title: Vascularization and bone regeneration in a critical sized defect using 2-N,6-O-sulfated chitosan nanoparticles incorporating BMP-2.
abstract: An ideal bone tissue engineering graft should have both excellent pro-osteogenesis and pro-angiogenesis to rapidly realize the bone regeneration in vivo. To meet this goal, 2-N,6-O-sulfated chitosan (26SCS) based nanoparticle (S-NP) was successfully developed and showed a dose-dependent enhancement on angiogenesis in vitro. For the repair of a critical sized defect in rabbit radius, we developed BMP-2 loaded S-NP (BMP-2/S-NP) with protein loading efficiency of 1.4 ± 0.2% and fabricated a gelatin sponge (G) based implant loaded with BMP-2/S-NP (BMP-2/S-NP/G). This implant exerted a delivery of BMP-2 with an initial burst release of 15.3 ± 4.1% in first 24 h and a gradual release for 21 days to 77.8 ± 3.6%. The in vitro ALP assay revealed that the activity of released BMP-2 from BMP-2/S-NP/G was maintained after 3-d and 7-d delivery and further enhanced after 14-d delivery compared with the original BMP-2. Furthermore, the in vivo effects of BMP-2/S-NP/G on the bone regeneration and vessel formation in the critical sized defect (18 mm) of rabbit radius were investigated by synchrotron radiation-based micro-computed tomography (SRμCT) imaging, three dimensional micro-computed tomographic (μCT) imaging, histological analysis, immunohistochemistry and biomechanical measurement. Based on the results, both peripheral vessel and new vessel formation were significantly increased by the BMP-2/S-NP/G treatment, along with the bridged defects at as early as 2 weeks, the healed defects at 8 weeks and the reunion of bone marrow cavity at 12 weeks. The results indicated that both controlled release of active BMP-2 and favorable vascularization at the defect site contributed by BMP-2/S-NP/G played a crucial role in accelerating and promoting bone augmentation. This study suggests that BMP-2/S-NP/G demonstrates promise for vascularization and bone regeneration in clinical case of large defect.
authors.affiliation: The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China; Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, PR China; Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Cao
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Juan
authors.initials: J
authors.lastname: Hou
authors.forename: Wanli
authors.initials: W
authors.lastname: Xing
authors.forename: Changsheng
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D001861:Bone Regeneration / Q000502:physiology*; D002470:Cell Survival; D048271:Chitosan / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry*; D018919:Neovascularization, Physiologic; D011817:Rabbits; D023822:Tissue Engineering; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D055396:Bone Morphogenetic Protein 2; C480355:chitosan sulfate; D005780:Gelatin; D048271:Chitosan
keywords: Angiogenesis; BMP; Bone regeneration; Chitosan; Nanoparticle