Solid Free-Form Fabrication of Tissue-Engineering Scaffolds with a Poly(lactic-co-glycolic acid) Grafted Hyaluronic Acid Conjugate Encapsulating an Intact Bone Morphogenetic Protein-2/Poly(ethylene glycol) Complex

Abstract

Despite wide applications of bone morphogenetic protein-2 (BMP-2), there are few methods to incorporate BPM-2 within polymeric scaffolds while maintaining biological activity. Solid free-form fabrication (SFF) of tissue-engineering scaffold is successfully carried out with poly(lactic-co-glycolic acid) grafted hyaluronic acid (HA-PLGA) encapsulating intact BMP-2/poly(ethylene glycol) (PEG) complex. HA-PLGA conjugate is synthesized in dimethyl sulfoxide (DMSO) by the conjugation reaction of adipic acid dihydrazide modified HA (HA-ADH) and PLGA activated with N,N'-dicyclohexylcarbodilmide (DCC) and N-hydroxysuccinimide (NHS). BMP-2 is complexed with PEG, which is encapsulated within the PLGA domain of the HA-PLGA conjugate by SFF to prepare tissue-engineering scaffolds. In vitro release tests confirm the sustained release of intact BMP-2 from the scaffolds for up to a month. After confirmation of the enhanced osteoblast cell growth, and high gene-expression levels of alkaline phosphatase (ALP), osteocalcin (OC), and osterix (OSX) in the cells, the HA-PLGA/PEG/BMP-2 scaffolds are implanted into calvarial bone defects of Sprague Dawley (SD) rats. Microcomputed tomography (mu CT) and histological analyses with Masson's trichrome, and hematoxylin and eosin (H&E) staining reveal effective bone regeneration on the scaffolds of HA-PLGA/PEG/BMP-2 blends.