Evaluation of a new biphasic calcium phosphate for maxillary sinus floor elevation: Micro-CT and histomorphometrical analyses.

OBJECTIVES: Synthetic biphasic calcium phosphate (BCP) with a hydroxyapatite/ß-tricalcium phosphate (HA/ß-TCP) ratio of 60/40 (BCP60/40) is successfully used as alternative for autologous bone in patients undergoing maxillary sinus floor elevation (MSFE) for dental implant placement. A high percentage of HA in BCP60/40 may hamper efficient scaffold remodeling. Osteogenesis and neovascularization are pivotal in effective bone regeneration. We aimed to investigate whether differences exist in osteogenic and/or vasculogenic potential of BCP60/40 and BCP20/80 in patients undergoing MSFE. MATERIALS AND METHODS: Twenty patients undergoing MSFE were treated with BCP60/40 (n = 10) or BCP20/80 (n = 10). Bone and graft volumes were determined by micro-computed tomography and histomorphometrical analysis of biopsies of the augmented region. Osteoid volumes, number of osteoclasts, and blood vessels were determined by histomorphometrical analysis. The biopsies were taken 6.5 months (26 weeks) postoperatively prior to dental implant placement. RESULTS: Bone and osteoid volumes were 9.7% and 0.8% higher at the most cranial side of the BCP20/80 biopsies compared to the BCP60/40 biopsies. Graft volumes, number of osteoclasts, and blood vessels were similar in both groups. CONCLUSIONS: BCP20/80 showed enhanced osteogenic potential in patients undergoing MSFE compared to BCP60/40, due to either a faster bone remodeling rate or an earlier start of bone formation in BCP20/80-treated patients, suggesting that a higher TCP content positively contributes to the bone remodeling rate. Therefore, BCP20/80 might perform better, at least in the short term, as a scaffold for bone augmentation in the MSFE model than BCP60/40 as more bone is formed, and more osteoid is deposited at the cranial side in BCP20/80-treated patients compared to BCP60/40-treated patients. However, catch-up of BCP60/40 in the long term cannot be ruled out.

Mechanoresponsiveness of human adipose stem cells on nanocomposite and micro-hybrid composite.

Resin-based composites are used for bone repair applications and comprise resin matrix and different sized filler particles. Nanometer-sized filler particles improve composite's mechanical properties compared with micrometer-sized filler particles, but whether differences exist in the biological response to these composites is unknown. Natural bone comprises a nanocomposite structure, and nanoscale interactions with extracellular matrix components influence stem cell differentiation. Therefore we hypothesized that nanometer-sized filler particles in resin-based composites enhance osteogenic differentiation of stem cells showing a more bone cell-like response to mechanical loading compared with micrometer-sized filler particles. Pulsating fluid flow (PFF; 5 Hz, mean shear stress: 0.7 Pa; 1 h) rapidly, within 5 min, increased nitric oxide production in human adipose stem cells (hASCs) on nanocomposite, but not on micro-hybrid composite. PFF increased RUNX2 expression in hASCs on micro-hybrid composite, but not on nanocomposite after 2 h post-incubation. PFF did not affect mean cell orientation and shape index of hASCs on both composites. In conclusion, the PFF-increased nitric oxide production in hASCs on nanocomposite, and increased osteogenic differentiation of hASCs on micro-hybrid composite suggest different responses to mechanical loading of hASCs on composite with nanometer-sized and micrometer-sized filler particles. This might have important implications for bone tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2986-2994, 2017.

Enhanced Osteogenic and Vasculogenic Differentiation Potential of Human Adipose Stem Cells on Biphasic Calcium Phosphate Scaffolds in Fibrin Gels.

For bone tissue engineering synthetic biphasic calcium phosphate (BCP) with a hydroxyapatite/ß-tricalcium phosphate (HA/ß-TCP) ratio of 60/40 (BCP60/40) is successfully clinically applied, but the high percentage of HA may hamper efficient scaffold remodelling. Whether BCP with a lower HA/ß-TCP ratio (BCP20/80) is more desirable is still unclear. Vascular development is needed before osteogenesis can occur. We aimed to test the osteogenic and/or vasculogenic differentiation potential as well as degradation of composites consisting of human adipose stem cells (ASCs) seeded on BCP60/40 or BCP20/80 incorporated in fibrin gels that trigger neovascularization for bone regeneration. ASC attachment to BCP60/40 and BCP20/80 within 30 min was similar (>93%). After 11 days of culture BCP20/80-based composites showed increased alkaline phosphatase activity and DMP1 gene expression, but not RUNX2 and osteonectin expression, compared to BCP60/40-based composites. BCP20/80-based composites also showed enhanced expression of the vasculogenic markers CD31 and VEGF189, but not VEGF165 and endothelin-1. Collagen-1 and collagen-3 expression was similar in both composites. Fibrin degradation was increased in BCP20/80-based composites at day 7. In conclusion, BCP20/80-based composites showed enhanced osteogenic and vasculogenic differentiation potential compared to BCP60/40-based composites in vitro, suggesting that BCP20/80-based composites might be more promising for in vivo bone augmentation than BCP60/40-based composites.