Magnesium reduces calcification in bovine vascular smooth muscle cells in a dose-dependent manner

Abstract

Background.Vascular calcification (VC), mainly due to elevated phosphate levels, is one major problem in patients suffering from chronic kidney disease. In clinical studies, an inverse relationship between serum magnesium and VC has been reported. However, there is only few information about the influence of magnesium on calcification on a cellular level available. Therefore, we investigated the effect of magnesium on calcification induced by β-glycerophosphate (BGP) in bovine vascular smooth muscle cells (BVSMCs).Methods.BVSMCs were incubated with calcification media for 14 days while simultaneously increasing the magnesium concentration. Calcium deposition, transdifferentiation of cells and apoptosis were measured applying quantification of calcium, von Kossa and Alizarin red staining, real-time reverse transcription–polymerase chain reaction and annexin V staining, respectively.Results.Calcium deposition in the cells dramatically increased with addition of BGP and could be mostly prevented by co-incubation with magnesium. Higher magnesium levels led to inhibition of BGP-induced alkaline phosphatase activity as well as to a decreased expression of genes associated with the process of transdifferentiation of BVSMCs into osteoblast-like cells. Furthermore, estimated calcium entry into the cells decreased with increasing magnesium concentrations in the media. In addition, higher magnesium concentrations prevented cell damage (apoptosis) induced by BGP as well as progression of already established calcification.Conclusions.Higher magnesium levels prevented BVSMC calcification, inhibited expression of osteogenic proteins, apoptosis and further progression of already established calcification. Thus, magnesium is influencing molecular processes associated with VC and may have the potential to play a role for VC also in clinical situations.

Magnesium in Man: Implications for Health and Disease

“…Low serum Mg 2ϩ levels are associated with vascular calcification, and hemodialysis patients with higher serum Mg 2ϩ levels show higher survival (258,259). Although the mechanisms of action are not completely understood, there are two contributing factors: 1) Mg 2ϩ prevents the formation and deposition of Ca/P nanocrystals and the development of appatite structures (83); and 2) Mg 2ϩ inhibits the transdifferentiation of the smooth muscle cells in the vessel well into osteoblast-like cells (282). In both processes Mg 2ϩ prevents vascular calcifiction, and thus hypomagnesemic patients are at risk.…”

Phosphate control in dialysis

“…42 An interesting feature of magnesium is its inhibiting effect on vascular calcifications in in-vitro and experimental models. 43 Some authors observed a significant association between low serum magnesium levels and vascular calcifications in 390 hemodialysis patients. 44 The role of possible magnesium accumulation in bone tissues is still uncertain.…”

Lowering vascular calcification burden in chronic kidney disease: Is it possible?

“…In hemodialysis and peritoneal dialysis patients, lower serum magnesium but still within the normal range was associated with an increased severity of vascular calcification [50,51] . In vitro studies have demonstrated the protective effect of increasing magnesium concentration on vascular smooth muscle cell calcification through an upregulation of anti-calcification proteins including matrix gla protein and osteopontin [52][53][54] . The combined magnesium-calcium phosphate binder (calcium acetate 435 mg/magnesium carbonate 235 mg) available in Europe has similar efficacy to sevelamer in reducing serum phosphate and without the side effect of increasing serum ionized calcium.…”