title: Tissue response and orbital floor regeneration using cyclic acetal hydrogels.
abstract: Orbital floor injuries are a common form of traumatic craniofacial injury that may not heal properly through the body's endogenous response. Reconstruction is often necessary, and an optimal method does not exist. We propose a tissue engineering approach for orbital bone repair based upon a cyclic acetal biomaterial formed from 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD) and poly(ethylene glycol) diacrylate (PEGDA). The EHD monomer and PEGDA polymer may be fabricated into an EH-PEG hydrogel by radical polymerization. The objectives of this work were to study (1) the tissue response to EH-PEG hydrogels in an orbital bone defect and (2) the induction of bone formation by delivery of bone morphogenetic protein-2 (BMP-2) from EH-PEG hydrogels. EH-PEG hydrogels were fabricated and implanted into an 8-mm rabbit orbital floor defect. Experimental groups included unloaded EH-PEG hydrogels, and EH-PEG hydrogels containing 0.25 microg and 2.5 microg BMP-2/implant. Results demonstrated that the unloaded hydrogel was initially bordered by a fibrin clot and then by fibrous encapsulation. BMP-2 loaded EH-PEG hydrogels, independent of concentration, were surrounded by fibroblasts at both time points. Histological analysis also demonstrated that significant bone growth was present at the 2.5 microg BMP-2/implant group at 28 days. This work demonstrates that the EH-PEG construct is a viable option for use and delivery of BMP-2 in vivo.
authors.affiliation: Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Martha W
authors.initials: MW
authors.lastname: Betz
authors.forename: John F
authors.initials: JF
authors.lastname: Caccamese
authors.forename: Domenick P
authors.initials: DP
authors.lastname: Coletti
authors.forename: John J
authors.initials: JJ
authors.lastname: Sauk
authors.forename: John P
authors.initials: JP
authors.lastname: Fisher
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage; D001861:Bone Regeneration; D020100:Hydrogels / Q000737:chemistry*; D008446:Maxillofacial Injuries / Q000628:therapy; D009917:Orbital Fractures / Q000628:therapy*; D011817:Rabbits; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D055396:Bone Morphogenetic Protein 2; D020100:Hydrogels