 Crystalline Mg–Zn–Ca ternary alloys have recently attracted significant
interest for biomedical implant applications due to their promising
biocompatibility, bioactivity, biodegradability and mechanical
properties. The objective of this study was to characterize as-cast
Mg–xZn–0.5Ca (x = 0.5, 1.0, 2.0, 4.0 wt.%) alloys, and determine the
adhesion and morphology of bone marrow derived mesenchymal stem cells
(BMSCs) at the interface with the Mg–xZn–0.5Ca alloys. The direct
culture method (i.e. seeding cells directly onto the surface of the
sample) was established in this study to probe the highly dynamic
cell–substrate interface and thus to elucidate the mechanisms of BMSC
responses to dynamic alloy degradation. The results showed that the BMSC
adhesion density on these alloys was similar to the cell-only positive
control and the BMSC morphology appeared more anisotropic on the rapidly
degrading alloy surfaces in comparison with the cell-only positive
control. Importantly, neither culture media supplemented with up to
27.6 mM Mg2+ ions nor media intentionally adjusted up to
alkaline pH 9 induced any detectable adverse effects on BMSC responses.
We speculated that degradation-induced dynamic surface topography played
an important role in modulating cell morphology at the interface. This
study presents a clinically relevant in vitro model for screening
bioresorbable alloys, and provides useful design guidelines for
determining the degradation rate of implants made of Mg–Zn–Ca alloys. |
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