In vitro ceramic scaffold mineralization: comparison between histological and micro-computed tomographical analysis.

The porous structure of beta-tricalcium phosphate (β-TCP) scaffolds was assessed by conventional histomorphometry and micro-computed tomography (micro-CT) to evaluate the substitutability of time-consuming histomorphometry by rapid micro-CT. Extracellular matrix mineralization on human mesenchymal stem cell seeded β-TCP scaffolds was scanned by means of micro-CT after 6 weeks in cultivation and evaluated morphometrically. For the histomorphometric analysis, undecalcified sections were prepared in the mediosagittal plane of the cylindrical tissue-engineered constructs. The sections were scanned at a nominal resolution of 8 μm and stained with von Kossa and Toluidine Blue. Pores were analyzed with both methods for morphometrical parameters such as horizontal/vertical diameter and pore/mineralized tissue area. Results showed highly significant correlations between histomorphometry and micro-CT for pore horizontal length (r = 0.95), pore vertical length (r = 0.96), pore area (r = 0.97), and mineralized tissue area (r = 0.82). Mean percentage differences between histomorphometry and micro-CT measurements ranged from 1.4% (pore vertical diameter) to 14.0% (area of mineralized tissue). With its high image precision, micro-CT qualifies as an additional tool for endpoint evaluation measurements of mineralized tissue development within tissue-engineered constructs also in ceramic scaffolds.