Effects of magnesium degradation products on mesenchymal stem cell fate and osteoblastogenesis

The unique properties of magnesium (Mg) and its alloys that combine favourable mechanical properties, biocompatibility, and biodegradability, which until now have been restricted primarily to polymers, justify its study in the field of implantology. Previous in vivo studies have underlined the possible osteoconductive effects of Mg-based metals, and several in vitro studies have highlighted positive effects of Mg-enriched biomaterials. However, although the observed biological activity of magnesium is intriguing, it remains largely unexplored. Furthermore, due to increased regulations, the introduction of new implants on the market must be accompanied by thorough mechanistic understanding. Therefore, to mimic the in vivo effects of the degradation of Mg-based implants on mesenchymal stem cell differentiation during bone remodelling, non-haematopoietic multipotent foetal progenitor cells, i.e., human umbilical cord perivascular cells (HUCPV), were cultured for up to three weeks with or without osteoblastic differentiating media and with or without magnesium extract (approximately 5mM). To partially unveil the mechanism or to select paths for further investigation, a very broad selection of genes was chosen (e.g., those involved in osmolality sensing). Several classical bone markers were also studied at the gene and protein levels. The data suggest that Mg extract alone potentiates cell proliferation or delays the natural fate of maturation/differentiation. However, when the cells are driven toward osteoblastic differentiation, the effect of the Mg extract becomes much more complex, positively or negatively influencing differentiation via various pathways. These preliminary results confirm the choice of the various parameters utilised here and highzlight the importance of further studies.