Generation of novel blue natural biomaterials from fish scales for use in cornea repair and engineering

• Novel biomaterials for use in corneal regeneration can be generated by preconditioning scales obtained from different species of fish. • Fish scale biomaterials showed adequate optical and biomechanical properties and were biocompatible when grafted subcutaneously in vivo in laboratory rats. • These biomaterials support cell growth and survival and cultured cells showed positive expression of epithelial cel markers without altering their optical properties. • In vivo grafting on the rabbit cornea showed that these biomaterials are biocompatible, and grafted corneas expressed several markers of corneal differentiation. • Fish scale biomaterials demonstrated to be potential scaffolds for corneal repair and tissue engineering. Fish scale biomaterials (FSB) were obtained from red scorpionfish (SSC), salmon (SSA), white sea bream (DS) and European carp (CC). Native FSB were preconditioned and cellularized with limbal epithelial cells, and evaluated ex vivo and in vivo . Results showed that preconditioned FSB showed high light transmittance and low reflectance, absorption and scattering coefficients, and proper biomechanical properties. Then, we found that FSB were biocompatible in vivo , and subcutaneous grafting in laboratory animals was not associated with a pathological local or systemic reaction, especially in CC-FSB. After recellularization, FSB supported cell attachment, proliferation and differentiation, with positive expression of limbal epithelial cell markers, and very good optical properties, with the lowest levels of scattering and absorption found in CC-FSB. Intracorneal implant of CC-FSB in laboratory rabbits demonstrated that this biomaterial was also biocompatible to the native cornea, and corneas grafted with CC-FSB had normal expression of corneal epithelium and stromal markers, such as cytokeratin 3, crystallin alpha-A, p63, collagen, proteoglycans and lumican, and devoid of any detectable signs of rejection, inflammation or neovascularization. These findings indicate that CC-FSB potentially meet the criteria for biomaterials used in corneal regeneration, making it a promising candidate for corneal tissue engineering applications.