Valorization of sturgeon skin to produce biomedical-grade gelatin

Abstract

Gelatin, a collagen derivative used in tissue engineering, is often sourced from mammals; however, this raises concerns regarding diseases found in both humans and mammals. Therefore, this study aimed to valorize sturgeon skin, a processing by-product of caviar, to produce marine gelatin as a safe alternative to mammalian gelatin. To that end, acid-pretreated type A (ASG), alkali-pretreated type B (BSG), and alkali-acid-pretreated type C (CSG) gelatins were extracted from sturgeon skin. The ASG and CSG had high yield (dry weight basis) at 66.6% and 57.7%, respectively, with >97% gelatin content in samples, thicker α- and β-bands with minimal low molecular mass fragments in Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and <0.2 endotoxin units per mg. A heat-stable (37 °C) gelatin gel was developed using 1% (w/v) gelatin with 5.0 mM N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) crosslinking. The ASG and CSG gels showed higher elastic modulus and stress at break than porcine biomedical-grade type A skin gelatin (PSG). Proliferation of L929 fibroblasts, ATDC5 pre-chondrocytes, and MC3T3-E1 pre-osteoblasts on ASG, CSG, and PSG gels and control (cell culture well) were similar. The alkaline phosphatase activities of MC3T3-E1 cells cultured on the ASG, CSG, and PSG gels showed earlier activation than on the control, whereas mineral deposition was highest on the ASG gel. Considering the simple extraction, yield, and mineralization-inducing ability of MC3T3-E1 cells, ASG was the most suitable biomedical-grade gelatin alternative to mammalian gelatin. The present study proposes a novel valorization method for sturgeon skin to produce gelatin, which has biomedical applications.