Fabrication and evaluation of carbonate apatite-coated calcium carbonate bone substitutes for bone tissue engineering.

Carbonate apatite-coated calcium carbonate (CO Ap/CaCO ) was fabricated through a dissolution-precipitation reaction using CaCO granules as a precursor to accelerate bone replacement based on superior osteoconductivity of the CO Ap shell, along with Ca release from the CaCO core and quicker resorption of the CaCO core. In the present study, CaCO , 10% CO Ap/CaCO , 30% CO Ap/CaCO , and CO Ap granules were fabricated and examined histologically to evaluate their potential as bone substitutes. Larger contents of CaCO in the granules resulted in higher Ca release and promoted cell proliferation of murine preosteoblasts at 6 days compared with CO Ap. Interestingly, in a rabbit femur defect model, 10% CO Ap/CaCO induced significantly higher new bone formation and higher material resorption compared with CO Ap at 8 weeks. Nevertheless, CO Ap showed a superior osteoconductive potential compared with 10% CO Ap/CaCO at 8 weeks. All tested granules were most likely resorbed by cell mediation including multinucleated giant cell functions. Therefore, we conclude that CO Ap/CaCO has a positive potential for bone tissue engineering based on well-controlled calcium release, bone formation, and material resorption.