Approximately 75,000 tons of different sea urchin species are globally harvested for their edible gonads. Applying a circular economy approach, we have recently demonstrated that non-edible parts of the Mediterranean Sea urchin Paracentrotus lividus can be fully valorized into high-value products: antioxidant pigments (polyhydroxynaphthoquinones—PHNQs) and fibrillar collagen can be extracted to produce innovative biomaterials for biomedical applications. Can waste from other edible sea urchin species (e.g., Sphaerechinus granularis) be similarly valorised? A comparative study on PHNQs and collagen extraction was conducted. PHNQ extraction yields were compared, pigments were quantified and identified, and antioxidant activities were assessed (by ABTS assay) and correlated to specific PHNQ presence (i.e., spinochrome E). Similarly, collagen extraction yields were evaluated, and the resulting collagen-based biomaterials were compared in terms of their ultrastructure, degradation kinetics, and resistance to compression. Results showed a partially similar PHNQ profile in both species, with significantly higher yield in P. lividus, while S. granularis exhibited better antioxidant activity. P. lividus samples showed higher collagen extraction yield, but S. granularis scaffolds showed higher stability. In conclusion, waste from different species can be successfully valorised through PHNQ and collagen extraction, offering diverse applications in the biomedical field, according to specific technical requirements.

Preclinical investigations involving in vivo animal studies, are considered a crucial and mandatory step in pharmacological industry regulations. In recent years, as the ethical concerns associated with animal experimentation are becoming more relevant, substantial research efforts have been directed towards the development of novel in vitro methodological approaches aimed at minimizing the utilization of animals. Among those, three-dimensional (3D) cell culture systems have become one of the most promising substitutes for animal models. Skeletal muscle can be affected by genetic disorders and injuries. In this study, two types of 3D scaffolds (Coll and CollMA), prepared starting from a fibrillar collagen suspension extracted from sea urchin food waste, were used as platforms for the generation of 3D skeletal muscle tissue models. The scaffolds were cellularized with C2C12 myoblasts. As the culture period progressed, C2C12 cells gradually infiltrated and were viable throughout both scaffold types, establishing a multilayered cellular population. In the CollMA scaffold, the reciprocal Pax7/MyoD expression pattern suggests a progression of myoblasts towards myogenic commitment. Taken together, our results, although preliminary, suggest that sea urchin–derived collagen matrix represents a promising scaffold for skeletal muscle tissue engineering.