Natural Compounds From The Seafood Waste To Ameliorate Skin Repair

Wound healing is a complex process orchestrated by the dynamic interaction of multiple cell types and structural proteins aiming to restore the lost skin integrity. However, it does not always lead to wound closure, but it rather results in the formation of scar or, in different circumstances, the generation of chronic wounds. For this reason, wound care has been considered a worldwide challenge and an economical burden; thus, the development of new healing devices is widely investigated. Wound dressings cover the lesion protecting it from damage while promoting its healing. Furthermore, the creation of multifunctional wound dressings by adding bioactive molecules might further improve healing outcomes. Herein, we describe the application of a marine collagen-based wound dressing enriched with antioxidant molecules to treat skin wounds. Collagen and antioxidant pigments, namely polyhydroxynapthoquinones (PHNQs), were extracted from sea urchin (Paracentrotus lividus) food-waste. First, the biological activity of PHNQs was assessed in vitro. PHNQs were tested for cytotoxicity on dermal fibroblasts, then cells were exposed to non-cytotoxic concentrations in an oxidative stress environment to assess PHNQs antioxidant properties by investigating reactive oxygen species (ROS) concentration, mitochondrial membrane potential (ΔΨm), and protein expression of antioxidants enzymes. Secondly, PHNQs were incorporated into a collagen-based membrane (MCDT) and tested in an experimental wound model. Two circular skin lesions were surgically created on the back of 32 rats: one wound was left untreated, and one treated with the MCDT or MCDT added with pigments (A-MCDT). Wounds were monitored daily, and at 5- and 10-days post-wounding samples were collected for histopathological analysis and gene expression studies. PHNQs showed no cytotoxicity at low concentrations (1-10 μg/mL) and demonstrated to possess scavenging activity by reducing the ROS levels and protecting cells against oxidative stress. Moreover, they were able to maintain proper levels of ΔΨm and to upregulate the protein expression of SOD2. Histologically, at 5 days untread wounds showed a mild inflammatory infiltration whereas treated wounds showed a similar pattern of inflammatory cells but lower in A-MCDT-treated wounds. At 10 days, inflammation leveles were similar. Furthermore, treated lesions presented with a more abundant presence of granulation tissue (GT) at day 5 compared to untreated ones; nevertheless, at day 10 an opposite trend was observed: treated wounds, showed a higher maturation level of the GT and a more mature dermis, this result might be related to the up-regulated TIMP-2 gene expression, especially in the A-MCDT group. Also, re-epithelialization appeared higher in A-MCDT-treated wounds as they showed a more prominent presence of epithelium on the healing skin. This result is corroborated by the higher gene expression of MMP-9, a proteinase involved in keratinocyte migration. Overall, treated wounds showed a better trend of healing compared to untreated ones. Indeed, these wounds showed a better development of the GT into mature dermis and higher levels of re-epithelialization, both processes supported at the histological and molecular level. The addition of antioxidant pigments allowed an improved skin reparation as lower levels of ROS in the wound might have sustained proper and faster healing.