title: Osteoinduction by combining bone morphogenetic protein (BMP)-2 with a bioactive novel nanocomposite.
abstract: OBJECTIVE
  There is increasing application of bone morphogenetic proteins (BMPs) owing to their role in promoting fracture healing and bone fusion. However, an optimal delivery system has yet to be identified. The aims of this study were to synthesise bioactive BMP-2, combine it with a novel α-tricalcium phosphate/poly(D,L-lactide-co-glycolide) (α-TCP/PLGA) nanocomposite and study its release from the composite.
  
  
  METHODS
  BMP-2 was synthesised using an Escherichia coli expression system and purified. In vitro bioactivity was confirmed using C2C12 cells and an alkaline phosphatase assay. The modified solution-evaporation method was used to fabricate α-TCP/PLGA nanocomposite and this was characterised using X-ray diffraction and scanning electron microscopy. Functionalisation of α-TCP/PLGA nanocomposite by adsorption of BMP-2 was performed and release of BMP-2 was characterised using an enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Alkaline phosphatase activity of C2C12 cells was increased by the presence of all BMP-2/nanocomposite discs compared with the presence of a blank disc (p = 0.0022), and increased with increasing incubation concentrations of BMP-2, showing successful adsorption and bioactivity of BMP-2. A burst release profile was observed for BMP-2 from the nanocomposite.
  
  
  CONCLUSIONS
  Functionalisation of α-TCP/PLGA with BMP-2 produced osteoinduction and was dose-dependent. This material therefore has potential application as an osteoinductive agent in regenerative medicine.
authors.affiliation: University of Cambridge, Department of Materials Science, Pembroke Street, Cambridge CB2 3QZ, UK.
authors.forename: A
authors.initials: A
authors.lastname: Sharma
authors.forename: F
authors.initials: F
authors.lastname: Meyer
authors.forename: M
authors.initials: M
authors.lastname: Hyvonen
authors.forename: S M
authors.initials: SM
authors.lastname: Best
authors.forename: R E
authors.initials: RE
authors.lastname: Cameron
authors.forename: N
authors.initials: N
authors.lastname: Rushton
keywords: BMP-2; Ceramics; Nanocomposite; Orthopaedics; Osteoinduction; Polymer; Tissue engineering