title: Porous deproteinized bovine bone scaffold with three-dimensional localized drug delivery system using chitosan microspheres.
abstract: BACKGROUND
  Bone substation grafts, such as hydroxyapatite (HA) and tricalciumphosphate (TCP), have been extensively used in clinical applications, but evidence suggests that they offer poor osteoinductive properties compared to allografts and autografts. In order to increase bone growth with such grafts, Bone Morphogenetic Protein 2 (BMP-2) was incorporated into a three dimensional reservoir. The purpose of the present study was to develop a novel drug delivery system which is capable of controlled release of BMP-2.
  
  
  METHODS
  DBB were prepared from bovine cancellous bone harvested from fetal bovine femur or tibia and then sinting at 1000°C. BMP-2-loaded chitosan (CS) microspheres were fabricated by cross-linking. Then the treated DBB powders were blended with chitosan microspheres solution. Finally, the composites were lyophilized with a freeze dryer to obtain the DBB/CMs scaffolds. X-ray diffractor (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) were used to characterize the sample. The quantification of the delivery profile of BMP-2 was determined using an enzyme-linked immunosorbent assay (ELISA) kit. The in vitro assays were to characterize the biocompatibility of this composite.
  
  
  RESULTS
  In this study, BMP-2/Chitosan (CS) microspheres were successively loaded onto a deproteinized bovine bone (DBB) scaffold. The release profile of BMP-2 indicated an initial burst release followed by a more even sustained release. An in vitro bioactivity assay revealed that the encapsulated growth factor was biologically active.
  
  
  CONCLUSIONS
  The cell culture assay suggest that the excellent biocompatibility of the DBB- BMP-2/CS. Therefore, this novel microsphere scaffold system can be effectively used in current tissue engineering applications.
authors.affiliation: Center of Digital Dentistry, Peking University School and Hospital of Stomatology, 22 Zhongguancun Nandajie, Haidian District, Beijing, 100081, China. lq1996@163.com.|National Engineering Laboratory for Digital and Material Technology of Stomatology, 22 Zhongguancun Nandajie, Haidian District, Beijing, 100081, China. lq1996@163.com.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.affiliation: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, China. zhougang@buaa.edu.cn.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, China. xinyusmile_91@163.com.
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
authors.affiliation: National Engineering Laboratory for Digital and Material Technology of Stomatology, 22 Zhongguancun Nandajie, Haidian District, Beijing, 100081, China. shiipwangtong@163.com.
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
authors.affiliation: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, China. 1152363466@qq.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xi
authors.affiliation: National Engineering Laboratory for Digital and Material Technology of Stomatology, 22 Zhongguancun Nandajie, Haidian District, Beijing, 100081, China. tang_zhihui@live.cn.
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Tang
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage* / Q000494:pharmacology; D001842:Bone and Bones; D002417:Cattle; D002478:Cells, Cultured; D048271:Chitosan / Q000008:administration & dosage*; D020099:Coated Materials, Biocompatible; D016503:Drug Delivery Systems / Q000295:instrumentation*; D004343:Drug Implants; D005269:Femur / Q000196:embryology; D020869:Gene Expression Profiling; D008422:Materials Testing; D051379:Mice; D064347:Microscopy, Electrochemical, Scanning; D008863:Microspheres; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016062:Porosity; D012333:RNA, Messenger / Q000096:biosynthesis; D012886:Skull / Q000166:cytology; D017550:Spectroscopy, Fourier Transform Infrared; D013977:Tibia / Q000196:embryology; D054457:Tissue Scaffolds
chemical_list: D055396:Bone Morphogenetic Protein 2; D020099:Coated Materials, Biocompatible; D004343:Drug Implants; D012333:RNA, Messenger; D048271:Chitosan