title: BMP-2 and bFGF release and in vitro effect on human osteoblasts after adsorption to bone grafts and biomaterials.
abstract: OBJECTIVE
  Combination of scaffolds and growth factors is a promising option for several clinical problems in bone biomaterials. Simplified growth factor loading by adsorption from aqueous solution is one important option for this technology. We evaluated the adsorption followed by PBS rinsing, release and biological effect of transient loading with basic fibroblast growth factor (bFGF) and bone morphogenic protein 2 (BMP-2) on fresh frozen bone, processed bone matrix, collagen, and a ceramic material with immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and qRT-PCR.
  
  
  METHODS
  The study consisted of three in vitro experiments (immunofluorescence, ELISA, and qRT-PCR) in human osteoblasts (HOB). The first evaluated the adsorption of the growth factors bFGF and BMP-2 to the biomaterials, analyzed by immunofluorescence assays. The second experiment used ELISA to analyze the release of the growth factors from the matrix. The biological effect of the growth factors on HOB was then studied with qRT-PCR experiments as the third step.
  
  
  RESULTS
  Strongest sustained release peaks in ELISA were observed in bFGF loading on processed bone matrix (steam-resistant mineralized bone matrix, SMBM) with up to 553 pg/ml medium. BMP-2 loading was less effective in ELISA peak release experiments with up to 257 pg/ml medium in processed bone matrix (SMBM). bFGF showed also higher release peaks in collagen material (192 pg/ml) compared with BMP-2 (101 pg/ml). Cumulative release values 0-72 h were estimated. The expression of runX2, osteocalcin, and alkaline phosphatase as markers for osteoblast activity was correlating.
  
  
  CONCLUSIONS
  The results showed sustained release of BMP-2 and bFGF after transient loading on bone biomaterials with a stronger effect in biological scaffolds. This is interesting for therapeutic growth factor loading as well as insights in natural growth factor matrix deposition during bone healing.
authors.affiliation: Clinic for Oral and Maxillofacial Surgery, University of Marburg, Marburg, Germany. draenert@floriandraenert.com
authors.forename: Florian G
authors.initials: FG
authors.lastname: Draenert
authors.forename: Anna-Lena
authors.initials: AL
authors.lastname: Nonnenmacher
authors.forename: Peer W
authors.initials: PW
authors.lastname: Kämmerer
authors.forename: Jutta
authors.initials: J
authors.lastname: Goldschmitt
authors.forename: Wilfried
authors.initials: W
authors.lastname: Wagner
mesh_terms: D000327:Adsorption; D000469:Alkaline Phosphatase / Q000032:analysis / Q000187:drug effects; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D015415:Biomarkers / Q000032:analysis; D001857:Bone Matrix / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000493:pharmacokinetics* / Q000494:pharmacology; D001842:Bone and Bones; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D002516:Ceramics / Q000737:chemistry; D003094:Collagen / Q000737:chemistry; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis / Q000187:drug effects; D003692:Delayed-Action Preparations; D017886:Durapatite / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D016222:Fibroblast Growth Factor 2 / Q000493:pharmacokinetics* / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry; D010006:Osteoblasts / Q000187:drug effects*; D015675:Osteocalcin / Q000032:analysis / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: C525718:BMP2 protein, human; D001672:Biocompatible Materials; D015415:Biomarkers; D055396:Bone Morphogenetic Protein 2; D050659:Core Binding Factor Alpha 1 Subunit; D003692:Delayed-Action Preparations; C493709:RUNX2 protein, human; D016222:Fibroblast Growth Factor 2; D015675:Osteocalcin; D003094:Collagen; D017886:Durapatite; D000469:Alkaline Phosphatase