Dual-mode OCT/fluorescence system for monitoring the morphology and metabolism of laser-printed 3D full-thickness skin equivalents

The 3D structure of native human skin is fundamental for studying skin health,
diseases, wound healing, and for testing the safety of skin care products, as well as personalized
treatments for skin conditions. Tissue regeneration, driven by tissue engineering, often involves
creating full-thickness skin equivalents (FSE), which are widely used for developing both healthy
and diseased skin models. In this study, we utilized human skin cell lines to create FSE.
We designed high-resolution 3D scaffolds to support the growth and maturation of these skin
models. Additionally, we developed and validated a cost-effective, custom-built system combining
fluorescence spectroscopy (FS) and optical coherence tomography (OCT) for non-destructive
analysis of the metabolism and morphology of 3D FSEs. This system proved highly sensitive in
detecting fluorescence from key metabolic co-enzymes (NADH and FAD) in solutions and cell
suspensions, while OCT provided adequate resolution to observe the morphology of FSEs. As a
result, both the 3D FSE model and the dual-mode optical system hold significant potential for
use in 3D bioprinting of biological tissues, as well as in the development of cosmetics, drugs,
and in monitoring their maturation over time.