Effects of porous beta-tricalcium phosphate-based ceramics used as an E. coli-derived rhBMP-2 carrier for bone regeneration.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) requires carriers for clinical effectiveness. In this study, whether porous beta-tricalcium phosphate (β-TCP)-based ceramics are ideal carriers for rhBMP-2 was investigated. Hydroxyapatite (HA), β-TCP, TCP/HA (80 %/20 %), HA with rhBMP-2, TCP with rhBMP-2, and TCP/HA (80 %/20 %) with rhBMP-2 were manufactured by a sponge method with a pore size of 300 μm or more and macro-porosity of 83 %. The alkaline phosphatase (ALP) activity and ALP expression of the cells with 100 % β-TCP granules were more increased than the those of cells with 100 % HA and TCP/HA (80 %/20 %) at the baseline or when treated with 15 ng/ml of rhBMP-2. In an SD rat calvarial defect model, new bone formation was evidently shown in the TCP 100 %-rhBMP-2 and TCP/HA (80 %/20 %)-rhBMP-2 groups, showing that the most affected area was filled with newly-formed bone, that the percent bone volume and trabecular number were larger when compared to the groups without rhBMP-2 treatment at both 4 and 8 weeks after surgery using micro-CT and histology. Porous TCP-based ceramic granules enhanced the osteoblastic differentiation in the hMSC system when treated with 15 ng/ml of rhBMP-2 and accelerated bone-healing by trabecular number in a rat calvarial defect model. Thus, in this study it was proposed that TCP-based ceramics might be useful carriers of rhBMP-2.