acid-phosphatase and 4-dioxanone

A new type of degradable biomaterial with bone-inducing capacity was made by combining porous beta-tricalcium phosphate (beta-TCP) with a delivery system for recombinant human bone morphogenetic protein-2 (rhBMP-2). The BMP delivery system consisted of a block copolymer composed of poly-D,L-lactic acid with random insertion of p-dioxanone and polyethylene glycol (PLA-DX-PEG), a known biocompatible and biodegradable material. The efficacy of this biomaterial in terms of its bone-inducing capacity was examined by ectopic bone formation in the dorsal muscles of the mouse. In the beta-TCP implants coated with the PLA-DX-PEG polymer containing more than 0.0025% (w/w) of rhBMP-2, new ectopic bone tissues with marrow were consistently found on the surface of implants. The radiographic density of beta-TCP was diminished in a time-dependent manner. On histological examination, numerous multinucleated osteoclasts with positive tartrate-resistant acid-phosphatase (TRAP) staining were noted on the surface of the beta-TCP. These experimental results indicate that beta-TCP implants coated with synthetic rhBMP-2 delivery system might provide effective artificial bone-graft substitutes with osteoinductive capacity and biodegradable properties. In addition, this type of biomaterial may require less rhBMP-2 to induce significant new bone mass.

Topics: Absorbable Implants; Acid Phosphatase; Animals; Bone and Bones; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Bone Regeneration; Calcium Phosphates; Coated Materials, Biocompatible; Dioxanes; Drug Delivery Systems; Humans; Isoenzymes; Lactic Acid; Male; Mice; Mice, Inbred Strains; Microscopy, Electron, Scanning; Polyesters; Polyethylene Glycols; Polymers; Radiography; Recombinant Proteins; Surface Properties; Tartrate-Resistant Acid Phosphatase; Time Factors; Transforming Growth Factor beta