Porous Calcium Phosphate Granules Research Articles

The effect of bone marrow concentrate and hyperbaric oxygen therapy on bone repair.

Neoangiogenesis represents an essential part of bone regeneration. Therefore the improvement of neovascularization is the subject of various research approaches. In addition autologous mesenchymal stem cells concentrate in combination with bone substitute materials have been shown to support bone regeneration. In a rabbit model we examined the proposed synergistic effect of hyperbaric oxygen therapy (HBOT) and bone marrow concentrate (BMC) with porous calcium phosphate granules (CPG) on neoangiogenesis and osseous consolidation of a critical- size defect. The animal groups treated with HBOT showed a significantly higher microvessel density (MVD) by immunhistochemistry. Furthermore HBOT groups presented a significantly larger amount of new bone formation histomorphometrically as well as radiologically. We conclude that the increase in perfusion as a result of increased angiogenesis may play a key role in the effects of HBOT and consequently promotes bone healing.

Porous calcium phosphate granules containing drug-loaded polymeric nanoparticles for bone regeneration

A simple and highly efficient method for fabrication of drug-loaded porous calcium phosphate (CP) granules using biodegradable nanoparticles was developed in this study. Porous CP granules were used as a bone graft substitute with a localized drug delivery structure. Spherical CP granules with open micro-channels and PLGA nanoparticles loaded with dexamethasone (DEX) as a model drug were fabricated by a liquid nitrogen method and a single emulsion method, respectively. The produced nanoparticles were pre-coated with positively charged poly(ethyleneimmine) (PEI) molecules and then immobilized via electrical interaction in the micro-channels on the surfaces of CP granules, which have a negative charge. The results indicated that the PEI-coated PLGA nanoparticles loaded with DEX were successfully incorporated and well-dispersed in the micro-channels of the CP granules. The nanoparticles were not released from the CP granules and allowed a sustained release of DEX from the nanoparticle-based CP granules over the course of 1month.

Is hydroxyapatite cement an alternative for allograft bone chips in bone grafting procedures? A mechanical and histological study in a rabbit cancellous bone defect model.

To evaluate in vivo performance of hydroxyapatite cement (HAC) as a porous bone graft substitute, HAC was mixed (1:1 ratio) with either porous calcium-phosphate granules (80% tricalcium phosphate, 20% hydroxyapatite) or defatted morsellized cancellous bone (MCB) allograft and implanted bilaterally in cylindrical drill holes in distal femurs of rabbits. Groups with empty defects and impacted MCB were used for reference. After 8 weeks, one femur from each pair was examined histologically. All contralateral specimens and Time-0 specimens were used for mechanical indentation tests. Histology showed that some empty defects were filled with newly formed osteopenic bone after 8 weeks. The impacted MCB showed remodeling into new vital bone. Incorporation of the HAC/MCB composite was incomplete, whereas minimal new bone ingrowth was found in the HAC/granule composites. Though not different from each other, both composites were significantly stronger than empty defects, incorporated impacted MCB, and intact cancellous bone. At Time 0, the mechanical behavior of impacted MCB was similar to both HAC composites. In conclusion, composites of HAC and porous biomaterials can maintain relatively high strength over 8 weeks in vivo, but their incorporation into a new bony structure is slower than impacted MCB. The HAC/MCB composite showed favorable incorporation behavior.