The Biocompatibility Of Biodegradable Magnesium-6Zinc Alloy With Intestinal Epithelial Cells And Its Effect On The Tight Junction Of The Intestinal Tract

OBJECTIVE Because of its good mechanical properties and biodegradable characteristics, Mg–6Zn alloy may be a promising candidate for use in gastrointestinal reconstruction in medicine. In this study, we evaluate the biocompatibility of degradable Mg-6Zn alloys with intestinal epithelial cells(IEC-6) in vitro, and its effect on the tight junction of the intestinal tract in vivo.MATERIALS AND METHODS In vitro cell experiments and in vivo animal experiments were included in this research. Before and after Mg-6Zn alloys were implanted in rat's cecum, blood biochemical tests were performed. Tissue samples were taken for histological evaluation and immunohistochemical tests. X radiography was performed every week to evaculate the degradation after surgery. In the in vitro experiments, IEC-6 cells were cultured in different concentrations of Mg-6Zn alloy extracts. Cytotoxicity test was performed using the MTT method. Flow cytometry analyse was performed to evaluate the effect of Mg-6Zn alloy extracts on cell apoptosis. Real-time PCR was used to detect the function related factors.RESULTS In vivo animal experiments, it was found that the liver and kidney functions(CREA, BUN, GOT or GPT), as well as the serum magnesium were not influenced after the implantion of Mg–6Zn alloys. Histological evaculation and immunohistochemistry results demonstrated that there was no obvious change of the mucosa in the site where Mg–6Zn alloys were in contact and the expression of ZO-1, occluding and caspase-3 was enhanced in healing tissue. In vitro cell experiments, the Mg–6Zn alloy extracts(under the concentration of 40%) have no significant effect on the growth of IEC-6 cells. The cytotoxicity was Grade 0–1, according to ISO 10993-5: 2009. The results of flow cytometric analysis showed, with the concentration increased, Mg-6Zn alloy extracts(40% concentration) can improve the percentage of apoptosis. By RT-PCR, we found that Mg-6Zn extracts can up-regulate the expression of occludin?claudins and ZO-1 m RNA, and enhanced the expression of Caspase-3 m RNA at the concentration of 40%.CONCLUSIONS After the implantion of Mg–6Zn alloys in the rat cecum, there was no obvious change of the mucosa appeared in the site. And the serum magnesium, CREA, BUN, GOT or GPT were not significantly varied before and after the operation. The in vivo and in vitro experiments showed that the expression of factors related with the tight junction of the cecum was increased. The low concentrations of Mg-6Zn alloy extracts have no significant cytotoxicity on the IEC-6 cells, while the high concentration(40%) may cause apoptosis. Due to its biodegradable characteristics, good mechanical properties and biological security, we think the Mg–6Zn alloy therefore may be a promising candidate for use in the gastrointestinal reconstruction in medicine.