Coralline Hydroxyapatite Coated with a Layer Biomimetic Calcium Phosphate Containing BMP-2 Induces Dose-Related Ectopic Bone Formation in Wistar Rats

In order to evaluate loading methods and the dose dependency of bone morphogenetic protein 2 (BMP-2) in ectopic bone formation, an osteoinductive material consisting of commercially available coralline hydroxyapatite (CHA) was coated with a layer of biomimetic calcium phosphate (BioCaP) containing BMP-2 in different ways. Eight groups—each containing samples of 0.25 g CHA—were formed and coated with, respectively, BioCaP with internally incorporated BMP-2 in concentrations of 1, 5, 10, 20, 40 and 60 µg per sample, and the two control groups with BioCaP only and BioCaP with 20 µg of adsorbed BMP-2 per sample. The samples were implanted subcutaneously in 27 male Wistar rats. The histological results show that there is no bone formation in the group in which no BMP-2 was included. All samples with BioCaP containing BMP-2 show bone formation. The group with 20 µg of adsorbed BMP-2 per sample shows the least bone formation. Coating-incorporated BMP-2 is more efficient in inducing bone formation than adsorbed BMP-2. The group with 5 µg of coating-incorporated BMP-2 per sample shows the most bone formation. Increasing the amount of coating-incorporated BMP-2 up to 60 µg does not improve ectopic bone formation.

Case Series: Use of Coralline Hydroxyapatite Graft In Faciomaxillary Surgery

Bone grafting represents an important solution for defects in maxillofacial and orthopaedic surgeries. Ideal properties of a bone graft allow proper integration, enabling cosmetic appeal and mechanical functionality. Whilst current autograft, allograft and xenograft applications do exist and are regularly used clinically, they are associated with numerous solutions, such as availability, disease transmission and donor site morbidity. Synthetic and naturally sourced solutions can avoid these issues, whilst maintaining the ideal bone integrative properties of their autograft counterparts. This case series aims to identify the effectiveness of a natural bone graft substitute, coralline hydroxyapatite, in maxillofacial applications, and demonstrate that coralline hydroxyapatite encourages bone ingrowth for dental defects.

A Clinical Study of Early Intervention with Coralline Hydroxyapatite on Fresh Extraction Sockets

To clinically, histologically and radiologically evaluate the effects of early intervention on fresh extraction sockets, 30 patients were selected and assigned evenly into group A (blood clot) and group B (coralline hydroxyapatite). All participants underwent clinical examination. Oral plaster casts and panoramic radiographs were undertaken before tooth extraction and at 3–4 months after socket grafting. A 6–8 mm sample of longitudinal bone core was obtained using a 2 mm diameter trephine 3–4 month's post-operatively. Group A had a greater decrease in interdental papilla height, which was about 2–3 times more than that of group B (P >0.001). The buccal-lingual alveolar ridge width also absorbed more in group A (P >0.001). Radiological findings were similar. Group B had less new bone formation (P >0.001), and the residual rate was a little high. There was no statistical difference between the two groups in terms of new bone formation rating grade. Clinical, histological and radiological tissue differences were observed between sockets with and without biomaterial grafts 3–4 months after surgery. This indicates that early intervention of extraction sockets is clinically advantageous.

Osteogenic Potential of Human Umbilical Cord Mesenchymal Stem Cells on Coralline Hydroxyapatite/Calcium Carbonate Microparticles

Coralline hydroxyapatite/calcium carbonate (CHACC) is a biodegradable and osteoconductive bone graft material with promising clinical performance. CHACC has been shown to support proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells (MSCs)in vitroand demonstrated to work as a functional scaffold for bone formationin vivo.Umbilical cord matrix is a more accessible and abundant tissue source of MSCs, but its osteogenic capacity in comparison to human bone marrow when cultured on CHACC has not yet been demonstrated. In this study, we assessed the osteogenic differentiation capacity of human MSCs, isolated from bone marrow and umbilical cord matrix and characterised by flow cytometry, when cultured on 200–300 μm CHACC granules. The 3D cultures were characterised by brightfield and scanning electron microscopy (SEM). Osteogenic potential was assessed by immunocytochemistry and qPCR for key markers of bone differentiation (alkaline phosphatase, runx2, type I collagen, and osteocalcin). By day 1, the MSCs had enveloped the surface of the CHACC granules to form organoids, and by day 7, cells had proliferated to bridge nearby organoids. Extracellular matrix deposition and osteogenic differentiation were demonstrated by MSCs from both tissue sources at day 21. However, MSCs from bone marrow demonstrated superior osteogenic differentiation capability compared to those from umbilical cord matrix. In conclusion, it is possible to culture and induce osteogenic differentiation of umbilical cord matrix MSCs on CHACC. Further research is required to optimise the osteogenicity of umbilical cord matrix MSCs to release their full potential as a readily available, accessible, and abundant tissue source for bone tissue engineering.

Antibiotic Containing Poly Lactic Acid/Hydroxyapatite Biocomposite Coatings for Dental Implant Applications

The biodegradable and biocompatible antibiotic containing thin film composites are very appropriate biomaterials as coating materials for dental implants because of their adjustable drug loading and release rates for the prevention of implant related infections. Coralline hydroxyapatite (HAp) was loaded with gentamicin antibiotics and combined with a biodegradable polylactic acid (PLA) to form thin film composites. PLA-HAp, PLA-Gentamicin (GM) and PLA-HAp-GM composites were produced, and their dissolution studies were carried out in phosphate buffered saline under SINK conditions. It was observed that the coatings could be efficiently applied to titanium dental implants and the drug release rates can be efficiently controlled.

Hydroxyapatite/PLA Biocomposite Thin Films for Slow Drug Delivery of Antibiotics for the Treatment of Bone and Implant-Related Infections

Drug delivery systems were developed from coralline hydroxyapatite (HAp) and biodegradable polylactic acid (PLA). Gentamicin (GM) was loaded in either directly to PLA (PLAGM) or in HAp microspheres. Drug loaded HAp was used to make thin film composites (PLAHApGM). Dissolution studies were carried out in phosphate buffered saline (PBS. The release profiles suggested that HAp particles improved drug stabilization and availability as well control the release rate. The release also displays a steady state release. In vitro studies in human Adipose Derived Stem Cells (hADSCs) showed substantial quantities of cells adhering to hydroxyapatite containing composites. The results suggested that the systems could be tailored to release different clinical active substances for a wide range of biomedical applications.