Biocompatibility and osteogenic activity of guided bone regeneration membrane based on chitosan-coated magnesium alloy

Ideally, a guided bone regeneration membrane (GBRM) should possess high strength, as for titanium membranes, along with excellent biocompatibility and osteoconductivity, as for natural absorbable collagen membranes. Besides titanium, magnesium (Mg) is another metal widely used in the biomedical field, which also exhibits biodegradability. In this study, a composite chitosan-magnesium (CS-Mg) membrane was fabricated by dip-coating Mg alloy into chitosan solution. In vitro and in vivo tests were performed to investigate whether this membrane could be used as biodegradable GBRM, and the test results were compared with those obtained for a commercial GBRM (Heal-All). The microstructure was analyzed by scanning electron microscopy-electron dispersive spectroscopy. The degradation behavior was investigated by immersing the membranes into Dulbecco's modified Eagle medium (DMEM). The in vitro biocompatibility was evaluated by cell adhesion, cytotoxicity and alkaline phosphatase (ALP) assays using MG63 cells. The cytotoxicity and ALP assays were performed with diluted extracts of Mg, CS-Mg and Heal-All. The results show that CS-Mg has a suitable degradation rate, as well as similar cell adhesion and cytocompatibility to Heal-All. However, the 10% CS-Mg extracts exhibited higher ALP activity at 3 and 5 days (p < 0.05) compared with the medium control and the Heal-All extracts, but no differences with 10% Mg extracts (p > 0.05). Rabbit calvarial defects were used for testing the osteogenic activity in vivo. Three groups of samples were examined: CS-Mg, Heal-All, and a blank control. Higher amounts of new bone were formed for the CS-Mg and Heal-All groups (p < 0.05) compared with the blank control, whereas no significant differences between the CS-Mg and Heal-All groups were observed (p > 0.1). In conclusion, the CS-Mg membrane shows great potential for application as a biodegradable metallic GERM with excellent osteogenic activity.