title: Identification of bone morphogenetic proteins 2 and 4 in commercial demineralized freeze-dried bone allograft preparations: pilot study.
abstract: BACKGROUND
  Demineralized freeze-dried bone allografts (DFDBAs) have been proposed as a useful adjunct in periodontal therapy to induce periodontal regeneration through the induction of new bone formation. The presence of bone morphogenetic proteins (BMPs) within the demineralized matrix has been proposed as a possible mechanism through which DFDBA may exert its biologic effect. However, in recent years, the predictability of results using DFDBA has been variable and has led to its use being questioned. One reason for the variability in tissue response may be attributed to differences in the processing of DFDBA, which may lead to loss of activity of any bioactive substances within the DFDBA matrix. Therefore, the purpose of this investigation was to determine whether there are detectable levels of bone morphogenetic proteins in commercial DFDBA preparations.
  
  
  METHODS
  A single preparation of DFDBA was obtained from three commercial sources. Each preparation was studied in triplicate. Proteins within the DFDBA samples were first extracted with 4M guanidinium HCI for seven days at 40 degrees celsius and the residue was further extracted with 4M guanidinium HCL/EDTA for seven days at 40 degrees celsius. Two anti-human BMP-2 and -4 antibodies were used for the detection of the presence of BMP's in the extracts.
  
  
  RESULTS
  Neither BMP-2 nor BMP-4 was detected in any of the extracts. When recombinant human BMP-2 and -4 were added throughout the extraction process of DFDBA extraction, not only were intact proteins detected but smaller molecular weight fragments were also noted in the extract.
  
  
  CONCLUSIONS
  These results indicate that all of the DFDBA samples tested had no detectable amounts of BMP-2 and -4. In addition, an unknown substance present in the DFDBA may be responsible for degradation of whatever BMPs might be present.
authors.affiliation: Department of Dentistry, University of Queensland, Turbot Street, Brisbane, Queensland 4000, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: Z
authors.initials: Z
authors.lastname: Pujic
authors.forename: Y
authors.initials: Y
authors.lastname: Xiao
authors.forename: P M
authors.initials: PM
authors.lastname: Bartold
mesh_terms: D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D001857:Bone Matrix / Q000737:chemistry* / Q000637:transplantation; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000032:analysis*; D018786:Bone Substitutes / Q000032:analysis*; D016025:Bone Transplantation; D002614:Chelating Agents; D003648:Decalcification Technique; D004492:Edetic Acid; D005612:Freeze Drying; D019791:Guanidine; D006801:Humans; D008970:Molecular Weight; D010865:Pilot Projects; D011233:Precipitin Tests; D011489:Protein Denaturation; D011506:Proteins / Q000032:analysis; D011994:Recombinant Proteins; D014021:Tissue Preservation; D016212:Transforming Growth Factor beta / Q000032:analysis*; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; C525718:BMP2 protein, human; C525809:BMP4 protein, human; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D018786:Bone Substitutes; D002614:Chelating Agents; D011506:Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D004492:Edetic Acid; D019791:Guanidine