Effects on growth and osteogenic differentiation of mesenchymal stem cells by the strontium-added sol-gel hydroxyapatite gel materials

In the present study, strontium-modified hydroxyapatite gels (Sr-HA) at different concentrations were prepared using sol-gel approach and their effect on human-bone-marrow-derived mesenchymal stem cells, were evaluated. The effect of Strontium on physico-chemical and morphological properties of hydroxyapatite gel were evaluated. Morphological analyses (SEM and TEM) demonstrate that an increasing in the amount of Sr ions doped into HA made the agglomerated particles smaller. The substitution of large Sr2+ for small Ca2+ lead to denser atomic packing of the system causing retardation of crystals growth. The biological results demonstrated that hydroxyapatite gel containing from 0 to 20 mol% of Sr presented no cytotoxicity and promote the expression of osteogenesis related genes including an early marker for osteogenic differentiation ALP; a non-collagen protein OPN and a late marker for osteogenic differentiation OCN. Finally, the Sr-HA gels could have a great potential application as filler in bone repair and regeneration and used in especially in the osteoporotic disease.