title: Bone formation of Escherichia coli expressed rhBMP-2 on absorbable collagen block in rat calvarial defects.
abstract: OBJECTIVE
  The aim of this study was to evaluate the osteogenic and space-providing effect of rhBMP-2 produced in an Escherichia coli expression system (ErhBMP-2) with absorbable collagen block (ACB) as the carrier system in the rat calvarial defect model.
  
  
  METHODS
  Eight-millimeter diameter calvarial defects were created in 60 male Sprague-Dawley rats. The animals were divided into 6 groups containing 10 animals each that received sham-surgery control (no material applied), ACB control (ACB alone), or ErhBMP-2/ACB (ACB loaded with 0.025 mg/mL ErhBMP-2). Histological and histometric analysis was performed after 2- and 8-week healing intervals.
  
  
  RESULTS
  On histological observation, the level of bone formation in the defects was generally higher at 8 weeks than at 2 weeks. Surgical implantation of ErhBMP-2/ACB resulted in the enhanced bone regeneration compared with controls. Moreover, the collagen remnants of ACB appeared to be completely resorbed in ACB control and ErhBMP-2/ACB group after 8 weeks. Histometic analysis revealed that the ErhBMP-2/ACB group had a significantly greater augmented area, new bone area, and new bone ratio after 2 and 8 weeks than both control groups. However, there was no difference between 2 and 8 weeks in the ErhBMP-2/ACB group in all aspects of the augmented area, new bone area, and new bone ratio (P < .05).
  
  
  CONCLUSIONS
  ErhBMP-2 loaded on ACB can induce favorable bone formation in the rat calvarial defect model, but this collagen carrier in block type did not fulfill the space-maintaining expectations for bone formation by ErhBMP-2.
authors.affiliation: Department of Periodontology, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Jee-Hee
authors.initials: JH
authors.lastname: Jung
authors.forename: Jeong-Ho
authors.initials: JH
authors.lastname: Yun
authors.forename: Yoo-Jung
authors.initials: YJ
authors.lastname: Um
authors.forename: Ui-Won
authors.initials: UW
authors.lastname: Jung
authors.forename: Chang-Sung
authors.initials: CS
authors.lastname: Kim
authors.forename: Seong-Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Kyoo-Sung
authors.initials: KS
authors.lastname: Cho
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D001853:Bone Marrow / Q000473:pathology; D001857:Bone Matrix / Q000473:pathology; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000627:therapeutic use; D001861:Bone Regeneration / Q000502:physiology; D002113:Calcification, Physiologic / Q000502:physiology; D003094:Collagen / Q000627:therapeutic use*; D003238:Connective Tissue / Q000473:pathology; D004195:Disease Models, Animal; D004337:Drug Carriers; D004926:Escherichia coli; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D010006:Osteoblasts / Q000473:pathology; D010011:Osteocytes / Q000473:pathology; D010012:Osteogenesis / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000627:therapeutic use; D012886:Skull / Q000473:pathology / Q000601:surgery*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000627:therapeutic use
chemical_list: D001672:Biocompatible Materials; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004337:Drug Carriers; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D003094:Collagen