Diopside-tricalcium phosphate bioactive ceramics for osteogenic differentiation of human adipose stem cells

Ti scaffolds combined with autologous human adipose-derived mesenchymal stem cells (hASCs) have been successfully applied for regenerative cranio-maxillofacial bone therapies. Future challenges reside in regeneration of larger bone defects and displacement of the permanent Ti structure, thus, advanced resorbable scaffolds are needed. Composites of β-Ca₃ (PO₄ )₂ with 80 and 60 wt % of CaMg(SiO₃ )₂ with improved mechanical properties compared to tricalcium phosphate (TCP) materials are presented. Synthetic CaMg(SiO₃ )₂ and a precursor of Ca₃ (PO₄ )₂ were used to fabricate the composites and a reference β-Ca₃ (PO₄ )₂ material by uniaxial pressing and solid state sintering. Optimum sintering temperature of 1225°C was selected. Microstructural analysis and Weibull distributions of tensile strengths determined by the diametral compression of discs test are reported. Thermodynamic simulation of the dissolution process in simulated body fluid body fluid was done. The biological response with hASCs was analyzed using basic and osteogenic media. Viability and osteogenic potential-LIVE/DEAD assay; alkaline phosphatase activity and collagen type-I production-were characterized. The composites have higher tensile strength (>3×) than TCP materials, for similar reliability, and support viability and osteogenic differentiation of hASCs. Resorption of the high strength phase diopside is the slowest. The promising results reported here suggest possible uses of these bioactive β-Ca₃ (PO₄ )₂ -CaMg(SiO₃ )₂ ceramics together with hASCs in bone tissue engineering.