BACKGROUND:A novel biodegradable Mg-Zn alloy has been designed,in which the density and the Young's modulus are proximal to human bone,at the same time,it depletes the toxicity of aluminium and rare earth element in commercial magnesium alloys.OBJECTIVE:To evaluate the cytocompatibility of biodegradable Mg-Zn alloy.DESIGN,TIME AND SETTING:Contrast study was performed in the central laboratory of the Sixth People's Hospital of Shanghai Jiao Tong University between November 2007 and March 2008.MATERIALS:The Mg-6wt%Zn was prepared by School of Materials Science and Engineering of Shanghai Jiao Tong University,with the density was 1.82 g/cm3 and the Young's modulus was 44 GPa.L-929 cells for cytocompatibility test were provided by Chinese Academy of Science Type Culture Collection.Ten male New Zealand rabbits were employed in the hemolysis test.METHODS:The Mg-Zn alloy extraction medium was prepared by serial dilutions with fresh medium to 10%,50% and 100%.The experiments were carried out in a 96-well tissue-culture plate.Simple DMEM culture solution was taken as negative controls,while DMEM culture solution supplemented with 0.64% phenol served as positive controls.MAIN OUTCOME MEASURES:Relative proliferation rate of L-929 cells was determined at 2,4 and 7 days with MTT assay.The cytotoxicity of Mg-Zn alloy was evaluated according to ISO 10993-5:1999.The L-929 cell morphology and growth at 2,4 and 7 days were determined under inverted microscope.Based on ISO 10993-4:2002,hemolysis in vitro was evaluated through measuring erythrocyte lysis and ferrohemoglobin freeing degree with indirect contact method.RESULTS:The number of L-929 cells increased significantly and the morphology was not changed.The growth and morphology of cells in different Mg-Zn extraction medium had no difference from negative control group.Cytotoxicity test showed that biodegradable Mg-Zn alloy did not have obvious toxicity on L-929 cells,and the cytotoxicity of these extracts was in grade 0-1.Hemolysis test suggested that the Mg-Zn alloys did not have obvious hemolysis reaction,and the hemolysis index was 3.4%,which was less than the national standard (5%).CONCLUSION:The Mg-Zn alloys do not have obvious cytotoxicity and hemolysis reaction,which demonstrate that Mg-Zn alloys have good cytocompatibility.