title: [Preparation and ectopic osteoinduction study of macroporous bone substitute with calcium phosphate cements and rhBMP-2 loaded gelatin microspheres].
abstract: OBJECTIVE
  To prepare macroporous bone substitute composed of calcium phosphate cements and rhBMP-2 loaded gelatin microspheres, and to investigate ectopic osteoinduction of the composite.
  
  
  METHODS
  After being prepared by improved emulsified cold-condensation method and crosslinked by 5% genipin solution,gelatin microspheres (GMs) were observed by scanning electron microscope (SEM) and loaded with rhBMP-2 by adsorption. Macroporous bone substitute was developed by mixing calcium phosphate cement (CPC) with 2.5% GMs, being as the experimental group,and CPC with rhBMP-2 was the control group. After the both composites had been soaked in the sodium chloride for 1 week or 3 weeks, compressive strength of the composites were tested, and the cross-sections were observed by SEM. Concentrations of rhBMP-2 in the solutions at different time by ELISA method and the cumulative drug release amount was calculated. The composites had been implanted in the muscle bags of the mouses for 3 weeks. Then the tissues around the materials were collected, stained by hematoxylin and eosin, and Ca and ALP in the tissues were also measured.
  
  
  RESULTS
  Gelatin microspheres were spherical with diameters of (62 +/- 18) microm. Macropores appeared in the experimental materials 1 week and 3 weeks after being soaked,and total porosity, macroporosity, cumulative release amount of rhBMP-2 in the experimental group were higher than that in the control. But compressive strength of the experimental group was lower than that of the control group 3 weeks after being soaked. Results of HE stain showed chondral formation in both groups, but there were more chondral tissues in the experiment group, and so were the concentrations of Ca and ALP.
  
  
  CONCLUSIONS
  Macroporous calcium phosphate cement can be prepared by using rhBMP-2 loaded gelatin microspheres, and it is an excellent bone substitute due to it's proterty of promoting rhBMP release and powerful ectopic osteoinduction.
authors.affiliation: Department of Orthopaedics, Lanzhou General Hospital of PLA, Lanzhou 730050, Gansu, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Xu-dong
authors.initials: XD
authors.lastname: Liu
authors.forename: Xing-yan
authors.initials: XY
authors.lastname: Liu
authors.forename: Bao-feng
authors.initials: BF
authors.lastname: Ge
mesh_terms: D000818:Animals; D001843:Bone Cements / Q000737:chemistry*; D055396:Bone Morphogenetic Protein 2 / Q000737:chemistry*; D018786:Bone Substitutes / Q000737:chemistry / Q000494:pharmacology*; D002130:Calcium Phosphates / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D006801:Humans; D008297:Male; D051379:Mice; D008863:Microspheres; D010012:Osteogenesis / Q000187:drug effects*; D016062:Porosity; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: C525718:BMP2 protein, human; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D018786:Bone Substitutes; D002130:Calcium Phosphates; D011994:Recombinant Proteins; D005780:Gelatin; C020243:calcium phosphate