1. Applications and Efficacies of HA (Hydroxyapatite) American Institute of Medical Sales By: Fred Davis & Jeff Knight

6. Primary human osteoblast culture on 3D porous collagen- hydroxyapatite scaffolds. Guy Hilton Research Centre, Institute for Science and Technology in Medicine, Keele University, Thornburrow Drive, Hartshill ST4 7QB, Stoke-on-Trent, United Kingdom.

7. There is a need in tissue-engineering for 3D scaffolds that mimic the natural extracellular matrix of bone to enhance cell adhesion, proliferation, and differentiation. The scaffold is also required to be degradable. A highly porous scaffold has been developed to incorporate two of the extracellular components found in bone-collagen and hydroxyapatite (HA). The scaffold's collagen component is an afibrillar monomeric type I atelocollagen extracted from foetal calf's skin. This provided a novel environment for the inclusion of HA powder. Five hundred thousand primary human osteoblasts were seeded onto 4 mm cubed scaffolds that varied in ratio of HA to collagen. Weight ratios of 1:99, 25:75, 50:50, and 75:25 hydroxyapatite:collagen ( HA:Collagen ) were analysed .

8. The scaffolds plus cells were cultured for 21 days. DNA assays and live/dead viability staining demonstrated that all of the scaffolds supported cell proliferation and viability. An alkaline phosphatase assay showed similar osteoblast phenotype maintenance on all of the 3D scaffolds analysed at 21 days. MicroCT analysis demonstrated an increase in total sample volume (correlating to increase in unmineralised matrix production). An even distribution of HA throughout the collagen matrix was observed using this technique. Also at 3 weeks, reductions in the percentage of the mineralised phase of the constructs were seen. These results indicate that each of the ratios of HA/collagen scaffolds have great potential for bone tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

9. CELL-DERIVED MATRIX ENHANCES OSTEOGENIC PROPERTIES OF HYDROXYAPATITE. National O.Bohomolets Medical University, Department of Oral and Maxillofacial Surgery, Kyiv , Ukraine; Gregory.Tour@ki.se.

10. The study aimed to evaluate osteogenic properties of hydroxyapatite (HA) scaffold combined with extracellular matrix (ECM) derived in vitro from rat primary calvarial osteoblasts or dermal fibroblasts. The cellular viability, and the ECM deposited onto synthetic HA microparticles were assessed by MTT, Glycosaminoglycan , and Hydroxyproline assays as well as immunohistochemistry and scanning electron microscopy after 21 days of culture. The decellularized HA-ECM constructs were implanted in critical-sized calvarial defects of Sprague- Dowley rats, followed by bone repair and local inflammatory response assessments by histomorphometry and immunohistochemistry at 12 weeks postoperatively.

11. We demonstrated that HA supported cellular adhesion, growth and ECM production in vitro, and the HA-ECM constructs significantly enhanced calvarial bone repair (p<0.05, Mann-Whitney U test), compared to HA alone, despite the significantly increased number of CD68+ macrophages, and foreign body giant cells (p<0.05, Mann-Whitney U test). Selective accumulation of BSP, OPN and periostin was observed at the tissue-HA interfaces. In conclusion, in vitro-derived ECM mimics the native bone matrix, enhances the osteogenic properties of the HA microparticles , and might modulate the local inflammatory response in a bone repair-favorable way. Our findings highlight the ability to produce functional HA-ECM constructs for bone tissue engineering applications.