title: [Effects of impaction on tissue engineered bone modified by BMP-2 gene].
abstract: OBJECTIVE
  To observe effects of the direct impaction on the cell survival and the bone formation of the tissue engineered bone modified by the adenovirus mediated human bone morphogenetic protein 2 (Adv-hBMP2) gene and to verify the feasibility of the impacted grafting with it.
  
  
  METHODS
  The marrow stromal cells (MSCs) were separated from the canine bone marrow and were cultured. MSCs were transfected with the Adv-hBMP2 gene and combined with the freeze-dried cancellous bone (FDB) to form the tissue engineered bone. Four days after the combination, the tissue engineered bone was impacted in a simulated impactor in vitro and implanted in the mouse. The cell survivals were evaluated with SEM 1 and 4 days after the combination, immediately after the impaction, and 1 and 4 days after the impaction, respectively. The bone formation and the allograft absorption were histologically evaluated respectively.
  
  
  RESULTS
  There were multiple layers of the cells and much collagen on FDB before the impaction. Immediately after the impaction, most of the cells on the direct contact area disappeared and there was much debris on the section. Some of the cells died and separated from the surface of FDB at 1 day, the number of the cells decreased but the collagen increased on the surface at 4 days. Histologically, only the fibrous tissue was found in FDB without the cells, the bone formation on FDB was even in distribution and mass in appearance before the impaction, but declined and was mainly on the periphery after the impaction in the Adv-hBMP-2 modified tissue-engineered bone.
  
  
  CONCLUSIONS
  The simulated impaction can decrease the cells survival and the bone formation of the Adv-hBMP-2 modified tissue-engineered bone. The survival cells still function well. It is feasible to use the tissue engineered bone in the impaction graft.
authors.affiliation: Department of Orthopaedics, 9th People's Hospital, Medical College of Shanghai Jiaotong University, Shanghai 200011, P. R. China. yanmengning@yahoo.com.cn
authors.forename: Mengning
authors.initials: M
authors.lastname: Yan
authors.forename: Tingting
authors.initials: T
authors.lastname: Tang
authors.forename: Kerong
authors.initials: K
authors.lastname: Dai
authors.forename: Xinshe
authors.initials: X
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: Yue
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Yu
authors.forename: Jueren
authors.initials: J
authors.lastname: Lou
mesh_terms: D000256:Adenoviridae; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics*; D016025:Bone Transplantation; D002454:Cell Differentiation; D002478:Cells, Cultured; D004285:Dogs; D008297:Male; D051379:Mice; D008819:Mice, Nude; D030781:Organisms, Genetically Modified; D010012:Osteogenesis / Q000235:genetics; D023822:Tissue Engineering
chemical_list: D055396:Bone Morphogenetic Protein 2