Sustainable hydrogels from slaughterhouse waste: Vitreous humor for tissue engineering applications

Bioprocessing of slaughterhouse waste has paved the way for sustainable tissue engineering approaches that align with circular economy principles. Recent research demonstrates that efficient waste management across the entire food system can repurpose discarded tissues to extract bioactive molecules, tissue/organ templates, and biphasic materials. Hydrogels are notable examples of such materials, consisting of a unique porous network of biological macromolecules and liquid components. This architecture allows them to retain water while preserving their structural integrity and mechanical properties. The vitreous humor (VH) represents a compelling case within this paradigm. This perspective review explores the potential of animal-derived VH as a biomaterial for therapeutic applications by outlining its key structural and functional characteristics and examining its upcycling into functional hydrogels. The review then evaluates the biophysical properties of this gel obtained from both conventional (bovine, ovine, porcine, and caprine) and exotic (camelid) animal sources. Insights from the literature suggest that VH-based hydrogels show promise for various applications in additive manufacturing and regenerative medicine. Finally, the review identifies critical gaps in the research and challenges that must be addressed to facilitate the clinical translation of VH-derived biomaterials.