The effect of biomimetic coating and cuttlebone microparticle reinforcement on the osteoconductive properties of cellulose-based scaffolds.

Polymer-based scaffolds have already gained popularity in many biomedical applications due to convenient routes for fabrication and favourable structural, physicochemical and functional characteristics. However, polymeric scaffolds lack osteoconductivity and some synthetic polymers carry the risk of inflammatory response caused by degradation by-products. Those facts limit their practical use in bone tissue engineering. In this study, three-dimensional (3D) porous scaffolds from naturally derived polymer, namely regenerated cellulose, were prepared using a non-hydrolytic sol-gel and lyophilization techniques. To induce osteoconductive properties of the polymeric scaffolds, cuttlebone microparticles were immobilized and the surface coating was achieved via in vitro mineralization using 10-fold concentrated simulated body fluid (10x SBF). Biogenic activity of cuttlebone is explained by its chemical composition, which includes polysaccharide ß-chitin and macro-, micro- and trace elements favourable for mineralization. Parallel the scaffolds were examined during long-term (24 weeks) in vitro mineralization in 1x SBF for the purpose to investigate apatite-forming ability of the scaffolds. A nice cauliflower-like structures and needle-like dents of the spherical aggregates, which are characteristic to hydroxyapatite precursors, were observed on the surface of cellulose/cuttlebone scaffolds by SEM. 10x SBF coating enhanced cell attachment to the scaffolds because SBF elements are known to increase bioactivity by inducing re-deposition of carbonate apatite crystallites on scaffold surface. Additionally, calcium and phosphate depositions were clearly observed on the developed scaffolds using von Kossa and Alizarin Red S staining. Proliferative and osteoconductive effects on the osteoblast-like MG-63 cells demonstrate the cellulose/cuttlebone scaffolds soaked in 10x SBF as a favourable material for bone tissue engineering.

Osteoconductive 3D porous composite scaffold from regenerated cellulose and cuttlebone-derived hydroxyapatite.

Recently, usage of marine-derived materials in biomedical field has come into prominence due to their promising characteristics such as biocompatibility, low immunogenicity and wide accessibility. Among these marine sources, cuttlebone has been used as a valuable component with its trace elemental composition in traditional medicine. Recent studies have focused on the use of cuttlebone as a bioactive agent for tissue engineering applications. In this study, hydroxyapatite particles were obtained by hydrothermal synthesis of cuttlebone and incorporated to cellulose scaffolds to fabricate an osteoconductive composite scaffold for bone regeneration. Elemental analysis of raw cuttlebone material from different coastal zones and cuttlebone-derived HAp showed that various macro-, micro- and trace elements - Ca, P, Na, Mg, Cu, Sr, Cl, K, S, Br, Fe and Zn were found in a very similar amount. Moreover, biologically unfavorable heavy metals, such as Ag, Cd, Pb or V, were not detected in any cuttlebone specimen. Carbonated hydroxyapatite particle was further synthesized from cuttlebone microparticles via hydrothermal treatment and used as a mineral filler for the preparation of cellulose-based composite scaffolds. Interconnected highly porous structure of the scaffolds was confirmed by micro-computed tomography. The mean pore size of the scaffolds was 510 µm with a porosity of 85%. The scaffolds were mechanically characterized with a compression test and cuttlebone-derived HAp incorporation enhanced the mechanical properties of cellulose scaffolds. In vitro cell culture studies indicated that MG-63 cells proliferated well on scaffolds. In addition, cuttlebone-derived hydroxyapatite significantly induced the ALP activity and osteocalcin secretion. Besides, HAp incorporation increased the surface mineralization which is the major step for bone tissue regeneration.

Cuttlebone as a Marine-Derived Material for Preparing Bone Grafts.

The use of synthetic materials for biomedical applications still presents issues owing to the potential for unfavourable safety characteristics. Currently, there is increasing interest in using natural, marine-derived raw materials for bone tissue engineering. In our study, the endoskeleton of the mollusc Sepia, i.e. cuttlebone (CB), was used with regenerated cellulose (RC) to prepare three-dimensional composite bone grafts. CB microparticles were mechanically immobilised within a cellulose gel, resulting in a macroporous structure upon lyophilisation. The interconnected porous structure of the regenerated cellulose/cuttlebone (RC/CB) composite was evaluated by micro-computed tomography. The porosity of the composite was 80%, and the pore size predominantly ranged from 200 to 500 µm. The addition of CB microparticles increased the specific scaffold surface by almost threefold and was found to be approximately 40 mm-1. The modulus of elasticity and compressive strength of the RC/CB composite were 4.0 ± 0.6 and 22.0 ± 0.9 MPa, respectively. The biocompatibility of the prepared RC/CB composite with rat hepatocytes and extensor digitorum longus muscle tissue was evaluated. The obtained data demonstrated that both the composite and cellulose matrix samples were non-cytotoxic and had no damaging effects. These results indicate that this RC/CB composite is a novel material suitable for bone tissue-engineering applications.