Bone-like matrix formation on magnesium and magnesium alloys

Abstract

Mg metal and its alloys have promise as a biocompatible, degradable biomaterials. This work evaluates the potential of in vitro cell culture work with osteoblast-like cells on Mg based materials, and investigates cell differentiation and growth on Mg alloyed with various non-toxic or low-toxicity elements. Mg based substrates support the adhesion, differentiation and growth of stromal cells towards an osteoblast-like phenotype with the subsequent production of a bone like matrix under in vitro conditions. No significant difference in the final tissue layer is observed on pure Mg, an AZ21 alloy or a 0.5 wt% Ca alloy. Only a 0.8 wt% Ca alloy which shows complete structural disintegration shows minimal cell growth. Due to association of non-soluble degradation products formed when Mg is incubated in physiological-like fluid, mass changes typically used to report Mg degradation are not viable estimates of degradation. Methods quantifying the time dependent change in the mechanical integrity of samples as a function of incubation time are required for a proper assessment of Mg degradation. We conclude that in vitro cell culture of bone cells on Mg substrates is expected to be a viable screening technique to assess the relative biological activity of Mg-based materials.

Assessment of Cellular Reactions to Magnesium as Implant Material in Comparison to Titanium and to Glyconate Using the Mouse Tail Model

“…Osteoinductive properties, which were observed for magnesium implants in previous in vitro [14] and in vivo studies with magnesium implant materials [15,11,19] , could not be confirmed in the present study. Although calcium phosphate precipitates were already found on the surface of magnesium after two weeks of implantation; which corresponds to an in vitro study, in which calcium phosphate precipitates were described on pure magnesium surface in synthetic biological media [20] , chondromatosis or cellular bone structures could not be observed even after an implantation period of 32 weeks.…”

The effects of surface and biomolecules on magnesium degradation and mesenchymal stem cell adhesion

“…Pietak et al reported very similar total protein synthesis and alkaline phosphatase activity in comparison with the glass control when rat bone marrow derived stromal cells were directly cultured on the Mg sample (99.8% purity) and the glass control for 8 days. 35 However, it is impossible to compare these results and draw a meaningful conclusion at this stage because of the significant variations in the surface, purity, and dimension of Mg samples as well as the cells used and the methods of cell culture and detection. To reduce the use of laboratory animals and speed up the new alloy development and screening, it is definitely necessary to develop standardized in vitro tests and establish models that can predict in vivo performance based on in vitro data.…”

Surface characterization and cytocompatibility evaluation of silanized magnesium alloy AZ91 for biomedical applications

“…Adding 9% Al to a Mg-Zn alloy yields the AZ91 alloy that has a higher corrosion resistance than Al-free Mg alloys and pure Mg [6][7][8], probably owing to the β-Mg 17 Al 12 phase. However, Mg alloys with relatively high Al content suppress cell growth on their surface [9].…”