Less complex systems are often used to predict the behavior in more complex systems and correlations between the two are very important. In this study, a pluripotent Mesenchymal Stem Cell (MSC) model, C3H/10T1/2, was used for the study of three bioceramic materials, namely the hydroxyapatite (HA), α-Tricalcium phosphate (α-TCP) and β-Tricalcium phosphate (β-TCP). Biochemical methods (ALP enzymatic assay and RT-qPCR) and physical assessment (DAPI staining and SEM) were employed to assess the osteo-inductivity of the materials. The predicted osteo-inductivity from the experiments were utilized both to compare with a less complex system (Simulated Body Fluid system) and a more complex system (in vivo bone formation / osteo-inductivity in dog) in order to assess two correlations....[ Read more ]

Less complex systems are often used to predict the behavior in more complex systems and correlations between the two are very important. In this study, a pluripotent Mesenchymal Stem Cell (MSC) model, C3H/10T1/2, was used for the study of three bioceramic materials, namely the hydroxyapatite (HA), α-Tricalcium phosphate (α-TCP) and β-Tricalcium phosphate (β-TCP). Biochemical methods (ALP enzymatic assay and RT-qPCR) and physical assessment (DAPI staining and SEM) were employed to assess the osteo-inductivity of the materials. The predicted osteo-inductivity from the experiments were utilized both to compare with a less complex system (Simulated Body Fluid system) and a more complex system (in vivo bone formation / osteo-inductivity in dog) in order to assess two correlations.

Among the bone markers selected for the biochemical assessment, alkaline phosphate (ALPL) shows the most prominent difference among different materials and across time period. Thus it is chosen as the marker for comparison and the relative expression is: HA > β-TCP > α-TCP. The cell density and proliferation difference from the DAPI staining, TCP (α and β) >> HA, implies the osteo-inductivity of cells is: HA > TCP as differentiated cells proliferate less. SEM examination shows that the cells on the porous scaffolds of the evaluated materials were distributed across the pores and bone “nodules” were observed.

The SBF study in this project shows that the surface CaP formation ability is: HA > β-TCP > α-TCP, suggesting there may be correlation between the surface CaP formation ability and the in vitro osteo-inductivity. On the other hand, the in vitro osteo-inductivity, HA > β-TCP > α-TCP, matches with the in vivo osteo-inductivity described in previous in vivo study. It was concluded that the ALP expression of 10T1/2 cells cultured on bioceramics may provide a reflective measurement to predict the in vivo osteo-inductivity of bioceramics.

The results of this work suggest two possible correlations: one between in vitro osteo-inductivity and in vitro surface CaP formation in SBF and another one between in vitro osteo-inductivity and in vivo osteo-inductivity. These are useful for predicting material bioactivity using less complex systems.