New frontiers in applied zoology: innovative 3D marine-derived collagen scaffolds for regenerative medicine

Living organisms, and particularly marine ecosystems, are a huge source of still largely unexplored “blue” innovations for different human applications. The sustainable exploitation of resources from the sea and their eco-friendly management are currently two of the main challenges of marine biotechnology. Among the others, marine biomaterials (and marine collagens in particular) are a frontier field in regenerative medicine. Echinoderms, and especially echinoids, have been recently proposed as sustainable sources of marine collagen for this purpose. Particularly from Paracentrotus lividus peristomial membranes high value fibrillar collagen can be obtained to prepare very thin but resistant two-dimensional (2D) membranes, useful for Guided Tissue Regeneration (FERRARIO et al. 2016). In this work, we developed and optimized a new protocol to produce three-dimensional (3D) scaffolds for novel tissue engineering applications, such as skin regeneration. Different collagen and additive (ethanol) concentrations were tested as well as two freeze-drying conditions: -80°C vs -196°C. The so obtained 3D scaffolds were characterized and compared in terms of ultrastructure, stability and behaviour in wet conditions. The dry scaffolds observed at SEM presented a highly porous structure which could be tuned according to the different protocol conditions. Once identified the best protocol in terms of ultrastructural features and stability it was used to prepare sponge-like scaffolds (1-2 mm in thickness) to perform experiments of cell seeding with mammalian fibroblasts. In parallel, to evaluate the biocompatibility of this novel marine collagen biomaterial, in vivo tests were performed by sub-skin implantation of thin membranes in rat models. First results indicated that the animals did not show clinical signs of sufferance nor marked inflammatory reactions (i.e. rejection, abscess formation) compared to commercial bovine collagen devices used as controls, suggesting a promising biocompatibility of this material. Overall, our data indicated that sea urchins might be considered a valuable eco-friendly alternative source of marine collagen to produce different types of devices for regenerative medicine applications, including complex 3D scaffolds. Further in vivo tests with larger size animals (i.e. sheep) are necessary to validate the biocompatibility of this innovative marine biomaterial and to test its actual efficacy in promoting tissue regeneration.