman imaging to visualize molecular features corresponding to the three-dimensional architecture of the epidermis. Spatially resolved Raman spectra, combined with multivariate data analysis, enabled the identification of cell-layer–specific molecular signatures. Based on the region-specific spectra analysis, component C5 was predominantly localized to the basal layer within rete ridges and was characterized by β-sheet–enriched keratin features. This spatially restricted distribution reflects the molecular microenvironment of epidermal stem cell niches, suggesting that C5 may serve as a biomarker for basal stem cell populations associated with skin undulations. These findings provide insight into the molecular basis of epidermal architecture and demonstrate the potential of Raman spectroscopy as a label-free tool for evaluating stem cell localization and differentiation status. Competing Interest Statement The authors have declared no competing interest.