Distinguishing matrix-associated mineralization from solution-driven calcium phosphate precipitation in osteogenic culture

In osteogenic culture under baseline conditions (10 mM β-glycerophosphate, 2-day renewal), matrix-associated mineralization activates first, with solution-driven calcium-phosphate precipitation starting about 18 h later.

• Why it matters: Mineral accumulation is often taken as evidence of cell-guided extracellular matrix mineralization, but it can also reflect nonphysiological calcium-phosphate precipitation from the medium.
• What they did: A kinetic model coupled β-GP hydrolysis, medium renewal, matrix-associated precursor formation and maturation, and solution-driven precipitation; parameter sweeps, global sensitivity, published time-course comparisons, and equifinality analysis were used.
• The result: When matrix capacity was approached, extra phosphate mainly increased non-matrix deposition, and parameter sets with similar total mineral produced matrix-associated fractions from 0.17 to 1.00.