Bone formation in beta-tricalcium phosphate-filled bone defects of the rat femur: morphometric analysis and expression of bone related protein mRNA.

The purpose of the current study was to evaluate the bone formation when beta-tricalcium phosphate (TCP) was implanted in bone defects of rat femurs. beta-TCP granules were applied to defects created in the femurs of 65 male rats who were sacrificed 3, 7, 10, 14 or 30 days later. Bone tissues were embedded in paraffin, serial sections were cut and then stained with hematoxylin-eosin. Histomorphometric analyses were also conducted. Furthermore, total mRNAs were extracted, homogenized, and reverse transcribed, after which quantitative PCR assays were conducted with a LightCycler using the double-stranded DNA dye Syber Green I with primers for either rat osteopontin or osteocalcin. Tissues in defects without beta-TCP were used as controls. The amount of newly formed bone tissue in the beta-TCP implanted group was significantly greater in both the side areas and the central area of defects than in the control group. Expressions of osteopontin and osteocalcin mRNAs of cells in the defects of the experimental group were up-regulated compared with the control group at all time periods. Taken together, these results prove that beta-TCP is an appropriate material for osteoconduction and promotes bone formation in bone defects.