title: Soft and hard tissue response to photocrosslinked poly(propylene fumarate) scaffolds in a rabbit model.
abstract: The treatment of large cranial defects may be greatly improved by the development of precisely formed bone tissue engineering scaffolds. Such scaffolds could be constructed by using UV laser stereolithography to photocrosslink a linear, biodegradable polymer into a three-dimensional implant. We have previously presented a method to photocrosslink the biodegradable polyester, poly(propylene fumarate) (PPF). To ensure the safety and effectiveness of this technique, the soft and hard tissue response to photocrosslinked PPF scaffolds of different pore morphologies was investigated. Four classes of photocrosslinked PPF scaffolds, constructed with differing porosities (57-75%) and pore sizes (300-500 or 600-800 microm), were implanted both subcutaneously and in 6.3-mm-diameter cranial defects in a rabbit model. The rabbits were sacrificed at 2 and 8 weeks, and the implants were analyzed by light microscopy, histological scoring analysis, and histomorphometric analysis. Results showed the PPF scaffolds elicit a mild tissue response in both soft and hard tissues. Inflammatory cells, vascularization, and connective tissue were observed at 2 weeks; a decrease in inflammatory cell density and a more organized connective tissue were observed at 8 weeks. Scaffold porosity and scaffold pore size were not found to significantly affect the observed tissue response. Evidence of scaffold surface degradation was noted both by histology and histomorphometric analysis. Bone ingrowth in PPF scaffolds implanted into cranial defects was <3% of the defect area. The results indicate that photocrosslinked PPF scaffolds are biocompatible in both soft and hard tissues and thus may be an attractive platform for bone tissue engineering.
authors.affiliation: Department of Bioengineering, Rice University, Houston, Texas, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Fisher
authors.forename: Johan W M
authors.initials: JW
authors.lastname: Vehof
authors.forename: David
authors.initials: D
authors.lastname: Dean
authors.forename: Jan Paul C M
authors.initials: JP
authors.lastname: van der Waerden
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Holland
authors.forename: Antonios G
authors.initials: AG
authors.lastname: Mikos
authors.forename: John A
authors.initials: JA
authors.lastname: Jansen
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000737:chemistry* / Q000494:pharmacology* / Q000627:therapeutic use; D003238:Connective Tissue / Q000187:drug effects; D003432:Cross-Linking Reagents; D005650:Fumarates / Q000494:pharmacology / Q000627:therapeutic use*; D007249:Inflammation; D023421:Models, Animal; D010777:Photochemistry; D011126:Polypropylenes / Q000494:pharmacology / Q000627:therapeutic use*; D011817:Rabbits; D012886:Skull / Q000166:cytology / Q000187:drug effects; D023822:Tissue Engineering / Q000009:adverse effects / Q000379:methods* / Q000592:standards
chemical_list: D018786:Bone Substitutes; D003432:Cross-Linking Reagents; D005650:Fumarates; D011126:Polypropylenes; C097850:poly(propylene fumarate)