New Methodological Approach to Follow the Re‐Epithelialisation Phase in the Wound Healing Process on a <scp>3D</scp> Full Thickness Skin Model

Scratch assays are commonly used as screening tools to assess the skin regenerative potential of new active ingredients; however, they lack the complexity of 3D stratified epidermis. Previously, a 3D migration model was developed to mimic the re-epithelialisation, especially phase III and IV of the wound healing process. To monitor the regenerative process on this model, Papanicolaou staining paired with histological observation at each day of the study was used. Unfortunately, the potential of this 3D model as a screening tool was limited since this methodology is time consuming, and its invasive nature implicates a large number of samples and high variability. An alternative method allowing evaluation of re-epithelialisation in 3D would circumvent these limitations and consolidate the in vitro evaluation model. This study introduces a novel methodology employing non-invasive Optical Coherence Tomography (OCT) and image processing algorithms, combined with a final quantification of the histological quality, to evaluate re-epithelialisation in a 3D skin model. OCT technology showed a high correlation to the previously described Papanicolaou staining technique. Moreover, two pro-epithelialisation compounds, oncostatin M (OSM) and ascorbic acid (VITC), were used as positive controls, bestowing the model with different repair profiles. This approach represents a significant advancement over traditional methods by proposing a reliable and robust evaluation method, extending the capability of the 3D in vitro model as a potential screening tool to understand the mechanisms of action of pro-epithelialisation actives in the process of skin regeneration and healing.