title: Novel osteoinductive photo-cross-linkable chitosan-lactide-fibrinogen hydrogels enhance bone regeneration in critical size segmental bone defects.
abstract: The purpose of this study was to develop and characterize a novel photo-cross-linkable chitosan-lactide-fibrinogen (CLF) hydrogel and evaluate the efficacy of bone morphogenetic protein-2 (BMP-2) containing a CLF hydrogel for osteogenesis in vitro and in vivo. We synthesized the CLF hydrogels and characterized their chemical structure, degradation rate, compressive modulus and in vitro BMP-2 release kinetics. We evaluated bioactivities of the BMP-2 containing CLF hydrogels (0, 50, 100 and 500ngml(-1)) in vitro using W-20-17 preosteoblast mouse bone marrow stromal cells and C2C12 mouse myoblast cells. The effect of BMP-2 containing CLF gels (0, 0.5, 1, 2 and 5μg) on bone formation was evaluated using rat critical size segmental bone defects for 4weeks. Fourier transform infrared spectroscopy spectra and scanning electron microscopy images showed chemical and structural changes by the addition of fibrinogen into the chitosan-lactide copolymer. The incorporation of fibrinogen molecules significantly increased the compressive modulus of the hydrogels. The in vitro BMP-2 release study showed initial burst releases from the CLF hydrogels followed by sustained releases, regardless of the concentration of the BMP-2 over 4weeks. Cells in all groups were viable in the presence of the hydrogels regardless of BMP-2 doses, indicating non-cytotoxicity of hydrogels. Alkaline phosphate activity and mineralization of cells exhibited dose dependence on BMP-2 containing CLF hydrogels. Radiography, microcomputed tomography and histology confirmed that the BMP-2 containing CLF hydrogels prompted neo-osteogenesis and accelerated healing of the defects in a dose-dependent manner. Thus the CLF hydrogel is a promising delivery system of growth factors for bone regeneration.
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Sungwoo
authors.initials: S
authors.lastname: Kim
authors.affiliation: Extremity Trauma & Regenerative Medicine Task Area, US Army Institute of Surgical Research, San Antonio, TX, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Bedigrew
authors.affiliation: Department of Craniomaxillofacial Regenerative Medicine, Dental and Trauma Research Detachment, United States Army Institute of Surgical Research, Fort Sam Houston, TX, USA.
authors.forename: Teja
authors.initials: T
authors.lastname: Guda
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Maloney
authors.affiliation: Department of Prosthodontics, Dental Science Research Institute and BK21 Project, School of Dentistry, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Sangwon
authors.initials: S
authors.lastname: Park
authors.affiliation: Extremity Trauma & Regenerative Medicine Task Area, US Army Institute of Surgical Research, San Antonio, TX, USA.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Wenke
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA; Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA. Electronic address: ypyang@stanford.edu.
authors.forename: Yunzhi Peter
authors.initials: YP
authors.lastname: Yang
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage* / Q000737:chemistry; D001861:Bone Regeneration / Q000187:drug effects* / Q000502:physiology; D048271:Chitosan / Q000737:chemistry* / Q000528:radiation effects; D019245:Compressive Strength; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000528:radiation effects; D003692:Delayed-Action Preparations / Q000008:administration & dosage* / Q000138:chemical synthesis; D004058:Diffusion; D004146:Dioxanes / Q000737:chemistry / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004339:Drug Compounding / Q000379:methods; D055119:Elastic Modulus; D005264:Femoral Fractures / Q000188:drug therapy* / Q000473:pathology; D005340:Fibrinogen / Q000737:chemistry* / Q000528:radiation effects; D020100:Hydrogels / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008297:Male; D008422:Materials Testing; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D003432:Cross-Linking Reagents; D003692:Delayed-Action Preparations; D004146:Dioxanes; D020100:Hydrogels; D005340:Fibrinogen; D048271:Chitosan; C091880:dilactide
keywords: BMP-2; Chitosan; Fibrinogen; Lactide; Photo-cross-linkable hydrogel