title: Sequential delivery of BMP-2 and IGF-1 using a chitosan gel with gelatin microspheres enhances early osteoblastic differentiation.
abstract: The purpose of this study was to develop and characterize a chitosan gel/gelatin microsphere (MSs) dual delivery system for sequential release of bone morphogenetic protein-2 (BMP-2) and insulin-like growth factor-1 (IGF-1) to enhance osteoblast differentiation in vitro. We made and characterized the delivery system based on its degree of cross-linking, degradation, and release kinetics. We also evaluated the cytotoxicity of the delivery system and the effect of growth factors on cell response using pre-osteoblast W-20-17 mouse bone marrow stromal cells. IGF-1 was first loaded into MSs, and then the IGF-1-containing MSs were encapsulated into the chitosan gel which contained BMP-2. Cross-linking of gelatin with glyoxal via Schiff bases significantly increased thermal stability and decreased the solubility of the MSs, leading to a significant decrease in the initial release of IGF-1. Encapsulation of the MSs into the chitosan gel generated polyelectrolyte complexes by intermolecular interactions, which further affected the release kinetics of IGF-1. This combinational delivery system provided an initial release of BMP-2 followed by a slow and sustained release of IGF-1. Significantly greater alkaline phosphatase activity was found in W-20-17 cells treated with the sequential delivery system compared with other treatments (P<0.05) after a week of culture.
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA.
authors.forename: Sungwoo
authors.initials: S
authors.lastname: Kim
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Kang
authors.forename: Chad A
authors.initials: CA
authors.lastname: Krueger
authors.forename: Milan
authors.initials: M
authors.lastname: Sen
authors.forename: John B
authors.initials: JB
authors.lastname: Holcomb
authors.forename: Di
authors.initials: D
authors.lastname: Chen
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Wenke
authors.forename: Yunzhi
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage* / Q000737:chemistry; D002214:Capsules / Q000737:chemistry; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D048271:Chitosan / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000138:chemical synthesis / Q000494:pharmacology*; D005780:Gelatin / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage* / Q000737:chemistry; D008422:Materials Testing; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects; D023822:Tissue Engineering / Q000379:methods*
chemical_list: C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D002214:Capsules; D003692:Delayed-Action Preparations; D005782:Gels; C519530:insulin-like growth factor-1, mouse; D007334:Insulin-Like Growth Factor I; D005780:Gelatin; D048271:Chitosan