title: Thermally cross-linked oligo(poly(ethylene glycol) fumarate) hydrogels support osteogenic differentiation of encapsulated marrow stromal cells in vitro.
abstract: A novel polymer, oligo(poly(ethylene glycol) fumarate) (OPF), cross-linked with a thermal radical initiation system has recently been developed in our laboratory as an injectable, biodegradable cell carrier for regeneration of orthopaedic tissues. The cross-linking, swelling, and degradative properties of hydrogels prepared from OPF with poly(ethylene glycol) of two different chain lengths were assessed. The two OPF types had similar gelation onset times ( approximately 3.6 min) but, when cross-linked for 8 min at 37 degrees C, exhibited significantly different swelling characteristics (fold swelling: 17.5 +/- 0.2 vs 13.4 +/- 0.4). Rat marrow stromal cells (MSCs) were then directly combined with the hydrogel precursors and encapsulated in a model OPF formulation at approximately 14 million cells/mL, cultured in vitro in the presence of osteogenic supplements (dexamethasone), and monitored over 28 days via histology. MSC differentiation in these samples (6 mm diameter x 0.5 mm thick before swelling), as determined by Von Kossa staining for calcified matrix, was apparent by day 21. At day 28, mineralized matrix could be seen throughout the samples, many microns away from the cells. These experiments strongly support the usefulness of thermally cross-linked OPF hydrogels as injectable cell carriers for bone regeneration.
authors.affiliation: Department of Bioengineering, Rice University, Houston, Texas 77251, USA.
authors.forename: Johnna S
authors.initials: JS
authors.lastname: Temenoff
authors.forename: Hansoo
authors.initials: H
authors.lastname: Park
authors.forename: Esmaiel
authors.initials: E
authors.lastname: Jabbari
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Conway
authors.forename: Tiffany L
authors.initials: TL
authors.lastname: Sheffield
authors.forename: Catherine G
authors.initials: CG
authors.lastname: Ambrose
authors.forename: Antonios G
authors.initials: AG
authors.lastname: Mikos
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D001854:Bone Marrow Cells / Q000166:cytology; D001861:Bone Regeneration; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D003432:Cross-Linking Reagents; D020100:Hydrogels / Q000138:chemical synthesis*; D008297:Male; D008422:Materials Testing; D010012:Osteogenesis; D011091:Polyesters / Q000138:chemical synthesis*; D011092:Polyethylene Glycols / Q000138:chemical synthesis*; D051381:Rats; D017208:Rats, Wistar; D017154:Stromal Cells / Q000166:cytology*; D013696:Temperature; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D003432:Cross-Linking Reagents; D020100:Hydrogels; D011091:Polyesters; C469550:oligo(poly(ethylene glycol)fumarate); D011092:Polyethylene Glycols