Osteogenic evaluation of calcium phosphate scaffold with drug-loaded poly (lactic-Co-glycolic acid) microspheres in beagle dogs

The goal of this study was to develop a bioactive hydroxyapatite (HA) scaffold as a calcium phosphatebased bioceramic using drug-loaded polymeric microspheres for bone regeneration. Dexamethasone (DEX) as a model bioactive molecule and poly (lactic-co-glycolic acid) (PLGA) microspheres as a carrier were employed. Polyethyleneimine was coated on DEX-loaded PLGA microsphere surfaces, resulting in a net positively-charged surface. With such modification of the PLGA microsphere surfaces, DEX-loaded PLGA microspheres were immobilized on the negatively charged HA scaffold surfaces. The release profile of DEX over a 4-week immersion study indicated an initial burst release followed by a sustained release. In vivo evaluation of the defects filled with DEX-loaded HA scaffolds indicated that new bone formation was enhanced when compared to defects that were either unfilled or filled only with HA scaffold. This innovative platform for bioactive molecule delivery more potently induced osteogenesis in vivo, which may be exploited in implantable bone graft substitutes for stem cell therapy or improved in vivo performance.