ABSTRACT
Porous composites composed of hydroxyapatite (HA), herb epimedium (EP), and chitosan (CS) were used to improve the repair of rabbit bone defects. The in vivo implantation of the HA/CS-EP showed that homogeneous bone formation occurred after 12 weeks' implantation and possessed good osteogenesis. The osteogenic process of the HA/CS-EP group was different from that of the HA/CS group. Direct bone formation of osteoblasts with HA/CS-EP as the matrix could be observed. Compared with the group filled with HA/CS, the group filled with HA/CS-EP showed significant increases in the number of osteoblasts and the bone formation area, and the areas of new bone formation in the HA/CS-EP group after 4 or 12 weeks' implantation reached 33% and 87%, respectively. The novel repair system of HA/CS-EP can induce bone formation, increase osteoblast quantity and improve osteogenesis, for EP can significantly promote the proliferation and activity of osteoblasts in the early stage and accelerate bone remodeling in the later stage. Composites containing EP could be a promising material with multifunctions of osteoinduction, osteoconduction and medication for bone repair, and herb medicine EP could be used as an osteoinduction material for bone tissue engineering.
Subject(s)
Bone Regeneration/drug effects , Bone Substitutes/therapeutic use , Epimedium/chemistry , Femoral Fractures/physiopathology , Femoral Fractures/therapy , Fracture Healing/drug effects , Plant Extracts/administration & dosage , Animals , Drug Implants/administration & dosage , Femoral Fractures/diagnosis , Guided Tissue Regeneration/instrumentation , Guided Tissue Regeneration/methods , Materials Testing , Osseointegration/drug effects , Rabbits , Treatment OutcomeABSTRACT
First-principles plane-wave calculations were performed to investigate the influences of intrinsic vacancy on the stability and elastic properties of hydroxyapatite (HA). Five types of vacancies, i.e. H, O, OH, Ca, and Ca(2+) vacancy, were considered. Formation energies were evaluated and compared with experimental measurements. It was shown that HA with a Ca(2+) vacancy is the most stable one among the considered systems. Elastic constants were estimated via curves of total energy against strain. Bulk, shear and Young's moduli, and Poisson's ratio are also evaluated to compare with the experimental value. The elastic properties of HA are significantly affected by the vacancy. Vacancy can soften HA via reducing its elastic moduli. The HA with Ca(2+) vacancy is the softest one among the considered systems. Electronic structures of HA with vacancy are also analyzed to explain the softening mechanisms.
