Cytocompatibility of Magnesium Alloys with Human Urothelial Cells: A Comparison of Three Culture Methodologies.

Magnesium (Mg) is a biodegradable metallic material, which has shown great potential for medical device applications. In this study, human urothelial cells (HUCs) were cultured with Mg-based substrates to investigate their cytocompatibility for potential urological device applications. Three different culture methodologies were explored to mimic different conditions, in an attempt to establish standard methods of evaluating cytocompatibility of Mg-based biomaterials for urological device applications. Direct culture is a suitable method when it is important to evaluate direct cell attachment on the biomaterial surfaces. Direct exposure culture is a desirable method for investigating the response of well-established cells in the body with newly implanted biomaterials. The exposure culture method is appropriate for evaluating cell-biomaterial interactions in the same environment, where they are not in direct contact with each other. The results showed differences in HUC behaviors with the same Mg-based substrates when different culture methods were used. The Mg-based substrates inhibited the HUC viability with direct contact at the cell-material interface in direct culture and direct exposure culture. The faster degrading Mg alloys containing yttrium reduced HUC density in direct culture, direct exposure culture, and exposure culture. The major soluble degradation products of Mg-based materials reduced HUC density significantly when the pH increased to 8.6 and above or the Mg ion concentration reached 10 mM and above. Mg-based biomaterials, especially the slower degrading alloys such as AZ31, should be further studied to determine their potential to be used for bioresorbable urological devices.