Collagen from a marine resource is believed to have more potential activity in bone tissue engineering and their bioactivity depends on biochemical and structural properties. 

Considering the above concept, pepsin soluble collagen (PSC) and soluble acid collagen (ASC) from blue shark (Prionace glauca) skin were extracted, and its biochemical and osteogenic properties were investigated.

The hydroxyproline content was higher in PSC than ASC, and the purified collagens contained three distinct bands α1, α2, and β dimer. , and the thermogravimetric data showed a two-step thermal degradation pattern. ASC had a sharp decline in viscosity at 20–30 °C. Scanning electron microscope (SEM) images revealed the fibrillar network structure of collagens.

Proliferation rates of the differentiated mouse bone marrow-mesenchymal stem (dMBMS) and differentiated osteoblastic (dMC3T3E1) cells were increased in collagen treated groups rather than the controls, and the effect was dose-dependent, which was further supported by higher osteogenic protein and mRNA expression in collagen treated bone cells.

Among two collagens, PSC had significantly increased dMBMS cell proliferation, and this was materialized through increasing RUNX2 and collagen-I expression in bone cells.

Sharkskin collagen

Accordingly, the collagens from blue shark skin with excellent biochemical and osteogenic properties could be a suitable biomaterial for therapeutic application.

In this study, two types of collagens, PSC and ASC were isolated and purified from blue shark skin, which contained three distinct chains, 2 alpha, and beta chains.

The amino acid composition and the FTIR secondary structure of PSC varied with ASC due to pepsin hydrolysis. Among two collagens, PSC had high thermal stability, which might be due to high imino acid content.

Most importantly, the obtained collagens promoted osteoblast cell growth and upregulated collagen synthesis in bone cells, which is a most desirable property of biomaterials for the treatment of a bone disorder.

The proliferation of differentiated osteogenic cells by blue sharkskin collagen may be achieved through activation of Runx2 dependent FAK/JNK signaling pathway.

Overall, the blue sharkskin collagens with good biochemical and osteogenic properties may be considered as a potential drug in biomedical application. Conversely, the in vivo evaluation of blue sharkskin collagen and its molecular interaction with bone cells needs to be addressed by further research to understand the actual mechanism of the action.