Matrix engineering for osteogenic differentiation of rabbit periosteal cells using alpha-tricalcium phosphate particles in a three-dimensional fibrin culture.

Tissue engineering using periosteal cells is a promising approach for bioactive bone repair. Of central importance in tissue engineering is the cell-matrix interaction. In the present study we tested in vitro the influence of alpha-tricalcium phosphate (alpha-TCP) particles on the expression of osteogenic markers in rabbit periosteal cells embedded in specially manufactured fibrin beads. After cell isolation from tibial periosteum of New Zealand White rabbits, and following monolayer culture, cells were embedded in alginate-fibrin beads containing 7.5% alpha-TCP particles and, as a control group, in beads without particles. The alginate was extracted immediately after polymerization. The beads were cultivated for at least 53 days. The DNA content, alkaline phosphatase activity, and osteocalcin level were determined. In monolayer culture the number of cells increased 6.5-fold. DNA content increased in both three-dimensional culture groups but was significantly higher in the beads containing alpha-TCP. Alkaline phosphatase activity increased in both groups without significant differences. Osteocalcin content was significantly higher in the beads containing alpha-TCP than it was in those without alpha-TCP. These observations indicate that matrix engineering using inorganic particles in fibrin culture can influence the osteogenic differentiation of mesenchymal cells. The three-dimensional culture system presented here facilitates the preparation of grafts for bone reconstruction. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 59: 690-696, 2002